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Sample records for light-cured dimethacrylate-based resins

  1. Effect of water storage on the translucency of silorane-based and dimethacrylate-based composite resins with fibres.

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    Ozakar Ilday, Nurcan; Celik, Neslihan; Bayindir, Yusuf Ziya; Seven, Nilgün

    2014-06-01

    The purposes of this study were (1) to determine the translucency of silorane and dimethacrylate-based composite resins and (2) to evaluate the effect of water storage and reinforcement with fibre on the translucency of composite resins. Two light-cured composite resins (A2 shade), Filtek Silorane (silorane-based composite) and Valux Plus (dimethacrylate-based composite), were used in this study. The first group was used as the control with no reinforcements, the second was reinforced with polyethylene (Ribbond THM) and the third was reinforced with a glass fibre (Everstick Net) for each composite resin. Colour measurements were measured against white and black backgrounds with a Shadepilot (Degu Dent Gmbh, Hanau, Germany) spectrophotometer and recorded under a D65 light source, which reflects daylight. CIELAB parameters of each specimen were recorded at baseline and at 24 h, 168 h and 504 h. Translucency of materials was calculated using the translucency parameter (TP) formula. Data were analyzed using repeated measures ANOVA and LSD post hoc tests (α=0.05). The highest baseline TP value was in the Valux Plus/non-fibre reinforced group (14.06±1) and the lowest in the Filtek Silorane/Ribond THM group (8.98±1.11). Repeated measures ANOVA revealed significant effects from the factors storage time, composite resin, composite resin×storage time and fibre×time (p=0.047; p=0.001; p=0.013; p=0.022, respectively). Within the limitations of the study, we concluded that inclusion of polyethylene and glass fibres did not alter the translucency of the different-based composite resins. The longest storage time resulted in the greatest change in translucency values of Filtek Silorane composite resins. Considering the translucencies of composites with different formulations in the selection of composite resins for aesthetic restorations is important in terms of obtaining optimal aesthetic outcomes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. CURING EFFICIENCY OF DUAL-CURE RESIN CEMENT UNDER ZIRCONIA WITH TWO DIFFERENT LIGHT CURING UNITS

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    Pınar GÜLTEKİN

    2015-04-01

    Full Text Available Purpose: Adequate polymerization is a crucial factor in obtaining optimal physical properties and a satisfying clinical performance from composite resin materials. The aim of this study was to evaluate the polymerization efficiency of dual-cure resin cement cured with two different light curing units under zirconia structures having differing thicknesses. Materials and Methods: 4 zirconia discs framework in 4 mm diameter and in 0.5 mm, 1 mm and 1.5 mm thickness were prepared using computer-aided design system. One of the 0.5 mm-thick substructures was left as mono-layered whereas others were layered with feldspathic porcelain of same thickness and ceramic samples with 4 different thicknesses (0.5, 1, 1.5 and 2.0 mm were prepared. For each group (n=12 resin cement was light cured in polytetrafluoroethylene molds using Light Emitting Diode (LED or Quartz-Tungsten Halogen (QHT light curing units under each of 4 zirconia based discs (n=96. The values of depth of cure (in mm and the Vickers Hardness Number values (VHN were evaluated for each specimen. Results: The use of LED curing unit produced a greater depth of cure compared to QTH under ceramic discs with 0.5 and 1 mm thickness (p<0.05.At 100μm and 300 μm depth, the LED unit produced significantly greater VHN values compared to the QTH unit (p<0.05. At 500 μm depth, the difference between the VHN values of LED and QTH groups were not statistically significant. Conclusion: Light curing may not result in adequate resin cement polymerization under thick zirconia structures. LED light sources should be preferred over QTH for curing dual-cure resin cements, especially for those under thicker zirconia restorations.

  3. Qualitative Beam Profiling of Light Curing Units for Resin Based Composites.

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    Haenel, Thomas; Hausnerová, Berenika; Steinhaus, Johannes; Moeginger, Ing Bernhard

    2016-12-01

    This study investigates two technically simple methods to determine the irradiance distribution of light curing units that governs the performance of a visible-light curing resin-based composites. Insufficient light irradiation leads to under-cured composites with poor mechanical properties and elution of residual monomers. The unknown irradiance distribution and its effect on the final restoration are the main critical issues requiring highly sophisticated experimental equipment. The study shows that irradiance distributions of LCUs can easily be determined qualitatively with generally available equipment. This significantly helps dentists in practices to be informed about the homogeneity of the curing lights. Copyright© 2016 Dennis Barber Ltd.

  4. Competitive light absorbers in photoactive dental resin-based materials.

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    Hadis, Mohammed A; Shortall, Adrian C; Palin, William M

    2012-08-01

    The absorbance profile of photoinitiators prior to, during and following polymerization of light curable resin-based materials will have a significant effect on the cure and color properties of the final material. So-called "colorless" photoinitiators are used in some light-activated resin-based composite restorative materials to lessen the yellowing effect of camphoroquinone (CQ) in order to improve the esthetic quality of dental restorations. This work characterizes absorption properties of commonly used photoinitiators, an acylphosphine oxide (TPO) and CQ, and assesses their influence on material discoloration. Dimethacrylate resin formulations contained low (0.0134 mol/dm(3)), intermediate (0.0405 mol/dm(3)) or high (0.0678 mol/dm(3)) concentrations of the photoinitiators and the inhibitor, butylated hydroxytoluene (BHT) at 0, 0.1 or 0.2% by mass. Disc shaped specimens (n = 3) of each resin were polymerized for 60s using a halogen light curing unit. Dynamic measurements of photoinitiator absorption, polymer conversion and reaction temperature were performed. A spectrophotometer was used to measure the color change before and after cure. GLM three-way analysis of variance revealed significant differences (pphotoinitiator type (df = 1; F = 176.12)>% BHT (df = 2, F = 13.17). BHT concentration affected the rate of polymerization and produced lower conversion in some of the CQ-based resins. Significant differences between photoinitiator type and concentrations were seen in color (where TPO resins became yellower and camphoroquinone resins became less yellow upon irradiation). Reaction temperature, kinetics and conversion also differed significantly for both initiators (presins producing a visually perceptible color change upon polymerization, the color change was significantly less than that produced with CQ-based resins. Although some photoinitiators such as TPO may be a more esthetic alternative to CQ, they may actually cause significant color contamination when

  5. Effect of High-Irradiance Light-Curing on Micromechanical Properties of Resin Cements

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    Anne Peutzfeldt

    2016-01-01

    Full Text Available This study investigated the influence of light-curing at high irradiances on micromechanical properties of resin cements. Three dual-curing resin cements and a light-curing flowable resin composite were light-cured with an LED curing unit in Standard mode (SM, High Power mode (HPM, or Xtra Power mode (XPM. Maximum irradiances were determined using a MARC PS radiometer, and exposure duration was varied to obtain two or three levels of radiant exposure (SM: 13.2 and 27.2 J/cm2; HPM: 15.0 and 30.4 J/cm2; XPM: 9.5, 19.3, and 29.7 J/cm2 (n=17. Vickers hardness (HV and indentation modulus (EIT were measured at 15 min and 1 week. Data were analyzed with nonparametric ANOVA, Wilcoxon-Mann-Whitney tests, and Spearman correlation analyses (α=0.05. Irradiation protocol, resin-based material, and storage time and all interactions influenced HV and EIT significantly (p≤0.0001. Statistically significant correlations between radiant exposure and HV or EIT were found, indicating that high-irradiance light-curing has no detrimental effect on the polymerization of resin-based materials (p≤0.0021. However, one resin cement was sensitive to the combination of irradiance and exposure duration, with high-irradiance light-curing resulting in a 20% drop in micromechanical properties. The results highlight the importance of manufacturers issuing specific recommendations for the light-curing procedure of each resin cement.

  6. Green LED as an Effective Light Source for Curing Acrylate-Based Dental Resins in Combination with Irgacure 784

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    Katalin Bukovinszky

    2018-01-01

    Full Text Available Low intensity green light emitting diodes (LED were shown to be an effective light source to induce the photopolymerization of an acrylate-based photocurable dental restorative resin mixture of bisphenol A glycerolate dimethacrylate (BisGMA, triethylene glycol dimethacrylate (TEGDMA, and diurethane dimethacrylate (UDMA, in combination with fluorinated diaryl titanocene (Irgacure 784. Dental matrices were prepared by the LED light source at different intensities. The mechanical properties, such as Vickers microhardness, compressive strength, diametric tensile strength, flexural strength, and E-modulus of the created samples, were investigated. The kinetics of the photopolymerization was followed by Raman spectroscopy and conversion values were determined. It was found that, despite its narrow-emission range centered at a wavelength of 531 nm, the green LED light source is suitable for the preparation of dental matrices with good mechanical properties and high conversion values.

  7. Light curing through glass ceramics: effect of curing mode on micromechanical properties of dual-curing resin cements.

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    Flury, Simon; Lussi, Adrian; Hickel, Reinhard; Ilie, Nicoleta

    2014-04-01

    The aim of this study was to investigate micromechanical properties of five dual-curing resin cements after different curing modes including light curing through glass ceramic materials. Vickers hardness (VH) and indentation modulus (Y HU) of Panavia F2.0, RelyX Unicem 2 Automix, SpeedCEM, BisCem, and BeautiCem SA were measured after 1 week of storage (37 °C, 100 % humidity). The resin cements were tested following self-curing or light curing with the second-generation light-emitting diode (LED) curing unit Elipar FreeLight 2 in Standard Mode (1,545 mW/cm(2)) or with the third-generation LED curing unit VALO in High Power Mode (1,869 mW/cm(2)) or in XtraPower Mode (3,505 mW/cm(2)). Light curing was performed directly or through glass ceramic discs of 1.5 or 3 mm thickness of IPS Empress CAD or IPS e.max CAD. VH and Y HU were analysed with Kruskal-Wallis tests followed by pairwise Wilcoxon rank sum tests (α = 0.05). RelyX Unicem 2 Automix resulted in the highest VH and Y HU followed by BeautiCem SA, BisCem, SpeedCEM, and finally Panavia F2.0. Self-curing of RelyX Unicem 2 Automix and SpeedCEM lowered VH and Y HU compared to light curing whereas self-curing of Panavia F2.0, BisCem, and BeautiCem SA led to similar or significantly higher VH and Y HU compared to light curing. Generally, direct light curing resulted in similar or lower VH and Y HU compared to light curing through 1.5-mm-thick ceramic discs. Light curing through 3-mm-thick discs of IPS e.max CAD generally reduced VH and Y HU for all resin cements except SpeedCEM, which was the least affected by light curing through ceramic discs. The resin cements responded heterogeneously to changes in curing mode. The applied irradiances and light curing times adequately cured the resin cements even through 1.5-mm-thick ceramic discs. When light curing resin cements through thick glass ceramic restorations, clinicians should consider to prolong the light curing times even with LED curing units providing high

  8. Effect of light dispersion of LED curing lights on resin composite polymerization.

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    Vandewalle, Kraig S; Roberts, Howard W; Andrus, Jeffrey L; Dunn, William J

    2005-01-01

    This study evaluated the effect of light dispersion of halogen and LED curing lights on resin composite polymerization. One halogen (Optilux 501, SDS/Kerr, Orange, CA, USA) and five light-emitting diode (LED) curing lights (SmartLite iQ, Dentsply Caulk, Milford, DE, USA; LEDemetron 1, SDS/Kerr; FLASHlite 1001, Discus Dental, Culver City, CA, USA; UltraLume LED 5, Ultradent Products, South Jordan, UT, USA; Allegro, Den-Mat, Santa Maria, CA, USA) were used in this study. Specimens (8 mm diameter by 2 mm thick) were made in polytetrafluoroethylene molds using hybrid (Z100, 3M ESPE, St. Paul, MN, USA) and microfill (A110, 3M ESPE) composite resins. The top surface was polymerized for 5 seconds with the curing light guide tip positioned at a distance of 1 and 5 mm. Degree of conversion (DC) of the composite specimens was analyzed on the bottom surface using micro-Fourier Transform Infrared (FTIR) spectroscopy (Perkin-Elmer FTIR Spectrometer, Wellesley, PA, USA) 10 minutes after light activation. DC at the bottom of the 2 mm specimen was expressed as a percentage of the mean maximum DC. Five specimens were created per curing light and composite type (n=5). Percent mean DC ratios and SDs were calculated for each light under each testing condition. Data were analyzed by analysis of variance (ANOVA)/Tukey's test (alpha = .05). A beam analyzer (LBA-700, Spiricon, Logan, UT, USA) was used to record the emitted light from the curing lights at 0 and 5 mm distances (n=5). A Top Hat factor was used to compare the quality of the emitted beam profile (LBA/PC, Spiricon). The divergence angle from vertical was also determined in the x- and y-axes (LBA/PC). Mean values and SDs were calculated for each light under each testing condition (0 and 5 mm, x- and y-axes) and analyzed by a two-way ANOVA/Tukey's test (alpha = .05). For DC ratios, significant differences were found based on curing light and curing distance (p < .05). At 1 mm, Optilux 501 and FLASHlite 1001 produced significantly

  9. Heat-cured acrylic resin versus light-activated resin: a patient, professional and technician-based evaluation of mandibular implant-supported overdentures.

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    Asal, S A; Al-AlShiekh, H M

    2017-12-01

    Although light-activated resins (Eclipse) have been reported to possess superior physical and mechanical properties compared with the heat-cured acrylic resins (Lucitone-199), a few studies have compared overdentures with a locator attachment constructed from heat-cured acrylic resins with those constructed from light-activated resins. This clinical study was designed to compare the performance of a mandibular implant-supported overdenture constructed from a heat-cured acrylic resin (Lucitone-199) with that of an overdenture constructed from a light-activated resin (Eclipse). Ten participants received two identical mandibular implant-retained overdentures (Lucitone-199 and Eclipse) opposing one maxillary denture in a random order. Each mandibular overdenture was delivered and worn for 6 months, and two weeks of rest was advised between wears to minimize any carryover effects. Three questionnaires were devised. The first questionnaire (patient evaluation) focused on evaluating different aspects of the denture and overall satisfaction. The second questionnaire (professional dentist evaluation) was based on a clinical evaluation of soft tissues, complications, and the applied technique. The third questionnaire (technician evaluation) involved ranking the different manufacturing steps of the denture and overall preferences. The obtained data was statistically analyzed using an independent sample t-test and the Wilcoxon rank-sum test. The clinician and technician preferred the Eclipse dentures because of their technical aspects, whereas the patients preferred the Lucitone-199 dentures for their aesthetic properties. Implant-supported overdentures constructed from a heat-cured acrylic resin showed superior aesthetics and had a better odor compared with those constructed from a light-cured resin.

  10. Does the light source affect the repairability of composite resins?

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    Karaman, Emel; Gönülol, Nihan

    2014-01-01

    The aim of this study was to examine the effect of the light source on the microshear bond strength of different composite resins repaired with the same substrate. Thirty cylindrical specimens of each composite resin--Filtek Silorane, Filtek Z550 (3M ESPE), Gradia Direct Anterior (GC), and Aelite Posterior (BISCO)--were prepared and light-cured with a QTH light curing unit (LCU). The specimens were aged by thermal cycling and divided into three subgroups according to the light source used--QTH, LED, or PAC (n = 10). They were repaired with the same substrate and a Clearfil Repair Kit (Kuraray). The specimens were light-cured and aged for 1 week in distilled water at 37 °C. The microshear bond strength and failure modes were assessed. There was no significant difference in the microshear bond strength values among the composite resins, except for the Filtek Silorane group that showed significantly lower bond strength values when polymerized with the PAC unit compared to the QTH or LED unit. In conclusion, previously placed dimethacrylate-based composites can be repaired with different light sources; however, if the composite to be repaired is silorane-based, then using a QTH or LED device may be the best option.

  11. Microhardness of resin composite materials light-cured through fiber reinforced composite.

    NARCIS (Netherlands)

    Fennis, W.M.M.; Ray, N.J.; Creugers, N.H.J.; Kreulen, C.M.

    2009-01-01

    OBJECTIVES: To compare polymerization efficiency of resin composite basing materials when light-cured through resin composite and fiber reinforced composite (FRC) by testing microhardness. METHODS: Simulated indirect restorations were prepared by application of resin composite (Clearfil AP-X) or FRC

  12. Effect of light-curing units on the thermal expansion of resin nanocomposites.

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    Park, Jeong-Kil; Hur, Bock; Ko, Ching-Chang; García-Godoy, Franklin; Kim, Hyung-Il; Kwon, Yong Hoon

    2010-12-01

    To examine the thermal expansion of resin nanocomposites after light-curing using different light-curing units. Four different resin nanocomposites and four different light-curing units [quartz-tungsten-halogen (QTH), light emitting diode (LED), laser, and plasma arc] were chosen. Metal dies were filled with resin to make specimens and light-cured. The light intensity and light-curing time of the QTH and LED light-curing units were 1000 mW/cm2 and 40 seconds, 700 mW/cm2 and 40 seconds for the laser, and 1600 mW/cm2 and 3 seconds for the plasma arc. The coefficient of thermal expansion (CTE) was evaluated using a thermomechanical analyzer (TMA) at temperatures ranging from 30-80 degrees C. The CTE of the resin nanocomposites tested ranged from 28.5 to 65.8 (x 10(-6)/ degrees C), depending on the product and type of light-curing unit used. Among the specimens, Grandio showed the lowest CTE. The specimens cured using the plasma arc unit (Apollo 95E) showed the highest CTE. There was a linear correlation between the CTE and filler content (vol%) (R: -0.94-0.99 depending on the light-curing unit). The results may suggest a careful selection of the light-curing unit because there was more expansion in the specimens cured using the plasma arc unit than those cured by the other units.

  13. A comparative evaluation of effect of modern-curing lights and curing modes on conventional and novel-resin monomers

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    Roy, Konda Karthik; Kumar, Kanumuru Pavan; John, Gijo; Sooraparaju, Sujatha Gopal; Nujella, Surya Kumari; Sowmya, Kyatham

    2018-01-01

    Aim: The aim of this study is to compare and to evaluate effect of curing light and curing modes on the nanohybrid composite resins with conventional Bis-GMA and novel tricyclodecane (TCD) monomers. Methodology: Two nanohybrid composites, IPS empress direct and charisma diamond were used in this study. Light-emitting diode (LED)-curing unit and quartz-tungsten-halogen (QTH)-curing unit which were operated into two different modes: continuous and soft start. Based on the composite resin, curing lights, and mode of curing used, the samples were divided into 8 groups. After polymerization, the samples were stored for 48 h in complete darkness at 37°C and 100% humidity. The Vickers hardness (VK) of the surface was determined with Vickers indenter by the application of 200 g for 15 s. Three VK readings were recorded for each sample surface both on top and bottom surfaces. For all the specimens, the three hardness values for each surface were averaged and reported as a single value. The mean VK and hardness ratio were calculated. The depth of cure was assessed based on the hardness ratio. Results: Comparison of mean hardness values and hardness ratios was done using ANOVA with post hoc Tukey's test. Conclusion: Both QTH- and LED-curing units had shown the adequate depth of cure. Soft-start-curing mode in both QTH- and LED-curing lights had effectively increased microhardness than the continuous mode of curing. TCD monomer had shown higher hardness values compared with conventional Bis-GMA-containing resin. PMID:29628651

  14. Effect of various infection-control methods for light-cure units on the cure of composite resins.

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    Chong, S L; Lam, Y K; Lee, F K; Ramalingam, L; Yeo, A C; Lim, C C

    1998-01-01

    This study (1) compared the curing-light intensity with various barrier infection-control methods used to prevent cross contamination, (2) compared the Knoop hardness value of cured composite resin when various barrier control methods were used, and (3) correlated the hardness of the composite resin with the light-intensity output when different infection-control methods were used. The light-cure unit tips were covered with barriers, such as cellophane wrap, plastic gloves, Steri-shields, and finger cots. The control group had no barrier. Composite resins were then cured for each of the five groups, and their Knoop hardness values recorded. The results showed that there was significant statistical difference in the light-intensity output among the five groups. However, there was no significant statistical difference in the Knoop hardness values among any of the groups. There was also no correlation between the Knoop hardness value of the composite resin with the light-intensity output and the different infection-control methods. Therefore, any of the five infection-control methods could be used as barriers for preventing cross-contamination of the light-cure unit tip, for the light-intensity output for all five groups exceeded the recommended value of 300 W/m2. However, to allow a greater margin of error in clinical situations, the authors recommend that the plastic glove or the cellophane wrap be used to wrap the light-cure tip, since these barriers allowed the highest light-intensity output.

  15. Bond strength of orthodontic light-cured resin-modified glass ionomer cement.

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    Cheng, Hsiang Yu; Chen, Chien Hsiu; Li, Chuan Li; Tsai, Hung Huey; Chou, Ta Hsiung; Wang, Wei Nan

    2011-04-01

    The purpose of this study was to compare the bond strengths and debonded interfaces achieved with light-cured resin-modified glass ionomer cement (RMGIC) and conventional light-cured composite resin. In addition, the effects of acid etching and water contamination were examined. One hundred human premolars were randomly divided into five equal groups. The mini Dyna-lock upper premolar bracket was selected for testing. The first four groups were treated with light-cured RMGIC with or without 15 per cent phosphoric acid-etching treatment and with or without water contamination preceding bracket bonding. The control samples were treated with the conventional light-cured Transbond composite resin under acid etching and without water contamination. Subsequently, the brackets were debonded by tensile force using an Instron machine. The modified adhesive remnant index (ARI) scores were assigned to the bracket base of the debonded interfaces using a scanning electron microscope. The bond strength and modified ARI scores were determined and analysed statistically by one-way analysis of variance and chi-square test. Under all four conditions, the bond strength of the light-cure RMGIC was equal to or higher than that of the conventional composite resin. The highest bond strength was achieved when using RMGIC with acid etching but without water contamination. The modified ARI scores were 2 for Fuji Ortho LC and 3 for Transbond. No enamel detachment was found in any group. Fifteen per cent phosphoric acid etching without moistening the enamel of Fuji Ortho LC provided the more favourable bond strength. Enamel surfaces, with or without water contamination and with or without acid etching, had the same or a greater bond strength than Transbond.

  16. Effect of light-curing units, post-cured time and shade of resin cement on knoop hardness.

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    Reges, Rogério Vieira; Costa, Ana Rosa; Correr, Américo Bortolazzo; Piva, Evandro; Puppin-Rontani, Regina Maria; Sinhoreti, Mário Alexandre Coelho; Correr-Sobrinho, Lourenço

    2009-01-01

    The aim of this study was to evaluate the Knoop hardness after 15 min and 24 h of different shades of a dual-cured resin-based cement after indirect photoactivation (ceramic restoration) with 2 light-curing units (LCUs). The resin cement Variolink II (Ivoclar Vivadent) shade XL, A2, A3 and opaque were mixed with the catalyst paste and inserted into a black Teflon mold (5 mm diameter x 1 mm high). A transparent strip was placed over the mold and a ceramic disc (Duceram Plus, shade A3) was positioned over the resin cement. Light-activation was performed through the ceramic for 40 s using quartz-tungsten-halogen (QTH) (XL 2500; 3M ESPE) or light-emitting diode (LED) (Ultrablue Is, DMC) LCUs with power density of 615 and 610 mW/cm(2), respectively. The Koop hardness was measured using a microhardness tester HMV 2 (Shimadzu) after 15 min or 24 h. Four indentations were made in each specimen. Data were subjected to ANOVA and Tukey's test (alpha=0.05). The QTH LCU provided significantly higher (pcement showed lower Knoop hardness than the other shades for both LCUs and post-cure times.

  17. Pulp chamber temperature rise during curing of resin-based composites with different light-curing units.

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    Durey, Kathryn; Santini, Ario; Miletic, Vesna

    2008-01-01

    The purpose of the present study was to measure the intrapulpal temperature rise occurring during polymerisation of different shades of resin-based composites (RBCs), and two light-emitting diode (LED) units. Seventy non-carious permanent molars, that had been extracted for orthodontic purposes and stored in 2% thymol for not more than four months, were selected. Patient age range was 11-18 years. Standard cavity preparation with standardised remaining dentine thickness and placement of thermocouples (TCs) was prepared using a novel split-tooth technique. Cavities were filled with one of two shades of RBC (A2 and C4, Filtek Z250, 3M ESPE, Seefeld, Germany), and cured with two LED high-intensity units (Elipar Freelight2, 3M ESPE, Seefeld, Germany; Bluephase, Ivoclar Vivadent, Schaan, Liechtenstein) and a conventional halogen light-curing unit (LCU) (Prismetics Lite 2, Dentsply, Weybridge, Surrey, UK) as a control. Pulp temperature rises during bonding [A2 results: H;2.67/0.48:E;5.24/1.32;B;5.99/1.61] were always greater than during RBC curing [A2 results: 2.44/0.63;E3.34/0.70;B3.38/0.60], and these were significant for both LED lights but not for the halogen control, irrespective of shade (Mann-Whitney test: 95% confidence limits). Temperature rises were at times in excess of the values normally quoted as causing irreversible pulp damage. Pulp temperature rises during bonding were higher with the LED lights than with the halogen control. There was no significant difference in temperature rise between the two LED lights when bonding but there was a significant difference between the two LED lights and the halogen control LCUs (Kruskal-Wallis Test: 95% confidence limits). The results support the view that there is a potential risk for heat-induced pulpal injury when light-curing RBCs. The risk is greater during bonding and with high energy, as compared to low-energy output systems. As the extent of tolerable thermal trauma by the pulp tissues is unknown, care and

  18. Preparation of a Bis-GMA-Free Dental Resin System with Synthesized Fluorinated Dimethacrylate Monomers

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    Shuzhen Luo

    2016-12-01

    Full Text Available With the aim of reducing human exposure to Bisphenol A (BPA derivatives in dentistry, a fluorinated dimethacrylate monomer was synthesized to replace 2,2-bis[4-(2-hydroxy-3-methacryloy-loxypropyl-phenyl]propane (Bis-GMA as the base monomer of dental resin. After mixing with reactive diluent triethyleneglycol dimethacrylate (TEGDMA, fluorinated dimethacrylate (FDMA/TEGDMA was prepared and compared with Bis-GMA/TEGDMA in physicochemical properties, such as double bond conversion (DC, volumetric shrinkage (VS, water sorption (WS and solubility (WSL, flexural strength (FS and modulus (FM. The results showed that, when compared with Bis-GMA based resin, FDMA-based resin had several advantages, such as higher DC, lower VS, lower WS, and higher FS after water immersion. All of these revealed that FDMA had potential to be used as a substitute for Bis-GMA. Of course, many more studies, such as biocompatibility testing, should be undertaken to prove whether FDMA could be applied in clinic.

  19. Shrinkage Characteristics of Experimental Polymer Containing Composites under Controlled Light Curing Modes

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    Alain Pefferkorn

    2012-01-01

    Full Text Available The adsorption of polymethylmethacrylate polymer of different molecular weight at the aerosil/ethyleneglycol- or 1,3 butanediol-dimethacrylate interfaces was determined to provide microstructured networks. Their structural characteristics were determined to be controlled by the amount of polymer initially supplied to the system. The sediment (the settled phase characteristics, determined as a function of the polymer concentration and the rate of the polymerization shrinkage determined for composite resins, obtained by extrusion of the sediment after centrifugation, were found to be correlated. The specific role of the adsorbed polymer was found to be differently perturbed with the supplementary supply of dimethacrylate based monomer additives. Particularly, the bisphenol A dimethacrylate that generated crystals within the sediment was found to impede the shrinkage along the crystal lateral faces and strongly limit the shrinkage along its basal faces. Addition of ethyleneglycol- or polyethylene-glycoldimethacrylate monomers was determined to modify the sedimentation characteristics of the aerosil suspension and the shrinkage properties of the composites. Finally, the effects of stepwise light curing methods with prolonged lighting-off periods were investigated and found to modify the development and the final values of the composite shrinkage.

  20. Applications of Blue Light-curing Acrylic Resin to Forensic Sample Preparation and Microtomy.

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    Groves, Ethan; Palenik, Christopher S

    2016-03-01

    This study discusses the results of an evaluation of a one-part blue light-curing acrylic resin for embedding trace evidence prior to the preparation of thin sections with a microtome. Through a comparison to several epoxy resins, the physical properties relevant to both trace evidence examination and analytical microscopy in general, including as viscosity, clarity, color, hardness, and cure speed, were explored. Finally, thin sections from paint samples embedded in this acrylic resin were evaluated to determine if, through smearing or impregnation, the resin contributed to the infrared spectra. The results of this study show that blue light-curing acrylic resins provide the desired properties of an embedding medium, generate high-quality thin sections, and can significantly simplify the preparation of paint chips, fibers and a multitude of other types of microscopic samples in the forensic trace evidence laboratory. © 2015 American Academy of Forensic Sciences.

  1. [Application of individual light-curing resin tray as edge plastic material in complete denture modulo].

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    Chai, Mei; Tang, Xuyan; Liang, Guangku

    2015-12-01

    To investigate clinical effect of individual light-curing resin tray as edge plastic material in complete denture modulo.
 A total of 30 patients with poor condition for alveolar ridge of mandible were chosen individual tray with individual light-curing resin tray for material edge shaping or traditional individual impression tray for edge shaping cream to produce complete denture. The operability, questionnaire about denture retention, comfort, mucosal cases and chewing function in the process of shaping the edge were investigated three months later after wearing dentures.
 There was no significant difference in retention, comfort, mucosa and the chewing function between the two mandibular denture impression methods. However, the patients with individual light-curing resin tray as edge shaping material felt better in the process than that in the patients with die-cream as the edge shaping material (P<0.05). Furthermore, the manipulation with individual light-curing resin tray as edge shaping material is easy for doctor.
 Although the clinical effect of Individual light-curing resin tray material as the edge shaping material is equal to that of impression cream, it saves time and human resource. Moreover, it is more acceptable for the patients and thus it can be spread in clinics.

  2. Effect of different light curing units on Knoop hardness and temperature of resin composite.

    Science.gov (United States)

    Guiraldo, Ricardo Danil; Consani, Simonides; Xediek Consani, Rafael Leonardo; Mendes, Wilson Batista; Lympius, Thais; Coelho Sinhoreti, Mario Alexandre

    2009-01-01

    To evaluate the influence of quartz tungsten halogen and plasma arc curing (PAC) lights on Knoop hardness and change in polymerization temperature of resin composite. Filtek Z250 and Esthet X composites were used in the shade A3. The temperature increase was registered with Type-k thermocouple connected to a digital thermometer (Iopetherm 46). A self-cured polymerized acrylic resin base was built in order to guide the thermocouple and to support the dentin disk of 1.0 mm thickness obtained from bovine tooth. On the acrylic resin base, elastomer mold of 2.0 mm was adapted. The temperature increase was measured after composite light curing. After 24 h, the specimens were submitted to Knoop hardness test (HMV-2000, Shimadzu, Tokyo, Japan). Data were submitted to ANOVA and Tukey's test (alpha = 0.05). For both composites, there were no significant differences (P > 0.05) in the top surface hardness; however, PAC promoted statistically lower (P 0.05). The standardized radiant exposure showed no influence on the temperature increase of the composite, however, showed significant effect on hardness values.

  3. Curing reaction of bisphenol-A based benzoxazine with cyanate ester resin and the properties of the cured thermosetting resin

    Directory of Open Access Journals (Sweden)

    H. Kimura

    2011-12-01

    Full Text Available Curing reaction of bisphenol-A based benzoxazine with cyanate ester resin and the properties of the cured thermosetting resin were investigated. The cure behavior of benzoxazine with cyanate ester resin was monitored by model reaction using nuclear magnetic resonance (NMR. As a result of the model reaction, the ring opening reaction of benzoxazine ring and thermal self-cyclotrimerization of cyanate ester group occurred, and then the phenolic hydoroxyl group generated by the ring opening reaction of benzoxazine ring co-reacted with cyanate ester group. The properties of the cured thermosetting resin were estimated by mechanical properties, electrical resistivity, water resistance and heat resistance. The cured thermosetting resin from benzoxazine and cyanate ester resin showed good heat resistance, high electrical resistivity and high water resistance, compared with the cured thermosetting resin from benzoxazine and epoxy resin.

  4. Effect of different light curing units on Knoop hardness and temperature of resin composite

    OpenAIRE

    Guiraldo Ricardo; Consani Simonides; Xediek Consani Rafael; Mendes Wilson; Lympius Thais; Coelho Sinhoreti Mario

    2009-01-01

    Aim: To evaluate the influence of quartz tungsten halogen and plasma arc curing (PAC) lights on Knoop hardness and change in polymerization temperature of resin composite. Materials and Methods: Filtek Z250 and Esthet X composites were used in the shade A3. The temperature increase was registered with Type-k thermocouple connected to a digital thermometer (Iopetherm 46). A self-cured polymerized acrylic resin base was built in order to guide the thermocouple and to support the dentin disk ...

  5. Curing potential of experimental resin composites with systematically varying amount of bioactive glass: Degree of conversion, light transmittance and depth of cure.

    Science.gov (United States)

    Par, Matej; Spanovic, Nika; Bjelovucic, Ruza; Skenderovic, Hrvoje; Gamulin, Ozren; Tarle, Zrinka

    2018-06-17

    The aim of this work was to investigate the curing potential of an experimental resin composite series with the systematically varying amount of bioactive glass 45S5 by evaluating the degree of conversion, light transmittance and depth of cure. Resin composites based on a Bis-GMA/TEGDMA resin with a total filler load of 70 wt% and a variable amount of bioactive glass (0-40 wt%) were prepared. The photoinitiator system was camphorquinone and ethyl-4-(dimethylamino) benzoate. The degree of conversion and light transmittance were measured by Raman spectroscopy and UV-vis spectroscopy, respectively. The depth of cure was evaluated according to the classical ISO 4049 test. The initial introduction of bioactive glass into the experimental series diminished the light transmittance while the further increase in the bioactive glass amount up to 40 wt% caused minor variations with no clear trend. The curing potential of the experimental composites was similar to or better than that of commercial resin composites. However, unsilanized bioactive glass fillers demonstrated the tendency to diminish both the maximum attainable conversion and the curing efficiency at depth. Experimental composite materials containing bioactive glass showed a clinically acceptable degree of conversion and depth of cure. The degree of conversion and depth of cure were diminished by bioactive glass fillers in a dose-dependent manner, although light transmittance was similar among all of the experimental composites containing 5-40 wt% of bioactive glass. Reduced curing potential caused by the bioactive glass has possible consequences on mechanical properties and biocompatibility. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. The effect of repeated preheating of dimethacrylate and silorane-based composite resins on marginal gap of class V restorations.

    Science.gov (United States)

    Alizadeh Oskoee, Parnian; Pournaghi Azar, Fatemeh; Jafari Navimipour, Elmira; Ebrahimi Chaharom, Mohammad Esmaeel; Naser Alavi, Fereshteh; Salari, Ashkan

    2017-01-01

    Background. One of the problems with composite resin restorations is gap formation at resin‒tooth interface. The present study evaluated the effect of preheating cycles of silorane- and dimethacrylate-based composite resins on gap formation at the gingival margins of Class V restorations. Methods. In this in vitro study, standard Class V cavities were prepared on the buccal surfaces of 48 bovine incisors. For restorative procedure, the samples were randomly divided into 2 groups based on the type of composite resin (group 1: di-methacrylate composite [Filtek Z250]; group 2: silorane composite [Filtek P90]) and each group was randomly divided into 2 subgroups based on the composite temperature (A: room temperature; B: after 40 preheating cycles up to 55°C). Marginal gaps were measured using a stereomicroscope at ×40 and analyzed with two-way ANOVA. Inter- and intra-group comparisons were analyzed with post-hoc Tukey tests. Significance level was defined at P composite resin type, preheating and interactive effect of these variables on gap formation were significant (Pcomposite resins (Pcomposite resins at room temperature compared to composite resins after 40 preheating cycles (Pcomposite re-sins. Preheating of silorane-based composites can result in the best marginal adaptation.

  7. Effect of zirconium nanoparticles on the mechanical properties of light-cured resin based dental composites

    International Nuclear Information System (INIS)

    Afza, N.; Anis, I.; Aslam, M.; Shah, M.R.; Hussain, M.T.; Bokhari, T.H.; Hussain, A.; Safdar, M.

    2012-01-01

    The aim of this study was to evaluate the mechanical properties of conventional composite resins (Solare-P) and the modified composite resin having mixed with zirconium nanoparticles. The composite resins are used to replace the missing tooth structure and improve esthetics. In this study, the composite was filled with increments in a mould which was 4 mm in depth and 3 mm in diameter. After filling, it was polymerized with halogen light curing unit for 20 seconds for each increment. In other experiments, the composite was mixed with zirconium nanoparticles and filled in the moulds with increments and polymerized for 20 seconds with halogen light curing unit for each increment. After keeping the moulds at 37 deg. C for 24 hours their mechanical properties including compressive force, %age elongation, compressive strength and hardness were evaluated. It was seen that by adding zirconium nanoparticles, compressive force, %age elongation, compressive strength and hardness increased significantly. Thus it was concluded that the new materials are better than the conventional compomers. (author)

  8. Correlating cytotoxicity to elution behaviors of composite resins in term of curing kinetic.

    Science.gov (United States)

    Meng, Junquan; Yang, Huichuan; Cao, Man; Li, Lei; Cai, Qing

    2017-09-01

    Cytotoxicity of photocurable composite resins is a key issue for their safe use in dental restoration. Curing kinetic and elution behaviors of the composite resin would have decisive effects on its cytotoxicity. In this study, composite resins composed of bisphenol-glycidyl dimethacrylate (Bis-GMA), triethyleneglycol dimethacrylate (TEGDMA), camphorquinone (CQ), N,N-dimethylaminoethyl methacrylate (DMAEMA) and barium glass powders were prepared by setting the photoinitiators CQ/DMAEMA at 0.5wt%, 1wt% or 3wt% of the total weight of Bis-GMA/TEGDMA. The ratio of Bis-GMA/TEGDMA was 6:4, the ratio of CQ/DMAEMA was 1:1, and the incorporated inorganic powder was 75wt%. Then, curing kinetics were studied by using real-time Fourier transform infrared spectroscopy (FTIR) and photo-DSC (differential scanning calorimeter). Elution behaviors in both ethanol solution and deionized water were monitored by using liquid chromatogram/mass spectrometry (LC/MS). Cytotoxicity was evaluated by in vitro culture of L929 fibroblasts. Finally, they were all analyzed and correlated in terms of initiator contents. It was found that the commonly used 0.5wt% of photoinitiators was somewhat insufficient in obtaining composite resin with low cytotoxicity. Copyright © 2017. Published by Elsevier B.V.

  9. Visible light cure characteristics of a cycloaliphatic polyester dimethacrylate alternative oligomer to bisGMA.

    Science.gov (United States)

    Vaidyanathan, Tritala K; Vaidyanathan, Jayalakshmi

    2015-12-01

    Objective : The goal of this study was to characterize the light curing characteristics of a new oligomer PEM-665 designed to be used as an alternative monomer to BisGMA. Materials and methods : PEM-665 (P) and BisGMA (B) solutions were prepared with triethylene glycol dimethacrylate (T) diluent in different weight proportions (70/30 and 50/50). Solutions containing 70% P and 30% T were designated as 70PT, 70%B and 30%T as 70BT, 50%P and 50%T as 50PT and 50%B and 50%T as 50BT. The initiators were CQ (EDMAB was used as amine accelerator for CQ) and DPO in 1% concentration. Eight solutions were prepared in a factorial design: 70PT/DPO; 70PT/CQ; 50PT/DPO; 50PT/CQ; 70BT/DPO; 70BT/CQ; 50BT/DPO; 50BT/CQ. BISCO VIP visible light was used to cure the monomer solutions using 30 s exposure time and 400 W power setting. TA Instruments Differential Scanning Calorimeter (DSC 2910) was used to determine the heat of cure (J/g) during polymerization at 37 °C, from which molar heat of cure (kJ/mole) and %Conversion values were estimated. Results : Range of mean values as a function monomer selections were: heat of cure (J/g): 161.7 for 70PT/DPO system to 198.6 for 50BT/CQ system; molar heat of cure (kJ/mole): 67.3 for 70BT/DPO to 78.86 for 50PT/CQ; % conversion: 59.9 for 70BT/DPO to 70.3 for 50PT/CQ. Analysis of variance and Tukey HSD pairwise contrast showed statistically significant differences between % conversion means of PEM and BisGMA mixtures, with PEM mixtures showing significantly higher mean values. Conclusions : The results suggest that PEM-665 is a promising candidate material for dental polymer applications.

  10. Effect of light-curing units on microleakage under dental composite resins

    Science.gov (United States)

    Queiroz, R. S.; Bandéca, M. C.; Calixto, L. R.; Saade, E. G.; Nadalin, M. R.; Andrade, M. F.; Porto-Neto, S. T.

    2009-09-01

    The aim of this study was to determine the effect of two light-curing units (QTH and LED) on microleakage of Class II composite resin restorations with dentin cavosurface margins. Twenty extracted mandibular first premolars, free of caries and fractures were prepared two vertical “slot” cavities in the occluso-mesial and -destal surfaces (2 mm buccal-lingually, 2 mm proximal-axially and cervical limit in enamel) and divided into 4 equal groups ( n = 8): GI and GII: packable posterior composite light-activated with LED and QTH, respectively; GIII and GIV: micro-hybrid composite resin light-activated with LED and QTH, respectively. The composite resins were applied following the manufacturer’s instructions. After 24 h of water storage specimens were subjected to thermocycling for a total of 500 cycles at 5 and 55°C and the teeth were then sealed with impermeable material. Teeth were immersed in 0.5% Basic fuchsin during 24 h at room temperature, and zero to three levels of penetration score were attributed. The Mann-Whitney and Kruskal-Wallis tests showed significant statistically similar ( P > 0.05) from GI to GII and GIII to GIV, which the GII (2.750) had the highest mean scores and the GIII and GIV (0.875) had lowest mean scores. The use of different light-curing units has no influence on marginal integrity of Class II composite resin restorations and the proprieties of composite resins are important to reduce the microleakage.

  11. Mechanical properties and polymerization shrinkage of composite resins light-cured using two different lasers.

    Science.gov (United States)

    Kim, Tae-Wan; Lee, Jang-Hoon; Jeong, Seung-Hwa; Ko, Ching-Chang; Kim, Hyung-Il; Kwon, Yong Hoon

    2015-04-01

    The purpose of the present study was to investigate the usefulness of 457 and 473 nm lasers for the curing of composite resins during the restoration of damaged tooth cavity. Monochromaticity and coherence are attractive features of laser compared with most other light sources. Better polymerization of composite resins can be expected. Eight composite resins were light cured using these two lasers and a light-emitting diode (LED) light-curing unit (LCU). To evaluate the degrees of polymerization achieved, polymerization shrinkage and flexural and compressive properties were measured and compared. Polymerization shrinkage values by 457 and 473 nm laser, and LED ranged from 10.9 to 26.8, from 13.2 to 26.1, and from 11.5 to 26.3 μm, respectively. The values by 457 nm laser was significantly different from those by 473 and LED LCU (p0.05). For the tested LCUs, no specific LCU could consistently achieve highest strength and modulus from the specimens tested. Two lasers (457 and 473 nm) can polymerize composite resins to the level that LED LCU can achieve despite inconsistent trends of polymerization shrinkage and flexural and compressive properties of the tested specimens.

  12. Effect of different light curing units on Knoop hardness and temperature of resin composite

    Directory of Open Access Journals (Sweden)

    Guiraldo Ricardo

    2009-01-01

    Full Text Available Aim: To evaluate the influence of quartz tungsten halogen and plasma arc curing (PAC lights on Knoop hardness and change in polymerization temperature of resin composite. Materials and Methods: Filtek Z250 and Esthet X composites were used in the shade A3. The temperature increase was registered with Type-k thermocouple connected to a digital thermometer (Iopetherm 46. A self-cured polymerized acrylic resin base was built in order to guide the thermocouple and to support the dentin disk of 1.0 mm thickness obtained from bovine tooth. On the acrylic resin base, elastomer mold of 2.0 mm was adapted. The temperature increase was measured after composite light curing. After 24 h, the specimens were submitted to Knoop hardness test (HMV-2000, Shimadzu, Tokyo, Japan. Data were submitted to ANOVA and Tukey′s test (a = 0.05. Results: For both composites, there were no significant differences (P > 0.05 in the top surface hardness; however, PAC promoted statistically lower (P < 0.05 Knoop hardness number values in the bottom. The mean temperature increase showed no significant statistical differences (P > 0.05. Conclusion: The standardized radiant exposure showed no influence on the temperature increase of the composite, however, showed significant effect on hardness values.

  13. Thermal analysis of bulk filled composite resin polymerization using various light curing modes according to the curing depth and approximation to the cavity wall

    Directory of Open Access Journals (Sweden)

    Hoon-Sang Chang

    2013-07-01

    Full Text Available OBJECTIVE: The purpose of this study was to investigate the polymerization temperature of a bulk filled composite resin light-activated with various light curing modes using infrared thermography according to the curing depth and approximation to the cavity wall. MATERIAL AND METHODS: Composite resin (AeliteFlo, Bisco, Schaumburg, IL, USA was inserted into a Class II cavity prepared in the Teflon blocks and was cured with a LED light curing unit (Dr's Light, GoodDoctors Co., Seoul, Korea using various light curing modes for 20 s. Polymerization temperature was measured with an infrared thermographic camera (Thermovision 900 SW/TE, Agema Infra-red Systems AB, Danderyd, Sweden for 40 s at measurement spots adjacent to the cavity wall and in the middle of the cavity from the surface to a 4 mm depth. Data were analyzed according to the light curing modes with one-way ANOVA, and according to curing depth and approximation to the cavity wall with two-way ANOVA. RESULTS: The peak polymerization temperature of the composite resin was not affected by the light curing modes. According to the curing depth, the peak polymerization temperature at the depth of 1 mm to 3 mm was significantly higher than that at the depth of 4 mm, and on the surface. The peak polymerization temperature of the spots in the middle of the cavity was higher than that measured in spots adjacent to the cavity wall. CONCLUSION: In the photopolymerization of the composite resin, the temperature was higher in the middle of the cavity compared to the outer surface or at the internal walls of the prepared cavity.

  14. Effect of curing mode on the hardness of dual-cured composite resin core build-up materials

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    César Augusto Galvão Arrais

    2010-06-01

    Full Text Available This study evaluated the Knoop Hardness (KHN values of two dual-cured composite resin core build-up materials and one resin cement exposed to different curing conditions. Two dual-cured core build-up composite resins (LuxaCore®-Dual, DMG; and FluoroCore®2, Dentsply Caulk, and one dual-cured resin cement (Rely X ARC, 3M ESPE were used in the present study. The composite materials were placed into a cylindrical matrix (2 mm in height and 3 mm in diameter, and the specimens thus produced were either light-activated for 40 s (Optilux 501, Demetron Kerr or were allowed to self-cure for 10 min in the dark (n = 5. All specimens were then stored in humidity at 37°C for 24 h in the dark and were subjected to KHN analysis. The results were submitted to 2-way ANOVA and Tukey's post-hoc test at a pre-set alpha of 5%. All the light-activated groups exhibited higher KHN values than the self-cured ones (p = 0.00001, regardless of product. Among the self-cured groups, both composite resin core build-up materials showed higher KHN values than the dual-cured resin cement (p = 0.00001. LuxaCore®-Dual exhibited higher KHN values than FluoroCore®2 (p = 0.00001 when they were allowed to self-cure, while no significant differences in KHN values were observed among the light-activated products. The results suggest that dual-cured composite resin core build-up materials may be more reliable than dual-cured resin cements when curing light is not available.

  15. Degree of conversion of resin-based materials cured with dual-peak or single-peak LED light-curing units.

    Science.gov (United States)

    Lucey, Siobhan M; Santini, Ario; Roebuck, Elizabeth M

    2015-03-01

    There is a lack of data on polymerization of resin-based materials (RBMs) used in paediatric dentistry, using dual-peak light-emitting diode (LED) light-curing units (LCUs). To evaluate the degree of conversion (DC) of RBMs cured with dual-peak or single-peak LED LCUs. Samples of Vit-l-escence (Ultradent) and Herculite XRV Ultra (Kerr) and fissure sealants Delton Clear and Delton Opaque (Dentsply) were prepared (n = 3 per group) and cured with either one of two dual-peak LCUs (bluephase(®) G2; Ivoclar Vivadent or Valo; Ultradent) or a single-peak (bluephase(®) ; Ivoclar Vivadent). High-performance liquid chromatography and nuclear magnetic resonance spectroscopy were used to confirm the presence or absence of initiators other than camphorquinone. The DC was determined using micro-Raman spectroscopy. Data were analysed using general linear model anova; α = 0.05. With Herculite XRV Ultra, the single-peak LCU gave higher DC values than either of the two dual-peak LCUs (P < 0.05). Both fissure sealants showed higher DC compared with the two RBMs (P < 0.05); the DC at the bottom of the clear sealant was greater than the opaque sealant, (P < 0.05). 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin(®) TPO) was found only in Vit-l-escence. Dual-peak LED LCUs may not be best suited for curing non-Lucirin(®) TPO-containing materials. A clear sealant showed a better cure throughout the material and may be more appropriate than opaque versions in deep fissures. © 2014 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  16. Influence of light-curing units and restorative materials on the micro hardness of resin cements

    Directory of Open Access Journals (Sweden)

    Kuguimiya Rosiane

    2010-01-01

    Full Text Available Aim: The aim of this study was to evaluate the effect of indirect restorative materials (IRMs and light-curing units (LCUs on the micro hardness of dual-cured resin cement. Materials and Methods: A total of 36 cylindrical samples (2 mm thick were prepared with dual-cured resin cement (Relyx ARC photo-activated with either a QTH (Optilight Plus for 40s or a LED (Radii light-curing unit for 65s. Photo-activation was performed through the 2-mm- thick IRMs and the samples were divided into six groups (n=6 according to the combination of veneering materials (without, ceramic and indirect resin and LCUs (QTH and LED. In the control group, the samples were light-cured with a QTH unit without the interposition of any restorative material. Vickers micro hardness test was performed on the top and bottom surfaces of each sample (load of 50 g for 15 secs. The data were statistically analyzed using a three-way ANOVA followed by Tukey x s post-hoc test ( P < 0.05. Results: There were no statistically significant differences on the top surface between the light curing-units ( P > 0.05; however, the LED provided greater hardness on the bottom surface when a ceramic material was used ( P < 0.05. The mean hardness in photo-activated samples, in which there was no interposition of indirect materials, was significantly greater ( P < 0.01. Conclusions: It may be concluded that the interposition of the restorative material decreased the micro hardness in the deeper cement layer. Such decrease, however, was lower when the ceramic was interposed and the cement light-cured with LED.

  17. Structure/property relationships in methacrylate/dimethacrylate polymers for dental applications

    Science.gov (United States)

    Mehlem, Jeremy John

    Since its invention Bis-GMA or one of its analogs has been the main component of the polymer portion of composites for dental restorations. The need for dilution of Bis-GMA and its analogs to optimize its properties has long been recognized. Bis-GMA is a highly viscous monomer. This high viscosity leads to early vitrification, which limits conversion during cure. This viscosity also limits filler loading. Vitrification at low conversions leads to heterogeneous systems composed of low and high cross-link density phases. The low cross-link density phases behave as defects in the system; therefore, if the amount of low cross-link density phases in the system can be reduced and a more uniform network structure can be achieved, then the mechanical properties of the resin can be improved. Since the increase in viscosity during cure causes vitrification, it is logical that a system with a low initial viscosity will delay the onset of vitrification. Reactive diluents such as triethylene glycol dimethacrylate (TEGDMA) are effective at lower levels. However, large amounts negatively affect matrix properties by increasing polymerization shrinkage and water sorption. Shrinkage has been cited as one of the main deficiencies in dental composites. The goal of this project is to improve upon standard viscosity modifying comonomers such as triethylene glycol dimethacrylate. The comonomers that were explored were phenyloxyethyl methacrylate, cyclohexyl methacrylate, and tert-butylcylcohexyl methacrylate. Multicomponent systems based on analogs of ethylene glycol dimethacrylates with different length ethyl glycol chains were also examined. The substitution of monomethacrylates for TEGDMA as a comonomer resulted in enhanced or negligible affects on the mechanical properties of Bis-MEPP based polymer systems while reducing polymerization shrinkage. 129Xenon NMR and TappingMode(TM) AFM were used to characterize the heterogeneity of dimethacrylates systems during their cure cycle as well

  18. Effect of different light curing methods on mechanical and physical properties of resin-cements polymerized through ceramic discs

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    Isil Cekic-nagas

    2011-08-01

    Full Text Available OBJECTIVE: The aim of this study was to compare the polimerization ability of three different light-curing units (quartz tungsten halogen, light-emitting diodes and plasma arc and their exposure modes (high-intensity and soft-start by determination of microhardness, water sorption and solubility, and diametral tensile strength of 5 dual-curing resin cements. Material and methods: A total of 720 disc-shaped samples (1 mm height and 5 mm diameter were prepared from different dual-curing resin cements (Duolink, Nexus, Bifix-QM, Panavia F and RelyX Unicem. Photoactivation was performed by using quartz tungsten halogen (high-power and soft-up modes, light-emitting diode (standard and exponential modes and plasma arc (normal and ramp-curing modes curing units through ceramic discs. Then the samples (n=8/per group were stored dry in the dark at 37°C for 24 h. The Vickers hardness test was performed on the resin cement layer with a microhardness tester (Shimadzu HMV. For sorption and solubility tests; the samples were stored in a desiccator at 37°C and weighed to a constant mass. The samples were weighed both before and after being immersed in deionized water for different periods of time (24 h and 7 days and being desiccated. The diametral tensile strength of the samples was tested in a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed statistically by nonparametric Kruskal Wallis and Mann-Whitney U tests at 5% significance level. RESULTS: Resin cement and light-curing unit had significant effects (p0.05 were obtained with different modes of LCUs. Conclusion: The study indicates that polymerization of resin cements with different light-curing units may result in various polymer structures, and consequently different mechanical and physical properties.

  19. Temperature changes under demineralized dentin during polymerization of three resin-based restorative materials using QTH and LED units.

    Science.gov (United States)

    Mousavinasab, Sayed-Mostafa; Khoroushi, Maryam; Moharreri, Mohammadreza; Atai, Mohammad

    2014-08-01

    Light-curing of resin-based materials (RBMs) increases the pulp chamber temperature, with detrimental effects on the vital pulp. This in vitro study compared the temperature rise under demineralized human tooth dentin during light-curing and the degrees of conversion (DCs) of three different RBMs using quartz tungsten halogen (QTH) and light-emitting diode (LED) units (LCUs). Demineralized and non-demineralized dentin disks were prepared from 120 extracted human mandibular molars. The temperature rise under the dentin disks (n = 12) during the light-curing of three RBMs, i.e. an Ormocer-based composite resin (Ceram. X, Dentsply DeTrey), a low-shrinkage silorane-based composite (Filtek P90, 3M ESPE), and a giomer (Beautifil II, Shofu GmbH), was measured with a K-type thermocouple wire. The DCs of the materials were investigated using Fourier transform infrared spectroscopy. The temperature rise under the demineralized dentin disks was higher than that under the non-demineralized dentin disks during the polymerization of all restorative materials (p 0.05). Although there were no significant differences in the DCs, the temperature rise under demineralized dentin disks for the silorane-based composite was higher than that for dimethacrylate-based restorative materials, particularly with QTH LCU.

  20. Temperature changes under demineralized dentin during polymerization of three resin-based restorative materials using QTH and LED units

    Directory of Open Access Journals (Sweden)

    Sayed-Mostafa Mousavinasab

    2014-08-01

    Full Text Available Objectives Light-curing of resin-based materials (RBMs increases the pulp chamber temperature, with detrimental effects on the vital pulp. This in vitro study compared the temperature rise under demineralized human tooth dentin during light-curing and the degrees of conversion (DCs of three different RBMs using quartz tungsten halogen (QTH and light-emitting diode (LED units (LCUs. Materials and Methods Demineralized and non-demineralized dentin disks were prepared from 120 extracted human mandibular molars. The temperature rise under the dentin disks (n = 12 during the light-curing of three RBMs, i.e. an Ormocer-based composite resin (Ceram. X, Dentsply DeTrey, a low-shrinkage silorane-based composite (Filtek P90, 3M ESPE, and a giomer (Beautifil II, Shofu GmbH, was measured with a K-type thermocouple wire. The DCs of the materials were investigated using Fourier transform infrared spectroscopy. Results The temperature rise under the demineralized dentin disks was higher than that under the non-demineralized dentin disks during the polymerization of all restorative materials (p 0.05. Conclusions Although there were no significant differences in the DCs, the temperature rise under demineralized dentin disks for the silorane-based composite was higher than that for dimethacrylate-based restorative materials, particularly with QTH LCU.

  1. Analysis of gap formation at tooth-composite resin interface: effect of C-factor and light-curing protocol

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    Gustavo Oliveira dos Santos

    2007-08-01

    Full Text Available OBJECTIVE: The aim of this study was to evaluate the effect of C-factor and light-curing protocol on gap formation in composite resin restorations. Material and METHODS: Cylindrical cavities with 5.0 mm diameter and three different depths (A=1.0, B=2.0 and C=3.0 mm were prepared on the occlusal surface of 30 human molars and restored in a single increment with P 60. The composite resin was light-cured according to two protocols: standard - 850 mW/cm² / 20 s and gradual - 100 up to 1000 mW/cm² / 10 s + 1000 mW/cm² / 10 s. After storage in distilled water (37°C/7 days, the restorations were cut into three slices in a buccolingual direction and the gap widths were analyzed using a 3D-scanning system. The data were submitted to ANOVA and Student-Newman-Keuls test (alpha=0.05. RESULTS: ANOVA detected a significant influence for the C-factor and light-curing protocol as independent factors, and for the double interaction C-factor vs. light-curing protocol. Cavities with higher C-factor presented the highest gap formation. The gradual light-curing protocol led to smaller gap formation at cavity interfaces. CONCLUSIONS: The findings of this study suggest that the C-factor played an essential role in gap formation. The gradual light-curing protocol may allow relaxation of composite resin restoration during polymerization reaction.

  2. Curing kinetics of alkyd/melamine resin mixtures

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    Jovičić Mirjana C.

    2009-01-01

    Full Text Available Alkyd resins are the most popular and useful synthetic resins applied as the binder in protective coatings. Frequently they are not used alone but are modified with other synthetic resins in the manufacture of the coatings. An alkyd/melamine resin mixture is the usual composition for the preparation of coating called 'baking enamel' and it is cured through functional groups of resins at high temperatures. In this paper, curing kinetics of alkyd resins based on castor oil and dehydrated castor oil with melamine resin, has been studied by DSC method with programmed heating and in isothermal mode. The results determined from dynamic DSC curves were mathematically transformed using the Ozawa isoconversional method for obtaining the isothermal data. These results, degree of curing versus time, are in good agreement with those determined by the isothermal DSC experiments. By applying the Ozawa method it is possible to calculate the isothermal kinetic parameters for the alkyd/melamine resin mixtures curing using only calorimetric data obtained by dynamic DSC runs. Depending on the alkyd resin type and ratio in mixtures the values of activation energies of curing process of resin mixtures are from 51.3 to 114 kJ mol-1. The rate constant of curing increases with increasing the content of melamine resin in the mixture and with curing temperature. The reaction order varies from 1.12 to 1.37 for alkyd based on dehydrated castor oil/melamine resin mixtures and from 1.74 to 2.03 for mixtures with alkyd based on castor oil. Based on the results obtained, we propose that dehydrated castor oil alkyd/melamine resin mixtures can be used in practice (curing temperatures from 120 to 160°C.

  3. Conjugation of diisocyanate side chains to dimethacrylate reduces polymerization shrinkage and increases the hardness of composite resins.

    Science.gov (United States)

    Jan, Yih-Dean; Lee, Bor-Shiunn; Lin, Chun-Pin; Tseng, Wan-Yu

    2014-04-01

    Polymerization shrinkage is one of the main causes of dental restoration failure. This study tried to conjugate two diisocyanate side chains to dimethacrylate resins in order to reduce polymerization shrinkage and increase the hardness of composite resins. Diisocyanate, 2-hydroxyethyl methacrylate, and bisphenol A dimethacrylate were reacted in different ratios to form urethane-modified new resin matrices, and then mixed with 50 wt.% silica fillers. The viscosities of matrices, polymerization shrinkage, surface hardness, and degrees of conversion of experimental composite resins were then evaluated and compared with a non-modified control group. The viscosities of resin matrices increased with increasing diisocyanate side chain density. Polymerization shrinkage and degree of conversion, however, decreased with increasing diisocyanate side chain density. The surface hardness of all diisocyanate-modified groups was equal to or significantly higher than that of the control group. Conjugation of diisocyanate side chains to dimethacrylate represents an effective means of reducing polymerization shrinkage and increasing the surface hardness of dental composite resins. Copyright © 2012. Published by Elsevier B.V.

  4. Degree of conversion and surface hardness of resin cement cured with different curing units.

    Science.gov (United States)

    Ozturk, Nilgun; Usumez, Aslihan; Usumez, Serdar; Ozturk, Bora

    2005-01-01

    The aim of this study was to evaluate the degree of conversion and Vickers surface hardness of resin cement under a simulated ceramic restoration with 3 different curing units: a conventional halogen unit, a high-intensity halogen unit, and a light-emitting diode system. A conventional halogen curing unit (Hilux 550) (40 s), a high-intensity halogen curing unit used in conventional and ramp mode (Optilux 501) (10 s and 20 s, respectively), and a light-emitting diode system (Elipar FreeLight) (20 s, 40 s) were used in this study. The dual-curing resin cement (Variolink II) was cured under a simulated ceramic restoration (diameter 5 mm, height 2 mm), and the degree of conversion and Vickers surface hardness were measured. For degree of conversion measurement, 10 specimens were prepared for each group. The absorbance peaks were recorded using the diffuse-reflection mode of Fourier transformation infrared spectroscopy. For Vickers surface hardness measurement, 10 specimens were prepared for each group. A load of 200 N was applied for 15 seconds, and 3 evaluations of each of the samples were performed. Degree of conversion achieved with Optilux 501 (20 s) was significantly higher than those of Hilux, Optilux 501 (10 s), Elipar FreeLight (20 s), and Elipar FreeLight (40 s). For Vickers surface hardness measurement, Optilux 501 (20 s) produced the highest surface hardness value. No significant differences were found among the Hilux, Optilux 501 (10 s), Elipar FreeLight (20 s), and Elipar FreeLight (40 s). The high-intensity halogen curing unit used in ramp mode (20 s) produced harder resin cement surfaces than did the conventional halogen curing unit, high-intensity halogen curing unit used in conventional mode (10 s) and light-emitting diode system (20 s, 40 s), when cured through a simulated ceramic restoration.

  5. Degree of conversion of resin-based orthodontic bonding materials cured with single-wave or dual-wave LED light-curing units.

    Science.gov (United States)

    Santini, Ario; McGuinness, Niall; Nor, Noor Azreen Md

    2014-12-01

    To evaluate the degree of conversion (DC) of orthodontic adhesives (RBOAs) cured with dual peak or single peak light-emitting diode (LED) light-curing units (LCUs). Standardized samples of RBOAs, APCPlus, Opal® Bond® and LightBond(TM) were prepared (n = 3) and cured with one of two dual peak LCUs (bluephase® G2-Ivoclar-Vivadent or Valo-Ultradent) or a single peak control (bluephase® Ivoclar-Vivadent). The DC was determined using micro-Raman spectroscopy. The presence or absence of initiators other than camphorquinone was confirmed by high-performance liquid chromatography and nuclear magnetic resonance spectroscopy. Data were analysed using general linear model in Minitab 15 (Minitab Inc., State College, PA, USA). There was no significant difference in DC between APCPlus, and Opal® Bond (confidence interval: -3.89- to 2.48); significant difference between APCPlus and LightBond(TM) (-18.55 to -12.18) and Opal® Bond and Lightbond(TM) (-17.85 to -11.48); no significant difference between bluephase (single peak) and dual peak LCUs, bluephase G2 (-4.896 to 1.476) and Valo (-3.935 to 2.437) and between bluephase G2 and Valo (-2.225 to 4.147). APCPlus and Opal® Bond showed higher DC values than LightBond(TM) (P<0.05). Lucirin® TPO was found only in Vit-l-escence. Lucirin® TPO was not identified in the three orthodontic adhesives. All three LCUs performed similarly with the orthodontic adhesives: orthodontic adhesive make had a greater effect on DC than the LCUs. It is strongly suggested that manufacturers of resin-based orthodontic materials test report whether or not dual peak LCUs should be used with their materials. Dual peak LED LCUs, though suitable in the majority of cases, may not be recommended for certain non Lucirin® TPO-containing materials. © 2014 British Orthodontic Society.

  6. Influence of light curing unit and ceramic thickness on temperature rise during resin cement photo-activation.

    Science.gov (United States)

    Guiraldo, Ricardo Danil; Consani, Simonides; Mastrofrancisco, Sarina; Consani, Rafael Leonardo Xediek; Sinhoreti, Mario Alexandre Coelho; Correr-Sobrinho, Lourenço

    2008-11-01

    The aim of this study was to determine the effect of different ceramic thickness on heat generation during resin cement photo-activation by QTH (quartz-tungsten-halogen), LED (light emitting diode), and PAC (plasma arc-curing) LCUs (light curing units). The resin cement used was Rely X ARC (3M-ESPE), and the ceramic was IPS Empress Esthetic (Ivoclar-Vivadent), of which 0.7-, 1.4- and 2.0-mm thick disks, 0.8 mm in diameter were made. Temperature increase was recorded with a type-K thermocouple connected to a digital thermometer (Iopetherm 46). An acrylic resin base was built to guide the thermocouple and support the 1.0-mm thick dentin disk. A 0.1-mm thick black adhesive paper matrix with a perforation 6 mm in diameter was placed on the dentin to contain the resin cement and support the ceramic disks of different thicknesses. Three LCUs were used: QTH, LED and PAC. Nine groups were formed (n=10) according to the interaction: 3 ceramic thicknesses, 1 resin cement and 3 photo-activation methods. Temperature increase data were submitted to Tukey's test (5%). For all ceramic thicknesses, a statistically significant difference in temperature increase was observed among the LCUs, with the highest mean value for the QTH LCU (p0.05). The interaction of higher energy density with smaller ceramic thickness showed higher temperature increase values.

  7. Degree of conversion and bond strength of resin-cements to feldspathic ceramic using different curing modes

    Directory of Open Access Journals (Sweden)

    Veridiana Resende NOVAIS

    Full Text Available Abstract Resin cements have led to great advances in dental ceramic restoration techniques because of their ability to bond to both dental structures and restorative materials. Objective The aim of this study was to assess the performance of resin cements when different curing modes are used, by evaluating the degree of conversion and bond strength to a ceramic substrate. Material and Methods Three resin cements were evaluated, two dual-cured (Variolink II and RelyX ARC and one light-cured (Variolink Veneer. The dual-cured resin cements were tested by using the dual activation mode (base and catalyst and light-activation mode (base paste only. For degree of conversion (DC (n=5, a 1.0 mm thick feldspathic ceramic disc was placed over the resin cement specimens and the set was light activated with a QTH unit. After 24 h storage, the DC was measured with Fourier transform infrared spectroscopy (FTIR. For microshear bond strength testing, five feldspathic ceramic discs were submitted to surface treatment, and three cylindrical resin cement specimens were bonded to each ceramic surface according to the experimental groups. After 24 h, microshear bond testing was performed at 0.5 mm/min crosshead speed until the failure. Data were submitted to one-way ANOVA followed by Tukey test (p<0.05. Scanning electron microscopy (SEM was used for classifying the failure modes. Results Higher DC and bond strength values were shown by the resin cements cured by using the dual activation mode. The Variolink II group presented higher DC and bond strength values when using light-activation only when compared with the Variolink Veneer group. Conclusion The base paste of dual-cured resin cements in light-activation mode can be used for bonding translucent ceramic restorations of up to or less than 1.0 mm thick.

  8. Light-Cured Self-Etch Adhesives Undergo Hydroxyapatite-Triggered Self-Cure

    Science.gov (United States)

    Liu, Y.; Bai, X.; Liu, Y.W.; Wang, Y.

    2015-01-01

    Light cure is a popular mode of curing for dental adhesives. However, it suffers from inadequate light delivery when the restoration site is less accessible, in which case a self-cure mechanism is desirable to salvage any compromised polymerization. We previously reported a novel self-cure system mediated by ethyl 4-(dimethylamino)-benzoate (4E) and hydroxyapatite (HAp). The present work aims to investigate if such self-cure phenomenon takes place in adhesives that underwent prior inadequate light cure and to elucidate if HAp released from the dental etching process is sufficient to trigger it. Model self-etch adhesives were formulated with various components, including bis[2-methacryloyloxy)ethyl]-phosphate (2MP) as acidic monomer and trimethylbenzoyl-diphenylphosphine oxide (TPO) as photoinitiator. In vitro evolution of degree of conversion (DC) of HAp-incorporated adhesives was monitored by infrared spectroscopy during light irradiation and dark storage. Selected adhesives were allowed to etch and extract HAp from enamel, light-cured in situ, and stored in the dark, after which Raman line mapping was used to obtain spatially resolved DC across the enamel-resin interface. Results showed that TPO+4E adhesives reached DC similar to TPO-only counterparts upon completion of light irradiation but underwent another round of initiation that boosted DC to ~100% regardless of HAp level or prior light exposure. When applied to enamel, TPO-only adhesives had ~80% DC in resin, which gradually descended to ~50% in enamel, whereas TPO+4E adhesives consistently scored ~80% DC across the enamel-resin interface. These observations suggest that polymerization of adhesives that underwent insufficient light cure is salvaged by the novel self-cure mechanism, and such salvaging effect can be triggered by HAp released from dental substrate during the etching process. PMID:26635279

  9. Light-Cured Self-Etch Adhesives Undergo Hydroxyapatite-Triggered Self-Cure.

    Science.gov (United States)

    Liu, Y; Bai, X; Liu, Y W; Wang, Y

    2016-03-01

    Light cure is a popular mode of curing for dental adhesives. However, it suffers from inadequate light delivery when the restoration site is less accessible, in which case a self-cure mechanism is desirable to salvage any compromised polymerization. We previously reported a novel self-cure system mediated by ethyl 4-(dimethylamino)-benzoate (4E) and hydroxyapatite (HAp). The present work aims to investigate if such self-cure phenomenon takes place in adhesives that underwent prior inadequate light cure and to elucidate if HAp released from the dental etching process is sufficient to trigger it. Model self-etch adhesives were formulated with various components, including bis[2-methacryloyloxy)ethyl]-phosphate (2MP) as acidic monomer and trimethylbenzoyl-diphenylphosphine oxide (TPO) as photoinitiator. In vitro evolution of degree of conversion (DC) of HAp-incorporated adhesives was monitored by infrared spectroscopy during light irradiation and dark storage. Selected adhesives were allowed to etch and extract HAp from enamel, light-cured in situ, and stored in the dark, after which Raman line mapping was used to obtain spatially resolved DC across the enamel-resin interface. Results showed that TPO+4E adhesives reached DC similar to TPO-only counterparts upon completion of light irradiation but underwent another round of initiation that boosted DC to ~100% regardless of HAp level or prior light exposure. When applied to enamel, TPO-only adhesives had ~80% DC in resin, which gradually descended to ~50% in enamel, whereas TPO+4E adhesives consistently scored ~80% DC across the enamel-resin interface. These observations suggest that polymerization of adhesives that underwent insufficient light cure is salvaged by the novel self-cure mechanism, and such salvaging effect can be triggered by HAp released from dental substrate during the etching process. © International & American Associations for Dental Research 2015.

  10. Effect of light-curing method and indirect veneering materials on the Knoop hardness of a resin cement

    Directory of Open Access Journals (Sweden)

    Nelson Tetsu Iriyama

    2009-06-01

    Full Text Available This study evaluated the Knoop hardness of a dual-cured resin cement (Rely-X ARC activated solely by chemical reaction (control group or by chemical / physical mode, light-cured through a 1.5 mm thick ceramic (HeraCeram or composite (Artglass disc. Light curing was carried out using conventional halogen light (XL2500 for 40 s (QTH; light emitting diodes (Ultrablue Is for 40 s (LED; and Xenon plasma arc (Apollo 95E for 3 s (PAC. Bovine incisors had their buccal face flattened and hybridized. On this surface a rubber mold (5 mm in diameter and 1 mm in height was bulk filled with the resin cement. A polyester strip was seated for direct light curing or through the discs of veneering materials. After dry storage in the dark (24 h 37°C, the samples (n = 5 were sectioned for hardness (KHN measurements, taken in a microhardness tester (50 gF load 15 s. The data were statistically analyzed by ANOVA and Tukey's test (α = 0.05. The cement presented higher Knoop hardness values with Artglass for QTH and LED, compared to HeraCeram. The control group and the PAC/Artglass group showed lower hardness values compared to the groups light-cured with QTH and LED. PAC/HeraCeram resulted in the worst combination for cement hardness values.

  11. Influence of energy density of different light sources on knoop hardness of a dual-cured resin cement

    Directory of Open Access Journals (Sweden)

    Evandro Piva

    2008-06-01

    Full Text Available The purpose of this study was to evaluate the Knoop hardness of a dual-cured resin-based luting cement irradiated with different light sources as well energy density through a ceramic sample. Three light-curing unit (LCUs were tested: tungsten halogen light (HAL, light-emitting diode (LED and xenon plasma-arc (PAC lamp. Disc-shaped specimens were fabricated from a resin-based cement (Enforce. Three energy doses were used by modifying the irradiance (I of each LCU and the irradiation time (T: 24 Jcm-2 (I/2x2T, 24 Jcm-2 (IxT and 48 Jcm-2 (Ix2T. Energy doses were applied through a 2.0-mm-thick ceramic sample (Duceram Plus. Three groups underwent direct irradiation over the resin cement with the different LCUs and a chemically-activated group served as a control. Thirteen groups were tested (n=10. Knoop hardness number (KHN means were obtained from cross-sectional areas. Two-way ANOVA and the Holm-Sidak method were used for statistical comparisons of activation mode and energy doses (a=5%. Application of 48 J.cm-2 energy dose through the ceramic using LED (50.5±2.8 and HAL (50.9±3.7 produced significantly higher KHN means (p<0.05 than the control (44.7±3.8. LED showed statistically similar performance to HAL. Only HAL showed a relationship between the increase of LCU energy dose and hardness increase.

  12. Influence of energy density of different light sources on Knoop hardness of a dual-cured resin cement.

    Science.gov (United States)

    Piva, Evandro; Correr-Sobrinho, Lourenço; Sinhoreti, Mario Alexandre Coelho; Consani, Simonides; Demarco, Flávio Fernando; Powers, John Michael

    2008-01-01

    The purpose of this study was to evaluate the Knoop hardness of a dual-cured resin-based luting cement irradiated with different light sources as well energy density through a ceramic sample. Three light-curing unit (LCUs) were tested: tungsten halogen light (HAL), light-emitting diode (LED) and xenon plasma-arc (PAC) lamp. Disc-shaped specimens were fabricated from a resin-based cement (Enforce). Three energy doses were used by modifying the irradiance (I) of each LCU and the irradiation time (T): 24 Jcm(-2) (I/2x2T), 24 Jcm(-2) (IxT) and 48 Jcm(-2) (Ix2T). Energy doses were applied through a 2.0-mm-thick ceramic sample (Duceram Plus). Three groups underwent direct irradiation over the resin cement with the different LCUs and a chemically-activated group served as a control. Thirteen groups were tested (n=10). Knoop hardness number (KHN) means were obtained from cross-sectional areas. Two-way ANOVA and the Holm-Sidak method were used for statistical comparisons of activation mode and energy doses (alpha=5%). Application of 48 J.cm(-2) energy dose through the ceramic using LED (50.5+/-2.8) and HAL (50.9+/-3.7) produced significantly higher KHN means (p<0.05) than the control (44.7+/-3.8). LED showed statistically similar performance to HAL. Only HAL showed a relationship between the increase of LCU energy dose and hardness increase.

  13. Polymerization of dual cure resin cements applied for luting tooth colored fiber posts

    Directory of Open Access Journals (Sweden)

    Ghavam M.

    2007-05-01

    Full Text Available Background and Aim: Insufficient polymerization of resin cements is of considerable clinical importance, because of mechanical deficiencies and biological side effects of uncured resin. Dual cure resin cements are getting popular in luting tooth colored posts and although their curing is claimed to proceed chemically, polymerization efficiency in deep areas of canal is uncertain. The aim of this study was to evaluate degree of polymerization of dual-cure resin cements used for luting translucent and opaque fiber posts in different distances from the light tip. Materials and Methods: In this experimental in vitro study, degree of conversion of two dual cured resin cements, Rely X ARC (3M, ESPE and Nexus 2 (Kerr, USA were measured when used with DT-Light and DT-White posts (RTD, France. The light curing unit used was Optilux 501, with output of 650-700 mw/cm2 with emitting time of 60 seconds. Degree of conversion was measured in three different depths (4, 6, 8 mm by FTIR. The data were analyzed using ANOVA and Post hoc tests. P0.05. Nexus used with DT-Light had lower DC% in 8 mm depth (P<0.05. Nexus used with DT-White showed lower DC% in 8 mm depth compared to 4 mm depth. The control groups of both cements showed significant increased DC% in 4 mm depth compared to 6 and 8 mm depths (P<0.05. DT-White caused decreased DC% in both cements in 4 mm. DT-Light caused increased DC% of Rely X in 6 mm depth compared to DT-White and control. DT-Light increased DC% of Nexus in 6 and 8 mm depths, compared to DT-White and control groups. Conclusion: Based on the results of this study, application of translucent fiber posts has a significant effect on degree of polymerization in dual-cure resin cements, compared to opaque types. Their better light transmission to deep areas due to the effect of optical fibers, can lead to better results.

  14. The effect of different light-curing units on fatigue behavior and degree of conversion of a resin composite.

    Science.gov (United States)

    Lohbauer, Ulrich; Rahiotis, Christos; Krämer, Norbert; Petschelt, Anselm; Eliades, George

    2005-07-01

    The aim of this study was to investigate the effect of different light-curing units and irradiation modes on the mechanical fatigue strength and degree of conversion of a restorative resin composite. Conventional halogen, plasma arc and blue LED light-curing units were used for polymerization of a resin composite (Tetric) Ceram, Ivoclar, Vivadent, Liechtenstein). Initial fracture strength (FS) and flexural fatigue limit (FFL) as well as degree of conversion (DC) were measured. The FFL was determined under cyclic loading for 10(5) cycles in terms of a staircase approach. The specimens were stored for 14 days in 37 degrees C distilled water prior to testing. The curing efficiency was observed with Fourier transform infrared micromultiple internal reflectance spectroscopy. The measurements were carried out at 0.5 and 2.5 mm distance from the directly irradiated surface after 14 days storage in dark and dry conditions at 37 degrees C. The highest FS, FFL and DC were observed from high energy curing devices and from extended curing intervals. The conventional halogen light exhibited the most homogenous in-depth curing efficiency along with a low loss of mechanical resistance under cyclic fatigue. Evaluation of flexural fatigue limit and curing efficiency correlate in terms of decreased mechanical strength due to insufficient light-curing intervals or light intensities. Initial promising fracture strengths do not correlate with a clinically more relevant fatigue loading and with the in-depth degree of conversion, both accounting for a significantly reduced strength performance.

  15. A Fourier transform Raman spectroscopy analysis of the degree of conversion of a universal hybrid resin composite cured with light-emitting diode curing units.

    Science.gov (United States)

    Lindberg, Anders; Emami, Nazanin; van Dijken, Jan W V

    2005-01-01

    The degree of conversion (DC), of a universal hybrid resin composite cured with LED curing units with low and high power densities and a 510 mW/cm2 quartz tungsten halogen unit, was investigated with Fourier Transform Raman spectroscopy. Three curing depths (0, 2, 4mm) and 0 and 7 mm light guide tip - resin composite (LT - RC) distances were tested. The DC of the LED units varied between 52.3% - 59.8% at the top surface and 46.4% - 57.0% at 4 mm depth. The DC of specimen cured with a 0 mm LT- RC distance at 4 mm depth varied between 50.8% - 57.0% and with 7 mm distance between 46.4% - 55.4%. The low power density LED unit showed a significantly lower DC for both distances at all depth levels compared to the other curing units (p units were only found at the 4 mm depth level cured from 7 mm distance (p units. It can be concluded that the improved LED curing units could cure the studied resin composite to the same DC as the control unit.

  16. Effect of light energy density on conversion degree and hardness of dual-cured resin cement.

    Science.gov (United States)

    Komori, Paula Carolina de Paiva; de Paula, Andréia Bolzan; Martin, Airton Abrāo; Tango, Rubens Nisie; Sinhoreti, Mario Alexandre Coelho; Correr-Sobrinho, Lourenço

    2010-01-01

    This study evaluated the effect of different light energy densities on conversion degree (CD) and Knoop hardness number (KHN) of RelyX ARC (RLX) resin cement. After manipulation according to the manufacturer's instructions, RLX was inserted into a rubber mold (0.8 mm x 5 mm) and covered with a Mylar strip. The tip of the light-curing unit (LCU) was positioned in contact with the Mylar surface. Quartz-tungsten-halogen (QTH) and light-emitting diode (LED) LCUs with light densities of 10, 20 and 30 J/cm2 were used to light-cure the specimens. After light curing, the specimens were stored dry in lightproof containers at 37 degrees C. After 24 hours, the CD was analyzed by FT-Raman and, after an additional 24-hours, samples were submitted to Knoop hardness testing. The data of the CD (%) and KHN were submitted to two-way ANOVA and the Tukey's test (alpha = 0.05). QTH and LED were effective light curing units. For QTH, there were no differences among the light energy densities for CD or KHN. For LED, there was a significant reduction in CD with the light energy density set at 10 J/cm2. KHN was not influenced by the light-curing unit and by its light energy density.

  17. Light energy transmission and Vickers hardness ratio of bulk-fill resin based composites at different thicknesses cured by a dual-wave or a single-wave light curing unit.

    Science.gov (United States)

    Santini, Ario; Naaman, Reem Khalil; Aldossary, Mohammed Saeed

    2017-04-01

    To quantify light energy transmission through two bulk-fill resin-based composites and to measure the top to bottom surface Vickers hardness ratio (VHratio) of samples of various incremental thicknesses, using either a single-wave or dual-wave light curing unit (LCU). Tetric EvoCeram Bulk Fill (TECBF) and SonicFill (SF) were studied. Using MARC-RC, the irradiance delivered to the top surface of the samples 2, 3, 4 and 5 mm thick (n= 5 for each thickness) was adjusted to 800 mW/cm2 for 20 seconds (16 J/cm2) using either a single-wave, Bluephase or a dual-wave, Bluephase G2 LCUs. Light energy transmission through to the bottom surface of the specimens was measured at real time using MARC-RC. The Vickers hardness (VH) was determined using Vickers micro hardness tester and the VHratio was calculated. Data were analyzed using a general linear model in Minitab 16; α= 0.05. TECBF was more translucent than SF (Pwave Bluephase G2). SF showed significantly higher VH ratio than TECBF at all different thickness levels (P 0.05). TECBF showed significantly greater VH ratio when cured with the single-wave Bluephase than when using the dual-wave Bluephase G2 (Penergy through to the bottom surface and the VHratio are material dependent. Although TECBF is more translucent than SF, it showed lower VHratio compared to SF when cured with dual-wave Bluephase G2.

  18. The Effect of Lithium Disilicate Ceramic Thickness and Translucency on Shear Bond Strength of Light-cured Resin Cement

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    Mohammad Javad Moghaddas

    2017-09-01

    Full Text Available Introduction: To achieve acceptable clinical performance, a ceramic veneer must be bonded to enamel by well-polymerized resin cement. Among different factors, thickness and translucency of the ceramic may affect the resin cement polymerization. Thus, the current study evaluated the effect of the thickness and translucency of lithium disilicate ceramic on light-cured resin cement bond strength to enamel. Methods: In this laboratory study, 208 sound bovine incisors were equally divided into 16 groups (n = 13. The lithium disilicate ceramic cubes in four thicknesses (0.4, 0.6, 0.8 and 1 mm with four translucencies (high and medium opaque, high and low translucent were fabricated and bonded to prepared enamel surfaces using a light-cured translucent resin cement according to manufacturer recommendations. After 5000 cycles of thermocycling, the bonded specimens were placed in a universal testing machine and loaded to the point of fracture. To determine the mode of failure, each sample was observed under a stereomicroscope. Data were recorded and analyzed by Shapiro-Wilk test and two-way analysis of variance (ANOVA. Results: The ceramic thickness and translucency could not significantly affect shear bond strength (SBS of resin cement to enamel (p = 0.17 and p = 0.097, respectively.  The Adhesive and ceramic cohesive failures were reported as the maximum and minimum mode of failure, respectively. Conclusion: The SBS of the light-cured resin cement bonding to enamel and lithium disilicate ceramic was not affected by the translucency of ceramics having a thickness of less than 1 mm.

  19. Determination of unreacted monomers in restorative dental resins based on dimethacrylate by NMR hydrogen

    International Nuclear Information System (INIS)

    Correa, Ivo Carlos; Miranda Junior, Walter G.; Tavares, Maria Ines B.

    2001-01-01

    The presence of unreacted monomers after photo-activation of dental composites causes mechanical and biological properties to decrease and could be detected by NMR analysis. The aim of this study was to evaluate the percentage of leachable monomers of light-cured composites under the effect of variations of exposure time of photo activation by nuclear magnetic resonance of hydrogen in solution (NMR 1 H). The composite resins tested Z250 and Fill Magic obtained similar values of unreacted monomers (%) at photo curing time suggested by the manufacturer and values were also lower than Durafill and A110 concentrations. From the NMR results, one day extractable time was efficient to quantify the amount of residual monomers in the dental composites tested, unless for Durafill composite. (author)

  20. Flexural behaviour of post-cured composites at oral-simulating temperatures.

    Science.gov (United States)

    Ho, C T; Vijayaraghavan, T V; Lee, S Y; Tsai, A; Huang, H M; Pan, L C

    2001-07-01

    Post-curing treatments have been known to improve the mechanical stability of visible light-cured composites. After individual post-curing treatment, the flexural strength (FS) of four commercial direct/indirect placement composite materials which differ greatly in composition [oligocarbonate dimethacrylate (OCDMA)-based Conquest C & B (CQT), Bisphenol-A glycidyl dimethacrylate (BisGMA)-based Charisma, urethane dimethacrylate (UDMA)-based Concept (CCT), and BisGMA/UDMA-based Dentacolor] was evaluated under water in the temperature range of 12-50 degrees C. A control series was tested in air at room temperature (25 +/- 1 degrees C). Data were analysed using ANOVA and Duncan's test. Flexural strengths overall decreased (20-40%, P OCDMA-based materials. Post-cured composites can be significantly affected by exposure to oral environments. Different composition determines the degree of influence.

  1. Evaluation of compatibility between different types of adhesives and dual-cured resin cement.

    Science.gov (United States)

    Franco, Eduardo B; Lopes, Lawrence G; D'alpino, Paulo H P; Pereira, José C; Mondelli, Rafael F L; Navarro, Maria F L

    2002-01-01

    The objective of this in vitro study was to evaluate the bonding compatibility between different adhesives and a dual-cured resin cement, using a conventional tensile bond test. The adhesives used were: Prime & Bond (PB) (Dentsply) (PB), Scotchbond Multi Purpose (SB) (3M), and the activator Self Cure (SC) (Dentsply). The dual-curing resin cement used was Enforce (EF) (Dentsply). Six groups with five specimens in each were tested: G1: EF/PB/EF (light cured); G2: EF/SB/EF (light cured); G3: EF/PB+SC/EF (light cured); G4: EF/PB+SC/EF (only chemically cured); G5: EF/EF (light cured); G6: EF/EF (only chemically cured). The resin cement was applied in two stainless steel molds with a cone-shaped perforation measuring 4 mm in diameter and 1 mm in thickness, and the adhesive was applied between them. Ten minutes after specimens were cured, the tensile strength was measured in a universal testing machine at a crosshead speed of 0.5 mm/min. The mean values (MPa) +/- SD obtained in each experimental group were: G1: 1.4 +/- 0.2; G2: 1.3 +/- 0.2; G3: 1.2 +/- 0.4; G4: 0.8 +/- 0.2; G5: 1.2 +/- 0.1; G6: 0.7 +/- 0.1. The results were statistically evaluated using nonparametric Kruskal-Wallis and Dunn tests (p adhesives used with dual-cured resin cement. The lowest tensile bond strength values occurred in the absence of photoactivation.

  2. Influence of Emission Spectrum and Irradiance on Light Curing of Resin-Based Composites.

    Science.gov (United States)

    Shimokawa, Cak; Sullivan, B; Turbino, M L; Soares, C J; Price, R B

    This study examined the influence of different emission spectra (single-peak and broad-spectrum) light-curing units (LCUs) delivering the same radiant exposures at irradiance values of 1200 or 3600 mW/cm 2 on the polymerization and light transmission of four resin-based composites (RBCs). Two prototype LCUs that used the same light tip, but were either a single-peak blue or a broad-spectrum LED, were used to deliver the same radiant exposures to the top surfaces of the RBCs using either standard (1200 mW/cm 2 ) or high irradiance (3600 mW/cm 2 ) settings. The emission spectrum and radiant power from the LCUs were measured with a laboratory-grade integrating sphere coupled to a spectrometer, and the light beam was assessed with a beam profiler camera. Four RBCs (Filtek Supreme Ultra A2, Tetric EvoCeram A2, Tetric EvoCeram T, and TPH Spectra High Viscosity A2) were photoactivated using four different light conditions: single-peak blue/standard irradiance, single-peak blue/high irradiance, broad-spectrum/standard irradiance, and broad-spectrum/high irradiance. The degree of conversion (N=5) and microhardness at the top and bottom of 2.3-mm-diameter by 2.5-mm-thick specimens (N=5) were analyzed with analysis of variance and Tukey tests. The real-time light transmission through the RBCs was also measured. For all light conditions, the 2.3-mm-diameter specimens received a homogeneous irradiance and spectral distribution. Although similar radiant exposures were delivered to the top surfaces of the RBCs, the amount of light energy emitted from the bottom surfaces was different among the four RBCs, and was also greater for the single-peak lights. Very little violet light (wavelengths below 420 nm) reached the bottom of the 2.5-mm-thick specimens. The degree of conversion and microhardness results varied according to the RBC (pspectrum lights, while at the bottom, where little violet light was observed, the results were equal or higher when they were photoactivated with

  3. [Ru(bipy)3]2+ nanoparticle-incorporate dental light cure resin to promote photobiomodulation therapy for enhanced vital pulp tissue repair

    Science.gov (United States)

    Mosca, Rodrigo C.; Young, Nicholas; Zeituni, Carlos A.; Arany, Praveen R.

    2018-02-01

    The use of nanoparticle on dental light cure resin is not new, currently several compounds (nanoadditives) are used to promote better communication between the restorative material and biological tissues. The interest for this application is growing up to enhance mechanical proprieties to dental tissue cells regeneration. Bioactive nanoparticles and complex compounds with multiple functions are the major target for optimizing the restorative materials. In this work, we incorporate [Ru(bipy)3]2+ nanoparticles, that absorbs energy at 450 nm (blue-light) and emits strongly at 620 nm (red-light), in PLGA Microspheres and insert it in Dental Light Cure Resin to promote the Photobiomodulation Therapy (PBM) effects to accelerate dental pulp repair by in vitro using cytotoxicity and proliferation assay.

  4. Effect of bench time polymerization on depth of cure of dental composite resin

    Science.gov (United States)

    Harahap, K.; Yudhit, A.; Sari, F.

    2017-07-01

    The aim of this research was to investigate the effect of bench time before light cured polymerization on the depth of cure of dental composite resin. Nanofiller composite resin (Filtek Z350 XT,3M, ESPE,China) was used in this study. Sixty samples of nanofiller composite resin were made and divided into control and test groups with bench time for 0, 15, 30, 45, and 60 min. For the test group, composite resins were stored in refrigerator with 4°C temperatures. Meanwhile, for the control groups, the composite resin was stored at room temperature. The samples were prepared using metal mould with size diameter of 6 mm and 4 mm in thickness. Samples were cured for 20 s by using visible blue light curing unit. Part of samples that unpolymerized were removed by using a plastic spatula. The remaining parts of samples were measured by digital caliper and noted as depth of cure (mm). Data were analyzed to one-way ANOVA and LSD tests (p≤0.05). Results showed there was no significance differences between test groups (p=0.5). A 60 minutes bench time group showed the highest depth of cure value among test group, and it was almost similar with control group value. It can be concluded that longer bench time can increase the depth of cure of composite resin.

  5. A comparison of the accuracy of patterns processed from an inlay casting wax, an auto-polymerized resin and a light-cured resin pattern material.

    Science.gov (United States)

    Rajagopal, Praveen; Chitre, Vidya; Aras, Meena A

    2012-01-01

    Traditionally, inlay casting waxes have been used to fabricate patterns for castings. Newer resin pattern materials offer greater rigidity and strength, allowing easier laboratory and intraoral adjustment without the fear of pattern damage. They also claim to possess a greater dimensional stability when compared to inlay wax. This study attempted to determine and compare the marginal accuracy of patterns fabricated from an inlay casting wax, an autopolymerized pattern resin and a light polymerized pattern resin on storage off the die for varying time intervals. Ten patterns each were fabricated from an inlay casting wax (GC Corp., Tokyo, Japan), an autopolymerized resin pattern material (Pattern resin, GC Corp, Tokyo, Japan) and a light-cured resin pattern material (Palavit GLC, Hereaus Kulzer GmbH, Germany). The completed patterns were stored off the die at room temperature. Marginal gaps were evaluated by reseating the patterns on their respective dies and observing it under a stereomicroscope at 1, 12, and 24 h intervals after pattern fabrication. The results revealed that the inlay wax showed a significantly greater marginal discrepancy at the 12 and 24 h intervals. The autopolymerized resin showed an initial (at 1 h) marginal discrepancy slightly greater than inlay wax, but showed a significantly less marginal gap (as compared to inlay wax) at the other two time intervals. The light-cured resin proved to be significantly more dimensionally stable, and showed minimal change during the storage period. The resin pattern materials studied, undergo a significantly less dimensional change than the inlay waxes on prolonged storage. They would possibly be a better alternative to inlay wax in situations requiring high precision or when delayed investment (more than 1 h) of patterns can be expected.

  6. Effect of Light Curing Unit Characteristics on Light Intensity Output ...

    African Journals Online (AJOL)

    Background: Modern dental composite restorations are wholly dependent on the use of Visible Light Curing devices. The characteristics of these devices may influence the quality of composite resin restorations. Objective: To determine the characteristics of light curing units (LCUs) in dental clinics in Nairobi and their effect ...

  7. [Physical and mechanical properties of the thermosetting resin for crown and bridge cured by micro-wave heating].

    Science.gov (United States)

    Kaneko, K

    1989-09-01

    A heating method using micro-waves was utilized to obtain strong thermosetting resin for crown and bridge. The physical and mechanical properties of the thermosetting resin were examined. The resin was cured in a shorter time by the micro-waves heating method than by the conventional heat curing method and the working time was reduced markedly. The base resins of the thermosetting resin for crown and bridge for the micro-waves heating method were 2 PA and diluent 3 G. A compounding volume of 30 wt% for diluent 3 G was considered good the results of compressive strength, bending strength and diametral tensile strength. Grams of 200-230 of the filler compounded to the base resins of 2 PA-3 G system provided optimal compressive strength, bending strength and diametral tensile strength. A filler gram of 230 provided optimal hardness and curing shrinkage rate, the coefficient of thermal expansion became smaller with the increase of the compounding volume of the filler. The trial thermosetting resin for crown and bridge formed by the micro-waves heating method was not inferior to the conventional resin by the heat curing method or the light curing method.

  8. Battery Charge Affects the Stability of Light Intensity from Light-emitting Diode Light-curing Units.

    Science.gov (United States)

    Tongtaksin, A; Leevailoj, C

    This study investigated the influence of battery charge levels on the stability of light-emitting diode (LED) curing-light intensity by measuring the intensity from fully charged through fully discharged batteries. The microhardness of resin composites polymerized by the light-curing units at various battery charge levels was measured. The light intensities of seven fully charged battery LED light-curing units-1) LY-A180, 2) Bluephase, 3) Woodpecker, 4) Demi Plus, 5) Saab II, 6) Elipar S10, and 7) MiniLED-were measured with a radiometer (Kerr) after every 10 uses (20 seconds per use) until the battery was discharged. Ten 2-mm-thick cylindrical specimens of A3 shade nanofilled resin composite (PREMISE, Kerr) were prepared per LED light-curing unit group. Each specimen was irradiated by the fully charged light-curing unit for 20 seconds. The LED light-curing units were then used until the battery charge fell to 50%. Specimens were prepared again as described above. This was repeated again when the light-curing units' battery charge fell to 25% and when the light intensity had decreased to 400 mW/cm 2 . The top/bottom surface Knoop hardness ratios of the specimens were determined. The microhardness data were analyzed by one-way analysis of variance with Tukey test at a significance level of 0.05. The Pearson correlation coefficient was used to determine significant correlations between surface hardness and light intensity. We found that the light intensities of the Bluephase, Demi Plus, and Elipar S10 units were stable. The intensity of the MiniLED unit decreased slightly; however, it remained above 400 mW/cm 2 . In contrast, the intensities of the LY-A180, Woodpecker, and Saab II units decreased below 400 mW/cm 2 . There was also a significant decrease in the surface microhardnesses of the resin composite specimens treated with MiniLED, LY-A180, Woodpecker, and Saab II. In conclusion, the light intensity of several LED light-curing units decreased as the battery was

  9. Efficiency of light curing units in a government dental school.

    Science.gov (United States)

    Nassar, Hani M; Ajaj, Reem; Hasanain, Fatin

    2018-01-01

    The light intensity of a light-curing unit is a crucial factor that affects the clinical longevity of resin composites. This study aimed to investigate the efficiency of light-curing units in use at a local governmental dental school for curing conventional and bulk-fill resin materials. A total of 166 light-curing units at three locations were examined, and the brand, type, clinic location, diameter of curing tip, tip cleanliness (using a visual score), and the output (in mW/cm 2 using a digital radiometer) were recorded. Only 23.5% of the units examined had clean tips, with the graduate student clinical area containing the highest percentage of clean tips. Further, tips with poor cleanliness score values were associated with significantly lower output intensities. A small percentage (9.4%) of units was capable of producing intensities higher than 1,200 mW/cm 2 and lower than 600 mW/cm 2 (7.6%). The majority of the low intensity units were located in the undergraduate student area, which also contained the highest number of units with intensities between 900 and 1,200 mW/cm 2 . The output of all the units in service was satisfactory for curing conventional resin composites, and most units were capable of curing bulk-fill resin materials.

  10. Conjugation of diisocyanate side chains to dimethacrylate reduces polymerization shrinkage and increases the hardness of composite resins

    Directory of Open Access Journals (Sweden)

    Yih-Dean Jan

    2014-04-01

    Conclusion: Conjugation of diisocyanate side chains to dimethacrylate represents an effective means of reducing polymerization shrinkage and increasing the surface hardness of dental composite resins.

  11. Effect of curing light emission spectrum on the nanohardness and elastic modulus of two bulk-fill resin composites.

    Science.gov (United States)

    Issa, Yaser; Watts, David C; Boyd, Daniel; Price, Richard B

    2016-04-01

    To determine the nanohardness and elastic moduli of two bulk-fill resin based composites (RBCs) at increasing depths from the surface and increasing distances laterally from the center after light curing. Two bulk-fill dental RBCs: Tetric EvoCeram Bulk Fill (TECBF) and Filtek Bulk Fill Flowable (FBFF) were light cured in a metal mold with a 6mm diameter and a 10mm long semi-circular notch. The RBCs were photo-polymerized for 10s using a light emitting diode (LED) Bluephase Style curing light, with the original light probe that lacked the homogenizer. This light has two blue light and one violet light LED emitters. By changing the probe orientation over the mold, the light output from only two LEDs reached the RBC. Measurements were made using: (i) the light from one violet and one blue LED, and (ii) the light from the two blue LEDs. Five specimens of each RBC were made using each LED orientation (total 20 specimens). Specimens were then stored in the dark at 37°C for 24h. Fifty indents were made using an Agilent G200 nanoindentor down to 4mm from the surface and 2.5mm right and left of the centerline. The results were analyzed (alpha=0.05) using multiple paired-sample t-tests, ANOVA, Bonferroni post-hoc tests, and Pearson correlations. The elastic modulus and nanohardness varied according to the depth and the distance from the centerline. For TECBF, no significant difference was found between the spatial variations in the elastic modulus or hardness values when violet-blue or blue-blue LEDs were used. For FBFF, the elastic modulus and nanohardness on the side exposed to the violet emitter were significantly less than the side exposed to the blue emitter. A strong correlation between nanohardness and elastic modulus was found in all groups (r(2)=0.9512-0.9712). Resin polymerization was not uniform throughout the RBC. The nanohardness and elastic modulus across two RBC materials were found to decline differently according to the orientation of the violet and blue

  12. Effect of high intensity vs. soft-start halogen irradiation on light-cured resin-based composites. Part I. Temperature rise and polymerization shrinkage.

    Science.gov (United States)

    Hofmann, Norbert; Markert, Tanja; Hugo, Burkard; Klaiber, Bernd

    2003-12-01

    To determine polymerization shrinkage kinetics and temperature rise of light-cured resin-based composites after high intensity vs. soft-start quartz tungsten halogen irradiation. Shrinkage kinetics was evaluated using the "deflecting disk technique", modified for simultaneous measurement of temperature within the resin-based composite using a thermocouple. Additional irradiations after 60 and 65 minutes allowed the determination of temperature rises caused by radiation or by reaction heat. Four hybrids (Filtek Z250, Herculite, Solitaire 2, Tetric Ceram), an inhomogeneously filled hybrid (InTen-S) and a microfill (Filtek A110, formerly Silux Plus) were cured using the quartz tungsten halogen units Astralis 10 and Optilux 501 in the high intensity (A10 HiPo: 10 seconds at 1300 mW/cm2; OL Boost: 10 seconds at 1140 mW/cm2) or soft-start modes (A10 Pulse: increase to 700 mW/cm2 within 10 seconds, three periods of 2 seconds at 1300 mW/cm2 alternating with two periods of 2 seconds at 700 mW/cm2; OL Ramp: exponential increase within 10 seconds, followed by 10 seconds at 1140 mW/cm2). The soft-start protocols produced less contraction, and polymerization shrinkage started later and progressed slower (or: more slowly), compared to high intensity irradiation [correction]. The lowest shrinkage was observed for InTen-S, followed by Filtek Z250 and A110, whereas Solitaire 2, Herculite and Tetric Ceram scored highest for this parameter. Temperature rise was caused more or less equally by radiation and by reaction heat and reached values of up to 28.9 degrees C relative to a baseline of 37 degrees C. For some combinations of curing modes and resin-based composites, less heat was generated by the soft-start protocols and by Optilux 501.

  13. Effect of the irradiance distribution from light curing units on the local micro-hardness of the surface of dental resins.

    Science.gov (United States)

    Haenel, Thomas; Hausnerová, Berenika; Steinhaus, Johannes; Price, Richard B T; Sullivan, Braden; Moeginger, Bernhard

    2015-02-01

    An inhomogeneous irradiance distribution from a light-curing unit (LCU) can locally cause inhomogeneous curing with locally inadequately cured and/or over-cured areas causing e.g. monomer elution or internal shrinkage stresses, and thus reduce the lifetime of dental resin based composite (RBC) restorations. The aim of the study is to determine both the irradiance distribution of two light curing units (LCUs) and its influence on the local mechanical properties of a RBC. Specimens of Arabesk TOP OA2 were irradiated for 5, 20, and 80s using a Bluephase® 20i LCU in the Low mode (666mW/cm(2)), in the Turbo mode (2222mW/cm(2)) and a Celalux® 2 (1264mW/cm(2)). The degree of conversion (DC) was determined with an ATR-FTIR. The Knoop micro-hardness (average of five specimens) was measured on the specimen surface after 24h of dark and dry storage at room temperature. The irradiance distribution affected the hardness distribution across the surface of the specimens. The hardness distribution corresponded well to the inhomogeneous irradiance distributions of the LCU. The highest reaction rates occurred after approximately 2s light exposure. A DC of 40% was reached after 3.6 or 5.7s, depending on the LCU. The inhomogeneous hardness distribution was still evident after 80s of light exposure. The irradiance distribution from a LCU is reflected in the hardness distribution across the surface. Irradiance level of the LCU and light exposure time do not affect the pattern of the hardness distribution--only the hardness level. In areas of low irradiation this may result in inadequate resin polymerization, poor physical properties, and hence premature failure of the restorations as they are usually much smaller than the investigated specimens. It has to be stressed that inhomogeneous does not necessarily mean poor if in all areas of the restoration enough light intensity is introduced to achieve a high degree of cure. Copyright © 2014 Academy of Dental Materials. Published by

  14. [Effect of thermal cycling on surface microstructure of different light-curing composite resins].

    Science.gov (United States)

    Lv, Da; Liu, Kai-Lei; Yao, Yao; Zhang, Wei-Sheng; Liao, Chu-Hong; Jiang, Hong

    2015-04-01

    To evaluate the effect of thermal cycling on surface microstructure of different light-curing composite resins. A nanofilled composite (Z350) and 4 microhybrid composites (P60, Z250, Spectrum, and AP-X) were fabricated from lateral to center to form cubic specimens. The lateral surfaces were abrased and polished before water storage and 40 000 thermal cycles (5/55 degrees celsius;). The mean surface roughness (Ra) were measured and compared before and after thermal cycling, and the changes of microstructure were observed under scanning electron microscope (SEM). Significant decreases of Ra were observed in the composites, especially in Spectrum (from 0.164±0.024 µm to 0.140±0.017 µm, Presins, and fissures occurred on Z350 following the thermal cycling. Water storage and thermal cycling may produce polishing effect on composite resins and cause fissures on nanofilled composite resins.

  15. Influence of curing rate of resin composite on the bond strength to dentin

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Asmussen, E; Peutzfeldt, A

    2007-01-01

    @ 1000 mW/cm2) for all groups. A split Teflon mold was clamped to the treated dentin surface and filled with resin composite. The rate of cure was varied, using one of four LED-curing units of different power densities. The rate of cure was also varied using the continuous or pulse-delay mode....... In continuous curing mode, in order to give an energy density totaling 16 J/cm2, the power densities (1000, 720, 550, 200 mW/cm2) emitted by the various curing units were compensated for by the light curing period (16, 22, 29 or 80 seconds). In the pulse-delay curing mode, two seconds of light curing at one...... of the four power densities was followed by a one-minute interval, after which light cure was completed (14, 29, 27 or 78 seconds), likewise, giving a total energy density of 16 J/cm2. The specimens produced for each of the eight curing protocols and two resin composites (Tetric EvoCeram, Ivoclar Vivadent...

  16. Effectiveness of composite resin polymerization using light-emitting diodes (LEDs or halogen-based light-curing units Efetividade de polimerização de uma resina composta fotopolimerizada por diodos emissores de luz (LEDs ou luz halógena

    Directory of Open Access Journals (Sweden)

    Bianca Micali

    2004-09-01

    Full Text Available The clinical performance of composite resins is greatly influenced by the quality of the light-curing unit used. The aim of this study was to compare the efficiency of a commercial light-emitting diode (LED with that of a halogen-based light-curing unit by means of dye penetration of a micro hybrid composite resin. The composite resin evaluated was Filtek Z250 (3M Dental. The composite was filled into acrylic moulds that were randomly polymerized for 40 seconds by each of the light-emitting systems: light-emitting diode Ultraled (Dabi Atlante or halogen light Degulux (Degussa Hüls curing units. Immediately after polymerization, each specimen was individually immersed in 1 ml of 2% methylene blue solution at 37°C ± 2°C. After 24 hours, the specimens were rinsed under running distilled water for 1 minute and stored at 37°C ± 2°C at relative humidity for 24 hours. The composite resins were removed from the moulds and individually triturated before being immersed in new test tubes containing 1 ml of absolute alcohol for 24 hours. The solutions were filtered and centrifuged for 3 minutes at 4,000 rpm and the supernatant was used to determine absorbance in a spectrophotometer at 590 nm. To verify the differences between groups polymerized by LED or halogen light t-test was applied. No significant differences were found between composite resins light-cured by LED or halogen light-curing unit (p > 0.05. The commercially LED-based light-curing unit is as effective to polymerize hybrid composite resins as the halogen-based unit.A longevidade clínica das resinas compostas é grandemente influenciada pela qualidade do aparelho fotopolimerizador utilizado. O objetivo deste trabalho foi comparar a eficácia de um aparelho fotopolimerizador de diodos emissores de luz e a de um de luz halógena através do grau de penetração de um corante em uma resina composta micro-híbrida. A resina composta utilizada (Filtek Z250/3M Dental foi inserida em matrizes

  17. Influence of curing rate on softening in ethanol, degree of conversion, and wear of resin composite

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Peutzfeldt, Anne; Asmussen, Erik

    2011-01-01

    PURPOSE: To investigate the effect of curing rate on softening in ethanol, degree of conversion, and wear of resin composites. METHOD: With a given energy density and for each of two different light-curing units (QTH or LED), the curing rate was reduced by modulating the curing mode. Thus......, the irradiation of resin composite specimens (Filtek Z250, Tetric Ceram, Esthet-X) was performed in a continuous curing mode and in a pulse-delay curing mode. Wallace hardness was used to determine the softening of resin composite after storage in ethanol. Degree of conversion was determined by infrared...... exposed to the pulse-delay curing mode were softer than resin composites exposed to continuous cure (Pconversion (P

  18. Depth of cure of bulk-fill flowable composite resins.

    Science.gov (United States)

    Pedalino, Inaam; Hartup, Grant R; Vandewalle, Kraig S

    2015-01-01

    In recent years, manufacturers have introduced flowable composite resins that reportedly can be placed in increments of 4 mm or greater. The purpose of this study was to evaluate the depth of cure of bulk-fill flowable composite resins (SureFil SDR Flow, Grandio Flow, and Venus Bulk Fill) and a conventional flowable composite resin (Revolution Formula 2). Depth of cure was measured in terms of bottom-maximum Knoop hardness number (KHN) ratios and the International Organization for Standardization (ISO) 4049 scrape technique. Shades A2 and A3 of SureFil SDR Flow, Grandio Flow, and Revolution Formula 2 were tested. Venus Bulk Fill was tested in its only available shade (universal). Specimens in thicknesses of 2, 3, 4, 5, and 6 mm were polymerized for 20 or 40 seconds, and a hardness tester was used to determine the hardness ratios for each shade at each thickness. For the scraping technique, after specimens were exposed to the curing light, unpolymerized composite resin was removed with a plastic instrument, the polymerized composite was measured, and the length was divided by 2 per ISO guidelines. According to the KHN ratios and the scrape test, Venus Bulk Fill predictably exceeded the manufacturer's claim of a 4-mm depth of cure at both 20 and 40 seconds of curing time. The overall results for depth of cure showed that Venus Bulk Fill ≥ SureFil SDR Flow ≥ Grandio Flow ≥ Revolution Formula 2.

  19. Influence of light-exposure methods and depths of cavity on the microhardness of dual-cured core build-up resin composites

    Directory of Open Access Journals (Sweden)

    Keiichi YOSHIDA

    2014-01-01

    Full Text Available Objective: The purpose of this study was to evaluate the Knoop hardness number (KHN of dual-cured core build-up resin composites (DCBRCs at 6 depths of cavity after 3 post-irradiation times by 4 light-exposure methods. Material and Methods: Five specimens each of DCBRCs (Clearfil DC Core Plus [DCP] and Unifil Core EM [UCE] were filled in acrylic resin blocks with a semi-cylindrical cavity and light-cured using an LED light unit (power density: 1,000 mW/cm2at the top surface by irradiation for 20 seconds (20 s, 40 seconds (40 s, bonding agent plus 20 seconds (B+20 s, or 40 seconds plus light irradiation of both sides of each acrylic resin block for 40 seconds each (120 s. KHN was measured at depths of 0.5, 2.0, 4.0, 6.0, 8.0, and 10.0 mm at 0.5 hours, 24 hours, and 7 days post-irradiation. Statistical analysis was performed using repeated measures ANOVA and Tukey's compromise post-hoc test with a significance level of p0.05. In DCP, and not UCE, at 24 hours and 7 days post-irradiation, the B+20 s method showed significantly higher KHN at all depths of cavity, except the depth of 0.5 mm (p<0.05. Conclusion: KHN depends on the light-exposure method, use of bonding agent, depth of cavity, post-irradiation time, and material brand. Based on the microhardness behavior, DCBRCs are preferably prepared by the effective exposure method, when used for a greater depth of cavity.

  20. Effects of various light curing methods on the leachability of uncured substances and hardness of a composite resin.

    Science.gov (United States)

    Moon, H-J; Lee, Y-K; Lim, B-S; Kim, C-W

    2004-03-01

    The purpose of this study was to evaluate the effect of the various light curing units (plasma arc, halogen and light-emitting diodes) and irradiation methods (one-step, two-step and pulse) using different light energy densities on the leachability of unreacted monomers (Bis-GMA and UDMA) and the surface hardness of a composite resin (Z250, 3M). Leachability of the specimens immersed for 7 days in ethanol was analysed by HPLC. Vicker's hardness number (VHN) was measured immediately after curing (IC) and after immersion in ethanol for 7 days. Various irradiation methods with three curing units resulted in differences in the amount of leached monomers and VHN of IC when light energy density was lower than 17.0 J cm(-2) (P = 0.05). However, regardless of curing units and irradiation methods, these results were not different when the time or light energy density increased. When similar light energy density was irradiated (15.6-17.7 J cm(-2)), the efficiency of irradiation methods was different by the following order: one-step > or = two-step > pulse. These results suggest that the amount of leached monomers and VHN were influenced by forming polymer structure in activation and initiation stages of polymerization process with different light source energies and curing times.

  1. New-generation curing units and short irradiation time: the degree of conversion of microhybrid composite resin.

    Science.gov (United States)

    Scotti, Nicolla; Venturello, Alberto; Migliaretti, Giuseppe; Pera, Francesco; Pasqualini, Damiano; Geobaldo, Francesco; Berutti, Elio

    2011-09-01

    This in vitro study investigated the depth of cure of a microhybrid composite resin when cured with reduced times of exposure to three commercially available curing lights. Different sample thicknesses (1, 2, and 3 mm) were light cured in high intensity polymerization mode (2,400 mW/cm² for 5, 10, 15, and 20 seconds; 1,100 mW/cm² for 10, 20, 30, and 40 seconds; and 1,100 mW/cm² for 10, 20, 30, and 40 seconds, respectively). The degree of conversion (%) at the bottom of each sample was measured by Attenuated Total Reflection Fourier Transform Infrared (ATR F-TIR) analysis after each polymerization step. Data were analyzed by ANOVA for repeated measures, showing the degree of conversion was not influenced by the curing light employed (P = .622) but was significantly influenced by the thickness of composite resin (P conversion vs the shorter irradiation time permitted (T1) were not significant among different lamps but were significant among different thicknesses. The depth of cure of microhybrid composite resin appears not to be influenced by the curing light employed. Increased irradiation time significantly increases the degree of conversion. Thickness strongly influences depth of cure.

  2. Cure monitoring of epoxy resin by using fiber bragg grating sensor

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jin Hyuk [KEPCO, Naju (Korea, Republic of); Kim, Dae Hyun [Dept. of Mechanical and Automotive Engineering, Seoul National University of Science and Technology, Seoul (Korea, Republic of)

    2016-06-15

    In several industrial fields, epoxy resin is widely used as an adhesive for co-curing and manufacturing various structures. Controlling the manufacturing process is required for ensuring robust bonding performance and the stability of the structures. A fiber optic sensor is suitable for the cure monitoring of epoxy resin owing to the thready shape of the sensor. In this paper, a fiber Bragg grating (FBG) sensor was applied for the cure monitoring of epoxy resin. Based on the experimental results, it was demonstrated that the FBG sensor can monitor the status of epoxy resin curing by measuring the strain caused by volume shrinkage and considering the compensation of temperature. In addition, two types of epoxy resin were used for the cure-monitoring; moreover, when compared to each other, it was found that the two types of epoxy had different cure-processes in terms of the change of strain during the curing. Therefore, the study proved that the FBG sensor is very profitable for the cure-monitoring of epoxy resin.

  3. The effect of different light-curing units on tensile strength and microhardness of a composite resin

    Directory of Open Access Journals (Sweden)

    Eduardo Batista Franco

    2007-12-01

    Full Text Available The aim of this study was to evaluate the influence of different light-curing units on the tensile bond strength and microhardness of a composite resin (Filtek Z250 - 3M/ESPE. Conventional halogen (Curing Light 2500 - 3M/ESPE; CL and two blue light emitting diode curing units (Ultraled - Dabi/Atlante; UL; Ultrablue IS - DMC; UB3 and UB6 were selected for this study. Different light intensities (670, 130, 300, and 600 mW/cm², respectively and different curing times (20s, 40s and 60s were evaluated. Knoop microhardness test was performed in the area corresponding to the fractured region of the specimen. A total of 12 groups (n=10 were established and the specimens were prepared using a stainless steel mold composed by two similar parts that contained a cone-shaped hole with two diameters (8.0 mm and 5.0 mm and thickness of 1.0 mm. Next, the specimens were loaded in tensile strength until fracture in a universal testing machine at a crosshead speed of 0.5 mm/min and a 50 kg load cell. For the microhardness test, the same matrix was used to fabricate the specimens (12 groups; n=5. Microhardness was determined on the surfaces that were not exposed to the light source, using a Shimadzu HMV-2 Microhardness Tester at a static load of 50 g for 30 seconds. Data were analyzed statistically by two-way ANOVA and Tukey's test (p<0.05. Regarding the individual performance of the light-curing units, there was similarity in tensile strength with 20-s and 40-s exposure times and higher tensile strength when a 60-s light-activation time was used. Regarding microhardness, the halogen lamp had higher results when compared to the LED units. For all light-curing units, the variation of light-exposure time did not affect composite microhardness. However, lower irradiances needed longer light-activation times to produce similar effect as that obtained with high-irradiance light-curing sources.

  4. Assessing the irradiance delivered from light-curing units in private dental offices in Jordan.

    Science.gov (United States)

    Maghaireh, Ghada A; Alzraikat, Hanan; Taha, Nessrin A

    2013-08-01

    The authors conducted a study to examine the irradiance from light-curing units (LCUs) used in dental offices in Jordan. Two of the authors visited 295 private dental offices (15 percent) in Jordan and collected the following information about the LCUs: age, type (quartz-tungsten-halogen or light-emitting diode), date of last maintenance, type of maintenance, last date of use, number of times used during the day, availability of a radiometer, exposure time for each resin-based composite increment, size of light-curing tips and presence of resin-based composite on the tips. The authors used a radiometer to measure the irradiance from the LCUs. They used linear regression with stepwise correlation for the statistical analysis. The authors set the minimum acceptable irradiance at 300 milliwatts/square centimeter. The mean irradiance of the 295 LCUs examined was 361 mW/cm(2), and 136 LCUs (46.1 percent) delivered an irradiance of less than 300 mW/cm(2). The unit's age, type and presence of resin-based composite on the light-curing tips had a significant effect on the irradiance (P ≤ .001). Only 37 of the 141 quartz-tungsten-halogen units (26.2 percent) and 122 of the 154 light-emitting diode units (79.2 percent) delivered at least 300 mW/cm(2). Resin contamination on the light-curing tips had a significant effect on the irradiance delivered. The irradiance from the LCUs decreased with use. Practical Implications. The irradiance from many of the units in this study was less than 300 mW/cm(2), which may affect the quality of resin-based composite restorations. Dentists should monitor the performance of the LCUs in their offices weekly.

  5. Cycloaliphatic epoxide resins for cationic UV - cure

    International Nuclear Information System (INIS)

    Verschueren, K.; Balwant Kaur

    1999-01-01

    This paper introduces the cyclo - aliphatic epoxide resins used for the various applications of radiation curing and their comparison with acrylate chemistry. Radiation curable coatings and inks are pre - dominantly based on acrylate chemistry but over the last few years, cationic chemistry has emerged successfully with the unique properties inherent with cyclo - aliphatic epoxide ring structures. Wide variety of cationic resins and diluents, the formulation techniques to achieve the desired properties greatly contributes to the advancement of UV - curing technology

  6. Effects of layering technique on the shade of resin overlays and the microhardness of dual cure resin cement

    Directory of Open Access Journals (Sweden)

    Hoon-Sang Chang

    2014-06-01

    Full Text Available The purpose of this study was to assess the color of layered resin overlays and to test the early microhardness of dual cure resin cement (DCRC light cured through the layered resin overlays. Resin overlays of 1.5 mm thickness were fabricated with the A3 shade of Z350 (Group 1L, the A3B and A3E shades of Supreme XT (Group 2L, and the A3, E3, and T1 shades of Sinfony (Group 3L using one, two, and three layers, respectively (n = 7. Each layer of the resin overlays was set in equal thickness. The color of the resin overlays was measured with a colorimeter and compared with an A3 shade resin denture tooth. DCRC was light cured through the resin overlays, and the early microhardness of the DCRC was measured. The ΔE value between the denture tooth and the resin overlays and the Vickers hardness number (VHN of the DCRC were analyzed with one-way ANOVA and Tukey’s HSD test. The color differences were 8.9 ± 0.5, 5.3 ± 1.0, and 7.3 ± 0.5 and the VHNs were 19.4 ± 1.1, 21.1 ± 0.9, and 29.3 ± 0.6 for Groups 1L, 2L, and 3L, respectively. Therefore, to match the designated tooth color of resin inlays and to increase the early microhardness of DCRC, layered resin inlays are more appropriate than single-dentin-layer resin inlays. However, the translucent layer should be used cautiously because the color difference of resin inlays with a translucent layer was affected more than those without a translucent layer.

  7. Cytotoxicity of Light-Cured Dental Materials according to Different Sample Preparation Methods

    Directory of Open Access Journals (Sweden)

    Myung-Jin Lee

    2017-03-01

    Full Text Available Dental light-cured resins can undergo different degrees of polymerization when applied in vivo. When polymerization is incomplete, toxic monomers may be released into the oral cavity. The present study assessed the cytotoxicity of different materials, using sample preparation methods that mirror clinical conditions. Composite and bonding resins were used and divided into four groups according to sample preparation method: uncured; directly cured samples, which were cured after being placed on solidified agar; post-cured samples were polymerized before being placed on agar; and “removed unreacted layer” samples had their oxygen-inhibition layer removed after polymerization. Cytotoxicity was evaluated using an agar diffusion test, MTT assay, and confocal microscopy. Uncured samples were the most cytotoxic, while removed unreacted layer samples were the least cytotoxic (p < 0.05. In the MTT assay, cell viability increased significantly in every group as the concentration of the extracts decreased (p < 0.05. Extracts from post-cured and removed unreacted layer samples of bonding resin were less toxic than post-cured and removed unreacted layer samples of composite resin. Removal of the oxygen-inhibition layer resulted in the lowest cytotoxicity. Clinicians should remove unreacted monomers on the resin surface immediately after restoring teeth with light-curing resin to improve the restoration biocompatibility.

  8. Short communication: pre- and co-curing effect of adhesives on shear bond strengths of composite resins to primary enamel and dentine: an in vitro study.

    Science.gov (United States)

    Viswanathan, R; Shashibhushan, K K; Subba Reddy, V V

    2011-12-01

    To evaluate and compare shear bond strengths of composite resins to primary enamel and dentine when the adhesives are pre-cured (light cured before the application of the resin) or co-cured (adhesive and the resin light cured together). Buccal surfaces of 80 caries-free primary molars were wet ground to create bonding surfaces on enamel and dentine and specimens mounted on acrylic blocks. Two bonding agents (Prime and Bond NT® and Xeno III®) were applied to either enamel or dentine as per manufacturer's instructions. In 40 specimens, the bonding agent was light cured immediately after the application (pre-cured). The other 40 specimens were not light cured until the composite resin application (co-cured). Resin composite cylinders were made incrementally using acrylic moulds over the adhesives and light cured. Specimens were stored in deionised water for 24 hours at room temperature. Shear bond strength was measured using an Instron universal testing machine (in MPa) and was analysed with Student's unpaired t test. Light curing the adhesive separately produced significantly higher bond strengths to primary dentine than co-curing (padhesive separately did not produce significantly different bond strengths to primary enamel (p>0.05). Curing sequence had no significant effect on shear bond strength of adhesives on the primary enamel. Pre-curing adhesives before curing composite resins produced greater shear bond strength to primary dentine.

  9. Influência do tipo de ponteira condutora de luz na microdureza de uma resina composta Influence of the different light-curing TIPS in the microhardness of a composite resin

    Directory of Open Access Journals (Sweden)

    Máx Dobrovolski

    2010-01-01

    Full Text Available O objetivo desta pesquisa foi avaliar a influência do tipo de ponteira condutora de luz na microdureza de uma resina composta micro-híbrida. Foram confeccionados 14 corpos de prova da resina composta Opallis (FGM com dimensões: 5 x 2 mm, divididos em dois grupos de acordo com a ponteira condutora de luz do aparelho fotoativador de lâmpada halógena Optilight Plus - GNATUS/300 mW.cm-2. GI - ponteira condutora de luz de fibra óptica; GII - ponteira condutora de luz de polímero. Após 24 horas, as medidas de microdureza foram efetuadas com um microdurômetro HMV 2000 (Shimadzu Japão. Cinco penetrações foram efetuadas em cada superfície (topo e base totalizando 10 penetrações para cada corpo de prova. A análise estatística dos resultados realizada por meio do teste de ANOVA não apresentou diferenças significativas entre os tipos de ponta condutora de luz nas superfícies avaliadas. A análise estatística demonstrou diferença significativa nos valores médios de microdureza superficial entre as superfícies de topo e de base, para ambas as ponteiras. Com base nos resultados obtidos, foi possível concluir que as ponteiras de luz não interferem na microdureza da resina composta, e que ambas apresentaram diferenças estatisticamente significativas nos valores de microdureza das superfícies topo e base.The aim of this study is to evaluate the influence of the light-curing tips on the microhardness of a micro-hybrid composite resin. Fourteen samples of Opallis (FGM composite resin with 5 x 2 mm were prepared. The specimens were divided into two groups according to the light-curing tips from a halogen light curing unit (Optilight Plus -GNATUS/300 mW.cm-2: GI - optical fiber light-curing; GII - polymer light-curing. After 24 hours, the microhardness measurements were determined using the HMV 2000 (Shimadzu Japan. Five measurements were made on each surface (top and bottom totalizing 10 indentations for each sample. Statistical analysis

  10. Acrylated Palm Oil Resins for Radiation (UV) Curing of Over Print Varnish (OPV)

    International Nuclear Information System (INIS)

    Norshamsul Arif; Mohd Hilmi Mahmood; Khairul Zaman Mohd Dahlan; Rosley Che Ismail; Flora Sim; Sharilla Muhammad Faizal

    2010-01-01

    The purpose of this project was to determine the effects of Acrylated Epoxidized Palm Oil (EPOLA) on a radiation (UV) curing Over Print Varnish (OPV) application. The initial target was to produce an environmentally friendly resin (non-VOC) and reduce the dependence on petroleum (hydrocarbon) based products which are more toxic. Toxicity was determined via Acute Oral Toxicity (LD50), OECD 401 and Acute Toxicity (Dermal), OECD 402 technique whilst the reactivity, chemical resistance and other physical properties were obtained from actual printing application test. The developed EPOLA resin was combined with acrylated monomers, photo initiator(s) and additives in typical OPV formulation before being chemically converted into protective glossy printed film under Ultra Violet (UV-C) light. The gloss, flexibility and adhesion effects are significantly greater than conventional OPV epoxy based coupled with further extremely low irritancy to skin. The contributions of this project are twofold. First, the toxicity of developed acrylated Palm Oil resin is certainly lower than conventional epoxy acrylates resin. Secondly, the benefits towards radiation curing OPV applications were significantly demonstrated. (author)

  11. Polymerization and curing kinetics of furan resins under conventional and microwave heating

    International Nuclear Information System (INIS)

    Lopez de Vergara, Unai; Sarrionandia, Mariasun; Gondra, Koldo; Aurrekoetxea, Jon

    2014-01-01

    Graphical abstract: - Highlights: • The furan resin structure was investigated using IR and RMN techniques. • The polymerization of furan resins was developed based on multistage kinetics. • Vyazovkin numerical analysis was found the most accurate kinetic method. • Microwave curing of furan resins was much faster than thermal curing. - Abstract: The challenge of this work is the microwave curing study of low free-furfuryl alcohol content furan resins. The chemical characterization of the furan resins has been made by infrared spectroscopy and nuclear magnetic resonance spectroscopy. The chemical composition of the resin and its reactions with p-toluensulfonic acid are proposed, with the aim of understanding the mechanism responsible for the main reactions. The results show the presence of methyl and ether bridges between the furan rings, and the formation of ketone and conjugated structures. Furthermore, the curing kinetics of the furan resins has been characterized by differential scanning calorimetry. Different methods have been applied in order to obtain and compare the activation energy of the process. Vyazovkin numerical analysis was found the most accurate method. Finally, microwave and conventional curing processes has been compared. The analysis showed that microwave curing of furan resins was twice faster than thermal curing

  12. Polymerization and curing kinetics of furan resins under conventional and microwave heating

    Energy Technology Data Exchange (ETDEWEB)

    Lopez de Vergara, Unai, E-mail: bergara@gaiker.es [Plastics and Composites Department, Gaiker IK4 Research Centre, Parque Tecnológico, Ed. 202, 48170 Zamudio Spain (Spain); Mechanical Engineering and Industrial Manufacturing Department, Mondragón Unibertsitatea, Loramendi 4, 20500 Mondragón Spain (Spain); Sarrionandia, Mariasun [Mechanical Engineering and Industrial Manufacturing Department, Mondragón Unibertsitatea, Loramendi 4, 20500 Mondragón Spain (Spain); Gondra, Koldo [Plastics and Composites Department, Gaiker IK4 Research Centre, Parque Tecnológico, Ed. 202, 48170 Zamudio Spain (Spain); Aurrekoetxea, Jon [Mechanical Engineering and Industrial Manufacturing Department, Mondragón Unibertsitatea, Loramendi 4, 20500 Mondragón Spain (Spain)

    2014-04-01

    Graphical abstract: - Highlights: • The furan resin structure was investigated using IR and RMN techniques. • The polymerization of furan resins was developed based on multistage kinetics. • Vyazovkin numerical analysis was found the most accurate kinetic method. • Microwave curing of furan resins was much faster than thermal curing. - Abstract: The challenge of this work is the microwave curing study of low free-furfuryl alcohol content furan resins. The chemical characterization of the furan resins has been made by infrared spectroscopy and nuclear magnetic resonance spectroscopy. The chemical composition of the resin and its reactions with p-toluensulfonic acid are proposed, with the aim of understanding the mechanism responsible for the main reactions. The results show the presence of methyl and ether bridges between the furan rings, and the formation of ketone and conjugated structures. Furthermore, the curing kinetics of the furan resins has been characterized by differential scanning calorimetry. Different methods have been applied in order to obtain and compare the activation energy of the process. Vyazovkin numerical analysis was found the most accurate method. Finally, microwave and conventional curing processes has been compared. The analysis showed that microwave curing of furan resins was twice faster than thermal curing.

  13. Surface Modified Characteristics of the Tetracalcium Phosphate as Light-Cured Composite Resin Fillers

    Directory of Open Access Journals (Sweden)

    Wen-Cheng Chen

    2014-01-01

    Full Text Available The objectives of this study are to characterize the properties of light-cured composite resins that are reinforced with whisker surface-modified particles of tetracalcium phosphate (TTCP and to investigate the influence of thermal cycling on the reinforced composites properties. The characteristics of ultimate diametral tensile strength (DTS, moduli, pH values, and fracture surfaces of the samples with different amounts of surface-modified TTCP (30%–60% were determined before and after thermal cycling between 5°C and 55°C in deionized water for 600 cycles. The trends of all groups were ductile prior to thermal cycling and the moduli of all groups increased after thermal cycling. The ductile property of the control group without filler was not significantly affected. Larger amounts of fillers caused the particles to aggregate, subsequently decreasing the resin’s ability to disperse external forces and leading to brittleness after thermal cycling. Therefore, the trend of composite resins with larger amounts of filler would become more brittle and exhibited higher moduli after thermal cycling. This developed composite resin with surface modified-TTCP fillers has the potential to be successful dental restorative materials.

  14. A novel calorimetry technique for monitoring electron beam curing of polymer resins

    International Nuclear Information System (INIS)

    Chen, J.H.; Johnston, A.; Petrescue, L.; Hojjati, M.

    2006-01-01

    This paper describes the development of a calorimetry-based technique for monitoring of the curing of electron beam (EB) curable resins, including design of the calorimeter hardware and the development of an analytical model for calculating resin cure rates and radiation dose. Factors affecting the performance of the calorimeter were investigated. Experimental trials monitoring the curing of epoxy resin were conducted under single pass and multiple passes of EB irradiation. Results show that the developed calorimeter is a simple, inexpensive and reasonably accurate technique for monitoring the EB curing of cationic epoxies

  15. Effect of ultraviolet light irradiation and sandblasting treatment on bond strengths between polyamide and chemical-cured resin.

    Science.gov (United States)

    Asakawa, Yuya; Takahashi, Hidekazu; Iwasaki, Naohiko; Kobayashi, Masahiro

    2014-01-01

    The aim of this study was to evaluate the effects of ultraviolet light (UV) irradiation and sandblasting treatment on the shear bond strength between polyamide and chemical-cured resin. Three types of commercial polyamides were treated using UV irradiation, sandblasting treatment, and a combining sandblasting and UV irradiation. The shear bond strength was measured and analyzed using the Kruskal-Wallis test (α=0.05). Comparing shear bond strengths without surface treatment, from 4.1 to 5.7 MPa, the UV irradiation significantly increased the shear bond strengths except for Valplast, whose shear bond strengths ranged from 5.2 to 9.3 MPa. The sandblasting treatment also significantly increased the shear bond strengths (8.0 to 11.4 MPa). The combining sandblasting and UV irradiation significantly increased the shear bond strengths (15.2 to 18.3 MPa) comparing without surface treatment. This combined treatment was considered the most effective at improving the shear bond strength between polyamide and chemical-cured resin.

  16. Application conditions for ester cured alkaline phenolic resin sand

    Directory of Open Access Journals (Sweden)

    Ren-he Huang

    2016-07-01

    Full Text Available Five organic esters with different curing speeds: propylene carbonate (i.e. high-speed ester A; 1, 4-butyrolactone; glycerol triacetate (i.e. medium-speed ester B; glycerol diacetate; dibasic ester (DBE (i.e. low-speed ester C, were chosen to react with alkaline phenolic resin to analyze the application conditions of ester cured alkaline phenolic resin. The relationships between the curing performances of the resin (including pH value, gel pH value, gel time of resin solution, heat release rate of the curing reaction and tensile strength of the resin sand and the amount of added organic ester and curing temperature were investigated. The results indicated the following: (1 The optimal added amount of organic ester should be 25wt.%-30wt.% of alkaline phenolic resin and it must be above 20wt.%-50 wt.% of the organic ester hydrolysis amount. (2 High-speed ester A (propylene carbonate has a higher curing speed than 1, 4-butyrolactone, and they were both used as high-speed esters. Glycerol diacetate is not a high-speed ester in alkaline phenolic resin although it was used as a high-speed ester in ester cured sodium silicate sand; glycerol diacetate and glycerol triacetate can be used as medium-speed esters in alkaline phenolic resin. (3 High-speed ester A, medium-speed ester B (glycerol triacetate and low-speed ester C (dibasic ester, i.e., DBE should be used below 15 ìC, 35 ìC and 50 ìC, respectively. High-speed ester A or low-speed ester C should not be used alone but mixed with medium-speed ester B to improve the strength of the resin sand. (4 There should be a suitable solid content (generally 45wt.%-65wt.% of resin, alkali content (generally 10wt.%-15wt.% of resin and viscosity of alkaline phenolic resin (generally 50-300 mPa≤s in the preparation of alkaline phenolic resin. Finally, the technique conditions of alkaline phenolic resin preparation and the application principles of organic ester were discussed.

  17. Effect of microwave cured acrylic resin on candidal growth in complete denture

    International Nuclear Information System (INIS)

    Rasmy, A.H.M.

    2009-01-01

    This study was conducted to evaluate the effect of heat-cured acrylic resin denture base and microwave-cured acrylic resin denture base on candidal growth . Seven completely edentulous male patients with on history of denture wearing participated in this study. all the selected patients were re-habilitated by mucosa supported complete dentures .The dentures were constructed from conventional heat-cured acrylic resin denture base following monoplane concept of occlusion. Before dismissing the patients and one month after denture insertion, salivary samples were collected according to oral rinse technique. one month resting period was allowed so as candidal count can reach to normal, then dentures were re based using microwave-cured acrylic denture base, before denture insertion and one month after denture insertion, salivary sample were collected before and one month following the same oral rinse technique.

  18. Effect of dual-cure composite resin as restorative material on marginal adaptation of class 2 restorations.

    Science.gov (United States)

    Bortolotto, Tissiana; Melian, Karla; Krejci, Ivo

    2013-10-01

    The present study attempted to find a simple direct adhesive restorative technique for the restoration of Class 2 cavities. A self-etch adhesive system with a dual-cured core buildup composite resin (paste 1 + paste 2) was evaluated in its ability to restore proximo-occlusal cavities with margins located on enamel and dentin. The groups were: A, cavity filling (cf) with paste 1 (light-curing component) by using a layering technique; B, cf by mixing both pastes, bulk insertion, and dual curing; and C, cf by mixing both pastes, bulk insertion, and chemical curing. Two control groups (D, negative, bulk; and E, positive, layering technique) were included by restoring cavities with a classic three-step etch-and-rinse adhesive and a universal restorative composite resin. SEM margin analysis was performed before and after thermomechanical loading in a chewing simulator. Percentages (mean ± SD) of "continuous margins" were improved by applying the material in bulk and letting it self cure (54 ± 6) or dual cure (59 ± 9), and no significant differences were observed between these two groups and the positive control (44 ± 19). The present study showed that the dual-cured composite resin tested has the potential to be used as bulk filling material for Class 2 restorations. When used as filling materials, dual-cure composite resins placed in bulk can provide marginal adaptation similar to light-cured composites applied with a complex stratification technique.

  19. Translucency, opalescence and light transmission characteristics of light-cured resin composites.

    Science.gov (United States)

    Arimoto, Ayako; Nakajima, Masatoshi; Hosaka, Keiichi; Nishimura, Kozo; Ikeda, Masaomi; Foxton, Richard M; Tagami, Junji

    2010-11-01

    To evaluate the translucency, opalescence and light transmission characteristics of resin composites with different thicknesses. Disks of three resin composites (Estelite∑, Beautifil II, Clearfil Majesty) of A2 shade were prepared in diameter of 10mm with various thicknesses (0.5mm, 1.0mm and 2.0mm). Color was measured according to CIELAB color scale on a reflection spectrophotometer and a color haze meter, and translucency parameter (TP) and opalescence parameter (OP) were calculated. Using the distribution graphs of transmitted light intensity on a goniophotometer, diffusion factor (DF) as an indicator for a diffuse transmission property and peak gain (G0) for a straight-line transmission property were calculated. The TP and G0 values significantly decreased in the order: 0.5mm>1.0mm>2.0mm thickness (popalescence (OP) of resin composites had a significant correlation with a diffuse transmission property (DF). When more than 1.0mm thickness of resin composites, translucency and opalescence were influenced by the thickness, in which translucency significantly decreased and opalescence significantly increased. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  20. Cure shrinkage in casting resins

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, J. Brock [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-02-01

    A method is described whereby the shrinkage of a casting resin can be determined. Values for the shrinkage of several resin systems in frequent use by Sandia have been measured. A discussion of possible methods for determining the stresses generated by cure shrinkage and thermal contraction is also included.

  1. Dsc cure kinetics of an unsaturated polyester resin using empirical kinetic model

    International Nuclear Information System (INIS)

    Abdullah, I.

    2015-01-01

    In this paper, the kinetics of curing of unsaturated polyester resin initiated with benzoyl peroxide was studied. In case of unsaturated polyester (UP) resin, isothermal test alone could not predict correctly the curing time of UP resin. Therefore, isothermal kinetic analysis through isoconventional adjustment was used to correctly predict the curing time and temperature of UP resin. Isothermal kinetic analysis through isoconversional adjustment indicated that 97% of UP resin cures in 33 min at 120 degree C. Curing of UP resin through microwaves was also studied and found that 67% of UP resin cures in 1 min at 120 degree C. The crosslinking reaction of UP resin is so fast at 120 degree C that it becomes impossible to predict correctly the curing time of UP resin using isothermal test and the burial of C=C bonds in microgels makes it impossible to be fully cured by microwaves at 120 degree C. The rheological behaviour of unsaturated polyester resin was also studied to observe the change in viscosity with respect to time and temperature. (author)

  2. Curing kinetics of visible light curing dental resin composites investigated by dielectric analysis (DEA).

    Science.gov (United States)

    Steinhaus, Johannes; Hausnerova, Berenika; Haenel, Thomas; Großgarten, Mandy; Möginger, Bernhard

    2014-03-01

    During the curing process of light curing dental composites the mobility of molecules and molecule segments is reduced leading to a significant increase of the viscosity as well as the ion viscosity. Thus, the kinetics of the curing behavior of 6 different composites was derived from dielectric analysis (DEA) using especially redesigned flat sensors with interdigit comb electrodes allowing for irradiation at the top side and measuring the ion viscosity at the bottom side. As the ion viscosities of dental composites change 1-3 orders of magnitude during the curing process, DEA provides a sensitive approach to evaluate their curing behavior, especially in the phase of undisturbed chain growth. In order to determine quantitative kinetic parameters a kinetic model is presented and examined for the evaluation of the ion viscosity curves. From the obtained results it is seen that DEA might be employed in the investigation of the primary curing process, the quality assurance of ingredients as well as the control of processing stability of the light curing dental composites. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  3. Monitoring cure of composite resins using frequency dependent electromagnetic sensing techniques

    Science.gov (United States)

    Kranbuehl, D. E.; Hoff, M. S.; Loos, A. C.; Freeman, W. T., Jr.; Eichinger, D. A.

    1988-01-01

    A nondestructive in situ measurement technique has been developed for monitoring and measuring the cure processing properties of composite resins. Frequency dependent electromagnetic sensors (FDEMS) were used to directly measure resin viscosity during cure. The effects of the cure cycle and resin aging on the viscosity during cure were investigated using the sensor. Viscosity measurements obtained using the sensor are compared with the viscosities calculated by the Loos-Springer cure process model. Good overall agreement was obtained except for the aged resin samples.

  4. A Comparison of the Shear Bond Strength of Orthodontic Brackets Bonded With Light-Emitting Diode and Halogen Light-Curing Units

    Directory of Open Access Journals (Sweden)

    SM. Abtahi

    2006-09-01

    Full Text Available Statement of the problem: Various methods such as light emitting diode (LED have been used to enhance the polymerization of resin-based orthodontic adhesives. There is a lack of information on the advantages and disadvantages of different light curing systems.Purpose: The aim of this study was to compare the effect of LED and halogen light curing systems on the shear bond strength of orthodontic brackets.Materials and Methods: Forty extracted human premolars were etched with 37% phosphoric acid and cleansed with water spray and air dried. The sealant was applied on the tooth surface and the brackets were bonded using Transbond adhesive (3M Unitek,Monrovia, Calif. Adhesives were cured for 40 and 20 seconds with halogen (Blue Light, APOZA, Taiwan and LED (Blue dent, Smart, Yugoslavia light-curing systems,respectively. Specimens were thermocycled 2500 times (from 5 to 55 °C and the shear bond strength of the adhesive system was evaluated with an Universal testing machine (Zwick GmbH, Ulm, Germany at a crosshead speed of 1 mm/min until the bracketswere detached from the tooth. Adhesive remnant index (ARI scores were determined after bracket failure. The data were submitted to statistical analysis, using Mann-Whitney analysis and t-test.Results: No significant difference was found in bond strength between the LED and halogen groups (P=0.12. A significant difference was not observed in the adhesive remnant index scores between the two groups (P=0.97.Conclusion: Within the limitations of this in vitro study, the shear bond strength of resin-based orthodontic adhesives cured with a LED was statistically equivalent to those cured with a conventional halogen-based unit. LED light-curing units can be suggested for the polymerization of orthodontic bonding adhesives.

  5. Effects of He{sup +} ion implantation on surface properties of UV-cured Bis-GMA/TEGDMA bio-compatible resins

    Energy Technology Data Exchange (ETDEWEB)

    Fuentes, G.G., E-mail: gfuentes@ain.e [Center of Advanced Surface Engineering, AIN, Cordovilla-Pamplona, E-31191 (Spain); Esparza, J.; Rodriguez, R.J. [Center of Advanced Surface Engineering, AIN, Cordovilla-Pamplona, E-31191 (Spain); Manso-Silvan, M. [Departamento de Fisica Aplicada, Universidad Autonoma de Madrid, Cantoblanco, E-28049 (Spain); Palomares, J. [Instituto de Ciencia de Materiales de Madrid, ICMM-CSIC, Cantoblanco, E-28049 (Spain); Juhasz, J.; Best, S. [Cambridge Centre for Medical Materials, Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Str, Cambridge CB2 3QZ (United Kingdom); Mattilla, R.; Vallittu, P. [Institute of Dentistry, Turku Clinical Biomaterials Centre, Itaeinen Pitkaekatu 4, B FI-20520, Turku (Finland); Achanta, S. [Falex Tribology Wingepark 23 B, 3110 Rotselaar (Belgium); Giazzon, M.; Weder, G. [Centre Suisse d' Electronique et de Microtechnique, CSEM, Jaquet-Drot 1, CH-2002 Neuchatel (Switzerland); Donati, I. [Department of Life Sciences, University of Trieste, Via Licio Giorgieri 1, I 34127 Trieste (Italy)

    2011-01-15

    This work reports on the surface characterisation of 2,2-bis[4-(2-hydroxy-3-methacryloxyl-oxypropoxy)phenyl]propane/triethylene glycol dimethacrylate bio-compatible resins after high energy He{sup +} ion implantation treatments. The samples have been characterised by diffuse reflectance FT-IR, X-ray photo-electron spectroscopy, ultramicro-hardness and nano-scratch wear tests. In addition, osteblast cell assays MG-63 have been used to test the bio-compatibility of the resin surfaces after the ion implantation treatments. It has been observed that the maximum surface hardening of the resin surfaces is achieved at He-ion implantation energies of around 50 keV and fluences of 1 x 10{sup 16} cm{sup -2}. At 50 keV of He-ion bombardment, the wear rate of the resin surface decreases by a factor 2 with respect to the pristine resin. Finally, in vitro tests indicate that the He-ion implantation does not affect to the cell-proliferation behaviour of the UV-cured resins. The enhancement of the surface mechanical properties of these materials can have beneficial consequences, for instance in preventing wear and surface fatigue of bone-fixation prostheses, whose surfaces are continuously held to sliding and shearing contacts of sub-millimetre scale lengths.

  6. Bulk-fill resin composites: polymerization contraction, depth of cure, and gap formation.

    Science.gov (United States)

    Benetti, A R; Havndrup-Pedersen, C; Honoré, D; Pedersen, M K; Pallesen, U

    2015-01-01

    The bulk-filling of deep, wide dental cavities is faster and easier than traditional incremental restoration. However, the extent of cure at the bottom of the restoration should be carefully examined in combination with the polymerization contraction and gap formation that occur during the restorative procedure. The aim of this study, therefore, was to compare the depth of cure, polymerization contraction, and gap formation in bulk-fill resin composites with those of a conventional resin composite. To achieve this, the depth of cure was assessed in accordance with the International Organization for Standardization 4049 standard, and the polymerization contraction was determined using the bonded-disc method. The gap formation was measured at the dentin margin of Class II cavities. Five bulk-fill resin composites were investigated: two high-viscosity (Tetric EvoCeram Bulk Fill, SonicFill) and three low-viscosity (x-tra base, Venus Bulk Fill, SDR) materials. Compared with the conventional resin composite, the high-viscosity bulk-fill materials exhibited only a small increase (but significant for Tetric EvoCeram Bulk Fill) in depth of cure and polymerization contraction, whereas the low-viscosity bulk-fill materials produced a significantly larger depth of cure and polymerization contraction. Although most of the bulk-fill materials exhibited a gap formation similar to that of the conventional resin composite, two of the low-viscosity bulk-fill resin composites, x-tra base and Venus Bulk Fill, produced larger gaps.

  7. Effect of cure cycle on curing process and hardness for epoxy resin

    Directory of Open Access Journals (Sweden)

    2009-09-01

    Full Text Available A 3-dimensional finite element model is developed to simulate and analyze the temperature and degree of cure field of epoxy casting part during cure process. The present model based on general finite element software ABAQUS is verified by literature example and experimental data. The numerical results show good agreement with literature example and measured data, and are even more accurate than the simulation of literature. After modeling successfully, the influence of temperature cure cycle ramps have on the temperature and degree of cure gradient is investigated. Moreover, the effect of non-uniform temperature and degree of cure field within epoxy casting part on hardness is demonstrated. The present model provides an accurate and novel method that allows further insight into the process of cure for epoxy resin.

  8. Monitoring the Cure State of Thermosetting Resins by Ultrasound.

    Science.gov (United States)

    Lionetto, Francesca; Maffezzoli, Alfonso

    2013-09-05

    The propagation of low intensity ultrasound in a curing resin, acting as a high frequency oscillatory excitation, has been recently proposed as an ultrasonic dynamic mechanical analysis (UDMA) for cure monitoring. The technique measures sound velocity and attenuation, which are very sensitive to changes in the viscoelastic characteristics of the curing resin, since the velocity is related to the resin storage modulus and density, while the attenuation is related to the energy dissipation and scattering in the curing resin. The paper reviews the results obtained by the authors' research group in the last decade by means of in-house made ultrasonic set-ups for both contact and air-coupled ultrasonic experiments. The basics of the ultrasonic wave propagation in polymers and examples of measurements of the time-evolution of ultrasonic longitudinal modulus and chemical conversion of different thermosetting resins are presented. The effect of temperature on the cure kinetics, the comparison with rheological, low frequency dynamic mechanical and calorimetric results, and the correlation between ultrasonic modulus and crosslinking density will be also discussed. The paper highlights the reliability of ultrasonic wave propagation for monitoring the physical changes taking place during curing and the potential for online monitoring during polymer and polymer matrix composite processing.

  9. Monitoring the Cure State of Thermosetting Resins by Ultrasound

    Directory of Open Access Journals (Sweden)

    Alfonso Maffezzoli

    2013-09-01

    Full Text Available The propagation of low intensity ultrasound in a curing resin, acting as a high frequency oscillatory excitation, has been recently proposed as an ultrasonic dynamic mechanical analysis (UDMA for cure monitoring. The technique measures sound velocity and attenuation, which are very sensitive to changes in the viscoelastic characteristics of the curing resin, since the velocity is related to the resin storage modulus and density, while the attenuation is related to the energy dissipation and scattering in the curing resin. The paper reviews the results obtained by the authors’ research group in the last decade by means of in-house made ultrasonic set-ups for both contact and air-coupled ultrasonic experiments. The basics of the ultrasonic wave propagation in polymers and examples of measurements of the time-evolution of ultrasonic longitudinal modulus and chemical conversion of different thermosetting resins are presented. The effect of temperature on the cure kinetics, the comparison with rheological, low frequency dynamic mechanical and calorimetric results, and the correlation between ultrasonic modulus and crosslinking density will be also discussed. The paper highlights the reliability of ultrasonic wave propagation for monitoring the physical changes taking place during curing and the potential for online monitoring during polymer and polymer matrix composite processing.

  10. Evaluation of the polymerization shrinkage of experimental flowable composite resins through optical coherence tomography

    Science.gov (United States)

    Carneiro, Vanda S. M.; Mota, Cláudia C. B. O.; Souza, Alex F.; Cajazeira, Marlus R. R.; Gerbi, Marleny E. M. M.; Gomes, Anderson S. L.

    2018-02-01

    This study evaluated the polymerization shrinkage of two experimental flowable composite resins (CR) with different proportions of Urethane dimethacrylate (UDMA)/triethylene glycol dimethacrylate (TEGDMA) monomers in the organic matrix (50:50 and 60:40, respectively). A commercially available flowable CR, Tetric N-Flow (Ivoclair Vivadent, Liechtenstein, Germany), was employed as the control group. The resins were inserted in a cylindrical teflon mold (7 mm diameter, 0.6 mm height) and scanned with OCT before photoactivation, immediately after and 15 minutes after light-curing (Radii-Cal, SDI, Australia, 1,200 mW/cm2 ) exposure. A Callisto SD-OCT system (Thorlabs Inc, USA), operating at 930 nm central wavelength was employed for imaging acquisition. Cross-sectional OCT images were captured with 8 mm transverse scanning (2000x512 matrix), and processed by the ImageJ software, for comparison between the scanning times and between groups. Pearson correlation showed significant shrinkage for all groups in each time analyzed. Kruskal-Wallis test showed greater polymerization shrinkage for the 50:50 UDMA/TEGDMA group (p=0.001), followed by the control group (p=0.018). TEGDMA concentration was proportionally related to the polymerization shrinkage of the flowable composite resins.

  11. Composite cements benefit from light-curing.

    Science.gov (United States)

    Lührs, Anne-Katrin; De Munck, Jan; Geurtsen, Werner; Van Meerbeek, Bart

    2014-03-01

    To investigate the effect of curing of composite cements and a new ceramic silanization pre-treatment on the micro-tensile bond strength (μTBS). Feldspathic ceramic blocks were luted onto dentin using either Optibond XTR/Nexus 3 (XTR/NX3; Kerr), the silane-incorporated 'universal' adhesive Scotchbond Universal/RelyX Ultimate (SBU/RXU; 3M ESPE), or ED Primer II/Panavia F2.0 (ED/PAF; Kuraray Noritake). Besides 'composite cement', experimental variables were 'curing mode' ('AA': complete auto-cure at 21°C; 'AA*': complete auto-cure at 37°C; 'LA': light-curing of adhesive and auto-cure of cement; 'LL': complete light-curing) and 'ceramic surface pre-treatment' ('HF/S/HB': hydrofluoric acid ('HF': IPS Ceramic Etching Gel, Ivoclar-Vivadent), silanization ('S': Monobond Plus, Ivoclar-Vivadent) and application of an adhesive resin ('HB': Heliobond, Ivoclar-Vivadent); 'HF/SBU': 'HF' and application of the 'universal' adhesive Scotchbond Universal ('SBU'; 3M ESPE, only for SBU/RXU)). After water storage (7 days at 37°C), ceramic-dentin sticks were subjected to μTBS testing. Regarding the 'composite cement', the significantly lowest μTBSs were measured for ED/PAF. Regarding 'curing mode', the significantly highest μTBS was recorded when at least the adhesive was light-cured ('LA' and 'LL'). Complete auto-cure ('AA') revealed the significantly lowest μTBS. The higher auto-curing temperature ('AA*') increased the μTBS only for ED/PAF. Regarding 'ceramic surface pre-treatment', only for 'LA' the μTBS was significantly higher for 'HF/S/HB' than for 'HF/SBU'. Complete auto-cure led to inferior μTBS than when either the adhesive (on dentin) or both adhesive and composite cement were light-cured. The use of a silane-incorporated adhesive did not decrease luting effectiveness when also the composite cement was light-cured. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  12. SORPTION AND SOLUBILITY OF LOW-SHRINKAGE RESIN-BASED DENTAL COMPOSITES

    Directory of Open Access Journals (Sweden)

    Sevda Yantcheva

    2016-04-01

    Full Text Available Background: Resin-based composites are well-established restorative materials. However, these materials may absorb significant amounts of water when exposed to aqueous environments. Sorption and solubility are affecting composite restorations by two different mechanisms; the first is the up taking of water producing an increased weight and the second is the dissolution of materials in water, leading to a weight reduction of the final conditioned samples. Objective: To measure the water sorption and solubility of different low-shrinkage resin-based composites. Six materials were selected: Filtek P60, Filtek Ultimate, SonicFill, Filtek Silorane, Kalore and Venus Diamond. Materials and methods: Five disc specimens were prepared of each material and polymerized with diode light-curing unit. Water sorption and solubility of the different materials were were calculated by means of weighting the samples before and after water immersion and desiccation. Data were statistically analyzed using Shapiro-Wilk One Way Analysis of Variance followed by the Holm-Sidak comparison test . Results: There were significant differences (p<=0.001 between materials regarding sorption and solubility. Regarding sorption F. Silorane showed lowest values, followed by SonicFill, without significant difference between them. Statistical significant differences exist between F. Silorane and F.P60, F. Ultimate, Kalore. Significant differences exist between SonicFill and F. Ultimate. F.Silorane (-0.018 and Kalore (-0.010 showed lowest values of solubility but there were marginal difference among all composites investigated. Conclusions: 1.The material with lowest values of sorption and solubility was F.Silorane. 2. The attained sorption and solubility values for composites are influenced by the differences in resin matrix composition and filler contend. 3. Modifications of dimethacrylate matrix did not minimize significantly sorption and solubility of composites. 4. Besides water

  13. Post-cure depth of cure of bulk fill dental resin-composites.

    Science.gov (United States)

    Alrahlah, A; Silikas, N; Watts, D C

    2014-02-01

    To determine the post-cure depth of cure of bulk fill resin composites through using Vickers hardness profiles (VHN). Five bulk fill composite materials were examined: Tetric EvoCeram(®) Bulk Fill, X-tra base, Venus(®) Bulk Fill, Filtek™ Bulk Fill, SonicFill™. Three specimens of each material type were prepared in stainless steel molds which contained a slot of dimensions (15 mm × 4 mm × 2 mm), and a top plate. The molds were irradiated from one end. All specimens were stored at 37°C for 24h, before measurement. The Vickers hardness was measured as a function of depth of material, at 0.3mm intervals. Data were analysed by one-way ANOVA using Tukey post hoc tests (α=0.05). The maximum VHN ranged from 37.8 to 77.4, whilst the VHN at 80% of max.VHN ranged from 30.4 to 61.9. The depth corresponding to 80% of max.VHN, ranged from 4.14 to 5.03 mm. One-way ANOVA showed statistically significant differences between materials for all parameters tested. SonicFill exhibited the highest VHN (pFill the lowest (p≤0.001). SonicFill and Tetric EvoCeram Bulk Fill had the greatest depth of cure (5.03 and 4.47 mm, respectively) and was significant's different from X-tra base, Venus Bulk Fill and Filtek Bulk Fill (p≤0.016). Linear regression confirmed a positive regression between max.VHN and filler loading (r(2)=0.94). Bulk fill resin composites can be cured to an acceptable post-cure depth, according to the manufacturers' claims. SonicFill and Tetric EvoCeram Bulk Fill had the greatest depth of cure among the composites examined. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  14. Fracture resistance of premolar teeth restored with silorane-based or dimethacrylate-based composite resins.

    Science.gov (United States)

    Akbarian, Golsa; Ameri, Hamideh; Chasteen, Joseph E; Ghavamnasiri, Marjaneh

    2014-01-01

    To restore posterior teeth using low-shrinkage composite to minimize microleakage. To compare the fracture resistance of mesio-occlusal-distal (MOD) cavity preparations restored with either low-shrinkage composite or with dimethacrylate-based composite in conjunction with cavity liners and without them. The null hypothesis of the study is that there are no differences in either fracture resistance or fracture mode between the silorane group and dimethacrylate groups with and without the use of cavity liners. Sixty maxillary premolars were divided into six groups of 10. MOD cavities were prepared in four groups: F: posterior composite (Filtek P60); GF: 0.5-mm Glass Ionomer (Fuji LC) + posterior composite; FF: 0.5-mm flowable composite (Filtek Supreme XT) + posterior composite; and S: low-shrinkage composite (Filtek P90). Negative (N) and positive (P) control groups consisted of unrestored and sound teeth, respectively. The specimens were thermocycled and loaded. Data were analyzed using analysis of variance, Tukey, and chi-square tests (α = 0.05). Groups FF (1643.09 ± 187/80 N) and GF (1596.80 ± 163/93 N) (p = 0.06 > 0.05) were statistically identical, although less than group P (1742/33 ± 110/08 N), but still demonstrated greater fracture resistance than the other groups. The fracture resistance of group S (1434/69 ± 107/62 N) was identical to GF and FF (p = 0.06 > 0.05). The fracture resistance of F (1353/19 ± 233/90 N) was less than GF and FF, and statistically identical to S (p = 0.87 > 0.05). Silorane-based composite showed a resistance to fracture similar to methacrylate-based composite restorations regardless of whether cavity liners were used. The findings of this study support the selection of silorane-based composite for the restoration of maxillary premolars with standardized Class II cavity preparations in order to strengthen the resistance to fracture to the same extent as do dimethacrylate

  15. Stress and flow analyses of ultraviolet-curable resin during curing

    Science.gov (United States)

    Umezaki, Eisaku; Okano, Akira; Koyama, Hiroto

    2014-06-01

    The stress and flow generated in ultraviolet (UV)-curable resin during curing in molds were measured to investigate their relationship. The specimens were molds consisting of glass plates and acrylic bars, and UV-curable liquid resin. The specimens were illuminated from above with UV rays. Photoelastic and visual images were separately obtained at a constant time interval using cameras during curing. To help obtain the visual images, acrylic powder was mixed with the liquid resin. The stress was obtained from the photoelastic images by a digital photoelastic technique with phase stepping, and the flow was obtained from the visual images by a particle-tracking velocimetry technique. Results indicate that the stress generated in the UV-curable resin during curing depends on the degree of contact between the mold and the cured area of the resin, and is hardly related to the flow.

  16. Light resin curing devices - a hazard evaluation

    International Nuclear Information System (INIS)

    Glansholm, A.

    1985-09-01

    An evaluation has been made of optical hazards to the eye from 18 specified lamps designed for curing dental composite plastic fillings. Radiation source in all of the investigated units were incandescent lamps of the tungsten metal halide type. Ultraviolet and visible radiation was measured with a calibrated EGandG 585 spectroradiometer system. Tables and diagrams of spectral radiance (Wm -2 nm -1 sr -1 ) are given. Hazard evaluation based on the ACGIH Threshold Limit Values of ultraviolet and visible radiation gave the following results: 1. Ultraviolet radiation is of no concern ( -2 UVA at 10 cm). 2. Reflexes from teeth are harmless. 3. Retinal thermal injury hazard (permanent burn damage) is diminnutive and non-existent if the equipment is handled with sense (irradiation of an unprotected eye at a distance less than 10 cm should be avoided). 4. Retinal photochemical (blue-light) injury may appear after direct viewing of the end of the fiber-optics cable. A table with safe exposure time for each apparatus is given. Proper protective goggles can eliminate the blue-light hazard. (Author)

  17. Cytotoxicity and cytokine expression induced by silorane and methacrylate-based composite resins.

    Science.gov (United States)

    Longo, Daniele Lucca; Paula-Silva, Francisco Wanderley Garcia; Faccioli, Lucia Helena; Gatón-Hernández, Patrícia Maria; Queiroz, Alexandra Mussolino de; Silva, Léa Assed Bezerra da

    2016-01-01

    The aim of this study was to evaluate cytotoxicity and cytokine production induced by light-cured or non-light-cured methacrylate-based and silorane composite resins in RAW 264.7 macrophages. Cells were stimulated with the extracts from light-cured or non-light-cured composite resins. After incubation for 24 h, cytotoxicity was assessed with the lactate dehydrogenase (LDH) and methyl thiazolyl tetrazolium (MTT) assays, and total protein was quantified using the Lowry method. TNF-α detection was examined with an enzyme-linked immunosorbent assay (ELISA) conducted with cell supernatants after cell stimulation for 6, 12, and 24 h. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey's post hoc test (α=0.05). KaloreTM and FiltekTM Silorane were cytotoxic with or without light curing (p0.05). However, after 24 h FiltekTM Silorane inhibited the production of TNF-α (p<0.05). KaloreTM and FiltekTM Silorane were cytotoxic regardless of light curing. The extract obtained from KaloreTM after 15 days of incubation stimulated the production of TNF-α, unlike that obtained from FiltekTM Silorane.

  18. Influence of power density and primer application on polymerization of dual-cured resin cements monitored by ultrasonic measurement.

    Science.gov (United States)

    Takubo, Chikako; Yasuda, Genta; Murayama, Ryosuke; Ogura, Yukari; Tonegawa, Motoka; Kurokawa, Hiroyasu; Miyazaki, Masashi

    2010-08-01

    We used ultrasonic measurements to monitor the influence of power density and primer application on the polymerization reaction of dual-cured resin cements. The ultrasonic equipment comprised a pulser-receiver, transducers, and an oscilloscope. Resin cements were mixed and inserted into a transparent mould, and specimens were placed on the sample stage, onto which the primer, if used, was also applied. Power densities of 0 (no irradiation), 200, or 600 mW cm(-2) were used for curing. The transit time through the cement disk was divided by the specimen thickness to obtain the longitudinal sound velocity. When resin cements were light-irradiated, each curve displayed an initial plateau of approximately 1,500 m s(-1), which rapidly increased to a second plateau of 2,300-2,900 m s(-1). The rate of sound velocity increase was retarded when the cements were light-irradiated at lower power densities, and increased when the primer was applied. The polymerization behaviour of dual-cured resin cements was therefore shown to be affected by the power density of the curing unit and the application of self-etching primer. (c) 2010 The Authors. Journal compilation (c) 2010 Eur J Oral Sci.

  19. The characteristics of epoxy resin cured by {gamma}-ray and E-beam

    Energy Technology Data Exchange (ETDEWEB)

    Nho, Y.C. E-mail: ycnho@kaeri.re.kr; Kang, Phil Hyun; Park, Jong Seok

    2004-10-01

    Epoxy resins are widely used as high-performance thermosetting resins for many industrial applications. In this study, the effect of an electron beam (E-beam) and {gamma}-ray irradiation on the curing of epoxy resins was investigated. Diglycidyl ether of bisphenol-A(DGEBA), diglycidyl ether of bisphenol-F(DGEBF) as epoxy resins, triarylsulfonium hexafluoroantimonate(TASHFA), and triarylsulfonium hexafluorophosphate(TASHFP) as initiators were used in this study. The chemical and mechanical characteristics of irradiated epoxy resins were compared after curing of E-beam and {gamma}-ray irradiation up to 50 kGy in N{sub 2} and air atmosphere. We ascertained the effect of oxygen on the radiation curing of epoxy resin. The thermal properties of cured epoxy were investigated using DMA and TGA. Mechanical properties such as flexural strength were measured. The chemical structures of cured epoxy were characterized by FT-NIR. The gel fraction and the stress at yield of epoxy resins irradiated by E-beam and {gamma}-ray in N{sub 2} atmosphere were also compared with those of epoxy resins irradiated by E-beam and {gamma}-ray in air.

  20. Light output from six battery operated dental curing lights

    Energy Technology Data Exchange (ETDEWEB)

    Shimokawa, Carlos Alberto Kenji, E-mail: carlos.shimokawa@usp.br [University of São Paulo, School of Dentistry, Restorative Dentistry, Avenida Professor Lineu Prestes, 2227, 05508-000, São Paulo, São Paulo (Brazil); Dalhousie University, Faculty of Dentistry, Dental Clinical Sciences, 5981 University Avenue, B3H 4R2, Halifax, Nova Scotia (Canada); Turbino, Míriam Lacalle, E-mail: miturbin@usp.br [University of São Paulo, School of Dentistry, Restorative Dentistry, Avenida Professor Lineu Prestes, 2227, 05508-000, São Paulo, São Paulo (Brazil); Harlow, Jessie Eudora, E-mail: jessie.harlow@dal.ca [Dalhousie University, Faculty of Dentistry, Dental Clinical Sciences, 5981 University Avenue, B3H 4R2, Halifax, Nova Scotia (Canada); Price, Hannah Louise, E-mail: hannlprice@gmail.com [Dalhousie University, Faculty of Dentistry, Dental Clinical Sciences, 5981 University Avenue, B3H 4R2, Halifax, Nova Scotia (Canada); Price, Richard Bengt, E-mail: richard.price@dal.ca [Dalhousie University, School of Biomedical Engineering and Faculty of Dentistry, 5981 University Avenue, B3H 4R2, Halifax, Nova Scotia (Canada)

    2016-12-01

    Light Curing Units (LCUs) are used daily in almost every dental office to photocure resins, but because the light is so bright, the user is unable to tell visually if there are any differences between different LCUs. This study evaluated the light output from six dental LCUs: Elipar Deep Cure-S (3M ESPE), Bluephase G2 (Ivoclar Vivadent), Translux 2Wave (Heraeus Kulzer), Optilight Prime (Gnatus), Slim Blast (First Medica) and Led.B (Guilin Woodpecker) with a fully charged battery, after 50, and again after 100, 20 second light exposures. For each situation, the radiant power was measured 10 times with a laboratory-grade power meter. Then, the emission spectrum was measured using a fiber-optic spectrometer followed by an analysis of the light beam profile. It was found there were significant differences in the LCU power and the irradiance values between the LCUs (p < 0.01). The Optilight Prime and Slim Blast LCUs showed a significant reduction in light output after a 50 and 100 exposures, while Bluephase G2 exhibited a significant reduction only after 100 exposures (p < 0.01). The Bluephase G2 and Translux 2 Wave delivered an emission spectrum that had two distinct wavelength emission peaks. Only the Elipar Deep Cure-S and Bluephase G2 LCUs displayed homogeneous light beam profiles, the other LCUs exhibited highly non-homogeneous light beam profiles. It was concluded that contemporary LCUs could have very different light output characteristics. Both manufacturers and researchers should provide more information about the light output from LCUs. - Highlights: • The six LCUs delivered significantly different light output characteristics. • The use of a single irradiance value does not adequately describe the light output from a curing light. • Small differences in the tip area, or how it is defined, will have a large effect on the calculated irradiance. • In some cases there were large portions of the light tip that emitted less than 400 mW/cm². • The radiant

  1. Light output from six battery operated dental curing lights

    International Nuclear Information System (INIS)

    Shimokawa, Carlos Alberto Kenji; Turbino, Míriam Lacalle; Harlow, Jessie Eudora; Price, Hannah Louise; Price, Richard Bengt

    2016-01-01

    Light Curing Units (LCUs) are used daily in almost every dental office to photocure resins, but because the light is so bright, the user is unable to tell visually if there are any differences between different LCUs. This study evaluated the light output from six dental LCUs: Elipar Deep Cure-S (3M ESPE), Bluephase G2 (Ivoclar Vivadent), Translux 2Wave (Heraeus Kulzer), Optilight Prime (Gnatus), Slim Blast (First Medica) and Led.B (Guilin Woodpecker) with a fully charged battery, after 50, and again after 100, 20 second light exposures. For each situation, the radiant power was measured 10 times with a laboratory-grade power meter. Then, the emission spectrum was measured using a fiber-optic spectrometer followed by an analysis of the light beam profile. It was found there were significant differences in the LCU power and the irradiance values between the LCUs (p < 0.01). The Optilight Prime and Slim Blast LCUs showed a significant reduction in light output after a 50 and 100 exposures, while Bluephase G2 exhibited a significant reduction only after 100 exposures (p < 0.01). The Bluephase G2 and Translux 2 Wave delivered an emission spectrum that had two distinct wavelength emission peaks. Only the Elipar Deep Cure-S and Bluephase G2 LCUs displayed homogeneous light beam profiles, the other LCUs exhibited highly non-homogeneous light beam profiles. It was concluded that contemporary LCUs could have very different light output characteristics. Both manufacturers and researchers should provide more information about the light output from LCUs. - Highlights: • The six LCUs delivered significantly different light output characteristics. • The use of a single irradiance value does not adequately describe the light output from a curing light. • Small differences in the tip area, or how it is defined, will have a large effect on the calculated irradiance. • In some cases there were large portions of the light tip that emitted less than 400 mW/cm². • The radiant

  2. Pre-heated dual-cured resin cements: analysis of the degree of conversion and ultimate tensile strength

    Directory of Open Access Journals (Sweden)

    Flávio Álvares França

    2011-04-01

    Full Text Available This study evaluated the degree of conversion (DC and ultimate tensile strength (UTS of dual-cured resin cements heated to 50º C prior to and during polymerization. Disc- and hourglass-shaped specimens of Rely X ARC (RX and Variolink II (VII were obtained using addition silicon molds. The products were manipulated at 25º C or 50º C and were subjected to 3 curing conditions: light-activation through a glass slide or through a pre-cured 2-mm thick resin composite disc, or they were allowed to self-cure (SC. All specimens were dark-stored dry for 15 days. For DC analysis, the resin cements were placed into the mold located on the center of a horizontal diamond on the attenuated total reflectance element in the optical bench of a Fourier Transformed Infrared spectrometer. Infrared spectra (n = 6 were collected between 1680 and 1500 cm-1, and DC was calculated by standard methods using changes in ratios of aliphatic-to-aromatic C=C absorption peaks from uncured and cured states. For UTS test, specimens (n = 10 were tested in tension in a universal testing machine (crosshead speed of 1 mm/min until failure. DC and UTS data were submitted to 2-way ANOVA, followed by Tukey's test (α= 5%. Both products showed higher DC at 50º C than at 25º C in all curing conditions. No significant difference in UTS was noted between most light-activated groups at 25º C and those at 50º C. VII SC groups showed higher UTS at 50º C than at 25º C (p < 0.05. Increased temperature led to higher DC, but its effects on resin cement UTS depended on the curing condition.

  3. Palate Fracture Repair With Light-Cured Resin Splint: Technical Note.

    Science.gov (United States)

    Waldrop, Jimmy; Dale, Elizabeth L; Halsey, Jordan; Sargent, Larry A

    2015-10-01

    Palate fractures are rare, and their treatment is a matter of debate. Although some investigators have favored rigid plate fixation, others have reported successful treatment without it. Sagittal split and comminuted fractures can require rigid fixation to reduce the maxillary width; however, additional stabilization is needed. Also, palate repair without a splint is complicated by prolonged intermaxillary fixation (IMF), causing stiffness to the temporomandibular joint. We introduce a technique using a rapid light-cured resin (TRIAD TranSheet) frequently used by orthodontists for making dental retainers. Its use is similar to the splints traditionally created preoperatively, but obviates the need for making impressions, a model, and a molded splint. A series of 13 patients treated with this technique during a 5-year period is presented. The average duration of IMF was 4.7 weeks (range 3 to 6). The average duration of the palate splint was 8.4 weeks (range 5 to 12). One patient had malocclusion, but none had malunion, infection, or oronasal fistula. Our series has demonstrated a simple, cost-effective, and successful technique. It can be used alone or combined with rigid fixation and allows for a shortened duration of maxillomandibular fixation. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  4. In vitro antibacterial activity of a novel resin-based pulp capping material containing the quaternary ammonium salt MAE-DB and Portland cement.

    Science.gov (United States)

    Yang, Yanwei; Huang, Li; Dong, Yan; Zhang, Hongchen; Zhou, Wei; Ban, Jinghao; Wei, Jingjing; Liu, Yan; Gao, Jing; Chen, Jihua

    2014-01-01

    Vital pulp preservation in the treatment of deep caries is challenging due to bacterial infection. The objectives of this study were to synthesize a novel, light-cured composite material containing bioactive calcium-silicate (Portland cement, PC) and the antimicrobial quaternary ammonium salt monomer 2-methacryloxylethyl dodecyl methyl ammonium bromide (MAE-DB) and to evaluate its effects on Streptococcus mutans growth in vitro. The experimental material was prepared from a 2 : 1 ratio of PC mixed with a resin of 2-hydroxyethylmethacrylate, bisphenol glycerolate dimethacrylate, and triethylene glycol dimethacrylate (4 : 3 : 1) containing 5 wt% MAE-DB. Cured resin containing 5% MAE-DB without PC served as the positive control material, and resin without MAE-DB or PC served as the negative control material. Mineral trioxide aggregate (MTA) and calcium hydroxide (Dycal) served as commercial controls. S. mutans biofilm formation on material surfaces and growth in the culture medium were tested according to colony-forming units (CFUs) and metabolic activity after 24 h incubation over freshly prepared samples or samples aged in water for 6 months. Biofilm formation was also assessed by Live/Dead staining and scanning electron microscopy. S. mutans biofilm formation on the experimental material was significantly inhibited, with CFU counts, metabolic activity, viability staining, and morphology similar to those of biofilms on the positive control material. None of the materials affected bacterial growth in solution. Contact-inhibition of biofilm formation was retained by the aged experimental material. Significant biofilm formation was observed on MTA and Dycal. The synthesized material containing HEMA-BisGMA-TEGDMA resin with MAE-DB as the antimicrobial agent and PC to support mineralized tissue formation inhibited S. mutans biofilm formation even after aging in water for 6 months, but had no inhibitory effect on bacteria in solution. Therefore, this material shows

  5. Cure Behavior and Thermal Properties of Diepoxidized Cardanol Resin Cured by Electron Beam Process

    International Nuclear Information System (INIS)

    Cho, Donghwan; Cheon, Jinsil

    2013-01-01

    Thermal curing of epoxy resin requires high temperature, time-consuming process and the volatilization of hardener. It has known that electron beam curing of epoxy resin is a fast process and occurs at low or room temperature that help reduce residual mechanical stresses in thermosetting polymers. Diepoxidized cardanol (DEC) can be synthesized by an enzymatic method from cashew nut shell liquid (CNSL), that constitutes nearly one-third of the total nut weight. A large amount of CNSL can be formed as a byproduct of the mechanical processes used to render the cashew kerneledible and its total production approaches one million tons annually, which can be bio-degradable and replace the industrial thermosetting plastics. It is expected that DEC may be cured as in an epoxy resin, which was constituted on two epoxide group and long alkyl chain, and two-types of onium salts (cationic initiator) were used as a photo-initiator. The experimental variables of this study are type and concentration of photo-initiators and electron beam dosage. In this study, the effects of initiator type and concentration on the cure behavior and the thermal properties of DEC resin processed by using electron beam technology were studied using FT-IR, TGA, TMA, DSC, and DMA. Figure 1 is the FT-IR results, showing the change of chemical structure of pure DEC and electron beam cured DEC. The characteristic absorption peak of epoxide group appeared at 850cm -1 . The shape and the height were reduced when the sample was irradiated with electron beam. From this result, the epoxide groups is DEC were opened by electron beam and cured. After then, electron beam cured DEC was investigated the effect of forming 3-dimensional network

  6. Cure Behavior and Thermal Properties of Diepoxidized Cardanol Resin Cured by Electron Beam Process

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Donghwan; Cheon, Jinsil [Kumoh National Institute of Technology, Gumi (Korea, Republic of)

    2013-07-01

    Thermal curing of epoxy resin requires high temperature, time-consuming process and the volatilization of hardener. It has known that electron beam curing of epoxy resin is a fast process and occurs at low or room temperature that help reduce residual mechanical stresses in thermosetting polymers. Diepoxidized cardanol (DEC) can be synthesized by an enzymatic method from cashew nut shell liquid (CNSL), that constitutes nearly one-third of the total nut weight. A large amount of CNSL can be formed as a byproduct of the mechanical processes used to render the cashew kerneledible and its total production approaches one million tons annually, which can be bio-degradable and replace the industrial thermosetting plastics. It is expected that DEC may be cured as in an epoxy resin, which was constituted on two epoxide group and long alkyl chain, and two-types of onium salts (cationic initiator) were used as a photo-initiator. The experimental variables of this study are type and concentration of photo-initiators and electron beam dosage. In this study, the effects of initiator type and concentration on the cure behavior and the thermal properties of DEC resin processed by using electron beam technology were studied using FT-IR, TGA, TMA, DSC, and DMA. Figure 1 is the FT-IR results, showing the change of chemical structure of pure DEC and electron beam cured DEC. The characteristic absorption peak of epoxide group appeared at 850cm{sup -1}. The shape and the height were reduced when the sample was irradiated with electron beam. From this result, the epoxide groups is DEC were opened by electron beam and cured. After then, electron beam cured DEC was investigated the effect of forming 3-dimensional network.

  7. Silorane- and high filled-based"low-shrinkage" resin composites: shrinkage, flexural strength and modulus

    Directory of Open Access Journals (Sweden)

    Cesar Augusto Galvão Arrais

    2013-04-01

    Full Text Available This study compared the volumetric shrinkage (VS, flexural strength (FS and flexural modulus (FM properties of the low-shrinkage resin composite Aelite LS (Bisco to those of Filtek LS (3M ESPE and two regular dimethacrylate-based resin composites, the microfilled Heliomolar (Ivoclar Vivadent and the microhybrid Aelite Universal (Bisco. The composites (n = 5 were placed on the Teflon pedestal of a video-imaging device, and VS was recorded every minute for 5 min after 40 s of light exposure. For the FS and FM tests, resin discs (0.6 mm in thickness and 6.0 mm in diameter were obtained (n = 12 and submitted to a piston-ring biaxial test in a universal testing machine. VS, FS, and FM data were submitted to two-way repeated measures and one-way ANOVA, respectively, followed by Tukey's post-hoc test (a = 5%. Filtek LS showed lower VS than did Aelite LS, which in turn showed lower shrinkage than did the other composites. Aelite Universal and Filtek LS exhibited higher FS than did Heliomolar and Aelite LS, both of which exhibited the highest FM. No significant difference in FM was noted between Filtek LS and Aelite Universal, while Heliomolar exhibited the lowest values. Aelite LS was not as effective as Filtek LS regarding shrinkage, although both low-shrinkage composites showed lower VS than did the other composites. Only Filtek LS exhibited FS and FM comparable to those of the regular microhybrid dimethacrylate-based resin composite.

  8. Characterization of dimethacrylate polymeric networks: a study of the crosslinked structure formed by monomers used in dental composites.

    Science.gov (United States)

    Pfeifer, Carmem S; Shelton, Zachary R; Braga, Roberto R; Windmoller, Dario; Machado, José C; Stansbury, Jeffrey W

    2011-02-01

    The resin phase of dental composites is mainly composed of combinations of dimethacrylate comonomers, with final polymeric network structure defined by monomer type/reactivity and degree of conversion. This fundamental study evaluates how increasing concentrations of the flexible triethylene glycol dimethacrylate (TEGDMA) influences void formation in bisphenol A diglycidyl dimethacrylate (BisGMA) co-polymerizations and correlates this aspect of network structure with reaction kinetic parameters and macroscopic volumetric shrinkage. Photopolymerization kinetics was followed in real-time by a near-infrared (NIR) spectroscopic technique, viscosity was assessed with a viscometer, volumetric shrinkage was followed with a linometer, free volume formation was determined by positron annihilation lifetime spectroscopy (PALS) and the sol-gel composition was determined by extraction with dichloromethane followed by (1)H-NMR analysis. Results show that, as expected, volumetric shrinkage increases with TEGDMA concentration and monomer conversion. Extraction/(1)H-NMR studies show increasing participation of the more flexible TEGDMA towards the limiting stages of conversion/crosslinking development. As the conversion progresses, either based on longer irradiation times or greater TEGDMA concentrations, the network becomes more dense, which is evidenced by the decrease in free volume and weight loss after extraction in these situations. For the same composition (BisGMA/TEGDMA 60-40 mol%) light-cured for increasing periods of time (from 10 to 600 s), free volume decreased and volumetric shrinkage increased, in a linear relationship with conversion. However, the correlation between free volume and macroscopic volumetric shrinkage was shown to be rather complex for variable compositions exposed for the same time (600 s). The addition of TEGDMA decreases free-volume up to 40 mol% (due to increased conversion), but above that concentration, in spite of the increase in conversion

  9. A comparative evaluation of the marginal adaptation of a thermoplastic resin, a light cured wax and an inlay casting wax on stone dies: An in vitro study.

    Science.gov (United States)

    Gopalan, Reji P; Nair, Vivek V; Harshakumar, K; Ravichandran, R; Lylajam, S; Viswambaran, Prasanth

    2018-01-01

    Different pattern materials do not produce copings with satisfactory, marginal accuracy when used on stone dies at varying time intervals. The purpose of this study was to evaluate and compare the vertical marginal accuracy of patterns formed from three materials, namely, thermoplastic resin, light cured wax and inlay casting wax at three-time intervals of 1, 12, and 24 h. A master die (zirconia abutment mimicking a prepared permanent maxillary central incisor) and metal sleeve (direct metal laser sintering crown #11) were fabricated. A total of 30 stone dies were obtained from the master die. Ten patterns were made each from the three materials and stored off the die at room temperature. The vertical marginal gaps were measured using digital microscope at 1, 12, and 24 h after reseating with gentle finger pressure. The results revealed a significant statistical difference in the marginal adaptation of three materials at all the three-time intervals. Light cured wax was found to be most accurate at all time intervals, followed by thermoplastic resin and inlay casting wax. Furthermore, there was a significant difference between all pairs of materials. The change in vertical marginal gap from 1 to 24 h between thermoplastic resin and light cured wax was not statistically significant. The marginal adaptation of all the three materials used, was well within the acceptable range of 25-70 μm. The resin pattern materials studied revealed significantly less dimensional change than inlay casting wax on storage at 1, 12, and 24 h time intervals. They may be employed in situations where high precision and delayed investing is expected.

  10. Colour-stability and gloss-retention of silorane and dimethacrylate composites with accelerated aging.

    Science.gov (United States)

    Furuse, Adilson Y; Gordon, Kathryn; Rodrigues, Flávia P; Silikas, Nick; Watts, David C

    2008-11-01

    To evaluate the colour-stability and gloss-retention of silorane versus dimethacrylate composites exposed to accelerated aging from daylight radiation. Five disc-shaped specimens of photo-cured resin-composites were prepared and manually polished for each material (Filtek Silorane, Herculite XRV, Tetric Evoceram and QuiXfil). Colour and gloss were evaluated before and after periods (baseline, 24, 72, 120 and 192 h) of accelerated photo-aging in xenon light following ISO 7491:2000. Colour measurements were performed with a colourimeter according to the CIE-Lab colour-space. The colour change (DeltaE) for each time was calculated. The surface gloss was measured using a glossmeter. Results were evaluated using one-way ANOVA and Tukey tests (alpha=0.05). Correlations between logtime, DeltaE and gloss were evaluated using Pearson's correlation (alpha=0.05). Materials generally decreased in L and a and increased in b. The strong exception was Filtek Silorane which maintained a and b. DeltaE was found to be a positive linear function of logtime for all materials. Materials varied in the magnitude and rate of increase of DeltaE with logtime: QuiXfil>Tetric EvoCeram>(Filtek Silorane>or=Herculite XRV). DeltaE remainedGloss was found to be a negative linear function of logtime. Gloss was maximal in the sequence: Filtek Silorane approximately Tetric EvoCeram>Herculite XRV>QuiXfil. Silorane gave the best overall performance in stability over time, compared to a set of representative dimethacrylate composites.

  11. Effect of disposable infection control barriers on light output from dental curing lights.

    Science.gov (United States)

    Scott, Barbara A; Felix, Corey A; Price, Richard B T

    2004-02-01

    To prevent contamination of the light guide on a dental curing light, barriers such as disposable plastic wrap or covers may be used. This study compared the effect of 3 disposable barriers on the spectral output and power density from a curing light. The hypothesis was that none of the barriers would have a significant clinical effect on the spectral output or the power density from the curing light. Three disposable barriers were tested against a control (no barrier). The spectra and power from the curing light were measured with a spectrometer attached to an integrating sphere. The measurements were repeated on 10 separate occasions in a random sequence for each barrier. Analysis of variance (ANOVA) followed by Fisher's protected least significant difference test showed that the power density was significantly less than control (by 2.4% to 6.1%) when 2 commercially available disposable barriers were used (p 0.05). The effect of each of the barriers on the power output was small and probably clinically insignificant. ANOVA comparisons of mean peak wavelength values indicated that none of the barriers produced a significant shift in the spectral output relative to the control ( p > 0.05). Two of the 3 disposable barriers produced a significant reduction in power density from the curing light. This drop in power was small and would probably not adversely affect the curing of composite resin. None of the barriers acted as light filters.

  12. Influence of curing time, overlay material and thickness on three light-curing composites used for luting indirect composite restorations.

    Science.gov (United States)

    D'Arcangelo, Camillo; De Angelis, Francesco; Vadini, Mirco; Carluccio, Fabio; Vitalone, Laura Merla; D'Amario, Maurizio

    2012-08-01

    To assess the microhardness of three resin composites employed in the adhesive luting of indirect composite restorations and examine the influence of the overlay material and thickness as well as the curing time on polymerization rate. Three commercially available resin composites were selected: Enamel Plus HRI (Micerium) (ENA), Saremco ELS (Saremco Dental) (SAR), Esthet-X HD (Dentsply/DeTrey) (EST-X). Post-polymerized cylinders of 6 different thicknesses were produced and used as overlays: 2 mm, 3 mm, 3.5 mm, 4 mm, 5 mm, and 6 mm. Two-mm-thick disks were produced and employed as underlays. A standardized amount of composite paste was placed between the underlay and the overlay surfaces which were maintained at a fixed distance of 0.5 mm. Light curing of the luting composite layer was performed through the overlays for 40, 80, or 120 s. For each specimen, the composite to be cured, the cured overlay, and the underlay were made out of the same batch of resin composite. All specimens were assigned to three experimental groups on the basis of the resin composite used, and to subgroups on the basis of the overlay thickness and the curing time, resulting in 54 experimental subgroups (n = 5). Forty-five additional specimens, 15 for each material under investigation, were produced and subjected to 40, 80, or 120 s of light curing using a microscope glass as an overlay; they were assigned to 9 control subgroups (n = 5). Three Vicker's hardness (VH) indentations were performed on each specimen. Means and standard deviations were calculated. Data were statistically analyzed using 3-way ANOVA. Within the same material, VH values lower than 55% of control were not considered acceptable. The used material, the overlay thickness, and the curing time significantly influenced VH values. In the ENA group, acceptable hardness values were achieved with 3.5-mm or thinner overlays after 120 or 80 s curing time (VH 41.75 and 39.32, respectively), and with 2-mm overlays after 40 s (VH 54

  13. Effect of LED-LCU light irradiance distribution on mechanical properties of resin based materials

    International Nuclear Information System (INIS)

    Magalhães Filho, T.R.; Weig, K.M.; Costa, M.F.; Werneck, M.M.; Barthem, R.B.; Costa Neto, C.A.

    2016-01-01

    The objective of this study is to analyze the light power distribution along the tip end of the light guide of three LED-LCUs (Light Curing Units) and to evaluate its effect on the mechanical properties of a polymer based dental composite. Firstly, the light power distribution over the whole area of LED-LCU light guide surface was analyzed by three methods: visual projection observation, spectral measurement and optical spectral analysis (OSA). The light power distribution and the total irradiance were different for the three LEDs used, but the wavelength was within the camphorquinone absorption spectrum. The use of a blank sheet was quite on hand to make a qualitative analysis of a beam, and it is costless. Secondly, specimens of a hybrid composite with approximately 8 mm diameter and 2 mm thickness were produced and polymerized by 20 s exposition time to each LED-LCU. Thirdly, the elastic modulus (E) and hardness (HV) were measured throughout the irradiated area by instrumented micro-indentation test (IIT), allowing to correlate localized power and mechanical properties. Both E and HV showed to be very sensitive to local power and wavelength dependent, but they followed the beam power profile. It was also shown that the mechanical properties could be directly correlated to the curing process. Very steep differences in mechanical properties over very short distances may impair the material performance, since residual stresses can easily be built over it. - Highlights: • A resin based composite (RBC) was polymerized by three different Light Emitting Diodes. • Each LED had its beam profile visually, wavelength and power analyzed. • The effective polymerization power (EPP) varied from 28% to 52% of the total beam power. • Wavelength seems to be as relevant as power in the light curing process. • Mechanical properties depend on the simultaneous effect of wavelength and power.

  14. Effect of LED-LCU light irradiance distribution on mechanical properties of resin based materials

    Energy Technology Data Exchange (ETDEWEB)

    Magalhães Filho, T.R.; Weig, K.M. [Faculdade de Odontologia, Universidade Federal Fluminense, Rua São Paulo 28, CEP 24020-150 Niterói (Brazil); Engenharia Metalúrgica e de Materiais (COPPE), Universidade Federal do Rio de Janeiro, CP 68505, CEP: 21941-972 Rio de Janeiro (Brazil); Costa, M.F. [Engenharia Metalúrgica e de Materiais (COPPE), Universidade Federal do Rio de Janeiro, CP 68505, CEP: 21941-972 Rio de Janeiro (Brazil); Werneck, M.M. [Engenharia Elétrica (COPPE), Universidade Federal do Rio de Janeiro, CP 68504, CEP: 21941-972 Rio de Janeiro (Brazil); Barthem, R.B. [Instituto de Física, Universidade Federal do Rio de Janeiro, CP 68528, CEP: 21941-972 Rio de Janeiro (Brazil); Costa Neto, C.A., E-mail: celio@metalmat.ufrj.br [Engenharia Metalúrgica e de Materiais (COPPE), Universidade Federal do Rio de Janeiro, CP 68505, CEP: 21941-972 Rio de Janeiro (Brazil)

    2016-06-01

    The objective of this study is to analyze the light power distribution along the tip end of the light guide of three LED-LCUs (Light Curing Units) and to evaluate its effect on the mechanical properties of a polymer based dental composite. Firstly, the light power distribution over the whole area of LED-LCU light guide surface was analyzed by three methods: visual projection observation, spectral measurement and optical spectral analysis (OSA). The light power distribution and the total irradiance were different for the three LEDs used, but the wavelength was within the camphorquinone absorption spectrum. The use of a blank sheet was quite on hand to make a qualitative analysis of a beam, and it is costless. Secondly, specimens of a hybrid composite with approximately 8 mm diameter and 2 mm thickness were produced and polymerized by 20 s exposition time to each LED-LCU. Thirdly, the elastic modulus (E) and hardness (HV) were measured throughout the irradiated area by instrumented micro-indentation test (IIT), allowing to correlate localized power and mechanical properties. Both E and HV showed to be very sensitive to local power and wavelength dependent, but they followed the beam power profile. It was also shown that the mechanical properties could be directly correlated to the curing process. Very steep differences in mechanical properties over very short distances may impair the material performance, since residual stresses can easily be built over it. - Highlights: • A resin based composite (RBC) was polymerized by three different Light Emitting Diodes. • Each LED had its beam profile visually, wavelength and power analyzed. • The effective polymerization power (EPP) varied from 28% to 52% of the total beam power. • Wavelength seems to be as relevant as power in the light curing process. • Mechanical properties depend on the simultaneous effect of wavelength and power.

  15. Evaluation of wear rate of dental composites polymerized by halogen or LED light curing units

    Directory of Open Access Journals (Sweden)

    Alaghehmand H.

    2006-08-01

    Full Text Available Background and Aim: Sufficient polymerization is a critical factor to obtain optimum physical properties and clinical efficacy of resin restorations. The aim of this study was to evaluate wear rates of composite resins polymerized by two different systems Light Emitting Diodes (LED to and Halogen lamps. Materials and Methods: In this laboratory study, 20 specimens of A3 Tetric Ceram composite were placed in brass molds of 2*10*10 mm dimensions and cured for 40 seconds with 1 mm distance from surface. 10 specimens were cured with LED and the other 10 were cured with Halogen unit. A device with the ability to apply force was developed in order to test the wear of composites. After storage in distilled water for 10 days, the specimens were placed in the wear testing machine. A chrome cobalt stylus with 1.12 mm diameter was applied against the specimens surfaces with a load of 2 kg. The weight of each samples before and after 5000, 10000, 20000, 40000, 80000 and 120000 cycles was measured using an electronic balance with precision of 10-4 grams. Data were analyzed using t test and paired t test. P0.05. Conclusion: Based on the results of this study, LED and halogen light curing units resulted in a similar wear rate in composite resin restorations.

  16. Solid-state /sup 13/C NMR study of cured resorcinol-formaldehyde resins

    Energy Technology Data Exchange (ETDEWEB)

    Lippmaa, H.; Samoson, A.

    1988-08-01

    The curing process generally follows the pattern observed in the stage of prepolymer formation. Catalysts (NaOH, hexa, Mg(OCOCH/sub 3/)/sub 2/) that have no substantial influence on the isomeric composition of the resorcinol-formaldehyde prepolymers, do not affect the isomeric composition of the cured resins to any significant extent either. Isomeric composition of the cured resins depends mostly on the presence of water during the curing process, necessary for depolymerisation of the added paraformaldehyde. Curing in the melt leads to enhanced 2-substitution in the 1,3-dihydroxybenzene rings. In the /sup 13/C NMR spectra of cured powdered samples, the tendency of 5-methylresorcinol to form oligomers with a higher degree of 2-substitution than resorcinol is clearly apparent. Polycondensation process continues in the powdered resins after initial curing until complete consumption of all formaldehyde. Curing of phenol-formaldehyde resols proceeds through intermediate dimethylene ether formation.

  17. Fiber Optic Systems for Light Curing Rigidization of Inflatable Structures, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Light (UV and visible) curing composite matrix resins are being explored as an attractive means for rigidizing inflatable spacecraft for large space-deployed...

  18. Isothermal curing of polymer layered silicate nanocomposites based upon epoxy resin by means of anionic homopolymerisation

    International Nuclear Information System (INIS)

    Román, Frida; Calventus, Yolanda; Colomer, Pere; Hutchinson, John M.

    2013-01-01

    Highlights: • The nanocomposite with low content of clay displayed improved thermal properties. • The vitrification was observed in the isothermal curing. • Dielectric relaxations outside and inside of the clay galleries were detected. - Abstract: The use of an initiator, 4-(dimethylamino) pyridine (DMAP), to promote an anionic homopolymerisation reaction for the isothermal cure of polymer layered silicate (PLS) nanocomposites based on an epoxy resin, as well as the effect of the nanoclay content, have been studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dielectric relaxation spectroscopy (DRS) and transmission electron microscopy (TEM). The vitrification phenomenon was observed during the isothermal cure process, and it was found that the nanocomposite with a low clay content (2 wt%), denoted EDM2, shows improved thermal properties with respect to the unreinforced resin (denoted ED), while the nanocomposite with a higher clay content (5 wt%), denoted EDM5, displayed inferior properties. The cure kinetics were analysed by different methods, and it was observed that the activation energy and kinetic parameters of EDM2 were lower compared to the other two systems. Examination of the nanostructure of the cured EDM2 nanocomposite showed partial exfoliation, while the EDM5 system retains an intercalated nanostructure. In the DRS studies of the curing process of the EDM2 system, two dielectric relaxations were detected, which are associated with the molecular mobility in the curing reaction which takes place both outside and inside the clay galleries

  19. Effect of Microwave Cured Acrylic Resin on Candidal Growth in Complete denture

    International Nuclear Information System (INIS)

    Rasmy, A.H.M.

    2009-01-01

    This study was conducted to evaluate the effect of heat-cured acrylic resin denture base and microwave-cured acrylic resin denture base on Candidal growth. Seven completely edentulous male patients with no history of denture wearing participated in this study. All the selected patients were re-habilitated by mucosa supported complete dentures. The dentures were constructed from conventional heat-cured acrylic resin denture base following monoplane concept of occlusion. Before dismissing the patients and one month after denture insertion, salivary samples were collected according to oral rinse technique. One month resting period was allowed so as Candidal count can reach to normal. Then dentures were re based using microwave-cured acrylic denture base, before denture insertion and one month after denture insertion, salivary sample were collected before and one month following the same oral rinse technique. In the oral rinse technique, the patients were instructed to rinse their mouths with 10 mL of sterile phosphate buffered saline for 60 seconds. The rinse was then expectorated into a universal container and immediately transported to the laboratory for concentration by centrifugation, then cultured on sabouraud's dextrose agar plates which were incubated at 37 degree C for 48 hours. Microscopic examination and germ tube test were carried out for laboratory investigations. In addition, the morphological features of the isolated Candida from the samples tested in this study, were investigated using the scanning electron microscope(SEM)

  20. Photopolymerization of highly filled dimethacrylate-based composites using Type I or Type II photoinitiators and varying co-monomer ratios.

    Science.gov (United States)

    Randolph, Luc D; Steinhaus, Johannes; Möginger, Bernhard; Gallez, Bernard; Stansbury, Jeffrey; Palin, William M; Leloup, Gaëtane; Leprince, Julian G

    2016-02-01

    The use of a Type I photoinitiator (monoacylphosphine oxide, MAPO) was described as advantageous in a model formulation, as compared to the conventional Type II photoinitiator (Camphorquinone, CQ). The aim of the present work was to study the kinetics of polymerization of various composite mixtures (20-40-60-80 mol%) of bisphenol A glycidyl dimethacrylate/triethylene glycol dimethacrylate (BisGMA/TegDMA) containing either CQ or MAPO, based on real-time measurements and on the characterization of various post-cure characteristics. Polymerization kinetics were monitored by Fourier-transform near-infrared spectroscopy (FT-NIRS) and dielectric analysis (DEA). A range of postcure properties was also investigated. FT-NIRS and DEA proved complementary to follow the fast kinetics observed with both systems. Autodecceleration occurred after ≈1 s irradiation for MAPO-composites and ≈5-10 s for CQ-composites. Conversion decreased with increasing initial viscosity for both photoinitiating systems. However despite shorter light exposure (3s for MAPO vs 20s for CQ-composites), MAPO-composites yielded higher conversions for all co-monomer mixtures, except at 20 mol% BisGMA, the less viscous material. MAPO systems were associated with increased amounts of trapped free radicals, improved flexural strength and modulus, and reduced free monomer release for all co-monomer ratios, except at 20 mol% BisGMA. This work confirms the major influence of the initiation system both on the conversion and network cross-linking of highly-filled composites, and further highlights the advantages of using MAPO photoinitiating systems in highly-filled dimethacrylate-based composites provided that sufficient BisGMA content (>40 mol%) and adapted light spectrum are used. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  1. The influence of "C-factor" and light activation technique on polymerization contraction forces of resin composite

    Directory of Open Access Journals (Sweden)

    Sérgio Kiyoshi Ishikiriama

    2012-12-01

    Full Text Available OBJECTIVES: This study evaluated the influence of the cavity configuration factor ("C-Factor" and light activation technique on polymerization contraction forces of a Bis-GMA-based composite resin (Charisma, Heraeus Kulzer. MATERIAL AND METHODS: Three different pairs of steel moving bases were connected to a universal testing machine (emic DL 500: groups A and B - 2x2 mm (CF=0.33, groups C and D - 3x2 mm (CF=0.66, groups e and F - 6x2 mm (CF=1.5. After adjustment of the height between the pair of bases so that the resin had a volume of 12 mm³ in all groups, the material was inserted and polymerized by two different methods: pulse delay (100 mW/cm² for 5 s, 40 s interval, 600 mW/cm² for 20 s and continuous pulse (600 mW/cm² for 20 s. Each configuration was light cured with both techniques. Tensions generated during polymerization were recorded by 120 s. The values were expressed in curves (Force(N x Time(s and averages compared by statistical analysis (ANOVA and Tukey's test, p<0.05. RESULTS: For the 2x2 and 3x2 bases, with a reduced C-Factor, significant differences were found between the light curing methods. For 6x2 base, with high C-Factor, the light curing method did not influence the contraction forces of the composite resin. CONCLUSIONS: Pulse delay technique can determine less stress on tooth/restoration interface of adhesive restorations only when a reduced C-Factor is present.

  2. Factors affecting marginal integrity of class II bulk-fill composite resin restorations

    Science.gov (United States)

    Savadi Oskoee, Siavash; Bahari, Mahmoud; Jafari Navimipour, Elmira; Ajami, Amir Ahmad; Ghiasvand, Negar; Savadi Oskoee, Ayda

    2017-01-01

    Background. Bulk-fill composite resins are a new type of resin-based composite resins, claimed to have the capacity to be placed in thick layers, up to 4 mm. This study was carried out to evaluate factors affecting gap formation in Cl II cavities restored using the bulk-fill technique. Methods. A total of 60 third molars were used in this study. Two Cl II cavities were prepared in each tooth, one on the mesial aspect 1 mm coronal to the CEJ and one on the distal aspect 1 mm apical to the CEJ. The teeth were divided into 4 groups: A: The cavities were restored using the bulk-fill technique with Filtek P90 composite resin and its adhesive system and light-cured with quartz tungsten halogen (QTH) light-curing unit. B: The cavities were restored similar to that in group A but light-cured with an LED light-curing unit. C: The cavities were restored using the bulk-fill technique with X-tra Fil composite resin and Clearfil SE Bond adhesive system and light-cured with a QTH curing unit. D: The cavities were restored similar to that in group C but light-cured with an LED light-curing unit. The gaps were examined under a stereomicroscope at ×60. Data were analyzed with General Linear Model test. In cases of statistical significance (Pcomposite resin type and margin location (Pcomposite resin type were not significant; however, the cumulative effect of composite rein type*gingival margin was significant (P=0.04) Conclusion. X-tra Fil composite exhibited smaller gaps compared with Filtek P90 composite with both light-curing units. Both composite resins exhibited smaller gaps at enamel margins. PMID:28748051

  3. Microwave and thermal curing of an epoxy resin for microelectronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, K. [Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Pavuluri, S.K.; Leonard, M.T.; Desmulliez, M.P.Y. [MIcroSystems Engineering Centre (MISEC), Institute of Signals, Sensors and Systems, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Arrighi, V., E-mail: v.arrighi@hw.ac.uk [Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom)

    2015-09-20

    Graphical abstract: - Highlights: • Thermal and microwave curing of a commercial epoxy resin EO1080 are compared. • Microwave curing increases cure rate and does not adversely affect properties. • The curing of EO1080 is generally autocatalytic but deviates at high conversion. • Microwave radiation has a more complex effect on curing kinetics. - Abstract: Microwave curing of thermosetting polymers has a number of advantages to natural or thermal oven curing and is considered a cost-effective alternative. Here we present a detailed study of a commercially available epoxy resin, EO1080. Samples that are thermally cured are compared to curing using a recently developed modular microwave processing system. For commercial purposes it is crucial to demonstrate that microwave curing does not adversely affect the thermal and chemical properties of the material. Therefore, the kinetics of cure and various post cure properties of the resin are investigated. Attenuated Total Reflectance Fourier-Transform Infrared (ATR-FTIR) analysis shows no significant difference between the conventionally and microwave cured samples. Differential scanning calorimetry (DSC) is used to monitor the kinetics of the curing reaction, as well as determine the thermal and ageing properties of the material. As expected, the rate of curing is higher when using microwave energy and we attempt to quantify differences compared to conventional thermal curing. No change in glass transition temperature (T{sub g}) is observed. For the first time, enthalpy relaxation measurements performed on conventional and microwave cured samples are reported and these indicate similar ageing properties at any given temperature under T{sub g}.

  4. Microwave and thermal curing of an epoxy resin for microelectronic applications

    International Nuclear Information System (INIS)

    Johnston, K.; Pavuluri, S.K.; Leonard, M.T.; Desmulliez, M.P.Y.; Arrighi, V.

    2015-01-01

    Graphical abstract: - Highlights: • Thermal and microwave curing of a commercial epoxy resin EO1080 are compared. • Microwave curing increases cure rate and does not adversely affect properties. • The curing of EO1080 is generally autocatalytic but deviates at high conversion. • Microwave radiation has a more complex effect on curing kinetics. - Abstract: Microwave curing of thermosetting polymers has a number of advantages to natural or thermal oven curing and is considered a cost-effective alternative. Here we present a detailed study of a commercially available epoxy resin, EO1080. Samples that are thermally cured are compared to curing using a recently developed modular microwave processing system. For commercial purposes it is crucial to demonstrate that microwave curing does not adversely affect the thermal and chemical properties of the material. Therefore, the kinetics of cure and various post cure properties of the resin are investigated. Attenuated Total Reflectance Fourier-Transform Infrared (ATR-FTIR) analysis shows no significant difference between the conventionally and microwave cured samples. Differential scanning calorimetry (DSC) is used to monitor the kinetics of the curing reaction, as well as determine the thermal and ageing properties of the material. As expected, the rate of curing is higher when using microwave energy and we attempt to quantify differences compared to conventional thermal curing. No change in glass transition temperature (T g ) is observed. For the first time, enthalpy relaxation measurements performed on conventional and microwave cured samples are reported and these indicate similar ageing properties at any given temperature under T g

  5. Evaluation of temperature rise with different curing methods and units in two composite resins

    Directory of Open Access Journals (Sweden)

    Tabatabaei M

    2006-01-01

    Full Text Available Background and Aim: The majority of commercial curing units in dentistry are of halogen lamp type. The new polymerizing units such as blue LED are introduced in recent years. One of the important side effects of light curing is the temperature rise in composite resin polymerization which can affect the vitality of tooth pulp. The purpose of this study was to evaluate the temperature rise in two different composite resins during polymerization with halogen lamps and blue LED. Materials and Methods: This experimental study investigated the temperature rise in two different composites (Hybrid, Tetric Ceram/Nanofilled, Filteke Supreme of A2 shade polymerized with two halogen lamps (Coltolux 50, 350 mW/cm2 and Optilux 501 in standard, 820 mW/cm2 and Ramp, 100-1030 mW/cm2 operating modes and one blue LED with the intensity of 620 mW/cm2. Five samples for each group were prepared and temperature rise was monitored using a k-type thermocouple. Data were analyzed by one-way ANOVA, two-way ANOVA and Tukey HSD tests with P<0.05 as the limit of significance. Results: Light curing units and composite resins had statistically significant influence on the temperature rise (p<0.05. Significantly, lower temperature rise occurred in case of illumination with Coltolux 50.There was no significant difference between Optilux 501 in standard curing mode and LED. Tetric Ceram showed higher temperature rise. Conclusion: According to the results of this study the high power halogen lamp and LED could produce significant heat which may be harmful to the dental pulp.

  6. Micro-Raman spectroscopic analysis of the degree of conversion of composite resins containing different initiators cured by polywave or monowave LED units.

    Science.gov (United States)

    Miletic, Vesna; Santini, Ario

    2012-02-01

    To determine the degree of conversion (DC) over 48 h post-curing of resin mixtures containing trimethylbenzoyl-diphenylphosphine oxide (TPO) initiator cured by a polywave or a monowave LED light-curing unit (LCU). In resin mixtures based on equal weight percent (wt%) of BisGMA and TEGDMA the following initiators were added: 0.2 wt% camphorquinone (CQ)+0.8 wt% ethyl-4-dimethylaminobenzoate (EDMAB) (Group 1); 1 wt% TPO (Group 2) and 0.1 wt% CQ+0.4 wt% EDMAB+0.5 wt% TPO (Group 3). Half of the samples in each group (n=5) were cured using a polywave (bluephase(®) G2, Ivoclar Vivadent) or a monowave LED LCU (bluephase(®), Ivoclar Vivadent). The DC was measured using micro-Raman spectroscopy within 5 min and then 1, 3, 6, 24 and 48 h post-irradiation. The data were analysed using general linear model and two-way ANOVA for the factors 'time', 'material', 'surface' and 'LCU' at α=0.05. The initial DC values obtained upon light curing remained similar over a 48 h period. bluephase(®) G2 produced the highest DC in Group 2 followed by Group 3, and Group 1. bluephase(®) resulted in the highest DC in Group 1, followed by Group 2 and Group 3 (pconversion of uncured monomers was detected in an unfilled resin material over 48 h at 37°C. Copyright © 2011 Elsevier Ltd. All rights reserved.

  7. The curing behavior and properties of phthalonitrile resins using ionic liquids as a new class of curing agents

    Directory of Open Access Journals (Sweden)

    K. Cheng

    2017-11-01

    Full Text Available Binary blends composed of 1,3-bis (3,4-dicyanophenoxy benzene (3BOCN and ionic liquids (ILs with different molecular structures were prepared. The curing behavior of these 3BOCN/ILs blends were studied by thermogravimetric analysis (TGA, differential scanning calorimetry (DSC and rheological analysis. The study suggested that the blends possessed a wide processing window and the structures of ILs (anion, cation and alkyl chain length at cation had an effect on curing behavior. The 3BOCN/[EPy]BF4 resins were prepared at elevated temperature. IR spectra of the resins showed that there were triazine and isoindoline formed in curing process. The TGA and dynamic mechanical analysis (DMA revealed that the resins have excellent thermal stability together with high storage modulus and high glass transition temperature (Tg. Dielectric properties, long term oxidative aging and water uptake measurements of the resins suggested the IL brought some unique properties to the resins.

  8. Synthesis and curing of alkyd enamels based on ricinoleic acid

    Directory of Open Access Journals (Sweden)

    Jovičić Mirjana C.

    2010-01-01

    Full Text Available A combination of an alkyd resin with a melamine-formaldehyde resin gives a cured enamel film with the flexibility of the alkyd constituent and the high chemical resistance and hardness of the melamine resin at the same time. The melamine resin is a minor constituent and plays the role of a crosslinking agent. In this paper, alkyd resins of high hydroxyl numbers based on trimethylolpropane, ricinoleic acid and phthalic anhydride were synthesized. Two alkyds having 30 and 40 wt% of ricinoleic acid were formulated by calculation on alkyd constant. Alkyds were characterized by FTIR and by the determination of acid and hydroxyl numbers. Then synthesized alkyds were made into baking enamels by mixing with melamine-formaldehyde resins (weight ratio of 70:30 based on dried mass. Two types of commercial melamine resins were used: threeisobutoxymethyl melamine-formaldehyde resin (TIMMF and hexamethoxymethyl melamine resin (HMMMF. Prepared alkyd/melamine resin mixtures were cured in a differential scanning calorimeter (DSC under non-isothermal mode. Apparent degree of curing as a function of temperature was calculated from the curing enthalpies. Kinetic parameters of curing were calculated using Freeman-Carroll method. TIMMF resin is more reactive with synthesized alkyds than HMMMF resin what was expected. Alkyd resin with 30 wt% of ricinoleic acid is slightly more reactive than alkyd with 40 wt% of ricinoleic acid, probably because it has the high contents of free hydroxyl and acid groups. The gel content, Tg, thermal stability, hardness, elasticity and impact resistance of coated films cured at 150°C for 60 min were measured. Cured films show good thermal stability since the onset of films thermal degradation determined by thermogravimetric analysis (TGA is observed at the temperatures from 281 to 329°C. Films based on alkyd 30 are more thermal stable than those from alkyd 40, with the same melamine resin. The type of alkyd resin has no significant

  9. Interaction of LED light with coinitiator-containing composite resins: effect of dual peaks.

    Science.gov (United States)

    Sim, Jae-Seong; Seol, Hyo-Joung; Park, Jeong-Kil; Garcia-Godoy, Franklin; Kim, Hyung-Il; Kwon, Yong Hoon

    2012-10-01

    Recently the colour stability of composite resins has been an issue due to the emphasis on the aesthetics of restored teeth. The purpose of the present study was to investigate how dual-peak LED units affect the polymerization of coinitiator-containing composite resins. Five composite resins [coinitiator-containing: Aelite LS Posterior (AL), Tetric EvoCeram (TE), and Vit-l-escence (VI); only CQ-containing: Grandio (GD) and Filtek Z350 (Z3)] were light cured using four different light-curing units (LCUs). Among them, Bluephase G2 (BP) and G-light (GL) were dual-peak LED LCUs. Microhardness, polymerization shrinkage, flexural, and compressive properties were measured. BP and GL had no consistent effect on the microhardness of AL, TE, and VI on the top and bottom surfaces of resin specimens. Among the specimens, AL and VI showed the least (9.86-10.41 μm) and greatest (17.58-19.21 μm) polymerization shrinkage, respectively. However, the effect of BP and GL on the shrinkage of specimens was not consistent. Among the specimens, GD showed the greatest flexural properties [strength (FS) and modulus (FM)] and TE showed the lowest flexural and compressive properties [strength (CS) and modulus (CM)]. In same resin product, maximum FS and CS differences due to the different LCUs were 10.3-21.0% and 3.6-9.2%, respectively. Furthermore, the influences of BP and GL on FS and CS were not consistent. The tested dual-peak LED LCUs had no consistent synergic effect on the polymerization of coinitiator-containing composite resins as compared with QTH and single-peak LED LCUs. The dual-peak LED LCUs achieve a similar degree of polymerization in coinitiator-composite resins as QTH and single-peak LED LCUs did. Choice of LCU does not appear to be a determinant of the light curing of coinitiator-composite resins. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. In vitro comparative study of share bond of light cured composite resins with halogen light and argon laser, using stainless steel brackets on human premolars

    International Nuclear Information System (INIS)

    Carillo, Vitoria Eugenia Bismarck

    2004-01-01

    The aim of this study in vitro was to compare the share bond strength of the light-cured composite resins Transbond XT (Unitek), with halogen light and argon laser. The Adhesive Remmant Index (ARI) was also investigated. The brackets Dyna lock (3M-UNITEK) were bonded to 75 human premolars, divided into 5 groups (15 each) according to time and the polymerization: Group H20, 15 brackets bonded with halogen light for 20s (10s both sides); Group H40, 15 brackets bonded with halogen light for 40s (20s both sides); Group A40, 15 brackets bonded with argon laser for 40s (20s both sides); Group A20, 15 brackets bonded with argon laser for 20s (10s both sides); Group A10, 15 brackets bonded with argon laser for 10s (5s both sides). The pulpal temperature changes were determined during a polymerization, not exceeding 3,5 deg C. After bonding, the teeth were submitted to a thermo cycled of 700 cycles between 5 deg C and 55 deg C, to simulate the consuming that the light cured composite resin would have in a short space of time. The specimens were then placed in PVC ring and embedded in acrylic resin (Aero-Jet). The tensile bond strength test was performed on an Universal Machine set at a crosshead speed of 1,5 mm/min, and for each rupture we registered a graphic and the best load required in Newtons, was converted to MPa and kgf. The share bond strength showed bigger values for the exposure time of 20 seconds, for the Group bonded for halogen light (H20), 7,45 kgf (7,64 MPa) and for argon laser 7,50 kgf (7,69 MPa); lesser values for the exposure time of 40s for the Group with halogen light (H40), 6,15 kgf (6,30 MPa) and argon laser Group (A40), 6,20 kgf (6,35 MPa) 0; and A10, 4,85 kgf (4,97 MPa). In the ARI Index, only A40 Group showed the 1 Index, with statistical results. In this Group, less than half of the remainder adhesive stayed on the surface of the enamel, conferring specimens failed at the enamel-adhesive interface. The results of the in vitro study demonstrate that

  11. Correlation of shear and dielectric ion viscosity of dental resins - Influence of composition, temperature and filler content.

    Science.gov (United States)

    Steinhaus, Johannes; Hausnerova, Berenika; Haenel, Thomas; Selig, Daniela; Duvenbeck, Fabian; Moeginger, Bernhard

    2016-07-01

    Shear viscosity and ion viscosity of uncured visible light-curing (VLC) resins and resin based composites (RBC) are correlated with respect to the resin composition, temperature and filler content to check where Dielectric Analysis (DEA) investigations of VLC RBC generate similar results as viscosity measurements. Mixtures of bisphenol A glycidyl methacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) as well as the pure resins were investigated and compared with two commercial VLC dental resins and RBCs (VOCO, Arabesk Top and Grandio). Shear viscosity data was obtained using a Haake Mars III, Thermo Scientific. Ion viscosity measurements performed by a dielectric cure analyzer (DEA 231/1 Epsilon with Mini IDEX-Sensor, Netzsch-Gerätebau). Shear viscosity depends reciprocally on the mobility of molecules, whereas the ion viscosity also depends on the ion concentration as it is affected by both ion concentration and mixture viscosity. Except of pure TEGDMA, shear and ion viscosities depend on the resin composition qualitatively in a similar manner. Furthermore, shear and ion viscosities of the commercial VLC dental resins and composites exhibited the same temperature dependency regardless of filler content. Application of typical rheological models (Kitano and Quemada) revealed that ion viscosity measurements can be described with respect to filler contents of up to 30vol.%. Rheological behavior of a VLC RBC can be characterized by DEA under the condition that the ion concentration is kept constant. Both methods address the same physical phenomenon - motion of molecules. The proposed relations allows for calculating the viscosity of any Bis-GMA-TEGDMA mixture on the base of the viscosities of the pure components. This study demonstrated the applicability of DEA investigations of VLC RBCs with respect to quality assurance purposes. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  12. SEM and elemental analysis of composite resins

    International Nuclear Information System (INIS)

    Hosoda, H.; Yamada, T.; Inokoshi, S.

    1990-01-01

    Twenty-four chemically cured, 21 light-cured anterior, three light-cured anterior/posterior, and 18 light-cured posterior composite resins were examined using scanning electron microscopy, and the elemental composition of their filler particles was analyzed with an energy dispersive electron probe microanalyzer. According to the results obtained, the composite resins were divided into five groups (traditional, microfilled type, submicrofilled type, hybrid type, and semihybrid), with two additional hypothetical categories (microfilled and hybrid). Characteristics of each type were described with clinical indications for selective guidance of respective composite resins for clinical use

  13. Simulation of Air Entrapment and Resin Curing During Manufacturing of Composite Cab Front by Resin Transfer Moulding Process

    Directory of Open Access Journals (Sweden)

    Kuppusamy Raghu Raja Pandiyan

    2017-09-01

    Full Text Available Mould filling and subsequent curing are the significant processing stages involved in the production of a composite component through Resin Transfer Moulding (RTM fabrication technique. Dry spot formation and air entrapment during filling stage caused by improper design of filling conditions and locations that lead to undesired filling patterns resulting in defective RTM parts. Proper placement of inlet ports and exit vents as well as by adjustment of filling conditions can alleviate the problems during the mould filling stage. The temperature profile used to polymerize the resin must be carefully chosen to reduce the cure time. Instead of trial and error methods that are expensive, time consuming, and non-optimal, we propose a simulation-based optimization strategy for a composite cab front component to reduce the air entrapment and cure stage optimization. In order to be effective, the optimization strategy requires an accurate simulation of the process utilizing submodels to describe the raw material characteristics. Cure reaction kinetics and chemo-rheology were the submodels developed empirically for an unsaturated polyester resin using experimental data. The simulations were performed using commercial software PAM RTM 2008, developed by ESI Technologies. Simulation results show that the use of increase in injection pressure at the inlet filling conditions greatly reduce the air entrapped. For the cab front, the alteration of injection pressure with proper timing of vent opening reduced the air entrapped during mould filling stage. Similarly, the curing simulation results show that the use of higher mould temperatures effectively decreases the cure time as expected.

  14. Catalyzed Synthesis and Characterization of a Novel Lignin-Based Curing Agent for the Curing of High-Performance Epoxy Resin

    Directory of Open Access Journals (Sweden)

    Saeid Nikafshar

    2017-07-01

    Full Text Available In this study, lignin, an aromatic compound from the forestry industry, was used as a renewable material to synthesize a new aromatic amine curing agent for epoxy resin. Firstly, lignin was separated from black liquor and hydroxyl groups were converted to tosyl groups as leaving groups. Then, primary amination was conducted using an ammonia solution at high pressure and temperature, in the presence of a nano-alumina-based catalyst. The structure of the nanocatalyst was confirmed by FT-IR, ICP, SEM, and XPS analyses. According to the FT-IR spectra, a demethylation reaction, the substitution of hydroxyl groups with tosyl groups, and then an amination reaction were successfully performed on lignin, which was further confirmed by the 13C NMR and CHNS analyses. The active hydrogen equivalent of aminated lignin was determined and three samples with 9.9 wt %, 12.9 wt %, and 15.9 wt % of aminated lignin, as curing agents, were prepared for curing the diglycidyl ether of bisphenol A (DGEBA. The thermal characteristics of the curing process of these epoxy samples were determined by DSC and TGA analyses. Moreover, the mechanical performance of the cured epoxy systems, e.g., the tensile strength and Izod impact strength, were measured, showing that in the presence of 12.9 wt % aminated lignin, the mechanical properties of the aminated lignin-epoxy system exhibited the best performance, which was competitive, compared to the epoxy systems cured by commercial aromatic curing agents.

  15. Cure Kinetics of Benzoxazine/Cycloaliphatic Epoxy Resin by Differential Scanning Calorimetry

    Science.gov (United States)

    Gouni, Sreeja Reddy

    Understanding the curing kinetics of a thermoset resin has a significant importance in developing and optimizing curing cycles in various industrial manufacturing processes. This can assist in improving the quality of final product and minimizing the manufacturing-associated costs. One approach towards developing such an understanding is to formulate kinetic models that can be used to optimize curing time and temperature to reach a full cure state or to determine time to apply pressure in an autoclave process. Various phenomenological reaction models have been used in the literature to successfully predict the kinetic behavior of a thermoset system. The current research work was designed to investigate the cure kinetics of Bisphenol-A based Benzoxazine (BZ-a) and Cycloaliphatic epoxy resin (CER) system under isothermal and nonisothermal conditions by Differential Scanning Calorimetry (DSC). The cure characteristics of BZ-a/CER copolymer systems with 75/25 wt% and 50/50 wt% have been studied and compared to that of pure benzoxazine under nonisothermal conditions. The DSC thermograms exhibited by these BZ-a/CER copolymer systems showed a single exothermic peak, indicating that the reactions between benzoxazine-benzoxazine monomers and benzoxazine-cycloaliphatic epoxy resin were interactive and occurred simultaneously. The Kissinger method and isoconversional methods including Ozawa-Flynn-Wall and Freidman were employed to obtain the activation energy values and determine the nature of the reaction. The cure behavior and the kinetic parameters were determined by adopting a single step autocatalytic model based on Kamal and Sourour phenomenological reaction model. The model was found to suitably describe the cure kinetics of copolymer system prior to the diffusion-control reaction. Analyzing and understanding the thermoset resin system under isothermal conditions is also important since it is the most common practice in the industry. The BZ-a/CER copolymer system with

  16. [Aging of silorane- and methacrylate-based composite resins: effects on color and translucency].

    Science.gov (United States)

    Liu, Chang; Pan, Jie; Lin, Hong; Shen, Song

    2015-10-01

    To evaluate the color stability and translucency of silorane-based low shrinkage composite after in vitro aging procedures of thermal cycling and water storage respectively, and to compare with those of conventional methacrylate-based posterior composite. Three light-cured composite resins, dimethacrylate-based composite A (Filtek™ Z350), B (Filtek™ P60) and silorane-based composite C (Filtek™ P90), were tested in this study. Ten specimens (10 mm in diameter, 1 mm in height) of each composite were prepared. The ten specimens in each group were then divided into two subgroups (n = 5). One subgroup underwent thermal cycling [(5.0 ± 0.5)~(55.0 ± 1.0) °C, 10 000 cycles] and the other was stored in 37 C° distilled water for 180 days. With a spectrophotometer, the CIE L * a * b * parameters of the specimens were tested before and after artificial aging against white, medium grey and black backgrounds, respectively. △E, TP and △TP were calculated and data were analyzed using independent-samples t test and partial analysis (P composite showed color alteration above the clinically acceptable levels (△E > 3.3), and also showed higher △E with a statistically significant difference in comparison with the other composites (B and C) (P composite C showed more alteration compared with composite B (P composite underwent greater alteration with regard to color stability and translucency.

  17. Heat-cured Acrylic Resin versus Light-activated Resin: A Patient ...

    African Journals Online (AJOL)

    2018-01-30

    Jan 30, 2018 ... the performance of a mandibular implant‑supported overdenture constructed from a heat‑cured ... on evaluating different aspects of the denture and overall satisfaction. The second ... Any type of acrylic denture base fracture presents a .... occlusion, and ability to chew after using the assigned denture for 6 ...

  18. Shear bond strength evaluation of resin composite to resin-modified glass-ionomer cement using three different resin adhesives vs. glass-ionomer based adhesive

    Directory of Open Access Journals (Sweden)

    Mostafa Sadeghi

    2015-12-01

    Full Text Available Background: The clinical success of sandwich technique depends on the strength of resin-modified glass ionomer cement (RMGIC bonding to both dentin and resin composite. Therefore, the shear bond strength (SBS of resin composite bonded to RMGIC utilizing different resin adhesives versus a GIC-based adhesive was compared. Materials and methods: In this in vitro study, 84 holes (5×2 mm were prepared in acrylic blocks, randomly divided into seven groups (n=12 and filled with RMGIC (Light-Cured Universal Restorative, GC. In the Group I; no adhesive was applied on the RMGIC. In the Group II, non-etched and Group III was etched with phosphoric acid. In groups II and III, after rinsing, etch-and-rinse adhesive (OptiBond Solo Plus; in the Group IV; a two-step self-etch adhesive (OptiBond XTR and in Group V; a one-step self-etch (OptiBond All-in-One were applied on the cement surfaces. Group VI; a GIC-based adhesive (Fuji Bond LC was painted over the cement surface and cured. Group VII; the GIC-based adhesive was brushed over RMGIC followed by the placement of resin composite and co-cured. Afterward; resin composite (Point 4 cylinders were placed on the treated cement surfaces. The specimens were placed in 100% humidity at 37 ± 1°C and thermo cycled. The shear bond test was performed at a cross-head speed of 1 mm/min and calculated in MPa; the specimens were examined to determine mode of failure. The results were analyzed using one-way ANOVA and Tukey test. Results: The maximum (24.62±3.70 MPa and minimum (18.15±3.38 MPa SBS mean values were recorded for OptiBond XTR adhesive and the control group, respectively. The pairwise comparisons showed no significant differences between the groups that bonded with different adhesives. The adhesive failure was the most common failure mode observed. Conclusion: This study suggests that GIC-based adhesive could be applied over RMGIC as co-cure technique for sandwich restorations in lieu of employing the resin

  19. Critical parameters for electron beam curing of cationic epoxies and property comparison of electron beam cured cationic epoxies versus thermal cured resins and composites

    International Nuclear Information System (INIS)

    Janke, C.J.; Norris, R.E.; Yarborough, K.; Lopata, V.J.

    1997-01-01

    Electron beam curing of composites is a nonthermal, nonautoclave curing process offering the following advantages compared to conventional thermal curing: substantially reduced manufacturing costs and curing times; improvements in part quality and performance; reduced environmental and health concerns; and improvements in material handling. In 1994 a Cooperative Research and Development Agreement (CRADA), sponsored by the Department of Energy Defense Programs and 10 industrial partners, was established to advance electron beam curing of composites. The CRADA has successfully developed hundreds of new toughened and untoughened resins, offering unlimited formulation and processing flexibility. Several patent applications have been filed for this work. Composites made from these easily processable, low shrinkage material match the performance of thermal cured composites and exhibit: low void contents comparable to autoclave cured composites (less than 1%); superb low water absorption values in the same range as cyanate esters (less than 1%); glass transition temperatures rivaling those of polyimides (greater than 390 C); mechanical properties comparable to high performance, autoclave cured composites; and excellent property retention after cryogenic and thermal cycling. These materials have been used to manufacture many composite parts using various fabrication processes including hand lay-up, tow placement, filament winding, resin transfer molding and vacuum assisted resin transfer molding

  20. Modeling the curing process of thermosetting resin matrix composites

    Science.gov (United States)

    Loos, A. C.

    1986-01-01

    A model is presented for simulating the curing process of a thermosetting resin matrix composite. The model relates the cure temperature, the cure pressure, and the properties of the prepreg to the thermal, chemical, and rheological processes occurring in the composite during cure. The results calculated with the computer code developed on the basis of the model were compared with the experimental data obtained from autoclave-curved composite laminates. Good agreement between the two sets of results was obtained.

  1. Curing agent for polyepoxides and epoxy resins and composites cured therewith. [preventing carbon fiber release

    Science.gov (United States)

    Serafini, T. T.; Delvigs, P.; Vannucci, R. D. (Inventor)

    1981-01-01

    A curing for a polyepoxide is described which contains a divalent aryl radical such as phenylene a tetravalent aryl radical such as a tetravalent benzene radical. An epoxide is cured by admixture with the curing agent. The cured epoxy product retains the usual properties of cured epoxides and, in addition, has a higher char residue after burning, on the order of 45% by weight. The higher char residue is of value in preventing release to the atmosphere of carbon fibers from carbon fiber-epoxy resin composites in the event of burning of the composite.

  2. Correlation between clinical performance and degree of conversion of resin cements: a literature review

    Directory of Open Access Journals (Sweden)

    Grace DE SOUZA

    2015-08-01

    Full Text Available AbstractResin-based cements have been frequently employed in clinical practice to lute indirect restorations. However, there are numerous factors that may compromise the clinical performance of those cements. The aim of this literature review is to present and discuss some of the clinical factors that may affect the performance of current resin-based luting systems. Resin cements may have three different curing mechanisms: chemical curing, photo curing or a combination of both. Chemically cured systems are recommended to be used under opaque or thick restorations, due to the reduced access of the light. Photo-cured cements are mainly indicated for translucent veneers, due to the possibility of light transmission through the restoration. Dual-cured are more versatile systems and, theoretically, can be used in either situation, since the presence of both curing mechanisms might guarantee a high degree of conversion (DC under every condition. However, it has been demonstrated that clinical procedures and characteristics of the materials may have many different implications in the DC of currently available resin cements, affecting their mechanical properties, bond strength to the substrate and the esthetic results of the restoration. Factors such as curing mechanism, choice of adhesive system, indirect restorative material and light-curing device may affect the degree of conversion of the cement and, therefore, have an effect on the clinical performance of resin-based cements. Specific measures are to be taken to ensure a higher DC of the luting system to be used.

  3. Differential scanning calorimetry of the effects of temperature and humidity on phenol-formaldehyde resin cure

    Science.gov (United States)

    X.-M. Wang; B. Riedl; A.W. Christiansen; R.L. Geimer

    1994-01-01

    Phenol-formaldehyde (PF) resin is a widely used adhesive in the manufacture of wood composites. However, curing behaviour of the resin under various environmental conditions is not well known. A differential scanning calorimeter was employed to characterize the degree of resin cure in this study. Resin-impregnated glass cloth samples with varied moisture contents (0,31...

  4. Curing behavior and reaction kinetics of binder resins for 3D-printing investigated by dielectric analysis (DEA)

    Science.gov (United States)

    Möginger, B.; Kehret, L.; Hausnerova, B.; Steinhaus, J.

    2016-05-01

    3D-Printing is an efficient method in the field of additive manufacturing. In order to optimize the properties of manufactured parts it is essential to adapt the curing behavior of the resin systems with respect to the requirements. Thus, effects of resin composition, e.g. due to different additives such as thickener and curing agents, on the curing behavior have to be known. As the resin transfers from a liquid to a solid glass the time dependent ion viscosity was measured using DEA with flat IDEX sensors. This allows for a sensitive measurement of resin changes as the ion viscosity changes two to four decades. The investigated resin systems are based on the monomers styrene and HEMA. To account for the effects of copolymerization in the calculation of the reaction kinetics it was assumed that the reaction can be considered as a homo-polymerization having a reaction order n≠1. Then the measured ion viscosity curves are fitted with the solution of the reactions kinetics - the time dependent degree of conversion (DC-function) - for times exceeding the initiation phase representing the primary curing. The measured ion viscosity curves can nicely be fitted with the DC-function and the determined fit parameters distinguish distinctly between the investigated resin compositions.

  5. The effects of alkyd/melamine resin ratio and curing temperature on the properties of the coatings

    Directory of Open Access Journals (Sweden)

    RADMILA Z. RADICEVIC

    2005-04-01

    Full Text Available Synthetic resins are used as binders in protective coatings. An alkyd/melamine resin mixture is the usual composition for the preparation of a coating called “baking enamel” cured through functional groups of resins. The effects of the alkyd/butylated melamine resin ratio (from 85/15 to 70/30 and curing temperature (from 100°C to 160°C on the crosslinking and properties of the coating are presented in this paper. The degree of curing was determined by differential scanning calorimetry. These data were used for the estimation of the degree of crosslinking. The hardness, elasticity, impact resistance, degree of adherence and gloss were also determined. Optimal coating properties could be achieved with an alkyd/melamine resin ratio of 75/25, a curing temperature of 130 °C and a curing time of 30 min.

  6. Temperature rise induced by some light emitting diode and quartz-tungsten-halogen curing units.

    Science.gov (United States)

    Asmussen, Erik; Peutzfeldt, Anne

    2005-02-01

    Because of the risk of thermal damage to the pulp, the temperature rise induced by light-curing units should not be too high. LED (light emitting diode) curing units have the main part of their irradiation in the blue range and have been reported to generate less heat than QTH (quartz-tungsten-halogen) curing units. This study had two aims: first, to measure the temperature rise induced by ten LED and three QTH curing units; and, second, to relate the measured temperature rise to the power density of the curing units. The light-induced temperature rise was measured by means of a thermocouple embedded in a small cylinder of resin composite. The power density was measured by using a dental radiometer. For LED units, the temperature rise increased with increasing power density, in a statistically significant manner. Two of the three QTH curing units investigated resulted in a higher temperature rise than LED curing units of the same power density. Previous findings, that LED curing units induce less temperature rise than QTH units, does not hold true in general.

  7. Method for curing alkyd resin compositions by applying ionizing radiation

    International Nuclear Information System (INIS)

    Watanabe, T.; Murata, K.; Maruyama, T.

    1975-01-01

    An alkyd resin composition is prepared by dissolving a polymerizable alkyd resin having from 10 to 50 percent of oil length into a vinyl monomer. The polymerizable alkyd resin is obtained by a half-esterification reaction of an acid anhydride having a polymerizable unsaturated group and an alkyd resin modified with conjugated unsaturated oil having at least one reactive hydroxyl group per one molecule. The alkyd resin composition thus obtained is coated on an article, and ionizing radiation is applied on the article to cure the coated film thereon. (U.S.)

  8. Do water based resins find their use in radiation cure applications?

    International Nuclear Information System (INIS)

    Ravijst, J.-P.

    1995-01-01

    There is an increasing demand for UV/EB formulation without monomers. Water dilutable oligomers offer one approach to formulations of this type. Several ways to use water as a primary means of reducing oligomer viscosities are reviewed. A number of new water dilutable acrylate resins were prepared having different functionalities and properties. Depending on the structure, viscosity decreases significantly by adding water. Good reactivity, solvent and water resistance were achieved after curing

  9. Verification of the light intensity from halogens curing lamps in comparison with the manufacturer's specifications

    International Nuclear Information System (INIS)

    Morales Ramirez, Elvis

    2011-01-01

    The light intensity emitted from halogens curing lamps is measured to determine if photoactivation units utilized in the Caja Costarricense de Seguro Social are complied with the manufacturer's specifications of the lamp and the resin. The light intensity mW/cm 2 from halogens curing lamps operated by odontologist of the Caja Costarricense de Seguro Social is compared with the manufacturer's specifications of the lamp. The light intensity is compared with the manufacturer's specifications of the resin. The results obtained are analyzed to specify that lamp or lamps have presented light intensities lower to indication of the manufacturer. A list of recommendations is performed for each Servicio de Odontologia of the Caja Costarricense de Seguro Social of the Region Central Sur of the results reported [es

  10. Determination of unreacted monomers in restorative dental resins based on dimethacrylate by NMR hydrogen; Determinacao do teor de monomero residual em resinas restauradoras a base de dimetacrilatos por RMN de hidrogenio

    Energy Technology Data Exchange (ETDEWEB)

    Correa, Ivo Carlos; Miranda Junior, Walter G. [Sao Paulo Univ., SP (Brazil). Faculdade de Odontologia. Dept. de Materiais Dentarios]. E-mail: ivo@fo.usp.br; Tavares, Maria Ines B. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Macromoleculas]. E-mail: mibt@ima.ufrj.br

    2001-07-01

    The presence of unreacted monomers after photo-activation of dental composites causes mechanical and biological properties to decrease and could be detected by NMR analysis. The aim of this study was to evaluate the percentage of leachable monomers of light-cured composites under the effect of variations of exposure time of photo activation by nuclear magnetic resonance of hydrogen in solution (NMR{sup 1}H). The composite resins tested Z250 and Fill Magic obtained similar values of unreacted monomers (%) at photo curing time suggested by the manufacturer and values were also lower than Durafill and A110 concentrations. From the NMR results, one day extractable time was efficient to quantify the amount of residual monomers in the dental composites tested, unless for Durafill composite. (author)

  11. Fast Curing Bio-Based Phenolic Resins via Lignin Demethylated under Mild Reaction Condition

    Directory of Open Access Journals (Sweden)

    Jiongjiong Li

    2017-09-01

    Full Text Available Demethylation technique has been used to enhance lignin reactivity for preparation of phenolic resins. However, the demethylation efficiency and the demethylated lignin (DL reactivity were still unsatisfactory. To improve the demethylation efficiency, alkali lignin was demethylated under different mild conditions using sodium sulfite as a catalyst. Lignin and DL were characterized by 1H-NMR (nuclear magnetic resonance and Fourier transform infrared (FT-IR spectroscopy to determine the demethylation mechanism. With the demethylation of lignin, the methoxyl group content decreased from 1.93 m mol/g to 1.09 m mol/g, and the phenolic hydroxyl group content increased from 0.56 m mol/g to 0.82 m mol/g. These results revealed that methoxyl groups were attacked by SO32−, and some methoxyl groups were converted to phenolic hydroxyl groups by a nucleophilic substitution reaction, generating DL with high reactivity. The chemical properties of lignin-based phenolic resins were studied by 13C-NMR and FT-IR spectroscopy, and their physical properties were also investigated. The results indicated that lignin-based phenolic resins exhibited faster curing rate and shorter gel time. In addition, the bonding strength increased from 0.92 MPa to 1.07 MPa, and the formaldehyde emission decreased from 0.58 mg/L to 0.22 mg/L after lignin demethylated at the optimum condition.

  12. Effects on microstrain and conversion of flowable resin composite using different curing modes and units.

    Science.gov (United States)

    Tseng, Wan-Yu; Chen, Ruey-Song; Wang, Jaw-Lin; Lee, Ming-Shu; Rueggeberg, Frederick A; Chen, Min-Huey

    2007-05-01

    The flowable resin composite, Tetric Flow, was used to measure microstrain and degree of conversion after hardening with each of three curing machines: XL3000(XL) for 10, 20, 30, and 40 s; Optilux 501 using conventional mode (OC) for 10, 20, 30, and 40 s, as well as Optilux boost (OB, 10 s) and ramp modes (OR, 20 s); and LEDemetron (LEDe) for 10, 20, 30, and 40 s. The emitted power density and spectral distribution of the three light curing units were also measured. The LEDe output energy spectrum was centralized between 425 and 490 nm, which encompasses the excited wavelength of camphorquinone. The microstrain produced by the curing process is as a second-degree polynomial for each light source. The OB microstrain was highest, while the OR microstrain was lower. The ranking in order of degree of monomer conversion was as follows: XL10 conversion cured with OB was significant higher than other curing modes except OC30, OC40, LEDe30, LEDe40, and XL40. The conversion value of XL10 was the lowest. The LEDe produced higher conversion for the same emitted energy compared to the two halogen units.

  13. CURING OF POLYMERIC COMPOSITES USING MICROWAVE RESIN TRANSFER MOULDING (RTM

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    R. YUSOFF

    2007-08-01

    Full Text Available The main objective of this work is to compare the difference between microwave heating and conventional thermal heating in fabricating carbon/epoxy composites. Two types of epoxy resin systems were used as matrices, LY5052-HY5052 and DGEBA-HY917-DY073. All composite samples were fabricated using resin transfer moulding (RTM technique. The curing of the LY5052-HY5052-carbon and the DGEBA-HY917-DY073-carbon composite systems, were carried out at 100 °C and 120 °C, respectively. Microwave heating showed better temperature control than conventional heating, however, the heating rate of the microwave cured samples were slower than the conventionally cured samples. This was attributed to the lower power (250 W used when heating with microwaves compared to 2000 W used in conventional heating. Study of thermal characteristics as curing progressed showed that the polymerisation reaction occurred at a faster rate during microwave curing than in conventional curing for both the DGEBA and the LY/HY5052 carbon composite systems. The actual cure cycle was reduced from 60 minutes to 40 minutes when using microwaves for curing DGEBA-carbon composites. As for LY/HY5052-carbon composites, the actual cure cycle was reduced from 3 hours to 40 minutes. Both conventional and microwave heating yielded similar glass transition temperatures (120 °C for DGEBA systems and 130 °C for LY/HY5052 systems. Microwave cured composites had higher void contents than conventionally cured composites (2.2-2.8% and 1.8-2.4% for DGEBA and LY/HY5052 microwave cured composites, respectively, compared to 0.2-0.4% for both DGEBA and LY/HY5052 thermally cured composites. C-scan traces showed that all composites, regardless of methods of curing, had minimal defects.

  14. Thermal, spectral, and surface properties of LED light-polymerized bulk fill resin composites.

    Science.gov (United States)

    Pişkin, Mehmet Burçin; Atalı, Pınar Yılmaz; Figen, Aysel Kantürk

    2015-02-01

    The aim of this study was to evaluate the thermal, spectral, and surface properties of four different bulk fill materials – SureFil SDR (SDR, Dentsplay DETREY), QuixFil (QF, Dentsplay DETREY), X-tra base (XB, Voco) X-tra fil (XF, Voco) – polymerized by light-emitting diode (LED). Resin matrix, filler type, size and amount, and photoinitiator types influence the degree of conversion. LED-cured bulk fill composites achieved sufficient polymerization. Scanning electron microscope (SEM) analysis revealed different patterns of surface roughness, depending on the composite material. Bulk fill materials showed surface characteristics similar to those of nanohybrid composites. Based on the thermal analysis results, glass transition (T(g)) and initial degradation (T(i)) temperatures changed depending on the bulk fill resin composites.

  15. Effect of light curing tip distance and resin shade on microhardness of a hybrid resin composite Efeito da distância da ponta do aparelho de fotoativação e da cor na microdureza superficial de um compósito híbrido

    Directory of Open Access Journals (Sweden)

    Flávio Henrique Baggio Aguiar

    2005-12-01

    Full Text Available Resin composite shades and resin composite polymerization performed with a distanced light tip are factors that can affect polymerization effectiveness. Thisin vitro study aimed to evaluate the influence of curing tip distance and resin shade on the microhardness of a hybrid resin composite (Z250 - 3M ESPE. Forty-five resin composite specimens were randomly prepared and divided into nine experimental groups (n = 5: three curing tip distances (2 mm, 4 mm, and 8 mm and three resin shades (A1, A3.5, and C2. All samples were polymerized with a continuous output at 550 mW/cm². After 24 hours, Knoop microhardness measurements were obtained on the top and bottom surfaces of the sample, with a load of 25 grams for 10 seconds. Five indentations were performed on each surface of each sample. Results showed that bottom surface samples light-cured at 2 mm and 4 mm presented significantly higher hardness values than samples light-cured at 8 mm. The resin shade A1 presented higher hardness values and was statistically different from C2. The resin shade A3.5 did not present statistical differences from A1 and C2. For the top surface, there were no statistical differences among the curing tip distances. For all experimental conditions, the top surface showed higher hardness values than the bottom surface. It was concluded that light curing tip distance and resin shade are important factors to be considered for obtaining adequate polymerization.A cor do compósito e a polimerização realizada com a ponta do aparelho de fotoativação distante da superfície do compósito são fatores que podem afetar a efetividade de polimerização. Assim, o objetivo deste estudo in vitro foi avaliar a influência desses fatores na microdureza superficial de um compósito híbrido (Z250 - 3M ESPE. Quarenta e cinco espécimes de compósito foram aleatoriamente preparados de acordo com os nove grupos experimentais (n = 5: três distâncias de fotoativação (2 mm, 4 mm e 8 mm e

  16. Effect of reduced exposure times on the cytotoxicity of resin luting cements cured by high-power led

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    Gulfem Ergun

    2011-06-01

    Full Text Available OBJECTIVE: Applications of resin luting agents and high-power light-emitting diodes (LED light-curing units (LCUs have increased considerably over the last few years. However, it is not clear whether the effect of reduced exposure time on cytotoxicity of such products have adequate biocompatibility to meet clinical success. This study aimed at assessing the effect of reduced curing time of five resin luting cements (RLCs polymerized by high-power LED curing unit on the viability of a cell of L-929 fibroblast cells. MATERIAL AND METHODS: Disc-shaped samples were prepared in polytetrafluoroethylene moulds with cylindrical cavities. The samples were irradiated from the top through the ceramic discs and acetate strips using LED LCU for 20 s (50% of the manufacturer's recommended exposure time and 40 s (100% exposure time. After curing, the samples were transferred into a culture medium for 24 h. The eluates were obtained and pipetted onto L-929 fibroblast cultures (3x10(4 per well and incubated for evaluating after 24 h. Measurements were performed by dimethylthiazol diphenyltetrazolium assay. Statistical significance was determined by two-way ANOVA and two independent samples were compared by t-test. RESULTS: Results showed that eluates of most of the materials polymerized for 20 s (except Rely X Unicem and Illusion reduced to a higher extent cell viability compared to samples of the same materials polymerized for 40 s. Illusion exhibited the least cytotoxicity for 20 s exposure time compared to the control (culture without samples followed by Rely X Unicem and Rely X ARC (90.81%, 88.90%, and 83.11%, respectively. For Rely X ARC, Duolink and Lute-It 40 s exposure time was better (t=-1.262 p=0,276; t=-9.399 p=0.001; and t=-20.418 p<0.001, respectively. CONCLUSION: The results of this study suggest that reduction of curing time significantly enhances the cytotoxicity of the studied resin cement materials, therefore compromising their clinical

  17. Effect of ultraviolet light irradiation period on bond strengths between fiber-reinforced composite post and core build-up composite resin.

    Science.gov (United States)

    Asakawa, Yuya; Takahashi, Hidekazu; Iwasaki, Naohiko; Kobayashi, Masahiro

    2014-01-01

    The aim of the present study was to characterize the effects of the ultraviolet light (UV) irradiation period on the bond strength of fiber-reinforced composite (FRC) posts to core build-up resin. Three types of FRC posts were prepared using polymethyl methacrylate, urethane dimethacrylate, and epoxy resin. The surfaces of these posts were treated using UV irradiation at a distance of 15 mm for 0 to 600 s. The pull-out bond strength was measured and analyzed with the Dunnett's comparison test (α=0.05). The bond strengths of the post surfaces without irradiation were 6.9 to 7.4 MPa; those after irradiation were 4.2 to 26.1 MPa. The bond strengths significantly increased after 15 to 120-s irradiation. UV irradiation on the FRC posts improved the bond strengths between the FRC posts and core build-up resin regardless of the type of matrix resin.

  18. Preparation and Characterization of UV-Curable Cyclohexanone-Formaldehyde Resin and Its Cured Film Properties

    Directory of Open Access Journals (Sweden)

    Guang Yang

    2014-01-01

    Full Text Available UV-curable cyclohexanone-formaldehyde (UVCF resin was prepared with cyclohexanone-formaldehyde (CF resin, isophorone diisocyanate (IPDI, and pentaerythritol triacrylate (PETA as base substance, bridging agent, and functional monomer, respectively. The structure of UVCF was characterized by Fourier transform infrared spectroscopy (FT-IR, 1H-nuclear magnetic resonance spectroscopy (1H-NMR, and gel permeation chromatography (GPC. The viscosity and photopolymerization behavior of the UV-curable formulations were studied. The thermal stability and mechanical properties of the cured films were also investigated. The results showed that UVCF resin was successfully prepared, the number of average molecular weight was about 2010, and its molecular weight distribution index was 2.8. With the increase of UVCF resin content, the viscosity of the UV-curable formulations increased. After exposure to UV irradiation for 230 s, the photopolymerization conversion of the UV-curable formulations was above 80%. Moreover, when the UVCF content was 60%, the formulations had high photopolymerization rate, and the cured UVCF films showed good thermal stability and mechanical properties.

  19. Preparation of low viscosity epoxy acrylic acid photopolymer prepolymer in light curing system

    Science.gov (United States)

    Li, P.; Huang, J. Y.; Liu, G. Z.

    2018-01-01

    With the integration and development of materials engineering, applied mechanics, automatic control and bionics, light cured composite has become one of the most favourite research topics in the field of materials and engineering at home and abroad. In the UV curing system, the prepolymer and the reactive diluent form the backbone of the cured material together. And they account for more than 90% of the total mass. The basic properties of the cured product are mainly determined by the prepolymer. A low viscosity epoxy acrylate photosensitive prepolymer with a viscosity of 6800 mPa • s (25 °C ) was obtained by esterification of 5 hours with bisphenol A epoxy resin with high epoxy value and low viscosity.

  20. Cure Cycle Design Methodology for Fabricating Reactive Resin Matrix Fiber Reinforced Composites: A Protocol for Producing Void-free Quality Laminates

    Science.gov (United States)

    Hou, Tan-Hung

    2014-01-01

    For the fabrication of resin matrix fiber reinforced composite laminates, a workable cure cycle (i.e., temperature and pressure profiles as a function of processing time) is needed and is critical for achieving void-free laminate consolidation. Design of such a cure cycle is not trivial, especially when dealing with reactive matrix resins. An empirical "trial and error" approach has been used as common practice in the composite industry. Such an approach is not only costly, but also ineffective at establishing the optimal processing conditions for a specific resin/fiber composite system. In this report, a rational "processing science" based approach is established, and a universal cure cycle design protocol is proposed. Following this protocol, a workable and optimal cure cycle can be readily and rationally designed for most reactive resin systems in a cost effective way. This design protocol has been validated through experimental studies of several reactive polyimide composites for a wide spectrum of usage that has been documented in the previous publications.

  1. Distance and protective barrier effects on the composite resin degree of conversion

    Science.gov (United States)

    Coutinho, Margareth; Trevizam, Natália Carvalho; Takayassu, Renata Nakase; Leme, Ariene Arcas; Soares, Giulliana Panfiglio

    2013-01-01

    Context: The food wrap films are used to cover the tip of curing light units in order to avoid contamination and prevent damage to the light guide. However, their effects on resin polymerization are not fully known. Aims: We investigated the effects on restoration efficiency of a food wrap protective barrier used on the tip of curing light units. Materials and Methods: For each treatment, five replications were performed, a total of 60 bovine incisor. The degree of conversion (%DC) of restorations with the composite resin Opallis EA2 was evaluated using 3 curing light devices (Optilux 501, Optilight and Ultra LED) and 2 curing distances (0 and 5 mm). The composite resin was tested for restoration of cavities in bovine crowns. %DC values were measured by the Fourier transform infrared spectroscopy-attenuated total reflectance technique. Statistical Analysis Used: The data were analyzed using 3-way ANOVA and Tukey's test. Results: Use of the protective film lowered %DC (F = 4.13; P = 0.05), and the effects of curing distance were associated to the curing light device (F = 3.61; P = 0.03). Conclusions: The distance from the light curing tip and use of a translucent protective barrier on the light-cure device can both impair composite resin %DC. PMID:24015001

  2. Effects of radiant exposure and wavelength spectrum of light-curing units on chemical and physical properties of resin cements

    Directory of Open Access Journals (Sweden)

    Adriano Fonseca Lima

    2016-11-01

    Full Text Available Objectives In this study, we evaluated the influence of different radiant exposures provided by single-peak and polywave light-curing units (LCUs on the degree of conversion (DC and the mechanical properties of resin cements. Materials and Methods Six experimental groups were established for each cement (RelyX ARC, 3M ESPE; LuxaCore Dual, Ivoclar Vivadent; Variolink, DMG, according to the different radiant exposures (5, 10, and 20 J/cm2 and two LCUs (single-peak and polywave. The specimens were made (7 mm in length × 2 mm in width × 1 mm in height using silicone molds. After 24 hours of preparation, DC measurement was performed using Fourier transform infrared spectrometry. The same specimens were used for the evaluation of mechanical properties (flexural strength, FS; elastic modulus, E by a three-point bending test. Data were assessed for normality, after which two-way analysis of variance (ANOVA and post hoc Tukey's test were performed. Results No properties of the Variolink cement were influenced by any of the considered experimental conditions. In the case of the RelyX ARC cement, DC was higher when polywave LCU was used; FS and E were not influenced by the conditions evaluated. The LuxaCore cement showed greater sensitivity to the different protocols. Conclusions On the basis of these results, both the spectrum of light emitted and the radiant exposure used could affect the properties of resin cements. However, the influence was material-dependent.

  3. Response behavior of an epoxy resin/amine curing agent/carbon black composite film to various solvents

    Energy Technology Data Exchange (ETDEWEB)

    Luo Yanling [School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China)]. E-mail: luoyl0401@yahoo.com.cn; Li Zhanqing [School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China); Lan Wenxiang [School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China)

    2007-04-25

    A novel polymer based sensitive film was prepared from thermosetting epoxy resins (EP) filled with carbon blacks. The curing reaction of amine curing agents with epoxy resins and the response of the curing resultants to solvent vapors were dealt with. The influence of the types and content of carbon blacks and curing agents, and curing temperatures and time on curing reactions and response selectivity of the conductive films were investigated. The structural characterization was conducted on a Fourier transform infrared spectrophotometer (FTIR). The results indicated that the conductive films showed high response selectivity to polar solvent vapors, especially to chloroform vapor, while no response was observed in non-polar solvent vapors. The responsivity of the film increased with the decreased carbon black contents. The film filled with acetylene carbon black gave an optimal response, with responsivity of about 700 times. The response performances were improved with the amount of curing agents increased, and an optimal response appeared at the amount of the curing agent of 8%. The film's responsivity was remarkably enhanced, the reversibility property, however, rapidly declined in the order of diethyleneltriamine < triethylenetetramine < ethylenediamine. The curing reaction tended to complete with the curing temperature elevated and the curing time prolonged. But the response performance dropped because of over cross-linking as the temperature was too high or the time was too long.

  4. Response behavior of an epoxy resin/amine curing agent/carbon black composite film to various solvents

    International Nuclear Information System (INIS)

    Luo Yanling; Li Zhanqing; Lan Wenxiang

    2007-01-01

    A novel polymer based sensitive film was prepared from thermosetting epoxy resins (EP) filled with carbon blacks. The curing reaction of amine curing agents with epoxy resins and the response of the curing resultants to solvent vapors were dealt with. The influence of the types and content of carbon blacks and curing agents, and curing temperatures and time on curing reactions and response selectivity of the conductive films were investigated. The structural characterization was conducted on a Fourier transform infrared spectrophotometer (FTIR). The results indicated that the conductive films showed high response selectivity to polar solvent vapors, especially to chloroform vapor, while no response was observed in non-polar solvent vapors. The responsivity of the film increased with the decreased carbon black contents. The film filled with acetylene carbon black gave an optimal response, with responsivity of about 700 times. The response performances were improved with the amount of curing agents increased, and an optimal response appeared at the amount of the curing agent of 8%. The film's responsivity was remarkably enhanced, the reversibility property, however, rapidly declined in the order of diethyleneltriamine < triethylenetetramine < ethylenediamine. The curing reaction tended to complete with the curing temperature elevated and the curing time prolonged. But the response performance dropped because of over cross-linking as the temperature was too high or the time was too long

  5. SYNTHESIS, THERMAL STUDIES AND CONVERSION DEGREE OF DIMETHACRYLATE POLYMERS USING NEW NON-TOXIC COINITIATORS

    Directory of Open Access Journals (Sweden)

    Rafael Turra Alarcon

    Full Text Available The aim of this paper is to replace toxic coinitiators (tertiary amines by non-toxic compounds such as glycerol and inositol (polyalcohol in dimethacrylate resins. For this purpose, mid infrared spectroscopy (MIR was used to calculate the monomers' degree of conversion (%DC; as well as simultaneous Thermogravimetric Analysis – Differential Thermal Analysis (TGA-DTA and Differential Scanning Calorimetry (DSC were conducted to evaluate thermal stability, degradation steps, and thermal events. The use of different initiator systems did not modify the thermal events or the thermal stability of each of the dimethacrylate resins. Results show a substitution of system 2 (toxicity by system 3 (low toxicity, which had a good conversion velocity and total conversion in some monomers, is plausible.

  6. Structure-to-property relationships in addition cured polymers. II - Resin Tg and composite initial mechanical properties of norbornenyl cured polyimide resins

    Science.gov (United States)

    Alston, William B.

    1986-01-01

    PRM (polymerization of monomeric reactants) methodology was used to prepare thirty different polyimide oligomeric resins. Monomeric composition as well as chain length between sites of crosslinks were varied to examine their effects on glass transition temperature (Tg) of the cured/postcured resins. An almost linear correlation of Tg versus molecular distance between the crosslinks was observed. An attempt was made to correlate Tg with initial mechanical properties (flexural strength and interlaminar shear strength) of unidirectional graphite fiber composites prepared with these resins. However, the scatter in mechanical strength data prevented obtaining as clear a correlation as was observed for the structural modification/crosslink distance versus Tg. Instead, only a range of composite mechanical properties was obtained at the test temperatures studied (room temperature, 288 and 316 C). Perhaps more importantly, what did become apparent during the attempted correlation study was: (1) that PMR methodology could be used to prepare composites from resins that contain a wide variety of monomer modifications, and (2) that these composites almost invariably provided satisfactory initial mechanical properties as long as the resins selected were melt processable.

  7. A Twofold Comparison between Dual Cure Resin Modified Cement and Glass Ionomer Cement for Orthodontic Band Cementation.

    Science.gov (United States)

    Attar, Hanaa El; Elhiny, Omnia; Salem, Ghada; Abdelrahman, Ahmed; Attia, Mazen

    2016-12-15

    To test the solubility of dual cure resin modified resin cement in a food simulating solution and the shear bond strength compared to conventional Glass ionomer cement. The materials tested were self-adhesive dual cure resin modified cement and Glass Ionomer (GIC). Twenty Teflon moulds were divided into two groups of tens. The first group was injected and packed with the modified resin cement, the second group was packed with GIC. To test the solubility, each mould was weighed before and after being placed in an analytical reagent for 30 days. The solubility was measured as the difference between the initial and final drying mass. To measure the Shear bond strength, 20 freshly extracted wisdom teeth were equally divided into two groups and embedded in self-cure acrylic resin. Four mm sections of stainless steel bands were cemented to the exposed buccal surfaces of teeth under a constant load of 500 g. Shear bond strength was measured using a computer controlled materials testing machine and the load required to deband the samples was recorded in Newtons. GIC showed significantly higher mean weight loss and an insignificant lower Shear bond strength, compared to dual cure resin Cement. It was found that dual cure resin modified cement was less soluble than glass ionomer cement and of comparable bond strength rendering it more useful clinically for orthodontic band cementation.

  8. Properties of discontinuous S2-glass fiber-particulate-reinforced resin composites with two different fiber length distributions.

    Science.gov (United States)

    Huang, Qiting; Garoushi, Sufyan; Lin, Zhengmei; He, Jingwei; Qin, Wei; Liu, Fang; Vallittu, Pekka Kalevi; Lassila, Lippo Veli Juhana

    2017-10-01

    To investigate the reinforcing efficiency and light curing properties of discontinuous S2-glass fiber-particulate reinforced resin composite and to examine length distribution of discontinuous S2-glass fibers after a mixing process into resin composite. Experimental S2-glass fiber-particulate reinforced resin composites were prepared by mixing 10wt% of discontinuous S2-glass fibers, which had been manually cut into two different lengths (1.5 and 3.0mm), with various weight ratios of dimethacrylate based resin matrix and silaned BaAlSiO 2 filler particulates. The resin composite made with 25wt% of UDMA/SR833s resin system and 75wt% of silaned BaAlSiO 2 filler particulates was used as control composite which had similar composition as the commonly used resin composites. Flexural strength (FS), flexural modulus (FM) and work of fracture (WOF) were measured. Fractured specimens were observed by scanning electron microscopy. Double bond conversion (DC) and fiber length distribution were also studied. Reinforcement of resin composites with discontinuous S2-glass fibers can significantly increase the FS, FM and WOF of resin composites over the control. The fibers from the mixed resin composites showed great variation in final fiber length. The mean aspect ratio of experimental composites containing 62.5wt% of particulate fillers and 10wt% of 1.5 or 3.0mm cutting S2-glass fibers was 70 and 132, respectively. No difference was found in DC between resin composites containing S2-glass fibers with two different cutting lengths. Discontinuous S2-glass fibers can effectively reinforce the particulate-filled resin composite and thus may be potential to manufacture resin composites for high-stress bearing application. Copyright © 2017. Published by Elsevier Ltd.

  9. The effects of different opacifiers on the translucency of experimental dental composite resins.

    Science.gov (United States)

    Haas, Karine; Azhar, Gulelala; Wood, Duncan J; Moharamzadeh, Keyvan; van Noort, Richard

    2017-08-01

    The aim of this study was to evaluate the effects of different opacifiers on the translucency of experimental dental composite-resins. Three metal oxides that are used as opacifiers were tested in this study: titanium oxide (TiO 2 ), aluminium oxide (Al 2 O 3 ) and zirconium oxide (ZrO 2 ). Experimental composite-resins were fabricated containing 25wt.% urethane dimethacrylate (UDMA)-based resin matrix and 75% total filler including different concentrations of metal oxides (0, 0.25, 0.5, 0.75 and 1wt.%) blended into silane treated barium-silicate filler. The specimens (15.5mm diameter and 1mm thickness) were light-cured and tested in the transmittance mode using a UV/VIS spectrophotometer at wavelengths from 380 to 700nm under a standard illuminant D65. The color differences (ΔE* ab) between different concentrations of opacifiers were also measured in transmittance mode based on their Lab values. Statistical analysis by ANOVA and Tukey's test showed a significant decrease (pcomposite-resins. There was a linear correlation between different concentrations of TiO 2 and Al 2 O 3 and total transmittance. Total transmittance was also found to be wavelength dependent. The color differences for the concentrations of 0-1wt.% of the opacifiers were above 1 ΔE* unit, with Al 2 O 3 showing the smallest color shift. The type and the amount of the opacifiers used in this study had a significant effect on the translucency of the experimental UDMA-based dental composite resins. The most effective opacifier was TiO 2 , followed by ZrO 2 and Al 2 O 3 in decreasing order, respectively. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  10. Radiation curing in the eighties

    International Nuclear Information System (INIS)

    Vrancken, A.

    1984-01-01

    The subject is discussed under the headings: introduction; what is radiation curing; history; radiation curable resins (with properties of products); ultraviolet and electron beam curing; photoinitiation and the ultraviolet light curing process; electron beam curing (initiation; electron beam accelerators); end uses (graphic arts; wood finishing; paper upgrading; adhesives; metal finishing; electronic chemical; floor coatings). (U.K.)

  11. Effect of different light-curing devices and aging procedures on composite knoop microhardness

    Directory of Open Access Journals (Sweden)

    Fernanda Regina Voltarelli

    2009-12-01

    Full Text Available The aim of this study was to evaluate the effect of light-curing devices (Halogen/HAL, Light Emitting Diodes/LED, Argon Laser/LAS and Plasma Arc/PAC and aging procedures (Mechanical Cycling/MC, Thermal Cycling/TC, Storage/S, MC+TC and MC+TC+S on the micro-hardness of bottom/B and top/T surfaces of 2-mm-high composite resin cylinders. The Knoop microhardness test (25 g, 20 s on both B and T was performed before and after each aging procedure. For B and T, before aging procedures, PAC showed reduced polymerization effectiveness when compared with HAL. In the T, after TC, PAC and LAS had also showed reduced polymerization effectiveness when compared to HAL and LED. For all light-curing devices, MC+TC+S and S affected the Knoop microhardness values. In the B, no difference could be observed among the aging procedures for PAC. From all light-curing units, PAC may have rendered composites of reduced quality and the storage aging procedures were the most harmful to the polymer hardness.

  12. Modeling Chronic Dacryocystitis in Rabbits by Nasolacrimal Duct Obstruction with Self-Curing Resin

    Directory of Open Access Journals (Sweden)

    Kai Hou

    2017-01-01

    Full Text Available We established a chronic dacryocystitis model by injecting of 0.05, 0.1, and 0.15 ml self-curing resin via the lacrimal punctum in rabbits. Animals were randomized into four groups (n=11 animals/group. The control group received 0.15 ml normal saline. Within three months postinjection, epiphora and eye discharge were observed. At the 90th day postlacrimal passage irrigation, CT dacryocystography was performed to find changes in the lacrimal image, and hematoxylin and eosin staining was made to identify pathological changes of the lacrimal sac. Three months postinjection, the rabbits in control group and those who received 0.05 and 0.1 ml self-curing resin failed to develop chronic dacryocystitis. However, 8/11 (72.7% rabbits those received 0.15 ml self-curing resin were symptomatic and showed complete reflux in lacrimal passage irrigation, indicating the obstruction of the nasolacrimal duct. CT dacryocystography showed that the obstruction was present only in the animals with chronic dacryocystitis. Pathological examinations of chronic dacryocystitis also revealed significantly inflammatory changes, such as mucus epithelium thickening, irregular papillary proliferation, and submucosal fibrous deposition. Local injection of 0.15 ml self-curing resin can induce permanent obstruction of the nasolacrimal duct in rabbits and establish a model of chronic dacryocystitis.

  13. Fracture toughness of heat cured denture base acrylic resin modified with Chlorhexidine and Fluconazole as bioactive compounds.

    Science.gov (United States)

    Al-Haddad, Alaa; Vahid Roudsari, Reza; Satterthwaite, Julian D

    2014-02-01

    This study investigated the impact of incorporating Chlorhexidine and Fluconazole as bioactive compounds on the fracture toughness of conventional heat cured denture base acrylic resin material (PMMA). 30 single edge-notched (SEN) samples were prepared and divided into three groups. 10% (mass) Chlorhexidine and 10% (mass) Diflucan powder (4.5% mass Fluconazole) were added to heat cured PMMA respectively to create the two study groups. A third group of conventional heat cured PMMA was prepared as the control group. Fracture toughness (3-point bending test) was carried out for each sample and critical force (Fc) and critical stress intensity factor (KIC) values measured. Data were subject to parametric statistical analysis using one-way ANOVA and Post hoc Bonferroni test (p=0.05). Fluconazole had no significant effect on the fracture toughness of the PMMA while Chlorhexidine significantly reduced the KIC and therefore affected the fracture toughness. When considering addition of a bioactive material to PMMA acrylic, Chlorhexidine will result in reduced fracture toughness of the acrylic base while Fluconazole has no effect. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. In vitro cytotoxicity of self-curing acrylic resins of different colors

    Directory of Open Access Journals (Sweden)

    Luciana Borges Retamoso

    2014-08-01

    Full Text Available OBJECTIVE: The aim of this study was to assess the in vitro cytotoxicity of acrylic resins of different colors over time. METHODS: Specimens were divided into 4 groups (n = 6 according to the color of the acrylic resin (Orto Class, Clássico, Campinas, São Paulo, Brazil: Group 1: clear acrylic resin; group 2: pink acrylic resin; group 3: blue acrylic resin and group 4: green acrylic resin. All specimens were fabricated according to the mass manipulation technique and submitted to mechanical polishing protocol. The control was performed with an amalgam specimen (C+, a glass specimen (C- and cell control (CC. Specimens were immersed in Minimum Eagle's Medium (MEM and incubated for 24 h at 37o C. The extracts from the experimental material were filtered and mixed with L929 fibroblast. Cytotoxicity was evaluated at 4 different times, 24, 48, 72 and 168 h. After contact, cells were incubated for 24 h and added to 100 µ of 0.01% neutral red dye. The cells were incubated for 3 h for pigment incorporation and fixed. Cells viability was determined by a spectroscopic (BioTek, Winooski, Vermont, USA with a 492-nm wavelength λ=492 nm. RESULTS: There were no statistical differences between the experimental groups and the CC and C- groups. CONCLUSION: Clear, pink, blue and green self-curing acrylic resins fabricated by means of the mass manipulation technique and mechanically polished are not cytotoxic. Neither the pigment added to the self-curing acrylic resin nor the factor of time influenced the cytotoxicity of the material.

  15. Effect of LED and Argon Laser on Degree of Conversion and Temperature Rise of Hybrid and Low Shrinkage Composite Resins.

    Science.gov (United States)

    Pahlevan, Ayob; Tabatabaei, Masumeh Hasani; Arami, Sakineh; Valizadeh, Sara

    2016-01-01

    Different light curing units are used for polymerization of composite resins. The aim of this study was to evaluate the degree of conversion (DC) and temperature rise in hybrid and low shrinkage composite resins cured by LED and Argon Laser curing lights. DC was measured using FTIR spectroscopy. For measuring temperature rise, composite resin samples were placed in Teflon molds and cured from the top. The thermocouple under samples recorded the temperature rise. After initial radiation and specimens reaching the ambient temperature, reirradiation was done and temperature was recorded again. Both temperature rise and DC data submitted to one-way ANOVA and Tukey-HSD tests (5% significance). The obtained results revealed that DC was not significantly different between the understudy composite resins or curing units. Low shrinkage composite resin showed a significantly higher temperature rise than hybrid composite resin. Argon laser caused the lowest temperature rise among the curing units. Energy density of light curing units was correlated with the DC. Type of composite resin and light curing unit had a significant effect on temperature rise due to polymerization and curing unit, respectively.

  16. Buffering Capacity of Fast-Growing Species and Curing Time of UF Resin Modified With Zinc Borate and Monoammonium Phosphate

    OpenAIRE

    Izran Kamal; Koh M. Poh; Tan Y. Eng; Xue J. Ren; Zaidon Ashaari; Faizah Abood; Guenter Beyer; Khairul Masseat

    2010-01-01

    Problem statement: Occupying a suitable hot pressing time for particleboard fabrication seems very tricky for manufacturers of the wood-based panel. Longer or shorter pressing times can affect physical and mechanical properties of the produced particleboards and that is why extra care should be given on this matter. Longer pressing time can cause resin in a particleboard to over-cure whereas shorter pressing time can cause insufficient curing of the resin. Determination of hot pressing time i...

  17. Effects of Surface Treatments of Montmorillonite Nanoclay on Cure Behavior of Diglycidyl Ether of Bisphenol A Epoxy Resin

    International Nuclear Information System (INIS)

    Tcherbi-Narteh, A.; Hosur, M.V.; Triggs, E.; Jelaani, S.

    2013-01-01

    Diglycidyl ether of Bisphenol A (DGEBA) based SC-15 epoxy resin was modified with three different commercially available montmorillonite (MMT) nanoclay: Nanomer I.28E and Cloisite 10A and 30B. Cure behavior of nanocomposites was studied using a variety of techniques. Primary focus of this study was to investigate influence of different surface modifications of MMT nanoclay on rheological properties and cure behavior of SC-15 epoxy resin. By adding MMT to SC-15 epoxy resin, chemistry of the epoxy is altered leading to changes in rheological properties and ultimately enthalpy and activation energy of reactions. Addition of Nanomer I.28E delayed gelation, while Cloisite 10A and 30B accelerated gelation, regardless of the curing temperature. Activation energy of reaction was lower with the addition of Nanomer I.28E and Cloisite 10A and higher for Cloisite 30B compared to neat SC-15 epoxy composite.

  18. A One-Component, Fast-Cure, and Economical Epoxy Resin System Suitable for Liquid Molding of Automotive Composite Parts

    Directory of Open Access Journals (Sweden)

    Yiru Wang

    2018-04-01

    Full Text Available Imidazole cured epoxy resin systems were evaluated for one-component, fast-curing resins for liquid molding of automotive composite parts according to industry requirements. It was demonstrated that an epoxy resin-1-(cyanoethyl-2-ethyl-4-methylimidazol(EP-1C2E4MIM system would cure in a few minutes at 120 °C, while exhibiting acceptable pot life, viscosity profiles, and low water absorption. Moreover, this system yielded high Tg parts with mechanical properties similar to the amine-epoxy systems, which are the mainstream two-component epoxy resin systems for automobiles.

  19. Influence of various irradiation processes on the mechanical properties and polymerisation kinetics of bulk-fill resin based composites.

    Science.gov (United States)

    Ilie, Nicoleta; Keßler, Andreas; Durner, Jürgen

    2013-08-01

    To assess the effect of irradiation time and distance of the light tip on the micro-mechanical properties and polymerisation kinetics of two bulk-fill resin-based composites at simulated clinically relevant filling depth. Micro-mechanical properties (Vickers hardness (HV), depth of cure (DOC) and indentation modulus (E)) and polymerisation kinetics (real-time increase of degree of cure (DC)) of two bulk-fill resin-based composites (Tetric EvoCeram(®) Bulk Fill, Ivoclar Vivadent and x-tra base, Voco) were assessed at varying depth (0.1-6mm in 100μm steps for E and HV and 0.1, 2, 4 and 6mm for DC), irradiation time (10, 20 or 40s, Elipar Freelight2) and distances from the light tip (0 and 7mm). Curing unit's irradiance was monitored in 1mm steps at distances up to 10mm away from the light tip on a laboratory-grade spectrometer. Multivariate analysis (α=0.05), Student's t-test and Pearson correlation analysis were considered. The influence of material on the measured mechanical properties was significant (η(2)=0.080 for E and 0.256 for HV), while the parameters irradiation time, distance from the light tip and depth emphasise a stronger influence on Tetric EvoCeram(®) Bulk Fill. The polymerisation kinetics could be described by an exponential sum function, distinguishing between the gel and the glass phase. The above mentioned parameters strongly influenced the start of polymerisation (gel phase), and were of less importance for the glass phase. Both materials enable at least 4mm thick increments to be cured in one step under clinically relevant curing conditions. The susceptibility to variation in irradiance was material dependent, thus properties measured under clinically simulated curing conditions might vary to a different extent from those measured under ideal curing conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Evaluation and comparison of anti-Candida effect of heat cure polymethylmethacrylate resin enforced with silver nanoparticles and conventional heat cure resins: An in vitro study

    Directory of Open Access Journals (Sweden)

    S Suganya

    2014-01-01

    Full Text Available Recent years have been dominated by research in nano science. Dentistry is no exception and there is increased research on nanoparticles in dentistry. Complete dentures increase the carriage of Candida in healthy patients, and the proliferation of C. albicans can be associated with denture-induced stomatitis. Purpose: To evaluate the anti-Candida effect of heat cure denture base resins reinforced with Ag° in the ratio of 4:1, 3:1, 2:1 (Groups B, C, and D, respectively to the weight of denture base resins. Materials and Methods: Ag° were synthesized by chemical reduction method, incorporated into the polymer powder according to the ratio for each group, subjected to polymerization and microbial assay was calculated for the reference C. albicans strains by agar diffusion method for the incubation period of 24 h. Results: Group D showed multifold decrease in the colony-forming units. Conclusion: The antimicrobial effect of silver could be used vividly in the denture base for immunocompromised and geriatric patients.

  1. A visible light-curable yet visible wavelength-transparent resin for stereolithography 3D printing

    Science.gov (United States)

    Park, Hong Key; Shin, Mikyung; Kim, Bongkyun; Park, Jin Woo; Lee, Haeshin

    2018-04-01

    Herein, a new polymeric resin for stereolithography (SLA) three-dimensional printing (SLA-3DP) is reported. An ultraviolet (UV) or visible (VIS) light source is critical for SLA printing technology. UV light can be used to manufacture 3D objects in SLA-3DP, but there are significant occupational safety and health issues (particularly for eyes). These issues prevent the widespread use of SLA-3DP at home or in the office. Through the use of VIS light, the safety and health issues can largely be solved, but only non-transparent 3D objects can be manufactured, which prevents the application of 3DP to the production of various common transparent consumer products. For these reasons, we developed a VIS light-curable yet visibly transparent resin for SLA-3DP, which also retains UV curability. The key was to identify the photoinitiator diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (DPTBP). DPTBP was originally designed as a UV photoinitiator, but we found that VIS light irradiation is sufficient to split DPTBP and generate radicals due to its slight VIS light absorption up to 420 nm. The cured resin displays high transparency and beautiful transparent colors by incorporating various dyes; additionally, its mechanical properties are superior to those of commercial resins (Arario 410) and photoinitiators (Irgacure 2959).

  2. The effect of curing units and methods on degree of conversion of two types of composite resins

    Directory of Open Access Journals (Sweden)

    Hasani Tabatabaei M

    2007-06-01

    Full Text Available Background and Aim: Halogen lamp is the commonly used light source for composite photo polymerization. Recently, high power halogen lamps, LED and plasma arc are introduced for improving the polymerization. The aim of this study was to investigate the effect of conventional and high power halogen lamps and LED light curing unit on degree of conversion of two different composite resins.Materials and Methods: In this in vitro experimental study two halogen units (Coltolux 50 with the intensity of  330 mW/cm2 and Optilux 501 with two different operating modes of standard with the intensity of 820 mW/cm2 and Ramp with the intentsiy of 100-1030mW/cm2 and one LED light curing unit (620 mW/cm2 were used. The composites were hybrid (Tetric ceram and nanofilled (Filteke supreme. Each materials/curing method contained three samples and degree of conversion (DC was measured with FTIR. Data were analyzed statistically with one way and two way ANOVA, Tukey HSD. P<0.05 was considered as the limit of significance.Results: Tetric ceram revealed higher DCthan Supreme. Tetric ceram showed a significant decrease in DC when Coltolux 50 was used in comparison to LED and Optilux 501. The latters did not show significant effect on DC of this material. DC of Supreme polymerized with various curing modes was not significantly different.Conclusion: Based on the results of this study, degree of conversion in hybrid composites was higher than nanofilled. In comparison with conventional halogen lamp (Coltolux 50, high intensity halogen lamps and LED unit significantly lead to higher degree of conversion in hybrid composites.

  3. The difference nanocomposite hardness level using LED photoactivation based on curing period variations

    Directory of Open Access Journals (Sweden)

    Hasiana Tatian

    2011-03-01

    Full Text Available Polimerizatian is the critical stage to determine the quality of composites resin, this involves isolated monomer carbon double bonds being converted to an extended network of single bonds. Physical and mechanical properties of composites are influenced by the level of conversion attained during polymerization. An adequate light intensity and light curing time are important to obtain the degree of polymerization. The objective of this study is to evaluate the difference of the hardness nanocomposites which activated by LED LCU based on the variation of curing times. This study is a true experimental research. The samples were made from nanocomposites material with cylinder form of 4 mm in depth, 6 mm in diameter. This samples divided into 3 groups of curing times. Group, I was cured for 20's curing time as a control due to manufactory recommended; Group II was cured for 30's, and Group III was cured for 40's and the hardness (Rebound hardness tester was determined using Rebound scale (RS and converted by Mohs scale (MS. There was a very significant level of hardness rate from each group using ANOVA test. The result of the study concludes that there were the differences on the nanocomposites hardness level cured under different curing times 20, 30 and 40 sec. The longer of curing times, the higher level of hardness.

  4. Synthesis, Characterization and Curing Studies of Thermosetting Epoxy Resin with Amines

    International Nuclear Information System (INIS)

    Lakshmi, B.; Mahendra, K. N.; Shivananda, K. N.

    2010-01-01

    A new hybrid thermosetting maleimido epoxy compound 4-(N-maleimidophenyl) glycidylether (N-MPGE) is prepared by reacting N-(4-hydroxyphenyl) maleimide (HPM) with Epichlorohydrin by using benzyltrimethylammonium chloride as a catalyst. The resulting compound possesses both the oxirane ring and maleimide group. The curing reaction of these maleimidophenyl glycidylether epoxy compound (N-MPGE) with amines as curing agents such as ethylendiamine (EDA), diethylentriamine (DETA) and triethylenetetramine (TETA), aminoethylpiperazine (AEP) and isophoronediamine, IPDA), are studied. Incorporation of maleimide groups in the epichlorohydrin provides cyclic imide structure and high cross-linking density to the cured resins. The cured samples exhibited good thermal stability, excellent chemical (acid/alkali/solvent) and water absorption resistance. Morphological studies by the SEM technique further confirmed the phase homogeneity net work of the cured systems

  5. Synthesis, Characterization and Curing Studies of Thermosetting Epoxy Resin with Amines

    Energy Technology Data Exchange (ETDEWEB)

    Lakshmi, B.; Mahendra, K. N. [Bangalore University, Bangalore (India); Shivananda, K. N. [Technion - Israel Institute of Technology, Haifa (Israel)

    2010-08-15

    A new hybrid thermosetting maleimido epoxy compound 4-(N-maleimidophenyl) glycidylether (N-MPGE) is prepared by reacting N-(4-hydroxyphenyl) maleimide (HPM) with Epichlorohydrin by using benzyltrimethylammonium chloride as a catalyst. The resulting compound possesses both the oxirane ring and maleimide group. The curing reaction of these maleimidophenyl glycidylether epoxy compound (N-MPGE) with amines as curing agents such as ethylendiamine (EDA), diethylentriamine (DETA) and triethylenetetramine (TETA), aminoethylpiperazine (AEP) and isophoronediamine, IPDA), are studied. Incorporation of maleimide groups in the epichlorohydrin provides cyclic imide structure and high cross-linking density to the cured resins. The cured samples exhibited good thermal stability, excellent chemical (acid/alkali/solvent) and water absorption resistance. Morphological studies by the SEM technique further confirmed the phase homogeneity net work of the cured systems.

  6. The effect of time between curing and tea immersion on composite resin discoloration.

    Science.gov (United States)

    Esmaeili, Behnaz; Afkhami, Solaleh; Abolghasemzadeh, Faezeh

    2018-01-01

    One common cause for the replacement of a composite restoration is discoloration. This in vitro study evaluated the effect of tea solution on the discoloration of 3 types of composites at different timepoints after curing. For this study, 150 disc-shaped specimens of 3 types of composite resin-a nanohybrid (Filtek Z350), a microhybrid (Filtek Z250), and a microfilled material (Heliomolar)-were prepared. Specimens were randomly divided into 5 subgroups (n = 10) according to the type of composite and the time from curing to immersion in a tea solution (none [immersed immediately], 1 hour, 6 hours, 12 hours, or 24 hours postcuring). The color for all specimens was measured before and after immersion in tea. Color change (ΔE*) for all specimens was measured, and a ΔE* value of less than 3.3 was considered clinically acceptable. Analysis of variance and a post hoc Tukey test were used to analyze the data (α = 0.05). Immediately after curing, the levels of composite discoloration were deemed clinically acceptable (ΔE* composites, the greatest color change was found immediately after curing (P composite resin specimens was significantly greater than that of Heliomolar specimens (P composite group than in the Heliomolar group (P composites were not significantly different from each other (P > 0.05), except with 12-hour postcure immersion. The results suggest that patients should avoid the intake of staining foods or beverages for at least 12 hours after placement of a composite resin restoration, although this restriction may be reduced to 1 hour for microfilled composite resins.

  7. Measurements of volatile compound contents in resins using a moisture analyzer.

    Science.gov (United States)

    Hashimoto, Masanori; Nagano, Futami; Endo, Kazuhiko; Ohno, Hiroki

    2010-02-01

    The contents of volatile adhesive compounds, such as water, solvents, and residual unpolymerized monomers, affect the integrity and durability of adhesive bonding. However, there is no method available that can be used to rapidly assess the residual solvent or water contents of adhesive resins. This study examined the effectiveness of a digital moisture analyzer to measure the volatile compound contents of resins. Five self-etching adhesives and seven experimental light-cured resins prepared with different contents (0, 10, and 20% by weight) of water or solvents (acetone and ethanol) were examined in this study. The resins were prepared using different methods (with and without air blast or light-curing) to simulate the clinical conditions of adhesive application. Resin weight changes (% of weight loss) were determined as the residual volatile compound contents, using the moisture analyzer. After the measurements, the resin films were examined using a scanning electron microscope. The weight changes of the resins were found to depend on the amount of water or solvents evaporating from the resin. Water and solvents were evaporated by air blast or light-curing, but some of the water and solvents remained in the cured resin. The moisture analyzer is easy to operate and is a useful instrument for using to measure the residual volatile compound contents of adhesive resin.

  8. Radiation curing of γ-Al2O3 filled epoxy resin

    International Nuclear Information System (INIS)

    Kang, Phil Hyun; Kim, Dong Jin; Nho, Young Chang

    2003-01-01

    Epoxy resins are widely utilized as high performance thermosetting resins for many industrial applications but characterized by a relatively low toughness. Recently, the incorporation with rigid inorganic was suggested to improve the mechanical properties of epoxy resins. In the present work, an attempt has been taken to disperse nano-sized γ- Al 2 O 3 particles into diglycidyl ether of bisphenol-A (DGEBA) epoxy resins for improvement of the mechanical properties. These hybrid epoxy-alumina composites were prepared using by the γ-ray curing technique that was conducted with 100kGy under nitrogen at room temperature. The composites were characterized by determining gel content, UTM (Instron model 4443), SEM, FT-IR studies

  9. Influence of light curing source on microhardness of composite resins of different shades Influência da fonte de luz polimerizadora na microdureza da resina composta de diferentes cores

    Directory of Open Access Journals (Sweden)

    André Luiz Fraga Briso

    2006-01-01

    Full Text Available INTRODUCTION: The evolution of light curing units can be noticed by the different systems recently introduced. The technology of LED units promises longer lifetime, without heating and with production of specific light for activation of camphorquinone. However, further studies are still required to check the real curing effectiveness of these units. PURPOSE: This study evaluated the microhardness of 4 shades (B-0.5, B-1, B-2 and B-3 of composite resin Filtek Z-250 (3M ESPE after light curing with 4 light sources, being one halogen (Ultralux - Dabi Atlante and three LED (Ultraled - Dabi Atlante, Ultrablue - DMC and Elipar Freelight - 3M ESPE. METHODS: 192 specimens were distributed into 16 groups, and materials were inserted in a single increment in cylindrical templates measuring 4mm x 4mm and light cured as recommended by the manufacturer. Then, they were submitted to microhardness test on the top and bottom aspects of the cylinders. RESULTS: The hardness values achieved were submitted to analysis of variance and to Tukey test at 5% confidence level. It was observed that microhardness of specimens varied according to the shade of the material and light sources employed. The LED appliance emitting greater light intensity provided the highest hardness values with shade B-0.5, allowing the best curing. On the other hand, appliances with low light intensity were the least effective. It was also observed that the bottom of specimens was more sensitive to changes in shade. CONCLUSION: Light intensity of LED light curing units is fundamental for their good functioning, especially when applied in resins with darker shades.INTRODUCTION: A evolução dos aparelhos fotopolimerizadores pode ser notada nos diferentes sistemas introduzidos recentemente no mercado. A tecnologia apresentada pelos aparelhos LED promete maior tempo de vida útil, não gerar aquecimento e produzir luz específica para a ativação da canforoquinona. No entanto, ainda são necess

  10. Comparison between two methods to evaluate temperature changes produced by composite light curing units and polymerization techniques.

    Science.gov (United States)

    Loureiro, F H F; Consani, S; Guiraldo, R D; Consani, R L X; Berger, S B; Carvalho, R V; Correr-Sobrinho, L; Sinhoreti, M A C

    2011-10-01

    This study evaluated the temperature change into the pulp chamber during the light curing of composite resin by direct (bovine tooth) and indirect (matrix) methods. Direct method: fifty standardized cavities (2x2x2 mm) were prepared in bovine incisors, which were randomly assigned to evaluation of the temperature changes in the pulp chamber. Indirect method: temperature changes were evaluated through a dentine slice of 1.0 mm thickness in a elastomer cubic mold (2x2x2 mm). Filtek Z250 composite resin (3M/ESPE) was photo-activated using three light curing units: quartz-tungsten-halogen (QTH) by continuous, soft-start or intermittent light modulations; light emitting diode (LED); and plasma arc-curing (PAC). Ten groups (N.=10) were established according to technique evaluation and photo-activation methods. All experiments were carried out in a controlled environment (37 °C and 50 ± 10% relative humidity). The temperature changes were recorded using a digital thermometer attached to a type-K thermocouple in contact with the dentin slice (indirect method) or in contact with the axial wall (dentin) of pulp chamber (direct method). The results were submitted to ANOVA and Tukey's test (α=0.05). Temperature changes were statistically higher for the matrix indirect method (2.56 ºC) than bovine teeth direct method (1.17ºC). The change temperature was statistically higher for the PAC (1.77 ºC) when compared to other photo-activation modes in bovine teeth direct method. The two methods of temperature evaluation were different, however indirect method detected the higher temperature increase. Higher energy density arising from the light curing units and polymerization techniques promoted higher temperature increase.

  11. Kinetic Parameters during Bis-GMA and TEGDMA Monomer Polymerization by ATR-FTIR: The Influence of Photoinitiator and Light Curing Source

    Directory of Open Access Journals (Sweden)

    Aline B. Denis

    2016-01-01

    Full Text Available This study aimed to analyze the kinetic parameters of two monomers using attenuated total reflectance Fourier transform infrared (ATR-FTIR: 2,2-bis-[4-(2-hydroxy-3-methacryloxypropyl-1-oxy-phenyl] propane (Bis-GMA and triethylene glycol dimethacrylate (TEGDMA. The following were calculated to evaluate the kinetic parameters: maximum conversion rate (Rpmax, time at the maximum polymerization rate (tmax, conversion at Rpmax, and total conversion recorded at the maximum conversion point after 300 s. Camphorquinone (CQ and phenyl propanedione (PPD were used in this study as photoinitiators, whereas N,N-dimethyl-p-toluidine (DMPT amine was used as a coinitiator. LED apparatus and halogen lamp were used in turn to evaluate the effect that light source had on the monomer kinetics. The mass concentration ratio for the three resin preparations was 0.7 : 0.3 for Bis-GMA and TEGDMA: R1 (CQ + DMPT, R2 (PPD + DMPT, and R3 (PPD + CQ + DMPT. The PPD association with the CQ photoinitiator altered the polymerization kinetics compared to a resin containing only the CQ photoinitiator. The light sources exhibited no significant differences for tmax of R1 and R3. Resins containing only the PPD initiator exhibited a higher tmax than those containing only CQ. However, the Rpmax decreased for resins containing the PPD photoinitiator.

  12. Compressive strength measurements of hybrid dental composites treated with dry heat and light emitting diodes (LED post cure treatment

    Directory of Open Access Journals (Sweden)

    Jenny Krisnawaty

    2014-11-01

    Full Text Available Hybrid composites are mostly used on large cavities as restorative dental materials, whether it is used directly or indirectly. The mechanical properties of composite resin shall increase if it is treated with post cure treatment. The aim of this study is to evaluate compressive strength differences between dry heat and Light Emitting Diodes (LED treatment on the hybrid dental composite. A quasi-experimental was applied on this research with a total of 30 samples that were divided into two groups. Each sample was tested using LLOYD Universal Testing Machine with 1 mm/min speed to evaluate the compressive strength. The compressive strength results were marked when the sample was broken. The results of two groups were then analyzed using t-test statistical calculation. The results of this study show that post cure treatment on hybrid composite using LED light box (194.138 MPa was lower than dry heat treatment (227.339 MPa, which was also significantly different from statistical analysis. It can be concluded that compressive strength of LED light box was lower than dry heat post-cure treatment on the hybrid composite resin.

  13. EVALUATION OF DIELECTRIC CURING MONITORING INVESTIGATING LIGHT-CURING DENTAL FILLING COMPOSITES

    Directory of Open Access Journals (Sweden)

    Johannes Steinhaus

    2011-05-01

    Full Text Available The aim of this study is the evaluation of a dielectric analysis (DEA method monitoring the curing behaviour of a light curing dental filling material in real-time. The evaluation is to extract the influence of light intensity on the photo-curing process of dental composite filling materials. The intensity change is obtained by measuring the curing process at different sample depth. It could be shown that increasing sample thickness, and therefore exponentially decreasing light intensity, causes a proportional decrease in the initial curing rate. Nevertheless, the results give rise to the assumption that lower illumination intensities over a long period cause higher overall conversion, and thus better mechanical properties. This would allow for predictions of the impact of different curing-rates on the final mechanical properties.

  14. Curing behavior and thermal properties of trifunctional epoxy resin cured by 4, 4’-diaminodiphenyl sulfone

    Directory of Open Access Journals (Sweden)

    2009-08-01

    Full Text Available A novel trifunctional epoxy resin 4-(3, 3-dihydro-7-hydroxy-2, 4, 4-trimethyl-2H-1-benzopyran-2-yl-1, 3-benzenediol glycidyl (shorted as TMBPBTH-EPOXY was synthesized in our lab to improve thermal performance. Its curing behavior and performance were studied by using 4, 4′-diaminodiphenyl sulfone (DDS as hardener with the mass ratio of 100:41 of TMBPBTH-EPOXY and DDS. The curing activation energy was investigated by differential scanning calorimetry (DSC to be 64.0 kJ/mol estimated by Kissinger’s method and 68.7 kJ/mol estimated by Flynn-Wall-Ozawa method respectively. Thermogravimetric analyzer (TGA was used to investigate the thermal decomposition of cured compounds. It was found that when curing temperature was lower than 180°C, the thermal decomposition temperature increased with the rise of curing temperature and curing time. On the other hand, when the curing temperature was higher than 180°C, the thermal decomposition temperature went down instead with the increase of curing time that might be the over-crosslinking of TMBPBTH-EPOXY and DDS hardener. The glass transition temperature (Tg of cured TMBPBTH-EPOXY/DDS compound determined by dynamic mechanical thermal analysis (DMTA is 290.1°C.

  15. Effect of dentin dehydration and composite resin polymerization mode on bond strength of two self-etch adhesives

    Directory of Open Access Journals (Sweden)

    Pooran Samimi

    2016-01-01

    Full Text Available Background: Dual-cured composite resins are similar to self-cured composite resins in some of their clinical applications due to inadequate irradiation, lack of irradiation, or delayed irradiation. Therefore, incompatibility with self-etch adhesives (SEAs should be taken into account with their use. On the other, the extent of dentin dehydration has a great role in the quality of adhesion of these resin materials to dentin. The aim of this study was to investigate the effect of dentin dehydration and composite resin polymerization mode on bond strength of two SEAs. Materials and Methods: A total of 120 dentinal specimens were prepared from extracted intact third molars. Half of the samples were dehydrated in ethanol with increasing concentrations. Then Clearfil SE Bond (CSEB and Prompt L-Pop (PLP adhesives were applied in the two groups. Cylindrical composite resin specimens were cured using three polymerization modes: (1 Immediate light-curing, (2 delayed light-curing after 20 min, and (3 self-curing. Bond strength was measured using universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed with two-way ANOVA and Duncan post hoc tests. Statistical significance was defined at P 0.05. PLP showed significant differences between subgroups with the lowest bond strength in hydrated dentin with delayed light-curing and self-cured mode of polymerization. Conclusion: Within the limitations of this study, a delay in composite resin light-curing or using chemically cured composite resin had a deleterious effect on dentin bond strength of single-step SEAs used in the study.

  16. UV curing silicon-containing epoxy resin and its glass cloth reinforced composites

    International Nuclear Information System (INIS)

    Yang Guang; Tang Zhuo; Huang Pengcheng

    2007-01-01

    A UV-curable cationic silicon-containing epoxy resin formulation was developed. The gel conversion of the cured resin after 10-min UV irradiation reached 80% in the presence of 5% diaryliodonium salt photoinitiator and 5.5% polyol chain transfer agent by cationic ring-opening polymerization. The glass cloth-reinforced composites were fabricated with the silicon-containing epoxy resin using the wet lay-up technique and UV irradiation. The mechanical properties of the composites were evaluated. Compared with glass cloth reinforced bisphenol A epoxy resin matrix composites, the silicon-containing epoxy resin matrix composites possessed higher tensile strength and interlayer shear strength which was 158.5MPa and 9.9MPa respectively while other mechanical properties such as flexural property and tensile modulus were similar. (authors)

  17. Valuation of the light intensity from curing lamps of the students of odontology of the Universidad de Costa Rica during 2011, with respect to the manufacturer's specifications

    International Nuclear Information System (INIS)

    Solano Badilla, Lucrecia

    2011-01-01

    The behavior of the light intensity from halogens curing lamps used by students at the Facultad de Odontologia of the Universidad de Costa Rica (UCR) is studied with respect to the manufacturer's specifications of the lamp and the resin. The distribution of the type of curing lamp per student is described, as well as some characteristics of them. The light intensity mW/cm 2 of the curing lamps operated by students at the Facultad de Odontologia is compared with the manufacturer's specifications of the lamp. The light intensity mW/cm 2 is compared with the manufacturer's specifications of the resin utilized, by brand, by students of the Facultad de Odontologia of the UCR for their photopolymerization [es

  18. Degree of conversion and microhardness of TPO-containing resin-based composites cured by polywave and monowave LED units.

    Science.gov (United States)

    Santini, Ario; Miletic, Vesna; Swift, Michael D; Bradley, Mark

    2012-07-01

    To determine the degree of conversion (DC) and Knoop microhardness (KHN) of resin-based composites (RBCs) containing trimethylbenzoyl-diphenylphosphine oxide (TPO) cured by polywave or monowave LED light-curing units (LCUs). Three groups (each n = 5) of Tetric EvoCeram (Ivoclar Vivadent), Vit-l-escence (Ultradent) and Herculite XRV Ultra (Kerr) were prepared in Teflon moulds (5mm in diameter and 2mm thick) and cured with polywave Bluephase(®) G2 (Ivoclar Vivadent), polywave Valo (Ultradent) or monowave Bluephase(®) (Ivoclar Vivadent; control) resulting in 9 groups. DC and KHN were determined using micro-Raman spectroscopy and Knoop microhardness, respectively. High-performance liquid chromatography and nuclear magnetic resonance spectroscopy were used to confirm the presence or absence of TPO in the three uncured materials. Data were statistically analysed using two-way and one-way ANOVA and DC and KHN were correlated using Pearson's correlation (α = 0.05). TPO was confirmed in Tetric EvoCeram and Vit-l-escence but not in Herculite XRV Ultra. All three LCUs produced comparable KHN for Tetric EvoCeram and Herculite XRV Ultra (p > 0.05). Both polywave LCUs resulted in significantly higher KHN for Vit-l-escence and higher DC in Tetric EvoCeram and Vit-l-escence than the monowave Bluephase(®) (p Conversely, Bluephase(®) showed higher DC than the two polywave LCUs in Herculite XRV Ultra (p conversion and KHN in the two TPO-containing RBCs, but not in Herculite XRV Ultra. DC and KHN were linearly correlated in all three RBCs. Vit-l-escence showed the highest DC and KHN of the three materials tested. The use of polywave LEDs significantly improves both the DC and KHN of materials which contain TPO. This should be taken into account when curing bleached shades of RBCs even if the manufacturers do not indicate the presence of TPO in their materials. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Effect of the solvent type and polymerization conditions on the curing kinetics, thermal and viscoelastic performance of poly(amide-imide resins

    Directory of Open Access Journals (Sweden)

    Z. Rasheva

    2015-03-01

    Full Text Available Isothermal and non-isothermal curing kinetics of both N-methyl-2-pyrrolidone (NMP and N-methylimidazole (MI based poly(amide-imide (PAI resins were investigated by DSC analysis using tightly closed high-pressure crucibles. Several exothermal peaks on the non-isothermal DSC-traces were observed and attributed to the reactions of different functional groups of PAI-resin. Furthermore the final conversion (polymerization degree of PAI was determined under isothermal conditions, simulating three programs with the post-curing temperatures set as 215, 240 and 270°C. For the MI-PAI based resin, the conversion values were found to be much higher compared to those for the NMP-PAI system. Compared to NMP-based PAI-resin, a shift of the main exothermal peaks to the lower temperatures was observed in the non-isothermal kinetic investigations when MI was used as a solvent. This was accompanied with a reduction of activation energy (Ea values, as up to a factor of 3 determined by the Flynn-Wall-Ozawa approach for all the main formation reactions. It indicates a catalytic effect of MI on the PAI polymerization. In addition, conversion values were determined according to the Di Benedetto equation for both systems cured using open molds in the oven. Regardless the different post-curing temperatures, the conversion values were similar for all the samples. Thermal and viscoelastic properties as well as crosslink density (nc were also investigated for these systems. It was found that the MI-based samples demonstrate lower nc values compared to the NMP-based ones at an almost two times higher storage modulus (E' at room temperature.

  20. Evaluation of the use of inorganic pigments and fillers in cure of epoxy resins by microwave irradiation

    International Nuclear Information System (INIS)

    Kersting, Daniel; Wiebeck, Helio

    2013-01-01

    The use of microwave in chemical processes began soon after the WW II. The mechanism of curing via microwave heating is independent of the thermal conductivity of the irradiated material and offers a good solution to operate with materials that do not have a good thermal conductivity, such as polymers. Despite these advantages, the use of multimode microwave ovens, the main source used today, indicates some challenges to overcome. Associated with the use of epoxy resins in various applications, the use of pigments and inorganic fillers has added more variables to be studied. Much of the inorganic fillers used commercially are good absorbers of microwave providing changes in the amount of radiation absorbed, and thus the amount of heat transferred to the epoxy resin curing process. After selecting the key fillers and pigments traditionally used in the production of parts with epoxy resins they were subjected to the same microwave irradiation for evaluation of their behavior alone. In order to observe the effect of mixtures 1, 2, and 5% by weight of filler were added to epoxy resin, and it was verified these effects in the curing process. The preliminary results are promising, because for the same cure cycle for different types of fillers added separately, gains in curing time were obtained, making the process of cure via microwave quick and efficient without substantial losses in thermal properties of the final products obtained. (author)

  1. Primary study on synthesis and characterization of the new type EB curable resins. Pt.1: Acrylic resins modified by light-oil

    International Nuclear Information System (INIS)

    Wei Jinshan; Yi Min; Wang Ruiyu; Li Jun; Ha Hongfei

    1995-01-01

    An acrylic resin modified by vegetable oil with high degree of unsaturation level has been synthesized. The characterization of coating film EB cured by the modified acrylic resin was studied primarily. The new type of EB curable acrylic resin is possessed of many merits such as cheap raw materials, simple synthesis technique and pretty characteristics of coating film. It is especially fit for timber surface coatings cured by EB radiation

  2. Adhesion of Candida albicans to Vanillin Incorporated Self-Curing Orthodontic PMMA Resin.

    Science.gov (United States)

    Zam, K.; Sawaengkit, P.; Thaweboon, S.; Thaweboon, B.

    2018-02-01

    It has been observed that there is an increase in Candida carriers during the treatment with orthodontic removable appliance. Vanillin is flavouring agent, which is known to have antioxidant and antimicrobial properties. The aim of this study was to evaluate the effect of vanillin incorporated PMMA on adhesion of Candida albicans. A total of 36 orthodontic self-curing PMMA resin samples were fabricated. The samples were divided into 3 groups depending on percentage of vanillin incorporated (0.1%, 0.5% and PMMA without vanillin as control). PMMA samples were coated with saliva. The adhesion assay was performed with C. albicans (ATCC 10231). The adherent yeast cells were stained with crystal violet and counted under microscope by random selection of 3 fields at 10X magnification. The statistical analyses performed by Kruskal Wallis and Mann Whitney non-parametric test. It was found that the PMMA resin samples with vanillin incorporation significantly reduced the adhesion of C. albicans as compared to the control group. This study indicates that vanillin incorporated resin can impede the adhesion of C. albicans to about 45 - 56 %. With further testing and development, vanillin can be employed as an antifungal agent to prevent adhesion of C. albicans to orthodontic self-curing PMMA resin.

  3. Mathematical Model For Autoclave Curing Of Unsaturated Polyester Based Composite Materials

    Directory of Open Access Journals (Sweden)

    Adnan A. Abdul Razak

    2013-05-01

    Full Text Available Heat transfer process involved in the autoclave curing of fiber-reinforced thermosetting composites is investigated numerically. A model for the prediction of the temperature and the extent of the reaction across the laminate thickness during curing process in the autoclave of unsaturated polyester based composite has been developed. The governing equation for one dimensional heat transfer, and accounting for the heat generation due to the exothermic cure reaction in the composites had been used.  It was found that the temperature at the central of the laminate increases up to the external imposed temperature, because of the thermal conductivity of the resin and fiber. The heat generated by the exothermic reaction of the resin is not adequately removed; the increase in the temperature at the center increases the resins rate reaction, which in turn generates more heat.

  4. Influence of ionizing radiation on the mechanical properties of BisGMA/TEGDMA based experimental resin

    International Nuclear Information System (INIS)

    LMP, Campos; Boaro, LC; LKG, Santos; Parra, DF; Lugão, AB

    2015-01-01

    Dental restorative composites are activated by visible light and the polymerization process, known as direct technique, is initiated by absorbing light in a specific wavelength range (450–500 nm). However this technique presented some disadvantages. If light is not inserted correctly, layers uncured can cause countless damage to restoration, especially with regard to mechanical properties. A clinical alternative used to reduce the shortcomings of direct application is the use of composite resins for indirect application. These composites are adaptations of resins prepared for direct use, with differences mainly in the healing process. Besides the traditional photoactivation, indirect application composites may be submitted to particular curing conditions, such as a slow curing rate, heating, vacuum, and inert-gas pressure leading to an oxygen-free environment. However few studies have been conducted on the process of post-curing by ionizing radiation at low doses. On this sense the purpose of this study was to evaluate possible interactions of ionizing radiation in the post-curing process of the experimental composites based on BisGMA/TEGDMA filled with silica Aerosil OX-50 silanized. Characterization of the experimental composites was performed by thermogravimetry analysis, infrared spectroscopy, elastic modulus and flexural strength. Statistical analysis of results was calculated by one-way ANOVA/Tukey's test. Cross-linking of the polymeric matrix caused by ionizing radiation, influenced the thermal stability of irradiated specimens. FTIR analysis showed that the ionizing radiation induced a post-cure reaction in the specimens. The irradiation dose influenced directly the mechanical properties that showed a strong positive correlation between flexural strength and irradiation and between modulus strength and irradiation. - Highlights: • Interactions of ionizing radiation in BisGMA/TEGDMA experimental dental composites filled with sylanized silica.

  5. Curing behaviour of epoxy resin/graphite composites containing ionic liquid

    International Nuclear Information System (INIS)

    Guo Baochun; Wan Jingjing; Lei Yanda; Jia Demin

    2009-01-01

    By adopting the isoconversional method, subtle changes in the curing activation energy (E α ) among epoxy resin/graphite composites by the inclusion of expanded graphite (EG), ionic liquid of 1-butyl-3-methyl-imidazolium hexafluorophosphate ([BMIm]PF 6 ) or their combination are shown in the whole conversion range. At lower concentrations (1 phr) of EG, compared with the E α of the neat epoxy resin, the composite with EG has a lower E α before the gelation, and a higher E α after the gelation. At higher concentrations of EG, however, in the whole conversion range, the composite with EG shows a higher E α compared with the neat epoxy resin. As the curing proceeded, a peculiar increase in E α is found in systems containing [BMIm]PF 6 . Due to the formation of hydrogen bonding between [BMIm]PF 6 and the hardener (Jeffamine), the reactivity of Jeffamine is considerably decreased, leading to a much higher E α in [BMIm]PF 6 -containing systems, especially at higher conversion. In systems containing a combination of [BMIm]PF 6 and EG, due to the interactions between EG and [BMIm]PF 6 , the shielding effect provided by the well-dispersed EG sheets constrains the formation of the hydrogen bonding between [BMIm]PF 6 and Jeffamine, leading to lowered E α compared with that for the system containing [BMIm]PF 6 only.

  6. Knoop hardness of ten resin composites irradiated with high-power LED and quartz-tungsten-halogen lights.

    Science.gov (United States)

    Price, Richard B T; Felix, Corey A; Andreou, Pantelis

    2005-05-01

    This study compared a high-power light-emitting-diode (LED) curing light (FreeLight 2, 3M ESPE) with a quartz-tungsten-halogen (QTH) light (TriLight, 3M ESPE) to determine which was the better at photo-polymerising 10 resin composites. Class I preparations were prepared 4-mm deep into human teeth and filled with 10 different composites. The composites were irradiated for 50% or 100% of their recommended times using the LED light, and for 100% of their recommended times with the QTH light on either the high or medium power setting. Fifteen minutes later, the Knoop hardness of the composites was measured to a depth of 3.5 mm from the surface. When irradiated by the LED light for their recommended curing times, the Knoop hardness of all 10 composites stayed above 80% of the maximum hardness of the composite to a depth of at least 1.5 mm; three composites maintained a Knoop hardness that was more than 80% of their maximum hardness to a depth of 3.5 mm. Repeated measurements analysis of variance indicated that all the two-way and three-way interactions between the curing light, depth, and composite were significant (p hardness values. The LED light, used for the composite manufacturer's recommended time, was ranked the best at curing the composites to a depth of 3mm (p power setting.

  7. Color Stability of Heat‑cure Acrylic Resin Subjected to Simulated ...

    African Journals Online (AJOL)

    Background: Regular usage of denture cleansers is recommended in complete denture wearers for effective plaque control, and these cleansers alter the physical properties of acrylic resin over a period of time. Thus, an in vitro study was carried out to assess the effect of denture cleansers on the color stability of heat‑cure ...

  8. Ultraviolet light and ultraviolet light-activated composite resins

    International Nuclear Information System (INIS)

    Murray, G.A.; Yates, J.L.; Newman, S.M.

    1981-01-01

    In a comparison of the UV light--activated composite resins, Estilux was polymerized to a significantly greater depth than the other composite resins. In general, Lee-fill polymerized the least. When comparing the UV light sources, the Lee light and the Duralux light did not significantly differ from each other, but both polymerized the materials tested to a significantly greater depth than the other light sources. Of the two time exposures, 60-second exposure provided a significantly greater depth of polymerization than 20 seconds for each light with each material

  9. Effect of resin chemistry on depth of cure and cytotoxicity of dental resin composites

    International Nuclear Information System (INIS)

    Susila Anand, V.; Balasubramanian, Venkatesh

    2014-01-01

    Highlights: • Dental composites have differences in polymerization within 2 mm thickness. • Degree of conversion alone may not affect the biocompatibility of composite. • Unreacted double bonds in dental composites may influence biocompatibility. • Magnitude of double bonds depends on the polymerization and chemical composition. • These influence biocompatibility especially if they possess lipophylic properties. -- Abstract: New dental composite restorative materials are being introduced aiming to overcome the disadvantages of contemporary materials. Hence there is a need to analyze the critical properties of these composites to aid in clinical application. This study aims to comparatively analyze the degree of conversion (DC), residual reactivity (DBC/reactivity) and cytotoxicity of 2 composites based on different resin chemistry. Ceram X and Filtek P90 were used in the study to prepare disc shaped samples of 2 mm thickness and 4 mm diameter. The samples for cytotoxicity were cured for 40 s and those of Fourier Transform Infra-red Spectroscopy (FTIR) (DBC/reactivity and DC) for 5 s, 10 s, 20 s and 40 s, at an average intensity of 800 mW/cm 2 with Quartz–Tungsten–Halogen (QTH) light. DC was calculated in 60–100 μm thick and 6 mm diameter samples. Double bonds concentration/reactivity was measured in approximately 80 μm thick sections prepared from the 2 mm thick discs using a hard tissue microtome. The cell viability was scored by Trypan blue exclusion staining technique at 24 h and 48 h. Both composites showed a progressive increase in double bonds/reactivity as the distance from curing probe increased which was inversely proportional to the curing time. The DC of Filtek P90 was 20% and 96% and that of Ceram X 33% and 50% at 5 s and 40 s, respectively. Ceram X showed statistically significantly higher cell viability score at both 24 h and 48 h than Filtek P90. The results were statistically analyzed using non-parametric Kruskal–Wallis, Mann

  10. Effect of resin chemistry on depth of cure and cytotoxicity of dental resin composites

    Energy Technology Data Exchange (ETDEWEB)

    Susila Anand, V. [Rehabilitation Bioengineering Group, Department of Engineering Design, Indian Institute of Technology Madras, Chennai 600036 (India); Department of Conservative Dentistry and Endodontics, Saveetha Dental College, Saveetha University, Chennai 600077 (India); Balasubramanian, Venkatesh, E-mail: chanakya@iitm.ac.in [Rehabilitation Bioengineering Group, Department of Engineering Design, Indian Institute of Technology Madras, Chennai 600036 (India)

    2014-02-15

    Highlights: • Dental composites have differences in polymerization within 2 mm thickness. • Degree of conversion alone may not affect the biocompatibility of composite. • Unreacted double bonds in dental composites may influence biocompatibility. • Magnitude of double bonds depends on the polymerization and chemical composition. • These influence biocompatibility especially if they possess lipophylic properties. -- Abstract: New dental composite restorative materials are being introduced aiming to overcome the disadvantages of contemporary materials. Hence there is a need to analyze the critical properties of these composites to aid in clinical application. This study aims to comparatively analyze the degree of conversion (DC), residual reactivity (DBC/reactivity) and cytotoxicity of 2 composites based on different resin chemistry. Ceram X and Filtek P90 were used in the study to prepare disc shaped samples of 2 mm thickness and 4 mm diameter. The samples for cytotoxicity were cured for 40 s and those of Fourier Transform Infra-red Spectroscopy (FTIR) (DBC/reactivity and DC) for 5 s, 10 s, 20 s and 40 s, at an average intensity of 800 mW/cm{sup 2} with Quartz–Tungsten–Halogen (QTH) light. DC was calculated in 60–100 μm thick and 6 mm diameter samples. Double bonds concentration/reactivity was measured in approximately 80 μm thick sections prepared from the 2 mm thick discs using a hard tissue microtome. The cell viability was scored by Trypan blue exclusion staining technique at 24 h and 48 h. Both composites showed a progressive increase in double bonds/reactivity as the distance from curing probe increased which was inversely proportional to the curing time. The DC of Filtek P90 was 20% and 96% and that of Ceram X 33% and 50% at 5 s and 40 s, respectively. Ceram X showed statistically significantly higher cell viability score at both 24 h and 48 h than Filtek P90. The results were statistically analyzed using non-parametric Kruskal

  11. Bond strength of a pit-and-fissure sealant associated to etch-and-rinse and self-etching adhesive systems to saliva-contaminated enamel: individual vs. simultaneous light curing.

    Science.gov (United States)

    Gomes-Silva, Jaciara Miranda; Torres, Carolina Paes; Contente, Marta Maria Martins Giamatei; Oliveira, Maria Angélica Hueb de Menezes; Palma-Dibb, Regina Guenka; Borsatto, Maria Cristina

    2008-01-01

    This study evaluated in vitro the shear bond strength (SBS) of a resin-based pit-and-fissure sealant [Fluroshield (F), Dentsply/Caulk] associated with either an etch-and-rinse [Adper Single Bond 2 (SB), 3M/ESPE] or a self-etching adhesive system [Clearfil S3 Bond (S3), Kuraray Co., Ltd.] to saliva-contaminated enamel, comparing two curing protocols: individual light curing of the adhesive system and the sealant or simultaneous curing of both materials. Mesial and distal enamel surfaces from 45 sound third molars were randomly assigned to 6 groups (n=15), according to the bonding technique: I - F was applied to 37% phosphoric acid etched enamel. The other groups were contaminated with fresh human saliva (0.01 mL; 10 s) after acid etching: II - SB and F were light cured separately; III - SB and F were light cured together; IV - S3 and F were light cured separately; V - S3 and F were light cured simultaneously; VI - F was applied to saliva-contaminated, acid-etched enamel without an intermediate bonding agent layer. SBS was tested to failure in a universal testing machine at 0.5 mm/min. Data were analyzed by one-way ANOVA and Fisher's test (alpha=0.05).The debonded specimens were examined with a stereomicroscope to assess the failure modes. Three representative specimens from each group were observed under scanning electron microscopy for a qualitative analysis. Mean SBS in MPa were: I-12.28 (+/-4.29); II-8.57 (+/-3.19); III-7.97 (+/-2.16); IV-12.56 (+/-3.11); V-11.45 (+/-3.77); and VI-7.47 (+/-1.99). In conclusion, individual or simultaneous curing of the intermediate bonding agent layer and the resin sealant did not seem to affect bond strength to saliva-contaminated enamel. S3/F presented significantly higher SBS than the that of the groups treated with SB etch-and-rinse adhesive system and similar SBS to that of the control group, in which the sealant was applied under ideal dry, noncontaminated conditions.

  12. Isothermal and non-isothermal cure of a tri-functional epoxy resin (TGAP): a stochastic TMDSC study

    OpenAIRE

    Hutchinson, John M.; Shiravand, Fatemeh; Calventus Solé, Yolanda; Fraga Rivas, Iria

    2012-01-01

    The isothermal cure of a highly reactive tri-functional epoxy resin, tri-glycidyl para-amino phenol (TGAP), with diamino diphenyl sulphone (DDS), at two different cure temperatures Tc has been studied by both conventional differential scanning calorimetry (DSC) and by a stochastic temperature modulated DSC technique, TOPEM. From a series of isothermal cure experiments for increasing cure times, the glass transition temperature Tg as a function of isothermal cure time is determined by co...

  13. Characterization and optimization of an inkjet-printed smart textile UV-sensor cured with UV-LED light

    Science.gov (United States)

    Seipel, S.; Yu, J.; Periyasamy, A. P.; Viková, M.; Vik, M.; Nierstrasz, V. A.

    2017-10-01

    For the development of niche products like smart textiles and other functional high-end products, resource-saving production processes are needed. Niche products only require small batches, which makes their production with traditional textile production techniques time-consuming and costly. To achieve a profitable production, as well as to further foster innovation, flexible and integrated production techniques are a requirement. Both digital inkjet printing and UV-light curing contribute to a flexible, resource-efficient, energy-saving and therewith economic production of smart textiles. In this article, a smart textile UV-sensor is printed using a piezoelectric drop-on-demand printhead and cured with a UV-LED lamp. The UVcurable ink system is based on free radical polymerization and the integrated UVsensing material is a photochromic dye, Reversacol Ruby Red. The combination of two photoactive compounds, for which UV-light is both the curer and the activator, challenges two processes: polymer crosslinking of the resin and color performance of the photochromic dye. Differential scanning calorimetry (DSC) is used to characterize the curing efficiency of the prints. Color measurements are made to determine the influence of degree of polymer crosslinking on the developed color intensities, as well as coloration and decoloration rates of the photochromic prints. Optimized functionality of the textile UV-sensor is found using different belt speeds and lamp intensities during the curing process.

  14. Comparação da influência entre tempos de polimerização em resinas compostas polimerizadas com LED e Luz Incandescente Comparison of the influence of curing times applied to composite resins cured with LED and Incandescent Light

    Directory of Open Access Journals (Sweden)

    Michele P. M. Ulhoa

    2007-09-01

    Full Text Available O propósito deste trabalho é fazer uma comparação entre resinas poliméricas dentárias, polimerizadas por aparelhos baseados em lâmpada halógena e diodo emissor de Luz (LED, utilizando-se o método do disco retificado aperfeiçoado para odontologia e os respectivos valores de microdureza. Foram realizados testes em amostras de resinas compostas de 5 diferentes marcas, polimerizadas a tempos de 10, 20 e 40 s, pelos dois aparelhos. A análise estatística dos valores de microdureza e agressividade permitiu concluir que estatisticamente não há correlação entre essas propriedades. Na análise de microdureza, a heterogeneidade característica do material implicou em resultados com valores de desvio padrão relativamente altos, de forma que não foi encontrada diferença estatística entre as amostras avaliadas. Na análise estatística dos ensaios baseados no método do disco retificado, a resina que apresentou maior desgaste nos ensaios, foi a Tetric Ceram, polimerizada pelo aparelho de LED por 10 s, cujo valor médio de agressividade obtido foi 0,170 mm³/N.m. A resina que sofreu menor desgaste foi a Charisma, polimerizada por Lâmpada Incandescente, por um tempo de 20 s, cuja média dos valores de agressividade foi 0,057 mm³/N.m.The purpose of this work was to compare polymeric dental resins cured with halogen lamp and with light emission diode (LED devices, using the grinding disk method customized for dentistry and the corresponding microhardness values. Tests were carried out on resin samples of five brands, which were cured for 10, 20 and 40 s with the two devices. The analysis of microhardness and aggressiveness has allowed us to conclude that there is no correlation between these properties. In Microhardness tests, the material heterogeneity has produced relative high standard deviation values and has not shown statistical differences between the analyzed samples. In the statistical analysis for the results with the grinding disk

  15. Flame Retardance and Physical Properties of Novel Cured Blends of Unsaturated Polyester and Furan Resins

    Directory of Open Access Journals (Sweden)

    Baljinder Kaur Kandola

    2015-02-01

    Full Text Available Novel blends of two furan resins with an unsaturated polyester have been prepared and cured by parallel free radical (for the unsaturated polyester and acid-catalysed crosslinking (for the furan resin to give co-cured composite materials. Although these materials have inferior physical properties, such as low Tg and low storage modulus compared with those of unsaturated polyester and furan resins alone, they show markedly improved flame retardance compared with that of the normally highly flammable unsaturated polyester. This increased flame retardance arises from a condensed phase mechanism in which the furanic component forms a semi-protective char, reducing rates of thermal degradation and total heat release and heat of combustion. The blends also burn with reduced smoke output compared with that from unsaturated polyester alone.

  16. The role of the epoxy resin: Curing agent ratio in composite interfacial strength by single fibre microbond test

    DEFF Research Database (Denmark)

    Minty, Ross; Thomason, James L.; Petersen, Helga Nørgaard

    2015-01-01

    This paper focuses on an investigation into the role of the epoxy resin: curing agent ratio in composite interfacial shear strength of glass fibre composites. The procedure involved changing the percentage of curing agent (Triethylenetetramine [TETA]) used in the mixture with several different...... percentages used, ranging from 4% up to 30%, including the stoichiometric ratio. It was found by using the microbond test, that there may exist a relationship between the epoxy resin to curing agent ratio and the level of adhesion between the reinforcing fibre and the polymer matrix of the composite....

  17. Preparation of unsaturated acrylic prepolymer and electron beam curing of its mixture with vinyl monomers

    International Nuclear Information System (INIS)

    Pyun, H.C.; Park, W.B.; Kim, K.Y.; Sung, K.Y.

    1980-01-01

    Electron beam curable prepolymers were prepared by the addition reaction of methyl methacrylate-glycidyl methacrylate copolymer with methacrylic acid, and electron beam curing was studied for the prepolymer and their mixtures of several kind of vinyl monomers. When the reaction was carried out in the presence of triethylbenzyl ammonium chloride in N,N-dimethyl formamide solution, the rate of addition reaction obeyed first-order kinetics. In the electron beam curing, the rate of gel formation of the prepolymer was slower than that of the mixtures of prepolymer and monomers. In the curing of mixtures of prepolymer with polyethyleneglycol dimethacrylates, the rate of gel formation increased with the increase in the degree of polymerization of polyethylene oxide fraction of polyethyleneglycol dimethacrylate, and decreased with the increase the polyethyleneglycol dimethacrylate content. The properties of cured coatings were also examined. (author)

  18. Use of 2,5-dimethyl-2,5-hexane diamine as a curing agent for epoxy resins. [Patent application

    Science.gov (United States)

    Rinde, J.A.; Newey, H.A.

    Primary diamines are prepared for use as a curing agent for epoxy resins. These curing agents can be used to form epoxy resin mixtures useful in filament winding and preimpregnated fiber molding and in formulating film adhesives, powder coatings and molding powders. The epoxy mixtures form for such uses a room temperature non-reacting, intermediate stable state which has a latent cross-linking capability.

  19. Microstructure aspects of radiation-cured networks: Cationically polymerized aromatic epoxy resins

    Science.gov (United States)

    Kowandy, Christelle; Ranoux, Guillaume; Walo, Marta; Vissouvanadin, Bertrand; Teyssedre, Gilbert; Laurent, Christian; Berquand, Alexandre; Molinari, Michaël; Coqueret, Xavier

    2018-02-01

    The thermo-mechanical properties and nanostructural features of epoxy aromatic resins cationically cured by UV-visible or electron beam radiation have been studied by FT-NIR spectroscopy, dynamic mechanical analysis (DMA), dielectric spectroscopy (DS), and atomic force microscopy (AFM). The influence of formulation (nature and content of onium salt) and of curing parameters (doses, thermal treatment) on the thermophysical have been investigated. The presence of several relaxation domains observed by DMA and DS analysis confirms the presence of heterogeneities in the cured materials. Network formation is described by the percolation of glassy nanoclusters which are evidenced by AFM analyses. AFM probing by quantitative nanomechanical measurements confirms the gradual build-up of the local Young's modulus in good agreement with the macroscopic value.

  20. Radiation curing of {gamma}-Al{sub 2}O{sub 3} filled epoxy resin

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Phil Hyun; Kim, Dong Jin; Nho, Young Chang [KAERI, Taejon (Korea, Republic of)

    2003-10-01

    Epoxy resins are widely utilized as high performance thermosetting resins for many industrial applications but characterized by a relatively low toughness. Recently, the incorporation with rigid inorganic was suggested to improve the mechanical properties of epoxy resins. In the present work, an attempt has been taken to disperse nano-sized {gamma}- Al{sub 2}O{sub 3} particles into diglycidyl ether of bisphenol-A (DGEBA) epoxy resins for improvement of the mechanical properties. These hybrid epoxy-alumina composites were prepared using by the {gamma}-ray curing technique that was conducted with 100kGy under nitrogen at room temperature. The composites were characterized by determining gel content, UTM (Instron model 4443), SEM, FT-IR studies.

  1. Electron beam curing of coatings

    International Nuclear Information System (INIS)

    Schmidt, J.; Mai, H.

    1986-01-01

    Modern low-energy electron beam processors offer the possibility for high-speed curing of coatings on paper, plastics, wood and metal. Today the electron beam curing gets more importance due to the increasing environmental problems and the rising cost of energy. For an effective curing process low-energy electron beam processors as well as very reactive binders are necessary. Generally such binders consist of acrylic-modified unsaturated polyester resins, polyacrylates, urethane acrylates or epoxy acrylates and vinyl monomers, mostly multifunctional acrylates. First results on the production of EBC binders on the base of polyester resins and vinyl monomers are presented. The aim of our investigations is to obtain binders with curing doses ≤ 50 kGy. In order to reduce the curing dose we studied mixtures of resins and acrylates. (author)

  2. Correlation between the state of cure of thermosetting resins and their properties

    International Nuclear Information System (INIS)

    Haffane, N.; Benameur, T.; Granger, R.; Vergnaud, J.M.

    1996-01-01

    Thermosetting resins, in the same way as polymers, are more and more used for coating metal sheets, in order to bring various interesting properties. An important problem arises with the cure of the thermoset, the process of cure being complex with heating conduction and convection and the heat generated by the cure reaction. The kinetics of the heat evolved from the overall cure reaction is determined through calorimetry experiments in scanning mode. The state of cure at time t is expressed by the heat generated by reaction up to time t as a fraction of the total heat generated. A numerical model taking all the facts into account is able to evaluate the profile of the state of cure developed through the thickness of the thermoset. The state of cure which derives from a theoretical point of view is correlated with some properties of interest for the coating, such as the hardness and the resistance to liquids. The resistance to water and ethanol is evaluated by determining the kinetics of absorption which is controlled by diffusion. copyright 1996 American Institute of Physics

  3. Assessment of the impact strength of the denture base resin polymerized by various processing techniques

    Directory of Open Access Journals (Sweden)

    Rajashree Jadhav

    2013-01-01

    Full Text Available Aim : To measure the impact strength of denture base resins polymerized using short and long curing cycles by water bath, pressure cooker and microwave techniques. Materials and Methods: For impact strength testing, 60 samples were made. The sample dimensions were 60 mm × 12 mm × 3 mm, as standardized by the American Standards for Testing and Materials (ASTM. A digital caliper was used to locate the midpoint of sample. The impact strength was measured in IZOD type of impact tester using CEAST Impact tester. The pendulum struck the sample and it broke. The energy required to break the sample was measured in Joules. Data were analyzed using Student′s " t" test. Results: There was statistically significant difference in the impact strength of denture base resins polymerized by long curing cycle and short curing cycle in each technique, with the long curing processing being the best. Conclusion: The polymerization technique plays an important role in the influence of impact strength in the denture base resin. This research demonstrates that the denture base resin polymerized by microwave processing technique possessed the highest impact strength.

  4. Effect of different light curing methods on the push-out bond strength of glass fiber post to different root canal regions

    Directory of Open Access Journals (Sweden)

    Ali Eskandarizadeh

    2016-07-01

    Full Text Available Background and Aims: Slow polymerization rate in early stage of light curing process leads to higher monomers movement and entering in polymer network that cause higher mechanical properties.The aim of this study was to evaluate the effect of light activation methodes (immediate, 5 and 10 minutes delay on the push-out bond strength of cemented fiber posts in different regions of root canal with two types of resin cements. Materials and Methods: In sixty extracted human single canal, the teeth were decoronated from cement enamel junction and after root canal therapy, FRC postec plus were cemented with two resin cements, Duolink and Variolink 2, in three curing methods; immediate, 5 and 10 minutes of delay. After storing in a dark place for 24 hours, they were cut into three sections: coronal, middle and apical. The push-out bond strength test was performed using a universal testing machine. The failure modes were observed using a stereomicroscope. Data were analyzed using ANOVA and Tukey post hoc test (P0.05. In immediate light curing method, regardless of root region, Duolink had higher push-out bond strength than that of Variolink 2 (P=0.02. In all subgroups, there were reductions in the bond strengths from coronal to apical. Mixed failure at the cement-fiber post interface was predominent in all groups. Conclusion: 5 and 10 minutes delay caused reduction in the push-out bond strength for Variolink 2 but did not have significant effect for Duolink resin cement.

  5. Comparison of water sorption and solubility of Acropars and Meliodent heat cure acrylic resins

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    Golbidi F

    2006-06-01

    Full Text Available Background and Aim: Water sorption and solubility are important properties of acrylic resins. Denture base acrylic resins have low solubility. This solubility results from the leaching out of unreacted monomer and water soluble additives into the oral fluids. The solubility of denture bases can cause oral soft tissue reactions. In addition, water absorbed into this material acts as a plasticizer and decreases the mechanical properties such as hardness, transverse strength, fatigue limit and also can change the color and dimensional stability. The aim of this study was to compare the water sorption and solubility of Acropars and Meliodent heat cure acrylic resins. Materials and Methods: This experimental study was performed on the basis of ADA specification No.12 and ISO No.1567 and standards NO: 2571 of Institute of Standards & Industrial Research of Iran. Six disc form samples of each acrylic resin were prepared, with the dimension of 50×0.5 mm. After desiccating, the samples were kept in an oven for 24 hours and weighed. Then they were immersed in water, kept in oven for 7 days and weighed again. After this phase, the samples were carried to a dessicator, for 24 hours and kept in an oven for drying and were weighed for the third time. Data were analyzed with Mann Whitney and one sample t-test. P<0.05 was considered as the limit of significance. Results: Water sorption mean values were 30.5±0.1 µg/mm3 or 0.76±0.01 mg/cm2 for Meliodent samples and 30.7±0.87 µg/mm3 or 0.77±0.009 mg/cm2 for Acropars samples. No significant difference was observed in water sorption of these two materials (P=0.9. Meliodent acrylic resin showed lower solubility (1.7±0.097 µg/mm3 or 0.042±0.001 mg/cm2 than Acropars acrylic resin (2.5±0.13 µg/mm3 or 0.062±0.001 mg/cm2 (P=0.002. Conclusion: Acropars heat cure acrylic resin matched well with the requirements of the international standards for water sorption, but its solubility was not favorable. This problem

  6. Evaluation of thermal conductivity of heat-cured acrylic resin mixed with A1203

    OpenAIRE

    Ebadian B.; Parkan MA.

    2002-01-01

    One of the most important characteristics of denture base is thermal conductivity. This property has a major role in secretions of salivary glands and their enzymes, taste of the food and gustatory response. Polymethyl methacrylate used in prosthodontics is relatively an insulator. Different materials such as metal fillers and ceramics have been used to solve this problem. The aim of this study was the evaluation of AI2O3 effect on thermal conductivity of heat-cured acrylic resin. Acrylic res...

  7. Effect of Resin Coating and Chlorhexidine on Microleakage of Two Resin Cements after Storage

    Directory of Open Access Journals (Sweden)

    F. Shafie

    2010-03-01

    Full Text Available Objective: Evaluating the effect of resin coating and chlorhexidine on microleakage of two resin cements after water storage.Materials and Methods: Standardized class V cavities were prepared on facial and lingual surfaces of one hundred twenty intact human molars with gingival margins placed 1mm below the cemento-enamel junction. Indirect composite inlays were fabricated and thespecimens were randomly assigned into 6 groups. In Groups 1 to 4, inlays were cemented with Panavia F2.0 cement. G1: according to the manufacturer’s instruction. G2: with light cured resin on the ED primer. G3: chlorhexidine application before priming. G4: withchlorhexidine application before priming and light cured resin on primer. G5: inlays were cemented with Nexus 2 resin cement. G6: chlorhexidine application after etching. Each group was divided into two subgroups based on the 24-hour and 6-month water storagetime. After preparation for microleakage test, the teeth were sectioned and evaluated at both margins under a 20×stereomicroscope. Dye penetration was scored using 0-3 criteria.The data was analyzed using Kruskal-Wallis and complementary Dunn tests.Results: There was significantly less leakage in G2 and G4 than the Panavia F2.0 control group at gingival margins after 6 months (P<0.05. There was no significant differences in leakage between G1 and G3 at both margins after 24 hours and 6 months storage. After 6months, G6 revealed significantly less leakage than G5 at gingival margins (P=0.033. In general, gingival margins showed more leakage than occlusal margins.Conclusion: Additionally, resin coating in self-etch (Panavia F2.0 and chlorhexidine application in etch-rinse (Nexus resin cement reduced microleakage at gingival margins after storage.

  8. Effect of light intensity and irradiation time on the polymerization process of a dental composite resin

    Directory of Open Access Journals (Sweden)

    Discacciati José Augusto César

    2004-01-01

    Full Text Available Polymerization shrinkage is a critical factor affecting the longevity and acceptability of dental composite resins. The aim of this work was to evaluate the effect of light intensity and irradiation time on the polymerization process of a photo cured dental composite resin by measuring the Vickers hardness number (VHN and the volumetric polymerization shrinkage. Samples were prepared using a dental manual light-curing unit. The samples were submitted to irradiation times of 5, 10, 20 and 40 s, using 200 and 400 mW.cm-2 light intensities. Vickers hardness number was obtained at four different moments after photoactivation (immediate, 1 h, 24 h and 168 h. After this, volumetric polymerization shrinkage values were obtained through a specific density method. The values were analyzed by ANOVA and Duncan's (p = 0.05. Results showed increase in hardness values from the immediate reading to 1 h and 24 h readings. After 24 h no changes were observed regardless the light intensities or activation times. The hardness values were always smaller for the 200 mW.cm-2 light intensity, except for the 40 s irradiation time. No significant differences were detected in volumetric polymerization shrinkage considering the light intensity (p = 0.539 and the activation time (p = 0.637 factors. In conclusion the polymerization of the material does not terminate immediately after photoactivation and the increase of irradiation time can compensate a lower light intensity. Different combinations between light intensity and irradiation time, i.e., different amounts of energy given to the system, have not affected the polymerization shrinkage.

  9. A comparative evaluation of the shear bond strength of five different orthodontic bonding agents polymerized using halogen and light-emitting diode curing lights: An in vitro investigation

    Directory of Open Access Journals (Sweden)

    Sujoy Banerjee

    2011-01-01

    Full Text Available Purpose: With the introduction of photosensitive (light-activated restorative materials in orthodontics, various methods have been suggested to enhance the polymerization of the materials used, including use of more powerful light curing devices. Bond strength is an important property and determines the amount of force delivered and the treatment duration. Many light-cured bonding materials have become popular but it is the need of the hour to determine the bonding agent that is the most efficient and has the desired bond strength. Aim: To evaluate and compare the shear bond strengths of five different orthodontic light cure bonding materials cured with traditional halogen light and low-intensity light-emitting diode (LED light curing unit. Materials and Methods: 100 human maxillary premolar teeth, extracted for orthodontic purpose, were used to prepare the samples. 100 maxillary stainless steel bicuspid brackets of 0.018 slot of Roth prescription, manufactured by D-tech Company, were bonded to the prepared tooth surfaces of the mounted samples using five different orthodontic bracket bonding light-cured materials, namely, Enlight, Fuji Ortho LC (resin-modified glass ionomer cement, Orthobond LC, Relybond, and Transbond XT. The bond strength was tested on an Instron Universal testing machine (model no. 5582. Results: In Group 1 (halogen group, Enlight showed the highest shear bond strength (16.4 MPa and Fuji Ortho LC showed the least bond strength (6.59 MPa (P value 0.000. In Group 2 (LED group, Transbond showed the highest mean shear bond strength (14.6 MPa and Orthobond LC showed the least mean shear bond strength (6.27 MPa (P value 0.000. There was no statistically significant difference in the shear bond strength values of all samples cured using either halogen (mean 11.49 MPa or LED (mean 11.20 MPa, as the P value was 0.713. Conclusion: Polymerization with both halogen and LED resulted in shear bond strength values which were above the

  10. Hardness evaluation of cured urea-formaldehyde resins with different formaldehyde/urea mole ratios using nanoindentation method

    Science.gov (United States)

    Byung-Dae Park; Charles R. Frihart; Yan Yu; Adya P. Singh

    2013-01-01

    To understand the influence of formaldehyde/urea (F/U) mole ratio on the properties of urea–formaldehyde (UF) resins, this study investigated hardness of cured UF resins with different F/U mole ratios using a nanoindentation method. The traditional Brinell hardness (HB) method was also used...

  11. Influence of post pattern and resin cement curing mode on the retention of glass fibre posts.

    Science.gov (United States)

    Poskus, L T; Sgura, R; Paragó, F E M; Silva, E M; Guimarães, J G A

    2010-04-01

    To evaluate the influence of post design and roughness and cement system (dual- or self-cured) on the retention of glass fibre posts. Two tapered and smooth posts (Exacto Cônico No. 2 and White Post No. 1) and two parallel-sided and serrated posts (Fibrekor 1.25 mm and Reforpost No. 2) were adhesively luted with two different resin cements--a dual-cured (Rely-X ARC) and a self-cured (Cement Post)--in 40 single-rooted teeth. The teeth were divided into eight experimental groups (n = 5): PFD--Parallel-serrated-Fibrekor/dual-cured; PRD--Parallel-serrated-Reforpost/dual-cured; TED--Tapered-smooth-Exacto Cônico/dual-cured; TWD--Tapered-smooth-White Post/dual-cured; PFS--Parallel-serrated-Fibrekor/self-cured; PRS--Parallel-serrated-Reforpost/self-cured; TES--Tapered-smooth-Exacto Cônico/self-cured; TWS--Tapered-smooth-White Post/self-cured. The specimens were submitted to a pull-out test at a crosshead speed of 0.5 mm min(-1). Data were analysed using analysis of variance and Bonferroni's multiple comparison test (alpha = 0.05). Pull-out results (MPa) were: PFD = 8.13 (+/-1.71); PRD = 8.30 (+/-0.46); TED = 8.68 (+/-1.71); TWD = 9.35 (+/-1.99); PFS = 8.54 (+/-2.23); PRS = 7.09 (+/-1.96); TES = 8.27 (+/-3.92); TWS = 7.57 (+/-2.35). No statistical significant difference was detected for posts and cement factors and their interaction. The retention of glass fibre posts was not affected by post design or surface roughness nor by resin cement-curing mode. These results imply that the choice for serrated posts and self-cured cements is not related to an improvement in retention.

  12. Mechanical properties of denture base resins: An evaluation

    Directory of Open Access Journals (Sweden)

    Pooran Chand

    2011-01-01

    Conclusion: The heat cure denture base material D (Trevalon "HI" was the strongest and C (Trevalon was the weakest among all materials used in this study. The study showed that the deflection of various denture base resins (A to D increases proportionately with the increase in load.

  13. Evaluation of thermal conductivity of heat-cured acrylic resin mixed with A1203

    Directory of Open Access Journals (Sweden)

    Ebadian B.

    2002-08-01

    Full Text Available One of the most important characteristics of denture base is thermal conductivity. This property has a major role in secretions of salivary glands and their enzymes, taste of the food and gustatory response. Polymethyl methacrylate used in prosthodontics is relatively an insulator. Different materials such as metal fillers and ceramics have been used to solve this problem. The aim of this study was the evaluation of AI2O3 effect on thermal conductivity of heat-cured acrylic resin. Acrylic resin was mixed with AI2O3 in two different weight rates (15 and 20 % of weight. So, group 1 and 2 were divided on this basis. Samples with pure acrylic resin were considered as control group. 18 cylindrical patterns were made in 9x9 mm dimensions and thermocouple wires embedded in each sample to act as conductor. The specimens were put in water with 70±1°C thermal range for 10 minutes. Then, thermal conductivity was measured. The results were analyzed with variance analysis and Dunken test. There was significant difference between thermal conductivity of all groups in all period times. It the first seconds, thermal conductivity in groups 1 and 2 were more than control group. Therefore, for developing of thermal conductivity of acrylic resin, A1203 can be used. Certainly, other characteristic of new resin should be evaluated.

  14. Comparison of Mechanical Properties of Resin Composites with Resin Modified Glass Ionomers

    Directory of Open Access Journals (Sweden)

    Taha NA

    2015-06-01

    Full Text Available Statement of Problem: There are controversial reports regarding physical and mechanical properties of resin composites and glass ionomer cements. Some revealed higher strength and hardness for resin composites while others showed a comparable value for glass ionomer cements. Evaluation of mechanical properties of different types of resin composites in comparison with resin modified glass ionomers is not widely studied. Objectives: To measure and compare the flexural strength and Vickers hardness of three resin composites and two resins modified glass ionomer cements before and after ageing. Materials and Methods: Three resin composites, i.e. Filtek Supreme XTE (3M ESPE, Ice (SDI, Gradia (GC, and two resins modified glass ionomers, i.e. Fuji II LC (GC and Riva Light Cure (SDI, were selected. Ten barshaped specimens were prepared for each material and cured using LED curing light. After 24 hours storage in distilled water at 37oC, the specimens were randomly divided into two equal groups (n=5. The first group was tested as a baseline and the second group was restored at 37oC for another 29 days. Flexural strength was performed by four-point bending test using universal testing machine at crosshead speed of 0.5mm/min, and the maximum load at failure was recorded. The specimen’s halves were used for evaluating Vickers hardness, using a Digital Hardness Tester (300 g/15 sec and the Vickers hardness number (VHN was recorded. Data were analyzed using one-way analysis of variance (ANOVA, Tukey’s and student’s t-test. Results: After 24 hours of immersion, the highest hardness number was found for Filtek Supreme and Ice and the highest flexural strength was obtained for Gradia. After 30 days of storage, hardness of Fuji II LC and Gradia showed a significant decrease; flexural strength of Ice and Fuji II LC revealed a significant increase while Gradia and Filtek Supreme showed a significant decrease. Conclusions: Resin modified glass ionomers showed

  15. Effects of blood contamination on resin-resin bond strength.

    Science.gov (United States)

    Eiriksson, Sigurdur O; Pereira, Patricia N R; Swift, Edward J; Heymann, Harald O; Sigurdsson, Asgeir

    2004-02-01

    Incremental placement and curing of resin composites has been recommended. However, this requires longer operating time, and therefore, increased risk of contamination. The purpose of this study was to evaluate the effects of blood contamination on microtensile bond strengths (microTBS) between resin interfaces and to determine the best decontamination method to re-establish the original resin-resin bond strength. The top surfaces of 64, 4-mm composite blocks (Z-250, Renew, APX, Pertac II) were untreated as the control, or were treated as follows: blood applied and dried on the surface (Treatment 1), blood applied, rinsed, dried (Treatment 2), blood applied, rinsed, and an adhesive applied (Single Bond, One-Step, Clearfil SE, Prompt L-Pop) (Treatment 3). Fresh composite was applied and light-cured in 2-mm increments. After 24 h storage in water, the specimens were sectioned into 0.7-mm thick slabs, trimmed to a cross-sectional area of 1 mm(2), and loaded to failure at a crosshead speed of 1 mm/min using an Instron universal testing machine. Data were analyzed using two-way ANOVA and Fisher's PLSD test (pcontamination resulted in resin-resin bond strengths of only 1.0-13.1 MPa. Rinsing raised bond strengths to over 40 MPa for each material. Use of an adhesive further increased bond strengths except for Pertac II. Rinsing blood from contaminated surfaces increases the resin-resin bond strength significantly and the application of an appropriate adhesive increases the bond strength to control levels.

  16. Structural investigation of e-beam cured epoxy resins through solid state NMR

    International Nuclear Information System (INIS)

    Alessi, Sabina; Spinella, Alberto; Caponetti, Eugenio; Dispenza, Clelia; Spadaro, Giuseppe

    2012-01-01

    In this paper the network structure of e-beam cured DGEBF based epoxy resins is investigated. Two epoxy systems, having different reactivity and cured in different process conditions, were analyzed through solid state NMR spectroscopy. The analysis shows that the more reactive system has higher cross-linking density and higher uniformity of network distribution. Similar information were obtained, in a previous work, on the same systems through dynamic mechanical thermal analysis. It is worth noting that unlike DMTA tests, which interfere with the molecular structure of the analyzed material, due to the heating during the analysis itself, more reliable information, without any artefact, are obtained by solid state NMR, carried out at constant room temperature. - Highlights: ► The structure of two e-beam cured epoxy systems is investigated through solid state NMR. ► The aim is to have direct information about the structure without inducing modifications. ► The different molecular structures are able to emphasize the response of solid state NMR. ► T 1 H, T 1ρ H and T CH measurements indicate different cross-linking degrees. ► The NMR results are in agreement with DMTA analysis performed in a previous paper.

  17. Preparation of hyperbranched poly (amidoamine)-grafted graphene nanolayers as a composite and curing agent for epoxy resin

    Science.gov (United States)

    Gholipour-Mahmoudalilou, Meysam; Roghani-Mamaqani, Hossein; Azimi, Reza; Abdollahi, Amin

    2018-01-01

    Thermal properties of epoxy resin were improved by preparation of a curing agent of poly (amidoamine) (PAMAM) dendrimer-grafted graphene oxide (GO). Hyperbranched PAMAM-modified GO (GD) was prepared by a divergent dendrimer synthesis methodology. Modification of GO with (3-Aminopropyl)triethoxysilane (APTES), Michael addition of methacrylic acid, and amidation reaction with ethylenediamine results in the curing agent of GD. Then, epoxy resin was cured in the presence of different amounts of GD and the final products were compared with ethylenediamine-cured epoxy resin (E) in their thermal degradation temperature and char contents. Functionalization of GO with APTES and hyperbranched dendrimer formation at the surface of GO were evaluated by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and thermogravimetric analysis (TGA) results. TGA results showed that the weight loss associated with chemical moieties in GONH2, GOMA, and GD is estimated to be 10.1, 12.2, and 14.1%, respectively. Covalent attachment of dendrimer at the surface of GO increases its thermal stability. TGA also showed that decomposition temperature and char content are higher for composites compared with E. Scanning and transmission electron microscopies show that flat and smooth graphene nanolayers are wrinkled in GO and re-stacking and flattening of nanolayers is observed in GD.

  18. Isothermal and non-isothermal cure of a tri-functional epoxy resin (TGAP): A stochastic TMDSC study

    International Nuclear Information System (INIS)

    Hutchinson, John M.; Shiravand, Fatemeh; Calventus, Yolanda; Fraga, Iria

    2012-01-01

    Highlights: ► First evaluation of T g of tri-functional epoxy resin TGAP by DSC. ► Clearly shows advantages of TOPEM for isothermal and non-isothermal cure analysis. ► Evidence of highly non-linear enthalpy relaxation in partially cured TGAP system. - Abstract: The isothermal cure of a highly reactive tri-functional epoxy resin, tri-glycidyl para-amino phenol (TGAP), with diamino diphenyl sulphone (DDS), at two different cure temperatures T c has been studied by both conventional differential scanning calorimetry (DSC) and by a stochastic temperature modulated DSC technique, TOPEM. From a series of isothermal cure experiments for increasing cure times, the glass transition temperature T g as a function of isothermal cure time is determined by conventional DSC from a second (non-isothermal) scan, and the vitrification time t v is obtained as the time at which T g = T c . In parallel, TOPEM experiments at the same T c lead directly to the determination of t v from the sigmoidal change in the quasi-static heat capacity. It is not possible to identify the glass transition temperature of the fully cured system, T g∞ , in a third scan by conventional DSC. In contrast, with TOPEM a second (non-isothermal) scan at 2 K/min after the isothermal cure gives rise to three separate transitions: devitrification of the partially cured and vitrified material; almost immediate vitrification as the T g of the system again rises; finally another devitrification, at a temperature approximating closely to T g∞ . Thus with TOPEM it is possible to obtain a calorimetric measure of the glass transition temperature of this fully cured system.

  19. Resin impregnation process for producing a resin-fiber composite

    Science.gov (United States)

    Palmer, Raymond J. (Inventor); Moore, William E. (Inventor)

    1994-01-01

    Process for vacuum impregnation of a dry fiber reinforcement with a curable resin to produce a resin-fiber composite, by drawing a vacuum to permit flow of curable liquid resin into and through a fiber reinforcement to impregnate same and curing the resin-impregnated fiber reinforcement at a sufficient temperature and pressure to effect final curing. Both vacuum and positive pressure, e.g. autoclave pressure, are applied to the dry fiber reinforcement prior to application of heat and prior to any resin flow to compact the dry fiber reinforcement, and produce a resin-fiber composite of reduced weight, thickness and resin content, and improved mechanical properties. Preferably both a vacuum and positive pressure, e.g. autoclave pressure, are also applied during final curing.

  20. Process for curing ionizing radiation-highly sensitive resin composition

    International Nuclear Information System (INIS)

    Araki, K.; Sasaki, T.; Tabei, K.; Goto, K.

    1979-01-01

    A process is described for curing a radiation curable composition consisting essentially of (a) an amide represented by the formula R,CONR 2 R 3 and (b) an unsaturated polyester resin by irradiating the composition with an ionizing radiation. R 1 is H, an alkyl groups having from 1 to 17 carbon atoms or an alkenyl groups having from 1 to 17 carbon atoms, and R 2 and R 3 are each -H, -CH 3 , or -CH 2 OH. R 1 and R 2 taken together represent alkylene having 2 to 5 carbon atoms

  1. Effect of Energy Drinks on Discoloration of Silorane and Dimethacrylate-Based Composite Resins.

    Science.gov (United States)

    Ahmadizenouz, Ghazaleh; Esmaeili, Behnaz; Ahangari, Zohreh; Khafri, Soraya; Rahmani, Aghil

    2016-08-01

    This study aimed to assess the effects of two energy drinks on color change (ΔE) of two methacrylate-based and a silorane-based composite resin after one week and one month. Thirty cubic samples were fabricated from Filtek P90, Filtek Z250 and Filtek Z350XT composite resins. All the specimens were stored in distilled water at 37°C for 24 hours. Baseline color values (L*a*b*) of each specimen were measured using a spectrophotometer according to the CIEL*a*b* color system. Ten randomly selected specimens from each composite were then immersed in the two energy drinks (Hype, Red Bull) and artificial saliva (control) for one week and one month. Color was re-assessed after each storage period and ΔE values were calculated. The data were analyzed using the Kruskal Wallis and Mann-Whitney U tests. Filtek Z250 composite showed the highest ΔE irrespective of the solutions at both time points. After seven days and one month, the lowest ΔE values were observed in Filtek Z350XT and Filtek P90 composites immersed in artificial saliva, respectively. The ΔE values of Filtek Z250 and Z350XT composites induced by Red Bull and Hype energy drinks were not significantly different. Discoloration of Filtek P90 was higher in Red Bull energy drink at both time points. Prolonged immersion time in all three solutions increased ΔE values of all composites. However, the ΔE values were within the clinically acceptable range (<3.3) at both time points.

  2. Visible Light Photoinitiator for 3D-Printing of Tough Methacrylate Resins

    Directory of Open Access Journals (Sweden)

    Bernhard Steyrer

    2017-12-01

    Full Text Available Lithography-based additive manufacturing was introduced in the 1980s, and is still the method of choice for printing accurate plastic parts with high surface quality. Recent progress in this field has made tough photopolymer resins and cheap LED light engines available. This study presents the influence of photoinitiator selection and post-processing on the thermomechanical properties of various tough photopolymers. The influence of three photoinitiators (Ivocerin, BAPO, and TPO-L on the double-bond conversion and mechanical properties was investigated by mid infrared spectroscopy, dynamic mechanical analysis and tensile tests. It was found that 1.18 wt % TPO-L would provide the best overall results in terms of double-bond conversion and mechanical properties. A correlation between double-bond conversion, yield strength, and glass transition temperature was found. Elongation at break remained high after post-curing at about 80–100%, and was not influenced by higher photoinitiator concentration. Finally, functional parts with 41 MPa tensile strength, 82% elongation at break, and 112 °C glass transition temperature were printed on a 405 nm DLP (digital light processing printer.

  3. Comparative study of the use of non-ionizing and ionizing radiation in the cure of epoxy resin: microwave versus electron electron

    Energy Technology Data Exchange (ETDEWEB)

    Kersting, Daniel, E-mail: daniel.kersting@usp.br [Centro Tecnologico da Marinha em Sao Paulo (CTMSP/USP), Sao Paulo, SP (Brazil); Wiebeck, Helio, E-mail: hwiebeck@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Escola Politecnica. Dept. de Engenharia Metalurgica; Marinucci, Gerson; Silva, Leonardo G.A. e, E-mail: marinuci@ipen.br, E-mail: gasilva@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    Several processes for curing epoxy resins were developed over the years. Two methods are discussed in this paper, in order to present the main advantages and disadvantages of using microwave radiation (non-ionizing radiation) and electron beam radiation (ionizing radiation). The microwave radiation is a non-ionizing radiation, with great power of penetration and transfer of heat in microwave absorbing materials, or materials with microwave absorbing fillers. The frequency usually used in research and development is 2.45 GHz, the same available in commercial equipment. The microwave effect provides increase on the collision velocity between the reactant which, combined with energy absorbed by the reaction system, accelerates the curing reaction. None modifications in the epoxy system are required to use microwave heating for the curing process.On the other hand, the electron beam is a form of ionizing radiation in which the high energy electrons have the ability to interact with the irradiated material and produce ions, free radicals, and molecules in excited state, which can be used to initiate and propagate a polymerization. Specific initiators are necessary for an effective cure of the resin. In this study, a DGEBA epoxy resin with initiators based on anhydride and amine was used under the same conditions indicated by the manufacturer. The curing of the catalyzed system was performed in a domestic microwave oven adapted for laboratory use. The degradation and glass transition temperatures were evaluated by thermal analysis techniques. For comparative purposes, it was used data available in the literature for electron beam irradiation. (author)

  4. Comparative study of the use of non-ionizing and ionizing radiation in the cure of epoxy resin: microwave versus electron electron

    International Nuclear Information System (INIS)

    Kersting, Daniel; Wiebeck, Helio

    2013-01-01

    Several processes for curing epoxy resins were developed over the years. Two methods are discussed in this paper, in order to present the main advantages and disadvantages of using microwave radiation (non-ionizing radiation) and electron beam radiation (ionizing radiation). The microwave radiation is a non-ionizing radiation, with great power of penetration and transfer of heat in microwave absorbing materials, or materials with microwave absorbing fillers. The frequency usually used in research and development is 2.45 GHz, the same available in commercial equipment. The microwave effect provides increase on the collision velocity between the reactant which, combined with energy absorbed by the reaction system, accelerates the curing reaction. None modifications in the epoxy system are required to use microwave heating for the curing process.On the other hand, the electron beam is a form of ionizing radiation in which the high energy electrons have the ability to interact with the irradiated material and produce ions, free radicals, and molecules in excited state, which can be used to initiate and propagate a polymerization. Specific initiators are necessary for an effective cure of the resin. In this study, a DGEBA epoxy resin with initiators based on anhydride and amine was used under the same conditions indicated by the manufacturer. The curing of the catalyzed system was performed in a domestic microwave oven adapted for laboratory use. The degradation and glass transition temperatures were evaluated by thermal analysis techniques. For comparative purposes, it was used data available in the literature for electron beam irradiation. (author)

  5. [Physical properties of resins for veneer crown. (Part 1) Bending strength of thermosetting methacrylic resins (author's transl)].

    Science.gov (United States)

    Kashiwada, T

    1979-01-01

    The physical properties of thermosetting methacrylic resins contain a kind or more than two kinds of cross linking agents were investigated. Knoop hardness and bending strength after drying, water sorption and thermal cycling were listed in table 4 and 5. Hydrophilic resins absorbed water about 3 times as much as hydrophobic resins. The materials contain a small amount of hydrophobic cross linking agents in MMA indicate comparatively excellent properties after drying, water sorption and thermal cycling. Knoop hardness of resins generally reduced by water sorption, especially in the case of the resin contains a large amount of triethylene glycol dimethacrylate.

  6. Comparison of the heat generation of light curing units.

    Science.gov (United States)

    Bagis, Bora; Bagis, Yildirim; Ertas, Ertan; Ustaomer, Seda

    2008-02-01

    The aim of this study was to evaluate the heat generation of three different types of light curing units. Temperature increases were recorded from a distance of 1 mm from a thermocouple to the tip of three different types of light curing units including one quartz-tungsten halogen (QTH), one plasma arc (PAC), and one light emitting diode (LED) unit. An experimental model was designed to fix the 1 mm distance between the tip of the light curing units and the thermocouple wire. Temperature changes were recorded in 10 second intervals up to 40 seconds. (10, 20, 30, and 40 seconds). Temperature measurements were repeated three times for every light curing unit after a one hour standby period. Statistical analysis of the results was performed using the analysis of variance (ANOVA) and the Bonferroni Test. The highest temperature rises (54.4+/-1.65 degrees C) occurred during activation of a PAC light curing unit for every test period (pdamage to the pulp.

  7. Time-dependent conversion of a methacrylate-based sealer polymerized with different light-curing units.

    Science.gov (United States)

    Beriat, Nilufer C; Ertan, Atilla; Cehreli, Zafer C; Gulsahi, Kamran

    2009-01-01

    The purpose of this study was to investigate the degree of conversion of a methacrylate-based sealer (Epiphany; Pentron Clinical Technologies, Wallingford, CT) with regard to the method of photoactivation, distance from the light-curing unit (LCU), and post-curing time. Freshly mixed Epiphany sealer was dispensed into half-pipe-shaped silicone moulds (n = 48), after which the specimens were photoactivated with one of the following LCUs from the coronal aspect: (1) quartz tungsten halogen/40 seconds and (2) light-emitting diode/20 seconds. In each specimen, the degree of conversion was measured at three different locations (coronal, middle, and apical) using Fourier transform infrared spectroscopy before and after photoactivation. The amount of conversion was approximately 50% after photoactivation and improved by approximately 10% after 15 days. Conversion of Epiphany was not affected by the type of LCU (p > 0.001) or the distance from the LCU (p > 0.001) but showed a significant increase within time (p < 0.001). These results indicate incomplete polymerization of Epiphany, despite a post-curing time of as long as 2 weeks in vitro.

  8. Novel halogen-free flame retardant thermoset from a hybrid hexakis (methoxymethyl melamine/phosphorus-containing epoxy resin cured with phenol formaldehyde novolac

    Directory of Open Access Journals (Sweden)

    2009-12-01

    Full Text Available This paper describes the curing behaviours, thermal properties and flame-resistance of a novel halogen-free epoxy hybrid thermoset, prepared by the curing reaction of hexakis (methoxymethyl melamine (HMMM, a phosphorouscontaining epoxy resin (EPN-D with 9, 10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO group and phenol formaldehyde novolac (n-PF. The resultant thermosets showed high glass-transition temperatures (Tg, 123–147°C as determined by thermal mechanical analysis (TMA, excellent thermal stability with high 5 wt% decomposition temperatures (Td,5% ≥308°C and high char yields (Yc ≥39.4 wt% from the thermogravimetric analysis (TGA. All the cured EPND/ HMMM/n-PF hybrid resins achieved the UL 94 V-0 grade with high limited oxygen indices (LOI > 45.7. It is found that phosphorous and nitrogen elements in the cured EPN-D/HMMM/n-PF hybrid resins had a positive synergistic effect on the improvement of the flame retardancy.

  9. Bulk-Fill Resin Composites

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Havndrup-Pedersen, Cæcilie; Honoré, Daniel

    2015-01-01

    the restorative procedure. The aim of this study, therefore, was to compare the depth of cure, polymerization contraction, and gap formation in bulk-fill resin composites with those of a conventional resin composite. To achieve this, the depth of cure was assessed in accordance with the International Organization...... for Standardization 4049 standard, and the polymerization contraction was determined using the bonded-disc method. The gap formation was measured at the dentin margin of Class II cavities. Five bulk-fill resin composites were investigated: two high-viscosity (Tetric EvoCeram Bulk Fill, SonicFill) and three low......-viscosity (x-tra base, Venus Bulk Fill, SDR) materials. Compared with the conventional resin composite, the high-viscosity bulk-fill materials exhibited only a small increase (but significant for Tetric EvoCeram Bulk Fill) in depth of cure and polymerization contraction, whereas the low-viscosity bulk...

  10. [Bonding of visible light cured composite resins to glass ionomer and Cermet cements].

    Science.gov (United States)

    Kakaboura, A; Vougiouklakis, G

    1990-04-01

    The "sandwich" technique involves combination of composite resins to etched glassionomer cements, is used today in restorative dentistry. The purpose of this study is to evaluate the bond strength between several composite resins and glass ionomer or cerment cements. Cylindrical specimens of the cements Ketac-Silver, Ionobond and GC-Lining Ce-ment were inserted in a mold and their flat free surfaces were etched for 30". Cylindrical plastic tubes were set upon each one of these surfaces and filled with the Composite resins Durafill, Brilliant Lux, Estilux posterior, Estilux posterior CVS and Herculite XR. Half of the specimens transferred in tap water for 24 hours and the others after thermocycling in the first month, kept for 4 months. Shear bond strengths were determined in Monsanto Testing Machine and some fractured surfaces were examined under SEM. The results of this investigation indicate that this technique produces bond strengths between composite resins and glassioners and the combination type of resin and type of cement, affects the values of the strength. Glass cermeet--small particle resin provides the most effective strength and glass ionomer--microfill resins the least. Storage time and thermocycling don't significantly effect the bond strength. SEM examination showed that all fracture failures were obtained in the cement while the opposite resin surfaces were covered with particles of the cements.

  11. Development of radiation curable surface coating based on soybean oil. part II: Evaluation of the prepared acrylated resin as surface coatings by using EB or UV sources for radiation curing applications

    International Nuclear Information System (INIS)

    Ibrahim, M.S.; Said, H.M.; Moussa, I.M.

    2005-01-01

    In recent years, there has been a growing trend in using vegetable oils as raw materials in acylation production that can be cured by UV/EB systems. The acrylated resin formulates by using individually different functional acrylate monomers were prepared and cured by EB or UV sources. The characterization properties of the cured films were investigated in terms of pendulum hardness, bending, impact, gloss, adhesion and chemical tests. Other formulations were prepared by mixing a constant ratio of different functional acrylate monomers and exposed to UV or EB irradiation. The results showed that the hardness of cured films were increased by increasing the functionality of monomers with excellent adhesion for all formulations but at expense of other properties involving bending and impact tests. Therefore, it can be deduce that the hardness of the curing surface coating by using EB was found to be nearly twice the hardness of the curing surface coating by using UV irradiation. Also, the best formulations which have given good chemical and mechanical properties are (mono-di) functional acrylate monomer resin under EB and (mono-tri) functional acrylate monomer resin under UV irradiation

  12. Synthesis and characterization of novel curing agents for surface coatings based on acrylamide copolymers

    International Nuclear Information System (INIS)

    Patel, N. V.; Parmar, R. J.; Parmar, J. S.

    2003-01-01

    The acrylamide based curing agents were prepared form methyl methacrylate-acrylamide copolymers by further methylolation and subsequent etherification with butanol. These were characterized for their various physico-chemical characteristics. Various sets of these ACAs were blended with hydroxyl functional acrylic resin to prepare the staving compared with the conventional melamine-formaldehyde based curing agent containing compositions. The films were also characterized thermogravimetric analysis and IR-spectra. The result reveals that the properties of certain compositions based on ACAs were remarkably better than those of conventional melamine-formaldehyde based curing agent based coatings

  13. The Effect of Resin-modified Glass-ionomer Cement Base and Bulk-fill Resin Composite on Cuspal Deformation.

    Science.gov (United States)

    Nguyen, K V; Wong, R H; Palamara, J; Burrow, M F

    2016-01-01

    This study investigated cuspal deformation in teeth restored with different types of adhesive materials with and without a base. Mesio-occluso-distal slot cavities of moderately large dimension were prepared on extracted maxillary premolars (n=24). Teeth were assigned to one of four groups and restored with either a sonic-activated bulk-fill resin composite (RC) (SonicFill), or a conventional nanohybrid RC (Herculite Ultra). The base materials used were a flowable nanofilled RC (Premise Flowable) and a high-viscosity resin-modified glass-ionomer cement (RMGIC) (Riva Light-Cure HV). Cuspal deflection was measured with two direct current differential transformers, each contacting a buccal and palatal cusp. Cuspal movements were recorded during and after restoration placement. Data for the buccal and palatal cusp deflections were combined to give the net cuspal deflection. Data varied widely. All teeth experienced net inward cuspal movement. No statistically significant differences in cuspal deflection were found among the four test groups. The use of a flowable RC or an RMGIC in closed-laminate restorations produced the same degree of cuspal movement as restorations filled with only a conventional nanohybrid or bulk-fill RC.

  14. Curing efficiency of three light emitting diode units at different curing profiles

    Directory of Open Access Journals (Sweden)

    Priyanka Verma

    2016-01-01

    Conclusions: Reduction of exposure time to 6 s with high-intensity curing light seemed to be clinically acceptable and should be recommended. Curing of metal brackets with single exposure from buccal side showed lower shear bond strength values.

  15. Influence of different light-curing units on the surface roughness of restorative materials: in situ study

    Directory of Open Access Journals (Sweden)

    Juliane Cristina Ciccone-Nogueira

    2007-09-01

    Full Text Available The aim of this study was to evaluate the influence of different light sources (LED and Halogen lamp on the roughness (superficial of composite resin (Filtek Z250, Filtek P60, Charisma and Durafill varying post-irradiation times, in an in situ experiment. For this purpose, 80 specimens were made in polyurethane moulds. Ten volunteers without medicament use and good oral condition were selected and from them study moulds were obtained. A palatal intra-oral acrylic resin appliance was made for each of the subjects of the experiment. In each appliance, two specimens of each material were fixed (LED/Halogen lamp - control group. Roughness tests were performed immediately and 30 days after initial light-curing. Statistical analysis was performed using ANOVA. Statistically significant difference was observed only between post-irradiation times, where the 30th day showed the highest roughness values. It be concluded that roughness was influenced only by post-irradiation times, presenting the 30- days period inferior behavior.

  16. Synthesis of iodine-containing cyclophosphazenes for using as radiopacifiers in dental composite resin

    International Nuclear Information System (INIS)

    Zhao, Yuchen; Lan, Jinle; Wang, Xiaoyan; Deng, Xuliang; Cai, Qing; Yang, Xiaoping

    2014-01-01

    In this study, a strategy of using iodine-containing cyclophosphazenes as radiopacifiers for dental composite resin was evaluated. It was hypothesized that cyclophosphazenes bearing both iodine and acrylate group swere able to endow composite resins radiopacity without compromising mechanical properties. The cyclophosphazene compounds were synthesized by subsequently nucleophilic substitution of hexachlorocyclotriphosphazene with hydroxyethyl methacrylate (HEMA) and 4-iodoaniline. Cyclotriphosphazenes containing two different molar ratios of HEMA to 4-iodoaniline (1:5 and 2:4) were obtained, and were identified with 1 H NMR, FT-IR, UV and mass spectroscopy. The iodine-containing cyclophosphazenes were able to dissolve well in bisphenol A glycidyl methacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) resin, and were added at two contents (10 or 15%wt. of the resin). The resins were photo-cured and post-thermal treated before characterizations. The resulting composite resins demonstrated the ability of blocking X-ray. And the addition of HEMA-co-iodoaniline substituted cyclotriphosphazenes caused minor adverse effect on the mechanical properties of the resins because the cyclotriphosphazenes could mix well and react with the resins. The presence of rigid phosphazene rings between resin backbones displayed an effective function of decreasing polymerization shrinkage. In summary, soluble and reactive iodine-containing cyclotriphosphazenes demonstrated advantages over traditional heavy metals or metal oxides in being used as additives for producing radiopaque dental resins. - Highlights: • Iodine-containing cyclotriphosphazenes were prepared via nucleophilic substitution. • The cyclotriphosphazenes endowed Bis-GMA/TEGDMA resins radiopacity. • The cyclotriphosphazenes caused a minor adverse effect on mechanical properties

  17. High Tg and fast curing epoxy-based anisotropic conductive paste for electronic packaging

    Science.gov (United States)

    Keeratitham, Waralee; Somwangthanaroj, Anongnat

    2016-03-01

    Herein, our main objective is to prepare the fast curing epoxy system with high glass transition temperature (Tg) by incorporating the multifunctional epoxy resin into the mixture of diglycidyl ether of bisphenol A (DGEBA) as a major epoxy component and aromatic diamine as a hardener. Furthermore, the curing behavior as well as thermal and thermomechanical properties were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermomechanical analysis (TMA). It was found that Tg obtained from tan δ of DGEBA/aromatic diamine system increased from 100 °C to 205 °C with the presence of 30 percentage by weight of multifunctional epoxy resin. Additionally, the isothermal DSC results showed that the multifunctional epoxy resin can accelerate the curing reaction of DGEBA/aromatic diamine system. Namely, a high degree of curing (˜90%) was achieved after a few minutes of curing at low temperature of 130 °C, owing to a large number of epoxy ring of multifunctional epoxy resin towards the active hydrogen atoms of aromatic diamine.

  18. Easy Debonding of Ceramic Brackets Bonded with a Light-Cured Orthodontic Adhesive Containing Microcapsules with a CO2 Laser.

    Science.gov (United States)

    Arima, Shiori; Namura, Yasuhiro; Tamura, Takahiko; Shimizu, Noriyoshi

    2018-03-01

    An easy debonding method for ceramic brackets using a light-cured Bis-GMA resin containing heat-expandable microcapsules and CO 2 laser was investigated. Ceramic brackets are used frequently in orthodontic treatment because of their desirable esthetic properties. However, the application of heavy force to ceramic brackets in debonding can fracture the tooth enamel and ceramic brackets, causing tooth pain. In total, 60 freshly extracted bovine permanent mandibular incisors were divided randomly into 10 groups of 6 specimens each, corresponding to the number of variables tested. Ceramic brackets were bonded to bovine permanent mandibular incisors using an orthodontic bonding agent containing heat-expandable microcapsules at different levels (0-30 wt%) and resin composite paste, and cured by a curing device. The bond strengths were measured before and after CO 2 laser irradiation, and the temperature increase in the pulp chamber in fresh human first premolars was also evaluated. With CO 2 laser irradiation for 5 sec to the bracket, the bond strength in the 25% microcapsule group decreased significantly, to ∼0.17-fold, compared with that of the no-laser group (p brackets, with less debonding time and enamel damage.

  19. High performance dental resin composites with hydrolytically stable monomers.

    Science.gov (United States)

    Wang, Xiaohong; Huyang, George; Palagummi, Sri Vikram; Liu, Xiaohui; Skrtic, Drago; Beauchamp, Carlos; Bowen, Rafael; Sun, Jirun

    2018-02-01

    The objectives of this project were to: 1) develop strong and durable dental resin composites by employing new monomers that are hydrolytically stable, and 2) demonstrate that resin composites based on these monomers perform superiorly to the traditional bisphenol A glycidyl dimethacrylate/triethylene glycol dimethacrylate (Bis-GMA/TEGDMA) composites under testing conditions relevant to clinical applications. New resins comprising hydrolytically stable, ether-based monomer, i.e., triethylene glycol divinylbenzyl ether (TEG-DVBE), and urethane dimethacrylate (UDMA) were produced via composition-controlled photo-polymerization. Their composites contained 67.5wt% of micro and 7.5wt% of nano-sized filler. The performances of both copolymers and composites were evaluated by a battery of clinically-relevant assessments: degree of vinyl conversion (DC: FTIR and NIR spectroscopy); refractive index (n: optical microscopy); elastic modulus (E), flexural strength (F) and fracture toughness (K IC ) (universal mechanical testing); Knoop hardness (HK; indentation); water sorption (W sp ) and solubility (W su ) (gravimetry); polymerization shrinkage (S v ; mercury dilatometry) and polymerization stress (tensometer). The experimental UDMA/TEG-DVBE composites were compared with the Bis-GMA/TEGDMA composites containing the identical filler contents, and with the commercial micro hybrid flowable composite. UDMA/TEG-DBVE composites exhibited n, E, W sp , W su and S v equivalent to the controls. They outperformed the controls with respect to F (up to 26.8% increase), K IC (up to 27.7% increase), modulus recovery upon water sorption (full recovery vs. 91.9% recovery), and stress formation (up to 52.7% reduction). In addition, new composites showed up to 27.7% increase in attainable DC compared to the traditional composites. Bis-GMA/TEGDMA controls exceeded the experimental composites with respect to only one property, the composite hardness. Significantly, up to 18.1% lower HK values in

  20. Advantages and drawbacks of Thiol-ene based resins for 3D-printing

    Science.gov (United States)

    Leonards, Holger; Engelhardt, Sascha; Hoffmann, Andreas; Pongratz, Ludwig; Schriever, Sascha; Bläsius, Jana; Wehner, Martin; Gillner, Arnold

    2015-03-01

    The technology of 3D printing is conquering the world and awakens the interest of many users in the most varying of applications. New formulation approaches for photo-sensitive thiol-ene resins in combination with various printing technologies, like stereolithography (SLA), projection based printing/digital light processing (DLP) or two-photon polymerization (TPP) are presented. Thiol-ene polymerizations are known for its fast and quantitative reaction and to form highly homogeneous polymer networks. As the resins are locally and temporally photo-curable the polymerization type is very promising for 3D-printing. By using suitable wavelengths, photoinitiator-free fabrication is feasible for single- and two photon induced polymerization. In this paper divinyl ethers of polyethylene glycols in combination with star-shaped tetrathiols were used to design a simple test-system for photo-curable thiol-ene resins. In order to control and improve curing depth and lateral resolution in 3D-polymerization processes, either additives in chemical formulation or process parameters can be changed. The achieved curing depth and resolution limits depend on the applied fabrication method. While two-/multiphoton induced lithography offers the possibility of micron- to sub-micron resolution it lacks in built-up speed. Hence single-photon polymerization is a fast alternative with optimization potential in sub-10-micron resolution. Absorber- and initiator free compositions were developed in order to avoid aging, yellowing and toxicity of resulting products. They can be cured with UV-laser radiation below 300 nm. The development at Fraunhofer ILT is focusing on new applications in the field of medical products and implants, technical products with respect to mechanical properties or optical properties of 3D-printed objects. Recent process results with model system (polyethylene glycol divinylether/ Pentaerithrytol tetrakis (3-mercaptopropionat), Raman measurements of polymer conversion

  1. Evaluation of Polymerization Efficacy in Composite Resins via FT-IR Spectroscopy and Vickers Microhardness Test

    Directory of Open Access Journals (Sweden)

    Tahereh-Sadat Jafarzadeh

    2015-12-01

    Full Text Available Background and aims. Polymerization efficacy affects the properties and performance of composite resin restorations.The purpose of this study was to evaluate the effectiveness of polymerization of two micro-hybrid, two nano-hybrid and one nano-filled ormocer-based composite resins, cured by two different light-curing systems, using Fourier transformation infrared (FT-IR spectroscopy and Vickers microhardness testing at two different depths (top surface, 2 mm. Materials and methods. For FT-IR spectrometry, five cylindrical specimens (5mm in diameter × 2 mm in length were prepared from each composite resin using Teflon molds and polymerized for 20 seconds. Then, 70-μm wafers were sectioned at the top surface and at2mm from the top surface. The degree of conversion for each sample was calculated using FT-IR spectroscopy. For Vickers micro-hardness testing, three cylindrical specimens were prepared from each composite resin and polymerized for 20 seconds. The Vickers microhardness test (Shimadzu, Type M, Japan was performed at the top and bottom (depth=2 mm surfaces of each specimen. Three-way ANOVA with independent variables and Tukey tests were performed at 95% significance level. Results. No significant differences were detected in degree of conversion and microhardness between LED and QTH light-curing units except for the ormocer-based specimen, CeramX, which exhibited significantly higher DC by LED. All the composite resins showed a significantly higher degree of conversion at the surface. Microhardness was not significantly affected by depth, except for Herculite XRV Ultra and CeramX, which showed higher values at the surface. Conclusion. Composite resins containing nano-particles generally exhibited more variations in degree of conversion and microhardness.

  2. Evaluation of Polymerization Efficacy in Composite Resins via FT-IR Spectroscopy and Vickers Microhardness Test.

    Science.gov (United States)

    Jafarzadeh, Tahereh-Sadat; Erfan, Mohammad; Behroozibakhsh, Marjan; Fatemi, Mostafa; Masaeli, Reza; Rezaei, Yashar; Bagheri, Hossein; Erfan, Yasaman

    2015-01-01

    Background and aims. Polymerization efficacy affects the properties and performance of composite resin restorations.The purpose of this study was to evaluate the effectiveness of polymerization of two micro-hybrid, two nano-hybrid and one nano-filled ormocer-based composite resins, cured by two different light-curing systems, using Fourier transformation infrared (FT-IR) spectroscopy and Vickers microhardness testing at two different depths (top surface, 2 mm). Materials and methods. For FT-IR spectrometry, five cylindrical specimens (5mm in diameter × 2 mm in length) were prepared from each composite resin using Teflon molds and polymerized for 20 seconds. Then, 70-μm wafers were sectioned at the top surface and at2mm from the top surface. The degree of conversion for each sample was calculated using FT-IR spectroscopy. For Vickers micro-hardness testing, three cylindrical specimens were prepared from each composite resin and polymerized for 20 seconds. The Vickers microhardness test (Shimadzu, Type M, Japan) was performed at the top and bottom (depth=2 mm) surfaces of each specimen. Three-way ANOVA with independent variables and Tukey tests were performed at 95% significance level. Results. No significant differences were detected in degree of conversion and microhardness between LED and QTH light-curing units except for the ormocer-based specimen, CeramX, which exhibited significantly higher DC by LED. All the composite resins showed a significantly higher degree of conversion at the surface. Microhardness was not significantly affected by depth, except for Herculite XRV Ultra and CeramX, which showed higher values at the surface. Conclusion. Composite resins containing nano-particles generally exhibited more variations in degree of conversion and microhardness.

  3. Effect of Reinforcement Using Stainless Steel Mesh, Glass Fibers, and Polyethylene on the Impact Strength of Heat Cure Denture Base Resin - An In Vitro Study.

    Science.gov (United States)

    Murthy, H B Mallikarjuna; Shaik, Sharaz; Sachdeva, Harleen; Khare, Sumit; Haralur, Satheesh B; Roopa, K T

    2015-06-01

    The impact strength of denture base resin is of great concern and many approaches have been made to strengthen acrylic resin dentures. The objective of this study was to compare the impact strength of the denture base resin with and without reinforcement and to evaluate the impact strength of denture base resin when reinforced with stainless steel mesh, glass fiber, and polyethylene fibers in the woven form. The specimens (maxillary denture bases) were fabricated using a standard polyvinylsiloxane mold with conventional heat cured polymethyl methacrylate resin. The specimens were divided into four groups (n = 10). Group I specimens or control group were not reinforced. Group II specimens were reinforced with stainless steel mesh and Group III and Group IV specimens were reinforced with three percent by weight of glass fibers and polyethylene fibers in weave form respectively. All the specimens were immersed in water for 1-week before testing. The impact strength was measured with falling weight impact testing machine. One-way analysis of variance and Tukey's post-hoc test were used for statistical analysis. Highest impact strength values were exhibited by the specimens reinforced with polyethylene fibers followed by glass fibers, stainless steel mesh, and control group. Reinforcement of maxillary complete dentures showed a significant increase in impact strength when compared to unreinforced dentures. Polyethylene fibers exhibit better impact strength followed by glass fibers and stainless steel mesh. By using pre-impregnated glass and polyethylene fibers in woven form (prepregs) the impact strength of the denture bases can be increased effectively.

  4. Effect of photocuring lamp type in the polymerization of various resins

    International Nuclear Information System (INIS)

    Lafuente, David; Blanco, Rosa; Brenes, Andrea

    2005-01-01

    Four different curing lamps were evaluated, a halogen and three LED technology with that are photocured five different resins. These four lamps have evaluated the surface hardness of the resin samples as a way of measuring the degree of polymerization. Comparing the Knoop surface hardness of the resin samples was found that the halogen light produced a greater surface hardness in all evaluated resins. (author) [es

  5. Evaluation of the surface roughness of three heat-cured acrylic denture base resins with different conventional lathe polishing techniques: A comparative study.

    Science.gov (United States)

    Rao, Duggineni Chalapathi; Kalavathy, N; Mohammad, H S; Hariprasad, A; Kumar, C Ravi

    2015-01-01

    Surface roughness promotes adhesion and colonization of denture plaque. Therefore, it is important to know the effects of polishing and finishing on the surface roughness of various acrylic resin materials. To evaluate and compare the effects of different conventional lathe polishing techniques on heat cured acrylic resins in producing surface roughness. Three different commercially available heat-cured acrylic resin materials namely DPI, Meliodent and Trevalon Hi were selected. 30 Specimens of each acrylic material (30 x 3 = 90, 10 x 60 x 2mm) were prepared and divided into 5 groups, each group consisted of 6 Nos. of specimens per material(6x3=18) and were grouped as Group A(unfinished), Group B (finished), Group C (Polishing Paste), Group D (Polishing Cake) and Group E (Pumice and Gold rouge). The resulted surface roughness (μm) was measured using Perthometer and observed under Scanning Electron Microscope. The values obtained were subjected statistical analyses. Among the materials tested, better results were obtained with Trevalon Hi followed by Meliodent and DPI. Among the polishing methods used, superior results were obtained with universal polishing paste followed by polishing cake; Pumice and Gold rouge. Although Pumice and Gold rouge values produced greater roughness value, they were well within the threshold value of 0.2 mm.

  6. Influence of storage times on bond strength of resin cements to root canal

    Directory of Open Access Journals (Sweden)

    Matheus Coêlho Bandéca

    2010-03-01

    Full Text Available The resin cements are responsible to retention of the indirect materials decreasing marginal leakage, increasing failure resistance compared with conventional cementation. The cementation within root canal is very hard due unfavorable conditions regarding the application of adhesive techniques caused by inadequate access. Therefore, considering the possibility to decrease steps of cementation, this study was performed to evaluate the bond strength of self-adhesive resin cement (RelyX TM U100, 3M ESPE and resin cement combined with self-ecthing adhesive system (Panavia® F 2.0, Kuraray light-cured with Quartz Tungsten Halogen (QTH following storage at 37 °C immediately after light-curing, 24 and 48 hours and 7 days. The root canals were prepared to receive the glass fiber post in the depth of 10 mm, irrigated with 17% EDTA and NaOCl, rinsed with distilled water and dried using paper points. The roots were perpendicularly sectioned into approximately 1 mm thick sections, obtaining ninety-six slices (n = 12. The slices were trimmed using a cylindrical diamond bur in the proximal surfaces until it touched the post and attached into a device, which were mounted on a strength tester (Bisco and loaded in tension at a speed of 0.5 mm/min until failure occurred at specimens. The analysis of variance (ANOVA and Tukey's post-hoc tests showed significant statistical differences (P .05. The resin cements 24 and 48 hours after light-curing were statistically similar among themselves (P > .05. The both resin cement showed similar bond strength into root canal on different storage times. The highest bond strength values of the resin cements were showed 7 days after curing.

  7. Marginal integrity of resin composite restorations restored with PPD initiatorcontaining resin composite cured by QTH, monowave and polywave LED units.

    Science.gov (United States)

    Bortolotto, Tissiana; Betancourt, Francisco; Krejci, Ivo

    2016-12-01

    This study evaluated the influence of curing devices on marginal adaptation of cavities restored with self-etching adhesive containing CQ and PPD initiators and hybrid composite. Twenty-four class V (3 groups, n=8) with margins located on enamel and dentin were restored with Clearfil S3 Bond and Clearfil APX PLT, light-cured with a monowave LED, multiwave LED and halogen light-curing unit (LCU). Marginal adaptation was evaluated with SEM before/after thermo-mechanical loading (TML). On enamel, significantly lower % continuous margins (74.5±12.6) were found in group cured by multiwave LED when compared to monowave LED (87.6±9.5) and halogen LCU (94.4±9.1). The presence of enamel and composite fractures was significantly higher in the group light-cured with multiwave LED, probably due to an increased materials' friability resulted from an improved degree of cure. The clinician should aware that due to a distinct activation of both initiators, marginal quality may be influenced on the long-term.

  8. Curing reactions of bismaleimide resins catalyzed by triphenylphosphine. High resolution solid-state 13C NMR study

    International Nuclear Information System (INIS)

    Shibahara, Sumio; Enoki, Takashi; Yamamoto, Takahisa; Motoyoshiya, Jiro; Hayashi, Sadao.

    1996-01-01

    The curing reactions of bismaleimide resins consisted of N,N'-4,4'-diphenylmethanebismaleimide (BMI) and o,o'-diallylbisphenol-A (DABA) in the presence of triphenylphosphine (TPP) as a catalyst were investigated. DSC measurements showed that the catalytic effect of TPP on the curing reaction of BMI was more in the presence of DABA than in its absence. In order to explore this curing reaction, N-phenylmaleimide (PMI) and o-allylphenol (AP) were selected as model compounds. The products of the PMI/TPP system were oligomers and polymers of PMI, whereas the main product of the PMI/AP/TPP system was the PMI trimer which had the five-membered ring formed via the phosphonium ylide intermediate. In these model reactions, 13 C NMR was found to be useful to distinguish between trimerization and polymerization of PMI. On the basis of the results of the model reactions, the curing reactions of bismaleimide resins were investigated by high resolution solid state 13 C NMR techniques. In the BMI/TPP system, maleimides polymerize above 175degC, but the polymerization does not proceed at 120degC. On the other hand, maleimides trimerize above 120degC in the presence of DABA and TPP. The mechanism of the trimerization is briefly discussed. (author)

  9. Effect of curing modes of dual-curing core systems on microtensile bond strength to dentin and formation of an acid-base resistant zone.

    Science.gov (United States)

    Li, Na; Takagaki, Tomohiro; Sadr, Alireza; Waidyasekera, Kanchana; Ikeda, Masaomi; Chen, Jihua; Nikaido, Toru; Tagami, Junji

    2011-12-01

    To evaluate the microtensile bond strength (μTBS) and acid-base resistant zone (ABRZ) of two dualcuring core systems to dentin using four curing modes. Sixty-four caries-free human molars were randomly divided into two groups according to two dual-curing resin core systems: (1) Clearfil DC Core Automix; (2) Estelite Core Quick. For each core system, four different curing modes were applied to the adhesive and core resin: (1) dual-cured and dual-cured (DD); (2) chemically cured and dual-cured (CD); (3) dual-cured and chemically cured (DC); (4) chemically cured and chemically cured (CC). The specimens were sectioned into sticks (n = 20 for each group) for the microtensile bond test. μTBS data were analyzed using two-way ANOVA and the Dunnett T3 test. Failure patterns were examined with scanning electron microscopy (SEM) to determine the proportion of each mode. Dentin sandwiches were produced and subjected to an acid-base challenge. After argon-ion etching, the ultrastructure of ABRZ was observed using SEM. For Clearfil DC Core Automix, the μTBS values in MPa were as follows: DD: 29.1 ± 5.4, CD: 21.6 ± 5.6, DC: 17.9 ± 2.8, CC: 11.5 ± 3.2. For Estelite Core Quick, they were: DD: 48.9 ±5.7, CD: 20.5 ± 4.7, DC: 41.4 ± 8.3, CC: 19.1 ± 6.0. The bond strength was affected by both material and curing mode, and the interaction of the two factors was significant (p < 0.001). Within both systems, there were significant differences among groups, and the DD group showed the highest μTBS (p < 0.05). ABRZ morphology was not affected by curing mode, but it was highly adhesive-material dependent. The curing mode of dual-curing core systems affects bond strength to dentin, but has no significant effect on the formation of ABRZ.

  10. Curing time effect on the fraction of 137Cs from cement- ion exchange resins-bentonite clay composition

    International Nuclear Information System (INIS)

    Plecas, I.; Dimovic, S.

    2007-01-01

    Curing conditions and time are critically important in leach studies since the extent of hydratation of the cement materials determines how much hydratation product develops and whether it is available to block the pore network, thereby reducing leaching.[1,2]. To assess the safety of disposal of radioactive waste material in cement, curing conditions and time of leaching radionuclide 137 Cs has been studied in this paper. Leaching tests in cement-ion exchange resins-bentonite matrix, were carried out in accordance with a method recommended by IAEA. Curing conditions and curing time prior to commencing the leaching test are critically important in leach studies since the extent of hydration of the cement materials determines how much hydration product develop and whether it is available to block the pore network, thereby reducing leaching. Incremental leaching rates R n (cm/d) of 137 Cs from cement-ion exchange resins-bentonite matrix after 180 days were measured. The results presented in this paper are examples of results obtained in a 20-year concrete testing project which will influence the design of the engineer trenches system for future central Serbian radioactive waste storing center. (author)

  11. Adhesion of resin composite core materials to dentin.

    Science.gov (United States)

    O'Keefe, K L; Powers, J M

    2001-01-01

    This study determined (1) the effect of polymerization mode of resin composite core materials and dental adhesives on the bond strength to dentin, and (2) if dental adhesives perform as well to dentin etched with phosphoric acid as to dentin etched with self-etching primer. Human third molars were sectioned 2 mm from the highest pulp horn and polished. Three core materials (Fluorocore [dual cured], Core Paste [self-cured], and Clearfil Photo Core [light cured]) and two adhesives (Prime & Bond NT Dual Cure and Clearfil SE Bond [light cured]) were bonded to dentin using two dentin etching conditions. After storage, specimens were debonded in microtension and bond strengths were calculated. Scanning electron micrographs of representative bonding interfaces were analyzed. Analysis showed differences among core materials, adhesives, and etching conditions. Among core materials, dual-cured Fluorocore had the highest bond strengths. There were incompatibilities between self-cured Core Paste and Prime & Bond NT in both etched (0 MPa) and nonetched (3.0 MPa) dentin. Among adhesives, in most cases Clearfil SE Bond had higher bond strengths than Prime & Bond NT and bond strengths were higher to self-etched than to phosphoric acid-etched dentin. Scanning electron micrographs did not show a relationship between resin tags and bond strengths. There were incompatibilities between a self-cured core material and a dual-cured adhesive. All other combinations of core materials and adhesives produced strong in vitro bond strengths both in the self-etched and phosphoric acid-etched conditions.

  12. Temperature rise produced by different light-curing units through dentin.

    Science.gov (United States)

    Yazici, A Rüya; Müftü, Ali; Kugel, Gerard

    2007-11-01

    This study investigated the temperature rise caused by different light curing units and the temperature increase in dentin of different thicknesses. Dentin discs of 1.0 and 2.0 mm thicknesses were prepared from extracted human mandibular molars. Temperatures were recorded directly at the surface of the light guide tip, under dentin discs with different thicknesses, and through a sandwich composed of 2 mm thick cured composite and dentin using a K-type thermocouple. The curing units used were two quartz-tungsten-halogen lights (Spectrum and Elipar Trilight-ET) and a light-emitting diode (LED). The highest temperature rise was observed under a Mylar strip using ET standard mode. Under 1 and 2 mm thick dentin barriers, the lowest temperature rise was measured for the LED curing light. Significant differences in temperature rise existed among all curing units except between the Spectrum and ET exponential modes under a 1 mm thick dentin barrier with cured composite. Temperature rises were insignificant between the Spectrum and ET exponential modes and between two modes of Trilight when the same experimental setup was used under a 2 mm thick dentin barrier. For all curing units, temperature elevation through 2 mm of dentin was less than for 1 mm of dentin thickness. The ET standard mode produced the highest and the LED produced the lowest temperature rise for all tested conditions. The thickness of dentin and light-curing unit might affect temperature transmission.

  13. effect of light curing unit characteristics on light intensity output

    African Journals Online (AJOL)

    2013-09-09

    Sep 9, 2013 ... in Nairobi and their effect on light intensity output, depth of cure (DOC) and ... result in gradual reduction in the energy output of ..... of LED lights are compared with QTH lights could ... influence on the SMH of dark shades.

  14. Comparison of silorane and methacrylate-based composites on the polymerization heat generated with different light-curing units and dentin thicknesses.

    Science.gov (United States)

    Guiraldo, Ricardo Danil; Consani, Simonides; Consani, Rafael Leonardo Xediek; Berger, Sandrine Bittencourt; Correr, Américo Bortolazzo; Sinhoreti, Mário Alexandre Coelho; Correr-Sobrinho, Lourenço

    2013-01-01

    This study evaluated the temperature variation in the pulp chamber during photoactivation of two restorative composite resins (Filtek P90 silorane-based composite and Heliomolar methacrylate-based composite) with either a quartz-tungsten-halogen (QTH) or light-emitting diodes (LED) light-curing unit (LCU) and using dentin thicknesses (0.5 and 1.0 mm). Standardized cavities (2x2x2 mm) were prepared in 80 bovine incisors, which were randomly assigned to 8 groups according to the photoactivation method and dentin thickness. Filtek P90 and Heliomolar (both in shade A3) were used with their respective adhesive systems (P90 self-etch primer / P90 adhesive bond and Excite adhesive). All experiments were carried out in a controlled environment (37°C). The temperature variations (°C) were recorded using a digital thermometer attached to a K-type thermocouple. The results were analyzed statistically by ANOVA and Tukey's test (α=0.05). For composite/dentin thickness interaction, temperature increase was significantly higher in 0.5 mm dentin thickness (40.07°C) compared with 1.0 mm dentin thickness (39.61°C) for Filtek P90. For composite/LCU interaction, the temperature increase was significantly higher for Filtek P90 (39.21°C - QTH and 40.47°C - LED) compared with Heliomolar (38.40°C - QTH and 39.30°C - LED). The silorane-based composite promoted higher temperature increase in the pulp chamber than the methacrylate-based composite.

  15. How does duration of curing affect the radiopacity of dental materials?

    Energy Technology Data Exchange (ETDEWEB)

    Bejeh Mir, Arash Poorsattar [School of Dentistry, Babol University of Medical Sciences, Babol (Iran, Islamic Republic of); Bejeh Mir, Morvarid Poorsattar [Private Practice of Orthodontics, Montreal (Canada)

    2012-06-15

    Clinicians commonly encounter cases in which it is difficult to determine whether adjacent radiopacities are normal or pathologic. The ideal radiopacity of composite resin is equal to or higher than that of the same thickness of aluminum. We aimed to investigate the possible effects of different curing times on the post-24-hour radiopacity of composite resins on digital radiographs. One mm thick samples of Filtek P60 and Clearfil resin composites were prepared and cured with three regimens of continuous 400 mW/cm{sup 2} irradiance for 10, 20 and 30 seconds. Along with a 12-step aluminum step wedge, digital radiographs were captured and the radiopacities were transformed to the equivalent aluminum thicknesses. Data were compared by a general linear model and repeated-measures of ANOVA. Overall, the calculated equivalent aluminum thicknesses of composite resins were increased significantly by doubling and tripling the curing times (F(2,8)=8.94, p=0.002). Notably, Bonferroni post-hoc tests confirmed that the radiopacity of the cured Filtek P60 was significantly higher at 30 seconds compared with 10 seconds (p=0.04). Although the higher radiopacity was observed by increasing the time, other comparisons showed no statistical significance (p>0.05). These results supported the hypothesis that the radiopacity of resin composites might be related to the duration of light curing. In addition to the current standards for radiopacity of digital images, defining a standard protocol for curing of dental materials should be considered, and it is suggested that they should be added to the current requirements for dental material.

  16. How does duration of curing affect the radiopacity of dental materials?

    International Nuclear Information System (INIS)

    Bejeh Mir, Arash Poorsattar; Bejeh Mir, Morvarid Poorsattar

    2012-01-01

    Clinicians commonly encounter cases in which it is difficult to determine whether adjacent radiopacities are normal or pathologic. The ideal radiopacity of composite resin is equal to or higher than that of the same thickness of aluminum. We aimed to investigate the possible effects of different curing times on the post-24-hour radiopacity of composite resins on digital radiographs. One mm thick samples of Filtek P60 and Clearfil resin composites were prepared and cured with three regimens of continuous 400 mW/cm 2 irradiance for 10, 20 and 30 seconds. Along with a 12-step aluminum step wedge, digital radiographs were captured and the radiopacities were transformed to the equivalent aluminum thicknesses. Data were compared by a general linear model and repeated-measures of ANOVA. Overall, the calculated equivalent aluminum thicknesses of composite resins were increased significantly by doubling and tripling the curing times (F(2,8)=8.94, p=0.002). Notably, Bonferroni post-hoc tests confirmed that the radiopacity of the cured Filtek P60 was significantly higher at 30 seconds compared with 10 seconds (p=0.04). Although the higher radiopacity was observed by increasing the time, other comparisons showed no statistical significance (p>0.05). These results supported the hypothesis that the radiopacity of resin composites might be related to the duration of light curing. In addition to the current standards for radiopacity of digital images, defining a standard protocol for curing of dental materials should be considered, and it is suggested that they should be added to the current requirements for dental material.

  17. Influence of aromatic amine hardeners in the cure kinetics of an epoxy resin used in advanced composites

    Directory of Open Access Journals (Sweden)

    Michelle Leali Costa

    2005-03-01

    Full Text Available Composite structures for aerospace applications are mainly made by the well-known prepreg technology. In order to achieve adequate prepreg processing schedules, and consequently maximum fiber strength utilization, one has to know in deep the cure kinetics of matrix, which held the fibers together. This work describes a procedure to study the cure kinetic and has as example how aromatic amine hardeners influence the cure kinetics of an epoxy resin used in advanced composites. The investigation was carried out by using the DSC technique and it was found that depending on the system used the cure kinetics of the formulation obeys order n or autocatalytic order.

  18. Foam, Foam-resin composite and method of making a foam-resin composite

    Science.gov (United States)

    Cranston, John A. (Inventor); MacArthur, Doug E. (Inventor)

    1995-01-01

    This invention relates to a foam, a foam-resin composite and a method of making foam-resin composites. The foam set forth in this invention comprises a urethane modified polyisocyanurate derived from an aromatic amino polyol and a polyether polyol. In addition to the polyisocyanurate foam, the composite of this invention further contains a resin layer, wherein the resin may be epoxy, bismaleimide, or phenolic resin. Such resins generally require cure or post-cure temperatures of at least 350.degree. F.

  19. Evaluation of phenyl-propanedione on yellowing and chemical-mechanical properties of experimental dental resin-based materials

    Directory of Open Access Journals (Sweden)

    Dayane Carvalho Ramos Salles de OLIVEIRA

    Full Text Available ABSTRACT Objective To evaluate the influence of phenyl-propanedione on yellowing and chemical-mechanical properties of experimental resin-based materials photoactivated using different light curing units (LCUs. Material and Methods Experimental resin-based materials with the same organic matrix (60:40 wt% BisGMA:TEGDMA were mechanically blended using a centrifugal mixing device. To this blend, different photoinitiator systems were added in equimolar concentrations with aliphatic amine doubled by wt%: 0.4 wt% CQ; 0.38 wt% PPD; or 0.2 wt% CQ and 0.19 wt% PPD. The degree of conversion (DC, flexural strength (FS, Young’s modulus (YM, Knoop hardness (KNH, crosslinking density (CLD, and yellowing (Y were evaluated (n=10. All samples were light cured with the following LCUs: a halogen lamp (XL 2500, a monowave LED (Radii, or a polywave LED (Valo with 16 J/cm2. The results were analysed by two-way ANOVA and Tukey’s test (α=0.05. Results No statistical differences were found between the different photoinitiator systems to KNH, CLS, FS, and YM properties (p≥0.05. PPD/CQ association showed the higher DC values compared with CQ and PPD isolated systems when photoactivated by a polywave LED (p≤0.05. Y values were highest for the CQ compared with the PPD systems (p≤0.05. Conclusion PPD isolated system promoted similar chemical and mechanical properties and less yellowing compared with the CQ isolated system, regardless of the LCU used.

  20. Effect of two lasers on the polymerization of composite resins: single vs combination.

    Science.gov (United States)

    Ro, Jung-Hoon; Son, Sung-Ae; Park, Jeong-kil; Jeon, Gye-Rok; Ko, Ching-Chang; Kwon, Yong Hoon

    2015-07-01

    The selection of a light-curing unit for the curing composite resins is important to achieve best outcomes. The purpose of the present study was to test lasers of 457 and 473 nm alone or in combination under different light conditions with respect to the cure of composite resins. Four different composite resins were light cured using five different laser combinations (530 mW/cm(2) 457 nm only, 530 mW/cm(2) 473 nm only, 177 mW/cm(2) 457 + 177 mW/cm(2) 473 nm, 265 mW/cm(2) 457 + 265 mW/cm(2) 473 nm, and 354 mW/cm(2) 457 + 354 mW/cm(2) 473 nm). Microhardness and polymerization shrinkage were evaluated. A light-emitting diode (LED) unit was used for comparison purposes. On top surfaces, after aging for 24 h, microhardness achieved using the LED unit and the lasers with different conditions ranged 42.4-65.5 and 38.9-67.7 Hv, respectively, and on bottom surfaces, corresponding ranges were 25.2-56.1 and 18.5-55.7 Hv, respectively. Of the conditions used, 354 mW/cm(2) 457 nm + 354 mW/cm(2) 473 nm produced the highest bottom microhardness (33.8-55.6 Hv). On top and bottom surfaces, microhardness by the lowest total light intensity, 354 (177 × 2) mW/cm(2), ranged 39.0-60.5 and 18.5-52.8 Hv, respectively. Generally, 530 mW/cm(2) at 457 nm produced the lowest polymerization shrinkage. However, shrinkage values obtained using all five laser conditions were similar. The study shows the lasers of 457 and 473 nm are useful for curing composite resins alone or in combination at much lower light intensities than the LED unit.

  1. Synthesis and Characterization of Bio-Oil Phenol Formaldehyde Resin Used to Fabricate Phenolic Based Materials.

    Science.gov (United States)

    Cui, Yong; Hou, Xiaopeng; Wang, Wenliang; Chang, Jianmin

    2017-06-18

    In this study, bio-oil from the fast pyrolysis of renewable biomass was used as the raw material to synthesize bio-oil phenol formaldehyde (BPF) resin-a desirable resin for fabricating phenolic-based material. During the synthesis process, paraformaldehyde was used to achieve the requirement of high solid content and low viscosity. The properties of BPF resins were tested. Results indicated that BPF resin with the bio-oil addition of 20% had good performance on oxygen index and bending strength, indicating that adding bio-oil could modify the fire resistance and brittleness of PF resin. The thermal curing behavior and heat resistance of BPF resins were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Results showed that adding bio-oil had an impact on curing characteristics and thermal degradation process of PF resin, but the influence was insignificant when the addition was relatively low. The chemical structure and surface characteristics of BPF resins were determined by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The analysis demonstrated that adding bio-oil in the amount of 20% was able to improve the crosslinking degree and form more hydrocarbon chains in PF resin.

  2. Vinyl ester resin and process for curing same with ionizing radiation in the presence of amines

    International Nuclear Information System (INIS)

    Mani, I.

    1975-01-01

    The addition of about 2 to 5 weight percent of certain amines to a thermosettable mixture of certain vinyl monomers and a polymerizable vinyl ester resin reduces the dosage level of ionizing radiation required to cure the mixture. (U.S.)

  3. A review of devices used for photocuring resin-based composites.

    Science.gov (United States)

    Small, B W

    2001-01-01

    Composite resin shrinks up to 5% by volume upon curing. This shrinkage and the associated contraction stress remain the two most significant clinical problems with curing resin composite restorations. Many patients continue to experience sensitivity following placement of direct composites and seating of indirect restorations utilizing resin cements. Unfortunately, some claims made by manufacturers or certain clinicians that promise to alleviate these problems are made from a marketing standpoint, with no refereed literature to support those claims. Even within the literature, contradictory results have been reported, perpetuating the confusion. It is of utmost importance that all practicing dentists be aware of the various types of curing systems available and the advantages and disadvantages of each system. It is the opinion of the author that no existing system will alleviate every problem. Until new composite systems are perfected, such as the cyclopolymerizable resins and expanding polymers, we will continue to have shrinkage and stress. Be aware of false claims, read and interpret the literature, and, most importantly, do what is best for your patients.

  4. Development of radiation-curable resin based on natural rubber

    Energy Technology Data Exchange (ETDEWEB)

    Mohd, Dahlan; Harun, Abdul Ghani [Nuclear Energy Unit, Bangi, Selangor (Malaysia)

    1994-12-31

    A new radiation curable resin based on natural rubber has been developed. The resin was based on the reaction between low molecular weight epoxidised natural rubber and acrylic acid. When formulated with reactive monomers and photoinitiator, it solidified upon irradiation with UV light. The resin may find applications in coating for cellulosic-based substrates and pressure-sensitive adhesive.

  5. Development of radiation-curable resin based on natural rubber

    International Nuclear Information System (INIS)

    Dahlan Mohd; Abdul Ghani Harun

    1993-01-01

    A new radiation curable resin based on natural rubber has been developed. The resin was based on the reaction between low molecular weight epoxidised natural rubber and acrylic acid. When formulated with reactive monomers and photoinitiator, it solidified upon irradiation with UV light. The resin may find applications in coating for cellulosic-based substrates and pressure-sensitive adhesive

  6. The influence of polishing techniques on pre-polymerized CAD\\CAM acrylic resin denture bases.

    Science.gov (United States)

    Alammari, Manal Rahma

    2017-10-01

    Lately, computer-aided design and computer-aided manufacturing (CAD/CAM) has broadly been successfully employed in dentistry. The CAD/CAM systems have recently become commercially available for fabrication of complete dentures, and are considered as an alternative technique to conventionally processed acrylic resin bases. However, they have not yet been fully investigated. The purpose of this study was to inspect the effects of mechanical polishing and chemical polishing on the surface roughness (Ra) and contact angle (wettability) of heat-cured, auto-cured and CAD/CAM denture base acrylic resins. This study was conducted at the Advanced Dental Research Laboratory Center of King Abdulaziz University from March to June 2017. Three denture base materials were selected: heat cure poly-methylmethacrylate resin, thermoplastic (polyamide resin) and (CAD\\CAM) denture base resin. Sixty specimens were prepared and divided into three groups, twenty in each. Each group was divided according to the polishing techniques into (Mech P) and (Chem P), ten specimens in each; surface roughness and wettability were investigated. Data were analyzed by SPSS version 22, using one-way ANOVA and Pearson coefficient. One-way analysis of variance (ANOVA) and post hoc tests were used for comparing the surface roughness values between three groups which revealed a statistical significant difference between them (p 1 CAD\\CAM denture base material (group III) showed the least mean values (1.08±0.23, 1.39±0.31, Mech P and Chem P respectively). CAD/CAM showed the least contact angle in both polishing methods, which were statistically significant at 5% level (p=0.034 and pCAD\\CAM denture base resin with superior smooth surface compared to chemical polishing. Mechanical polishing is considered the best effective polishing technique. CAD/CAM denture base material should be considered as the material of choice for complete denture construction in the near future, especially for older dental

  7. Temperature rise during adhesive and composite polymerization with different light-curing sources.

    Science.gov (United States)

    Pereira Da Silva, A; Alves Da Cunha, L; Pagani, C; De Mello Rode, S

    2010-05-01

    This study evaluated the temperature rise of the adhesive system Single Bond (SB) and the composite resins Filtek Z350 flow (Z) and Filtek Supreme (S), when polymerized by light-emitting diode (LED XL 3000) and quartz-tungsten halogen (QTH Biolux). Class V cavities (3 yen2 mm) were prepared in 80 bovine incisors under standardized conditions. The patients were divided as follows: G1: Control; G2: SB; G3: SB + Z; G4: SB + S. The groups were subdivided into two groups for polymerization (A: QTH, B: LED). Light curing was performed for 40 s and measurement of temperature changes during polymerization was performed with a thermocouple positioned inside the pulp chamber. Data were statistically analyzed using ANOVA and Tukey tests. The factors material (P<0.00001) and curing unit (P<0.00001) had significant influence on temperature rise. The lowest temperature increase (0.15 degrees C) was recorded in G2 B and the highest was induced in G1 A (0.75 degrees C, P<0.05). In all groups, lower pulp chamber temperature measurements were obtained when using LED compared to QTH (P<0.05). QTH caused greater increases in tooth temperature than LED. However, both sources did not increase pulpal temperature above the critical value that may cause pulpal damage.

  8. High T{sub g} and fast curing epoxy-based anisotropic conductive paste for electronic packaging

    Energy Technology Data Exchange (ETDEWEB)

    Keeratitham, Waralee, E-mail: waralee.ke@student.chula.ac.th; Somwangthanaroj, Anongnat, E-mail: anongnat.s@chula.ac.th [Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, 10330 (Thailand)

    2016-03-09

    Herein, our main objective is to prepare the fast curing epoxy system with high glass transition temperature (T{sub g}) by incorporating the multifunctional epoxy resin into the mixture of diglycidyl ether of bisphenol A (DGEBA) as a major epoxy component and aromatic diamine as a hardener. Furthermore, the curing behavior as well as thermal and thermomechanical properties were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermomechanical analysis (TMA). It was found that T{sub g} obtained from tan δ of DGEBA/aromatic diamine system increased from 100 °C to 205 °C with the presence of 30 percentage by weight of multifunctional epoxy resin. Additionally, the isothermal DSC results showed that the multifunctional epoxy resin can accelerate the curing reaction of DGEBA/aromatic diamine system. Namely, a high degree of curing (∼90%) was achieved after a few minutes of curing at low temperature of 130 °C, owing to a large number of epoxy ring of multifunctional epoxy resin towards the active hydrogen atoms of aromatic diamine.

  9. Formation of functionalized nanoclusters by solvent evaporation and their effect on the physicochemical properties of dental composite resins.

    Science.gov (United States)

    Rodríguez, Henry A; Giraldo, Luis F; Casanova, Herley

    2015-07-01

    The aim of this work was to study the effect of silica nanoclusters (SiNC), obtained by a solvent evaporation method and functionalized by 3-methacryloxypropyltrimethoxysilane (MPS) and MPS+octyltrimethoxysilane (OTMS) (50/50wt/wt), on the rheological, mechanical and sorption properties of urethane dimethylacrylate (UDMA)/triethylenglycol dimethacrylate (TEGDMA) (80/20wt/wt) resins blend. Silica nanoparticles (SiNP) were silanized with MPS or MPS+OTMS (50/50wt/wt) and incorporated in an UDMA-isopropanol mix to produce functionalized silica nanoclusters after evaporating the isopropanol. The effect of functionalized SiNC on resins rheological properties was determined by large and small deformation tests. Mechanical, thermal, sorption and solubility properties were evaluated for composite materials. The UDMA/TEGDMA (80/20wt/wt) resins blend with added SiNC (ca. 350nm) and functionalized with MPS showed a Newtonian flow behavior associated to their spheroidal shape, whereas the resins blend with nanoclusters silanized with MPS+OTMS (50/50wt/wt) (ca. 400nm) showed a shear-thinning behavior due to nanoclusters irregular shape. Composite materials prepared with bare silica nanoclusters showed lower compressive strength than functionalized silica nanoclusters. MPS functionalized nanoclusters showed better mechanical properties but higher water sorption than functionalized nanoclusters with both silane coupling agents, MPS and OTMS. The solvent evaporation method applied to functionalized nanoparticles showed to be an alternative way to the sinterization method for producing nanoclusters, which improved some dental composite mechanical properties and reduced water sorption. The shape of functionalized silica nanoclusters showed to have influence on the rheological properties of SiNC resin suspensions and the mechanical and sorption properties of light cured composites. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  10. Vinyl ester resin and process for curing same with ionizing radiation in the presence of amines

    International Nuclear Information System (INIS)

    Mani, I.

    1975-01-01

    The addition of about 1.5 to 5 weight percent of certain amines to a thermosettable mixture of an alkenyl aromatic monomer and a polymerizable vinyl ester resin reduces the dosage level of ionizing radiation required to cure the mixture. (U.S.)

  11. [Comparison of surface roughness of nanofilled and microhybrid composite resins after curing and polishing].

    Science.gov (United States)

    Jiang, Hong; Lv, Da; Liu, Kailei; Zhang, Weisheng; Yao, Yao; Liao, Chuhong

    2014-05-01

    To compare the surface roughness of nanofilled dental composite resin and microhybrid composite resins after curing and polishing. A nanofilled composite (Z350) and 4 microhybrid composites (P60, Z250, Spectrum, and AP-X) were fabricated from the lateral to the medial layers to prepare 8 mm×8 mm×5 mm cubical specimens. The 4 lateral surfaces of each specimens were polished with abrasive disks (Super-Snap). Profilometer was used to test the mean surface roughness (Ra) after polishing. P60 had the lowest Ra (0.125∓0.030 µm) followed by Z250 and Spectrum. The Ra of Z350 (0.205∓0.052 µm) was greater than that of the other 3 resins, and AP-X had the roughest surfaces. Under scanning electron microscope, the polished faces of P60 resin were characterized by minor, evenly distributed particles with fewer scratches; the polished faces of Z350 presented with scratches where defects of the filling material could be seen. The nanofilled composite Z350 has smooth surface after polishing by abrasive disks, but its smoothness remains inferior to that of other micro-hybrid composite resins.

  12. Synthesis and Characterization of Bio-Oil Phenol Formaldehyde Resin Used to Fabricate Phenolic Based Materials

    Directory of Open Access Journals (Sweden)

    Yong Cui

    2017-06-01

    Full Text Available In this study, bio-oil from the fast pyrolysis of renewable biomass was used as the raw material to synthesize bio-oil phenol formaldehyde (BPF resin—a desirable resin for fabricating phenolic-based material. During the synthesis process, paraformaldehyde was used to achieve the requirement of high solid content and low viscosity. The properties of BPF resins were tested. Results indicated that BPF resin with the bio-oil addition of 20% had good performance on oxygen index and bending strength, indicating that adding bio-oil could modify the fire resistance and brittleness of PF resin. The thermal curing behavior and heat resistance of BPF resins were investigated by differential scanning calorimetry (DSC and thermal gravimetric analysis (TGA. Results showed that adding bio-oil had an impact on curing characteristics and thermal degradation process of PF resin, but the influence was insignificant when the addition was relatively low. The chemical structure and surface characteristics of BPF resins were determined by Fourier transform infrared (FTIR spectroscopy and scanning electron microscopy (SEM. The analysis demonstrated that adding bio-oil in the amount of 20% was able to improve the crosslinking degree and form more hydrocarbon chains in PF resin.

  13. Effect of ceramic thickness and shade on mechanical properties of a resin luting agent.

    Science.gov (United States)

    Passos, Sheila Pestana; Kimpara, Estevão Tomomitsu; Bottino, Marco Antonio; Rizkalla, Amin S; Santos, Gildo Coelho

    2014-08-01

    This study aimed to investigate the influence of ceramic thickness and shade on the Knoop hardness and dynamic elastic modulus of a dual-cured resin cement. Six ceramic shades (Bleaching, A1, A2, A3, A3.5, B3) and two ceramic thicknesses (1 mm, 3 mm) were evaluated. Disk specimens (diameter: 7 mm; thickness: 2 mm) of the resin cement were light cured under a ceramic block. Light-cured specimens without the ceramic block at distances of 1 and 3 mm were also produced. The Knoop hardness number (KHN), density, and dynamic Young's moduli were determined. Statistical analysis was conducted using ANOVA and a Tukey B rank order test (p = 0.05). The bleaching 1-mm-thick group exhibited significantly higher dynamic Young's modulus. Lower dynamic Young's moduli were observed for the 3-mm-thick ceramic groups compared to bleaching 3-mm-thick group, and no difference was found among the other 3-mm groups. For the KHN, when A3.5 3-mm-thick was used, the KHN was significantly lower than bleaching and A1 1-mm-thick ceramic; however, no difference was exhibited between the thicknesses of the same shade. The dual-cured resin cement studied irradiated through the 1-mm-thick ceramic with the lightest shade (bleaching ceramic) exhibited a better elastic modulus, and there was no effect in KHN of the resin cement when light cured under different ceramic shades and thicknesses (1 and 3 mm), except when the A3.5 3-mm-thick ceramic was used. Variolink II irradiated through ceramic with the lowest chroma exhibited the highest elastic modulus; therefore, the light activation method might not be the same for all clinical situations. © 2014 by the American College of Prosthodontists.

  14. Biphenyl liquid crystalline epoxy resin as a low-shrinkage resin-based dental restorative nanocomposite.

    Science.gov (United States)

    Hsu, Sheng-Hao; Chen, Rung-Shu; Chang, Yuan-Ling; Chen, Min-Huey; Cheng, Kuo-Chung; Su, Wei-Fang

    2012-11-01

    Low-shrinkage resin-based photocurable liquid crystalline epoxy nanocomposite has been investigated with regard to its application as a dental restoration material. The nanocomposite consists of an organic matrix and an inorganic reinforcing filler. The organic matrix is made of liquid crystalline biphenyl epoxy resin (BP), an epoxy resin consisting of cyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (ECH), the photoinitiator 4-octylphenyl phenyliodonium hexafluoroantimonate and the photosensitizer champhorquinone. The inorganic filler is silica nanoparticles (∼70-100 nm). The nanoparticles were modified by an epoxy silane of γ-glycidoxypropyltrimethoxysilane to be compatible with the organic matrix and to chemically bond with the organic matrix after photo curing. By incorporating the BP liquid crystalline (LC) epoxy resin into conventional ECH epoxy resin, the nanocomposite has improved hardness, flexural modulus, water absorption and coefficient of thermal expansion. Although the incorporation of silica filler may dilute the reinforcing effect of crystalline BP, a high silica filler content (∼42 vol.%) was found to increase the physical and chemical properties of the nanocomposite due to the formation of unique microstructures. The microstructure of nanoparticle embedded layers was observed in the nanocomposite using scanning and transmission electron microscopy. This unique microstructure indicates that the crystalline BP and nanoparticles support each other and result in outstanding mechanical properties. The crystalline BP in the LC epoxy resin-based nanocomposite was partially melted during exothermic photopolymerization, and the resin expanded via an order-to-disorder transition. Thus, the post-gelation shrinkage of the LC epoxy resin-based nanocomposite is greatly reduced, ∼50.6% less than in commercialized methacrylate resin-based composites. This LC epoxy nanocomposite demonstrates good physical and chemical properties and good biocompatibility

  15. Long-term degradation of resin-based cements in substances present in the oral environment: influence of activation mode

    Directory of Open Access Journals (Sweden)

    Eduardo Moreira da SILVA

    2013-06-01

    Full Text Available Indirect restorations in contact with free gingival margins or principally within the gingival sulcus, where the presence of organic acids produced by oral biofilm is higher, may present faster degradation of the resin-based cement pellicle. Objectives To investigate the degradation of four resin-based cements: Rely X ARC (R, Variolink II (V, Enforce (E and All Cem (A, after immersion in distilled water (DW, lactic acid (LA and artificial saliva (AS and to analyze the influence of the activation mode on this response. Material and Methods Two activation modes were evaluated: chemical (Ch and dual (D. In the dual activation, a two-millimeter thick ceramic disk (IPS Empress System was interposed between the specimen and light-curing unit tip. Specimens were desiccated, immersed in distilled water, artificial saliva and lactic acid 0.1 M at 37°C for 180 days, weighed daily for the first 7 days, and after 14, 21, 28, 90 and 180 days and were desiccated again. Sorption and solubility (µg/mm 3 were calculated based on ISO 4049. The data were submitted to multifactor analysis of variance (MANOVA and Tukey's HSD test for media comparisons (α=0.05. Results Sorption was higher after immersion in LA (pD (p<0.05. The lowest solubility was presented by R (p<0.05. Conclusions Lactic acid increased the degradation of resin-based cements. Moreover, the physical component of activation, i.e., light-activation, contributed to a low degradation of resin-based cements.

  16. Comparative Evaluation of Shear Bond Strength and Debonding Characteristics using Conventional Halogen Light Curing Unit and LED Light Curing Unit: An in vitro Study

    Directory of Open Access Journals (Sweden)

    Amit Bhardwaj

    2013-01-01

    Conclusion: The result of this study showed promise for the orthodontic application of LED as light curing units and 20 seconds of exposure time is adequate for both LED and Halogen light, since increasing the curing time to 40 seconds showed no significant difference.

  17. Additional chemical polymerization of dual resin cements: reality or a goal to be achieved?

    Directory of Open Access Journals (Sweden)

    Luzia Sakaguti UMETSUBO

    Full Text Available Abstract Introduction This study serves as a warning to dentists and researchers that dual-cured resin cements may not polymerize completely under some prosthetic crowns. Objective The aim of this study was to analyse the polymerization degree of dual-cured resin cements under prosthetic barrier, by microhardness test. Material and method Three cements (Bistite II, RelyX ARC and Variolink II were light-cured through different barriers, placed between the cement and the light source: G1: without barrier; G2: composite resin (Cesead; G3: Inceram alumina; G4: IPS Empress; G5: Inceram zirconia; G6: tooth fragment. Photopolymerization was carried out using a halogen light unit (650 mW/cm2; microhardness was evaluated using the Microhardness Tester FM 700, under a load of 50gf with a dwell time of 15s, at two evaluation times (30min and 24h. Result The results were submitted to ANOVA and Tukey tests (5%. Both Inceram alumina and Inceram zirconia ceramic barriers hindered polymerization. Bistite, followed by RelyX and Variolink, exhibited the highest microhardness values (p<0.05. As the highest values were obtained without a barrier, it was determined that the barrier, followed by the tooth, influenced microhardness. Both Empress and Cesead had the smallest microhardness values but with no statistically significant difference between them. Conclusion The barrier negatively affected the microhardness of dual-cured resin cements; evaluation time did not affect microhardness values for most of the conditions tested. There is a limited effect of the chemical activator on the polymerization of some dual-cured cements, and their performance is product specific.

  18. effect of light intensity on the cure characteristics of photo

    African Journals Online (AJOL)

    2012-05-05

    May 5, 2012 ... Objective: To determine the light intensity emitted by light curing units (LCUs) and its effect on the cure characteristics of ... of carbon-carbon double bonds conversion (11-13). Additionally, the light intensity output of a ... increases within the unit and in the restoration. This heat not only contributes to the ...

  19. Mechanical and Thermal Properties of Dental Composites Cured with CAD/CAM Assisted Solid-State Laser

    Directory of Open Access Journals (Sweden)

    Roberto De Santis

    2018-03-01

    Full Text Available Over the last three decades, it has been frequently reported that the properties of dental restorative composites cured with argon laser are similar or superior to those achieved with conventional halogen and light emitting diode (LED curing units. Whereas laser curing is not dependent on the distance between the curing unit and the material, such distance represents a drawback for conventional curing units. However, a widespread clinical application of this kind of laser remains difficult due to cost, heavy weight, and bulky size. Recently, with regard to the radiation in the blue region of the spectrum, powerful solid-state lasers have been commercialized. In the current research, CAD (computer-aided design/CAM (computer-aided manufacturing assisted solid-state lasers were employed for curing of different dental restorative composites consisting of micro- and nanoparticle-reinforced materials based on acrylic resins. Commercial LED curing units were used as a control. Temperature rise during the photopolymerisation process and bending properties were measured. By providing similar light energy dose, no significant difference in temperature rise was observed when the two light sources provided similar intensity. In addition, after 7 days since curing, bending properties of composites cured with laser and LED were similar. The results suggested that this kind of laser would be suitable for curing dental composites, and the curing process does not suffer from the tip-to-tooth distance.

  20. Mechanical and Thermal Properties of Dental Composites Cured with CAD/CAM Assisted Solid-State Laser

    Science.gov (United States)

    De Santis, Roberto; Gloria, Antonio; Maietta, Saverio; Martorelli, Massimo; De Luca, Alessandro; Spagnuolo, Gianrico; Riccitiello, Francesco; Rengo, Sandro

    2018-01-01

    Over the last three decades, it has been frequently reported that the properties of dental restorative composites cured with argon laser are similar or superior to those achieved with conventional halogen and light emitting diode (LED) curing units. Whereas laser curing is not dependent on the distance between the curing unit and the material, such distance represents a drawback for conventional curing units. However, a widespread clinical application of this kind of laser remains difficult due to cost, heavy weight, and bulky size. Recently, with regard to the radiation in the blue region of the spectrum, powerful solid-state lasers have been commercialized. In the current research, CAD (computer-aided design)/CAM (computer-aided manufacturing) assisted solid-state lasers were employed for curing of different dental restorative composites consisting of micro- and nanoparticle-reinforced materials based on acrylic resins. Commercial LED curing units were used as a control. Temperature rise during the photopolymerisation process and bending properties were measured. By providing similar light energy dose, no significant difference in temperature rise was observed when the two light sources provided similar intensity. In addition, after 7 days since curing, bending properties of composites cured with laser and LED were similar. The results suggested that this kind of laser would be suitable for curing dental composites, and the curing process does not suffer from the tip-to-tooth distance. PMID:29584683

  1. Chemoviscosity modeling for thermosetting resins, 2

    Science.gov (United States)

    Hou, T. H.

    1985-01-01

    A new analytical model for simulating chemoviscosity of thermosetting resin was formulated. The model is developed by modifying the Williams-Landel-Ferry (WLF) theory in polymer rheology for thermoplastic materials. By assuming a linear relationship between the glass transition temperature and the degree of cure of the resin system under cure, the WLF theory can be modified to account for the factor of reaction time. Temperature dependent functions of the modified WLF theory constants were determined from the isothermal cure data of Lee, Loos, and Springer for the Hercules 3501-6 resin system. Theoretical predictions of the model for the resin under dynamic heating cure cycles were shown to compare favorably with the experimental data reported by Carpenter. A chemoviscosity model which is capable of not only describing viscosity profiles accurately under various cure cycles, but also correlating viscosity data to the changes of physical properties associated with the structural transformations of the thermosetting resin systems during cure was established.

  2. Dielectric Cure Monitoring of Thermosetting Matrix Composites

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyoung Geun [Agency for Defense Development, Daejeon (Korea, Republic of); Lee, Dae Gil [KAIST, Daejeon (Korea, Republic of)

    2003-10-15

    Cure monitoring can be used to improve the quality and productivity of thermosetting resin matrix composite products during their manufacturing process. In this work, the sensitivity of dielectrometry was improved by adequate separation the efforts of sensor and externals on the measured signal. A new algorithm to obtain the degree of cure during dielectric cure monitoring of glass/polyester and glass/epoxy composites was developed by employing a function of both temperature and dissipation factor, in which five cure monitoring parameters were used to calculate the degree of cure. The decreasing pattern of dissipation factor was compared with the relationships between the degree of cure and the resin viscosity. The developed algorithm might be employed for the in situ cure monitoring of thermosetting resin composites

  3. Dielectric Cure Monitoring of Thermosetting Matrix Composites

    International Nuclear Information System (INIS)

    Kim, Hyoung Geun; Lee, Dae Gil

    2003-01-01

    Cure monitoring can be used to improve the quality and productivity of thermosetting resin matrix composite products during their manufacturing process. In this work, the sensitivity of dielectrometry was improved by adequate separation the efforts of sensor and externals on the measured signal. A new algorithm to obtain the degree of cure during dielectric cure monitoring of glass/polyester and glass/epoxy composites was developed by employing a function of both temperature and dissipation factor, in which five cure monitoring parameters were used to calculate the degree of cure. The decreasing pattern of dissipation factor was compared with the relationships between the degree of cure and the resin viscosity. The developed algorithm might be employed for the in situ cure monitoring of thermosetting resin composites

  4. Study of the Solidification Dynamic of a Photocurable Resin by Photoacoustic

    Science.gov (United States)

    Jiménez-Pérez, J. L.; Cruz-Orea, A.; Pincel, P. Vieyra; Correa-Pacheco, Z. N.

    2017-08-01

    This paper reports on the photoacoustic (PA) study of a photopolymer (resin) that changes its physical properties when being irradiated with ultraviolet light from a xenon lamp. The wavelength range necessary for the curing of the resin, characterized by the PA technique, was found to be between 300 nm and 400 nm. PA measurements show a sigmoidal change of heat transport properties as a function of time during the curing process. By describing the PA signal evolution by a parametrized model, a characteristic curing time was introduced. The PA measurements were complemented with UV-Vis Spectroscopy, which was used to characterize the polymer in order to study the optical absorption. The proposed method can support the optimization of the settings of curing parameters in applications of stereolithography and 3D printing.

  5. Tensile and shear bond strength of hard and soft denture relining materials to the conventional heat cured acrylic denture base resin: An In-vitro study.

    Science.gov (United States)

    Lau, Mayank; Amarnath, G S; Muddugangadhar, B C; Swetha, M U; Das, Kopal Anshuraj Ashok Kumar

    2014-04-01

    The condition of the denture bearing tissues may be adversely affected by high stress concentration during function. Chairside Denture (Hard and Soft) reliners are used to distribute forces applied to soft tissues during function. Tensile and shear bond strength has been shown to be dependent on their chemical composition. A weak bond could harbor bacteria, promote staining and delamination of the lining material. To investigate tensile and shear bond strength of 4 different commercially available denture relining materials to conventional heat cured acrylic denture base resin. 4 mm sections in the middle of 160 Acrylic cylindrical specimens (20 mm x 8 mm) were removed, packed with test materials (Mollosil, G C Reline Soft, G C Reline Hard (Kooliner) and Ufi Gel Hard and polymerized. Specimens were divided into 8 groups of 20 each. Tensile and shear bond strength to the conventional heat cured acrylic denture base resin were examined by Instron Universal Tensile Testing Machine using the equation F=N/A (F-maximum force exerted on the specimen (Newton) and A-bonding area= 50.24 mm2). One-way ANOVA was used for multiple group comparisons followed by Bonferroni Test and Hsu's MCB for multiple pairwise comparisons to asses any significant differences between the groups. The highest mean Tensile bond strength value was obtained for Ufi Gel Hard (6.49+0.08 MPa) and lowest for G C Reline Soft (0.52+0.01 MPa). The highest mean Shear bond strength value was obtained for Ufi Gel Hard (16.19+0.1 MPa) and lowest for Mollosil (0.59+0.05 MPa). The Benferroni test showed a significant difference in the mean tensile bond strength and the mean shear bond strength when the two denture soft liners were compared as well as when the two denture hard liners were compared. Hsu's MCB implied that Ufi gel hard is better than its other closest competitors. The Tensile and Shear bond strength values of denture soft reliners were significantly lower than denture hard reliners. How to cite the

  6. Do the monomers release from the composite resins after artificial aging?

    Science.gov (United States)

    Tokay, Ugur; Koyuturk, Alp Erdin; Aksoy, Abdurrahman; Ozmen, Bilal

    2015-04-01

    The aim of this study is to measure the effect of thermal cycling on the amount of monomer released from three different composite materials by HPLC analysis method. Three different composite materials, inlay composite, posterior composite and micro-hybrid composite were used. Sixty cylinder specimens each with a dimension of approximately 1 cm width and 3 mm depth, were prepared before experiments were carried out. Inlay composite material was polymerized according to manufacturers' instructions. Thermal cycling device was used to simulate thermal differences which occur in the mouth media. Monomers were analyzed using HPLC technic after thermal cycling process. The amount of ethoxylated Bis-GMA and urethane dimethacrylate (UDMA) in inlay composite material, the amount of ethoxylated Bis-GMA in posterior composite material, the amount of ethoxylated Bis-GMA and triethyleneglycol dimethacrylate (TEGDMA) in micro-hybrid composite material were investigated. Monomer release of thermal cycles levels showed a linear increase in UDMA and TEGDMA (P < 0.05). In terms of thermal cycles levels, Bis-EMA released from posterior composite showed a cubic change (P < 0.001). It was observed that use of additional polymerization processes might have positive effect on the decrease of residual monomer. In the light of the results, we suggest that indirect composite resins have more outstanding features than direct composite resins in terms of biocompatibility. © 2015 Wiley Periodicals, Inc.

  7. Light-activation through indirect ceramic restorations: does the overexposure compensate for the attenuation in light intensity during resin cement polymerization?

    Directory of Open Access Journals (Sweden)

    Albano Luis Novaes Bueno

    2011-02-01

    Full Text Available OBJECTIVES: This study evaluated the effects of light exposure through simulated indirect ceramic restorations (SICR on hardness (KHN of dual-cured resin cements (RCs, immediately after light-activation and 24 h later. MATERIAL AND METHODS: Three dual-cured RCs were evaluated: Eco-Link (Ivoclar Vivadent, Rely X ARC (3M ESPE, and Panavia F (Kuraray Medical Inc.. The RCs were manipulated in accordance to the manufacturers' instructions and were placed into cylindrical acrylic matrixes (1-mm-thick and 4-mm diameter. The RC light-activation (Optilux 501; Demetron Kerr was performed through a glass slide for 120 s (control group, or through 2-mm or 4-mm thick SICRs (IPS Empress II; Ivoclar Vivadent. The specimens were submitted to KHN analysis immediately and 24 h after light-activation. The data obtained at the 2 evaluation intervals were submitted to 2-way ANOVA repeated measures and post-hoc Tukey's test (pre-set alpha of 5%. RESULTS: Lower KHN was observed when light-activation was performed through SICRs for Eco-Link at all evaluation intervals and for Rely X ARC 24 h later. For Panavia F, no significant difference in KHN was observed between control and experimental groups, regardless of evaluation interval. Most groups exhibited higher KHN after 24 h than immediately after light-activation, with the exception of Rely X ARC light-activated through SICR, as no significant difference in KHN was found between evaluation intervals. CONCLUSIONS: Light overexposure did not compensate for light intensity attenuation due to the presence of SICR when Rely X and Eco-Link were used. Although hardness of such RCs increased over a 24-h interval, the RCs subjected to light overexposure did not reach the hardness values exhibited after direct light exposure.

  8. An investigation on the effects of different polymerization techniques on dimensional changes ofAcropars, an Iranian autopolymerizing acrylic resin

    Directory of Open Access Journals (Sweden)

    Ebadian B

    2004-02-01

    Full Text Available Iranian product, Acropars autopolymerizing acrylic resin is nowadays widely used in"ndental prostheses. Dimensional change is a common problem among Iranian made acrylic resins in making"ncustom trays and record bases, seems to be more than the similar foreign products. In order to achieve a"ntechnique for making a record base with minimum dimensional changes, more research is necessary."nPurpose: The aim of the present study was to determine a curing technique for Iranian autopolymerizing"nacrylic resins leading to the least polymerization shrinkage and the most adaptation between record bases and"nstone casts."nMaterials and Methods: In this experimental study, 40 stone casts were divided into four 10- member group."nFor each group, polymerization shrinkage was determined at three points with one of the following"ntechniques: Bench curing, Curing under a coat of petroleum jelly , Curing in a monomer saturated"natmosphere, Curing in boiled water. Adaptation between bases and stone casts were measured at three points"n(the right and left crests of the ridge and the midpalatal region with a light-measuring microscope. To analyze"nthe data, Variance analysis was used."nResults: The monomer atmosphere technique showed the minimum dimensional changes and the samples in"nboiled water group had the maximum dimensional changes. No statistical differences were observed between"nother groups."nConclusion: More adaptation between record bases and stone casts was observed in monomer atmosphere"npolymerization technique. The differences between bench curing and curing under a coat of petroleum jelly"ntechniques with this method were not statistically significant. Therefore, it is suggested for making base"nrecords with maximum adaptation.

  9. Dielectric analysis of depth dependent curing behavior of dental resin composites.

    Science.gov (United States)

    Steinhaus, Johannes; Moeginger, Bernhard; Grossgarten, Mandy; Rosentritt, Martin; Hausnerova, Berenika

    2014-06-01

    The aim of this study is to investigate depth dependent changes of polymerization process and kinetics of visible light-curing (VLC) dental composites in real-time. The measured quantity - "ion viscosity" determined by dielectric analysis (DEA) - provides the depth dependent reaction rate which is correlated to the light intensity available in the corresponding depths derived from light transmission measurements. The ion viscosity curves of two composites (VOCO Arabesk Top and Grandio) were determined during irradiation of 40s with a light-curing unit (LCU) in specimen depths of 0.5/0.75/1.0/1.25/1.5/1.75 and 2.0mm using a dielectric cure analyzer (NETZSCH DEA 231 with Mini IDEX sensors). The thickness dependent light transmission was measured by irradiation composite specimens of various thicknesses on top of a radiometer setup. The shape of the ion viscosity curves depends strongly on the specimen thickness above the sensor. All curves exhibit a range of linear time dependency of the ion viscosity after a certain initiation time. The determined initiation times, the slopes of the linear part of the curves, and the ion viscosities at the end of the irradiation differ significantly with depth within the specimen. The slopes of the ion viscosity curves as well as the light intensity values decrease with depth and fit to the Lambert-Beer law. The corresponding attenuation coefficients are determined for Arabesk Top OA2 to 1.39mm(-1) and 1.48mm(-1), respectively, and for Grandio OA2 with 1.17 and 1.39mm(-1), respectively. For thicknesses exceeding 1.5mm a change in polymerization behavior is observed as the ion viscosity increases subsequent to the linear range indicating some kind of reaction acceleration. The two VLC composites and different specimen thicknesses discriminate significantly in their ion viscosity evolution allowing for a precise characterization of the curing process even with respect to the polymerization mechanism. Copyright © 2014. Published by

  10. Proceedings of workshop on surface finishing by radiation curing technology: radiation curing for better finishing

    International Nuclear Information System (INIS)

    1993-01-01

    This book compiled the paper presented at this workshop. The papers discussed are 1. Introduction to radiation curing, 2. Radiation sources -ultraviolet and electron beams, 3. UV/EB curing of surface coating - wood and nonwood substrates, 4. Development of EPOLA (epoxidised palm oil products acrylate) and its application, 5. Development of radiation-curable resin based natural rubber

  11. Proceedings of workshop on surface finishing by radiation curing technology: radiation curing for better finishing

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-12-31

    This book compiled the paper presented at this workshop. The papers discussed are 1. Introduction to radiation curing, 2. Radiation sources -ultraviolet and electron beams, 3. UV/EB curing of surface coating - wood and nonwood substrates, 4. Development of EPOLA (epoxidised palm oil products acrylate) and its application, 5. Development of radiation-curable resin based natural rubber.

  12. Strain development in a filled epoxy resin curing under constrained and unconstrained conditions as assessed by Fibre Bragg Grating sensors

    Directory of Open Access Journals (Sweden)

    2007-04-01

    Full Text Available The influence of adhesion to the mould wall on the released strain of a highly filled anhydride cured epoxy resin (EP, which was hardened in an aluminium mould under constrained and unconstrained condition, was investigated. The shrinkage-induced strain was measured by fibre optical sensing technique. Fibre Bragg Grating (FBG sensors were embedded into the curing EP placed in a cylindrical mould cavity. The cure-induced strain signals were detected in both, vertical and horizontal directions, during isothermal curing at 75 °C for 1000 minutes. A huge difference in the strain signal of both directions could be detected for the different adhesion conditions. Under non-adhering condition the horizontal and vertical strain-time traces were practically identical resulting in a compressive strain at the end of about 3200 ppm, which is a proof of free or isotropic shrinking. However, under constrained condition the horizontal shrinkage in the EP was prevented due to its adhesion to the mould wall. So, the curing material shrunk preferably in vertical direction. This resulted in much higher released compressive strain signals in vertical (10430 ppm than in horizontal (2230 ppm direction. The constrained cured EP resins are under inner stresses. Qualitative information on the residual stress state in the molding was deduced by exploiting the birefringence of the EP.

  13. Influence of irradiance on Knoop hardness, degree of conversion, and polymerization shrinkage of nanofilled and microhybrid composite resins.

    Science.gov (United States)

    Fugolin, Ana Paula Piovezan; Correr-Sobrinho, Lourenço; Correr, Américo Bortolazzo; Sinhoreti, Mário Alexandre Coelho; Guiraldo, Ricardo Danil; Consani, Simonides

    2016-01-01

    The purpose of this study was to investigate the influence of the irradiance emitted by a light-curing unit on microhardness, degree of conversion (DC), and gaps resulting from shrinkage of 2 dental composite resins. Cylinders of nanofilled and microhybrid composites were fabricated and light cured. After 24 hours, the tops and bottoms of the specimens were evaluated via indentation testing and Fourier transform infrared spectroscopy to determine Knoop hardness number (KHN) and DC, respectively. Gap width (representing polymerization shrinkage) was measured under a scanning electron microscope. The nanofilled composite specimens presented significantly greater KHNs than did the microhybrid specimens (P composite resin exhibited significantly greater DC and gap width than the nanofilled material (P composite resins.

  14. Properties of radiation cured coatings

    International Nuclear Information System (INIS)

    Larson, E.G.; Spencer, D.S.; Boettcher, T.E.; Melbauer, M.A.; Skarjune, R.P.

    1987-01-01

    Coatings were prepared from acrylate or methacrylate functionalized resins to study the effect of end group functionality on the physical properties of u.v. and electron beam cured coatings. Cure response was measured by solid state NMR and gel extraction, as expected, methacrylate resins cured much slower. Thermal Gravimetric Analysis (TGA) revealed acrylate coatings have greater thermal stability. Properties such as tensile strength and hardness showed little effect of end group functionality or curing method. The O 2 and H 2 O permeabilities of the coating were correlated with the processing conditions. (author)

  15. Bulk-Fill Composites: Effectiveness of Cure With Poly- and Monowave Curing Lights and Modes.

    Science.gov (United States)

    Gan, J K; Yap, A U; Cheong, J W; Arista, N; Tan, Cbk

    This study compared the effectiveness of cure of bulk-fill composites using polywave light-emitting diode (LED; with various curing modes), monowave LED, and conventional halogen curing lights. The bulk-fill composites evaluated were Tetric N-Ceram bulk-fill (TNC), which contained a novel germanium photoinitiator (Ivocerin), and Smart Dentin Replacement (SDR). The composites were placed into black polyvinyl molds with cylindrical recesses of 4-mm height and 3-mm diameter and photopolymerized as follows: Bluephase N Polywave High (NH), 1200 mW/cm 2 (10 seconds); Bluephase N Polywave Low (NL), 650 mW/cm 2 (18.5 seconds); Bluephase N Polywave soft-start (NS), 0-650 mW/cm 2 (5 seconds) → 1200 mW/cm 2 (10 seconds); Bluephase N Monowave (NM), 800 mW/cm 2 (15 seconds); QHL75 (QH), 550 mW/cm 2 (21.8 seconds). Total energy output was fixed at 12,000 mJ/cm 2 for all lights/modes, with the exception of NS. The cured specimens were stored in a light-proof container at 37°C for 24 hours, and hardness (Knoop Hardness Number) of the top and bottom surfaces of the specimens was determined using a Knoop microhardness tester (n=6). Hardness data and bottom-to-top hardness ratios were subjected to statistical analysis using one-way analysis of variance/Scheffe's post hoc test at a significance level of 0.05. Hardness ratios ranged from 38.43% ± 5.19% to 49.25% ± 6.38% for TNC and 50.67% ± 1.54% to 67.62% ± 6.96% for SDR. For both bulk-fill composites, the highest hardness ratios were obtained with NM and lowest hardness ratios with NL. While no significant difference in hardness ratios was observed between curing lights/modes for TNC, the hardness ratio obtained with NM was significantly higher than the hardness ratio obtained for NL for SDR.

  16. In vitro comparative study of share bond of light cured composite resins with halogen light and argon laser, using stainless steel brackets on human premolars; Estudo comparativo in vitro da capacidade adesiva da resina fotoativada pela luz halogena e por laser de argonio, utilizando-se brackets metalicos em pre-molares humanos

    Energy Technology Data Exchange (ETDEWEB)

    Carillo, Vitoria Eugenia Bismarck

    2004-07-01

    The aim of this study in vitro was to compare the share bond strength of the light-cured composite resins Transbond XT (Unitek), with halogen light and argon laser. The Adhesive Remmant Index (ARI) was also investigated. The brackets Dyna lock (3M-UNITEK) were bonded to 75 human premolars, divided into 5 groups (15 each) according to time and the polymerization: Group H20, 15 brackets bonded with halogen light for 20s (10s both sides); Group H40, 15 brackets bonded with halogen light for 40s (20s both sides); Group A40, 15 brackets bonded with argon laser for 40s (20s both sides); Group A20, 15 brackets bonded with argon laser for 20s (10s both sides); Group A10, 15 brackets bonded with argon laser for 10s (5s both sides). The pulpal temperature changes were determined during a polymerization, not exceeding 3,5 deg C. After bonding, the teeth were submitted to a thermo cycled of 700 cycles between 5 deg C and 55 deg C, to simulate the consuming that the light cured composite resin would have in a short space of time. The specimens were then placed in PVC ring and embedded in acrylic resin (Aero-Jet). The tensile bond strength test was performed on an Universal Machine set at a crosshead speed of 1,5 mm/min, and for each rupture we registered a graphic and the best load required in Newtons, was converted to MPa and kgf. The share bond strength showed bigger values for the exposure time of 20 seconds, for the Group bonded for halogen light (H20), 7,45 kgf (7,64 MPa) and for argon laser 7,50 kgf (7,69 MPa); lesser values for the exposure time of 40s for the Group with halogen light (H40), 6,15 kgf (6,30 MPa) and argon laser Group (A40), 6,20 kgf (6,35 MPa) 0; and A10, 4,85 kgf (4,97 MPa). In the ARI Index, only A40 Group showed the 1 Index, with statistical results. In this Group, less than half of the remainder adhesive stayed on the surface of the enamel, conferring specimens failed at the enamel-adhesive interface. The results of the in vitro study demonstrate that

  17. Inhibition of odontogenic differentiation of human dental pulp cells by dental resin monomers

    OpenAIRE

    Kwon, Ji Hyun; Park, Hee Chul; Zhu, Tingting; Yang, Hyeong-Cheol

    2015-01-01

    Background Dental resin monomers that are leached from the resin matrix due to incomplete polymerization can affect the viability and various functions of oral tissues and cells. In this study, the effects of triethylene glycol dimethacrylate (TEGDMA) and 2-hydroxyethyl methacrylate (HEMA) on odontogenic differentiation of human dental pulp cells (HDPCs) were examined. To mimic clinical situations, dental pulp cells were treated with resin monomers for 24?h prior to the analysis of alkaline p...

  18. Simulation and Validation of Injection-Compression Filling Stage of Liquid Moulding with Fast Curing Resins

    Science.gov (United States)

    Martin, Ffion A.; Warrior, Nicholas A.; Simacek, Pavel; Advani, Suresh; Hughes, Adrian; Darlington, Roger; Senan, Eissa

    2018-03-01

    Very short manufacture cycle times are required if continuous carbon fibre and epoxy composite components are to be economically viable solutions for high volume composite production for the automotive industry. Here, a manufacturing process variant of resin transfer moulding (RTM), targets a reduction of in-mould manufacture time by reducing the time to inject and cure components. The process involves two stages; resin injection followed by compression. A flow simulation methodology using an RTM solver for the process has been developed. This paper compares the simulation prediction to experiments performed using industrial equipment. The issues encountered during the manufacturing are included in the simulation and their sensitivity to the process is explored.

  19. Cure Cycle Optimization of Rapidly Cured Out-Of-Autoclave Composites

    Science.gov (United States)

    Dong, Anqi; Zhao, Yan; Zhao, Xinqing; Yu, Qiyong

    2018-01-01

    Out-of-autoclave prepreg typically needs a long cure cycle to guarantee good properties as the result of low processing pressure applied. It is essential to reduce the manufacturing time, achieve real cost reduction, and take full advantage of out-of-autoclave process. The focus of this paper is to reduce the cure cycle time and production cost while maintaining high laminate quality. A rapidly cured out-of-autoclave resin and relative prepreg were independently developed. To determine a suitable rapid cure procedure for the developed prepreg, the effect of heating rate, initial cure temperature, dwelling time, and post-cure time on the final laminate quality were evaluated and the factors were then optimized. As a result, a rapid cure procedure was determined. The results showed that the resin infiltration could be completed at the end of the initial cure stage and no obvious void could be seen in the laminate at this time. The laminate could achieve good internal quality using the optimized cure procedure. The mechanical test results showed that the laminates had a fiber volume fraction of 59–60% with a final glass transition temperature of 205 °C and excellent mechanical strength especially the flexural properties. PMID:29534048

  20. Structural and mechanical properties of a giomer-based bulk fill restorative in different curing conditions

    Directory of Open Access Journals (Sweden)

    Mustafa Sarp Kaya

    2018-01-01

    Full Text Available ABSTRACT Objective: The main goal of this study was to compare the polymerization degree of bulk-fill giomer resin cured with three different light-curing units (LCUs: a polywave third-generation (Valo; a monowave (DemiUltra: DU; and a second-generation LED (Optima 10: Opt LCUs by using structural and mechanical properties. Material and methods: Giomer samples of 2 and 4 mm cured with three LCUs were employed in vitro analysis. The degree of curing (DC% was determined with Fourier-Transform Infrared Spectroscopy (FTIR. Microstructural features were observed with scanning electron microscopy (SEM. Flexural strength (FS, compression strength (CS, elastic modulus and fracturing strain were determined for mechanical properties. Surface microhardness (SMH values were also measured. Oneway ANOVA, two-way analysis of variance and Tukey multiple comparison tests were used for statistically analyzing the FS and SMH. Results: DC% values were 58.2, 47.6, and 39.7 for the 2 mm samples cured with DU, Opt., and Valo LCUs, respectively. DC% values of the 4 mm samples were 50.4, 44.6, and 38.2 for DU, Opt, and Valo, respectively. SMH values were Valo, Optcured with Opt and DU exhibited higher FS values than Valo. CS values were similar but compressive modulus and fracturing strain (% varied depending on the curing protocol. Conclusions: Based on the results, it can be concluded that curing device and protocol strongly affect crosslinking reactions and thus DC%, SMH, compressive modulus and strain at break values. Consequently, it can be deduced that curing protocol is possibly the most important parameter for microstructure formation of highly-filled composite restoratives because it may bring some structural defects and physical frailties on restorations due to lower degree of polymerization.

  1. Characterization of heat emission of light-curing units.

    Science.gov (United States)

    Wahbi, Mohammed A; Aalam, F A; Fatiny, F I; Radwan, S A; Eshan, I Y; Al-Samadani, K H

    2012-04-01

    This study was designed to analyze the heat emissions produced by light-curing units (LCUs) of different intensities during their operation. The null hypothesis was that the tested LCUs would show no differences in their temperature rises. FIVE COMMERCIALLY AVAILABLE LCUS WERE TESTED: a "Flipo" plasma arc, "Cromalux 100" quartz-tungsten-halogen, "L.E. Demetron 1" second-generation light-emitting diode (LED), and "Blue Phase C5" and "UltraLume 5" third-generation LED LCUs. The intensity of each LCU was measured with two radiometers. The temperature rise due to illumination was registered with a type-K thermocouple, which was connected to a computer-based data acquisition system. Temperature changes were recorded in continues 10 and 20 s intervals up to 300 s. The Flipo (ARC) light source revealed the highest mean heat emission while the L.E. Demetron 1 LED showing the lowest mean value at 10 and 20 s exposure times. Moreover, Cromalux (QTH) recorded the second highest value for all intervals (12.71, 14.63, 14.60) of heat emission than Blue Phase C5 (LED) (12.25, 13.87, 13.69), interestingly at 20 s illumination for all intervals the highest results (18.15, 19.27, 20.31) were also recorded with Flipo (PAC) LCU, and the lowest (6.71, 5.97, 5.55) with L.E. Demetron 1 LED, while Blue Phase C5 (LED) recorded the second highest value at the 1st and 2nd 20 s intervals (14.12, 11.84, 10.18) of heat emission than Cromalux (QTH) (12.26, 11.43, 10.26). The speed of temperature or heat rise during the 10 and 20 s depends on light intensity of emitted light. However, the QTH LCU was investigated resulted in a higher temperature rise than LED curing units of the same power density. The PAC curing unit induced a significantly higher heat emission and temperature increase in all periods, and data were statistically different than the other tested groups (p < .05). LED (Blue Phase C5) was not statistically significant (p < .05) (at 10 s) than QTH units, also LED (Blue

  2. Effects of radiant exposure values using second and third generation light curing units on the degree of conversion of a lucirin-based resin composite.

    Science.gov (United States)

    Cardoso, Kelly Antonieta Oliveira Rodrigues de Faria; Zarpellon, Driellen Christine; Madruga, Camila Ferreira Leite; Rodrigues, José Augusto; Arrais, Cesar Augusto Galvão

    2017-01-01

    Using Fourier transform infrared analysis (FTIR) in vitro, the effects of varying radiant exposure (RE) values generated by second and third generation LED LCUs on the degree of conversion (DC) and maximum rate of polymerization (Rpmax) of an experimental Lucirin TPO-based RC were evaluated. 1 mm or 2 mm thick silicon molds were positioned on a horizontal attenuated total reflectance (ATR) unit attached to an infrared spectroscope. The RC was inserted into the molds and exposed to varying REs (18, 36 and 56 J/cm2) using second (Radii Plus, SDI) and third generation LED LCUs (Bluephase G2/Ivoclar Vivadent) or a quartz tungsten based LCU (Optilux 501/SDS Kerr). FTIR spectra (n=7) were recorded for 10 min (1 spectrum/s, 16 scans/spectrum, resolution 4 cm-1) immediately after their application to the ATR. The DC was calculated using standard techniques for observing changes in aliphatic to aromatic peak ratios both prior to, and 10 min after curing, as well as during each 1 second interval. DC and Rpmax data were analyzed using 3-way ANOVA and Tukey's post-hoc test (p=0.05). No significant difference in DC or Rpmax was observed between the 1 mm or 2 mm thick specimens when RE values were delivered by Optilux 501 or when the 1 mm thick composites were exposed to light emitted by Bluephase G2, which in turn promoted a lower DC when 18 J/cm2 (13 s) were delivered to the 2 mm thick specimens. Radii Plus promoted DC and Rpmax values close to zero under most conditions, while the delivery of 56 J/cm2 (40 s) resulted in low DC values. The third generation LCU provided an optimal polymerization of Lucirin TPO-based RC under most tested conditions, whereas the second generation LED-curing unit was useless regardless of the RE.

  3. Curing of polymer thermosets via click reactions and on demand processes

    Science.gov (United States)

    Brei, Mark Richard

    In the first project, an azide functional resin and tetra propargyl aromatic diamines were fabricated for use as a composite matrix. These systems take already established epoxy/amine matrices and functionalize them with click moieties. This allows lower temperatures to be used in the production of a thermoset part. These new systems yield many better mechanical properties than their epoxy/amine derivatives, but their Tgs are low in comparison. The second project investigates the characterization of a linear system based off of the above azide functional resin and a difunctional alkyne. Through selectively choosing catalyst, the linear system can show regioselectivity to either a 1,4-disubstituted triazole, or a 1,5-disubstituted triazole. Without the addition of catalyst, the system produces both triazoles in almost an equal ratio. The differently catalyzed systems were cured and then analyzed by 1H and 13C NMR to better understand the structure of the material. The third project builds off of the utility of the aforementioned azide/alkyne system and introduces an on-demand aspect to the curing of the thermoset. With the inclusion of copper(II) within the azide/alkyne system, UV light is able to catalyze said reaction and cure the material. It has been shown that the copper(II) loading levels can be extremely small, which helps in reducing the copper's effect on mechanical properties The fourth project takes a look at polysulfide-based sealants. These sealants are normally cured via an oxidative reaction. This project took thiol-terminated polysulfides and fabricated alkene-terminated polysulfides for use as a thiol-ene cured material. By changing the mechanism for cure, the polysulfide can be cured via UV light with the use of a photoinitiator within the thiol/alkene polysulfide matrix. The final chapter will focus on a characterization technique, MALDI-TOF, which was used to help characterize the above materials as well as many others. By using MALDI-TOF, the

  4. Wear Resistance of 3D Printing Resin Material Opposing Zirconia and Metal Antagonists.

    Science.gov (United States)

    Park, Ji-Man; Ahn, Jin-Soo; Cha, Hyun-Suk; Lee, Joo-Hee

    2018-06-20

    3D printing offers many advantages in dental prosthesis manufacturing. This study evaluated the wear resistance of 3D printing resin material compared with milling and conventional resin materials. Sixty substrate specimens were prepared with three types of resin materials: 3D printed resin, milled resin, and self-cured resin. The 3D printed specimens were printed at a build angle of 0° and 100 μm layer thickness by digital light processing 3D printing. Two kinds of abraders were made of zirconia and CoCr alloy. The specimens were loaded at 5 kg for 30,000 chewing cycles with vertical and horizontal movements under thermocycling condition. The 3D printed resin did not show significant difference in the maximal depth loss or the volume loss of wear compared to the milled and the self-cured resins. No significant difference was revealed depending on the abraders in the maximal depth loss or the volume loss of wear. In SEM views, the 3D printed resin showed cracks and separation of inter-layer bonds when opposing the metal abrader. The results suggest that the 3D printing using resin materials provides adequate wear resistance for dental use.

  5. Interactions between resin monomers and commercial composite resins with human saliva derived esterases.

    Science.gov (United States)

    Jaffer, F; Finer, Y; Santerre, J P

    2002-04-01

    Cholesterol esterase (CE) and pseudocholinesterase (PCE) have been reported to degrade commercial and model composite resins containing bisphenylglycidyl dimethacrylate (BisGMA), triethylene glycol dimethacrylate (TEGDMA) or the latter in combination with urethane modified BisGMA monomer systems. In addition, human saliva has been shown to contain esterase like activities similar to CE and PCE. Hence, it was the aim of the current study to determine to what extent human saliva could degrade two common commercial composite resins (Z250 from 3M Inc. and Spectrum TPH from L.D. Caulk) which contain the above monomer systems. Saliva samples from different volunteers were collected, processed, pooled, and freeze-dried. TEGDMA and BisGMA monomers were incubated with human saliva derived esterase activity (HSDEA) and their respective hydrolysis was monitored using high performance liquid chromatography (HPLC). Both monomers were completely hydrolyzed within 25 h by HSDEA. Photopolymerized composites were incubated with buffer or human saliva (pH 7.0 and 37 C) for 2, 8 and 16 days. The incubation solutions were analyzed using HPLC and mass spectrometry. Surface morphology characterization was carried out using scanning electron microscopy. Upon biodegradation, the Z250 composite yielded higher amounts of BisGMA and TEGDMA related products relative to the TPH composite. However, there were higher amounts of ethoxylated bis-phenol A released from the TPH material. In terms of total mass of products released, human saliva demonstrated a greater ability to degrade Z250. In summary, HSDEA has been shown to contain esterase activities that can readily catalyze the biodegradation of current commercial composite resins.

  6. Glass transition and degree of conversion of a light-cured orthodontic composite

    Directory of Open Access Journals (Sweden)

    Michela M. D. S. Sostena

    2009-12-01

    Full Text Available OBJECTIVE: This study evaluated the glass transition temperature (Tg and degree of conversion (DC of a light-cured (Fill Magic versus a chemically cured (Concise orthodontic composite. MATERIAL AND METHODS: Anelastic relaxation spectroscopy was used for the first time to determine the Tg of a dental composite, while the DC was evaluated by infrared spectroscopy. The light-cured composite specimens were irradiated with a commercial LED light-curing unit using different exposure times (40, 90 and 120 s. RESULTS: Fill Magic presented lower Tg than Concise (35-84ºC versus 135ºC, but reached a higher DC. CONCLUSIONS: The results of this study suggest that Fill Magic has lower Tg than Concise due to its higher organic phase content, and that when this light-cured composite is used to bond orthodontic brackets, a minimum energy density of 7.8 J/cm² is necessary to reach adequate conversion level and obtain satisfactory adhesion.

  7. Cellular effects of halogen blue light from dental curing unit

    International Nuclear Information System (INIS)

    Trosic, I.; Pavicic, I.; Jukic, S.

    2008-01-01

    Full text: Halogen curing lights are the most frequently used polymerization source in dental offices. Light-cured bonding systems have become increasingly popular among clinicians because they offer a number of advantages over self-cured adhesives. The effort to increase polymerization quality releases the commercially available high power light density dental curing units. Emitted visible blue light belongs to the range of nonionizing radiation. Common concern in both, patients and dentist grows with regard to the unfavorable effects on the pulp tissue. The aim of study was to evaluate the time and dose dependence effect of halogen light curing unit (Elipar TriLight, ESPE Dental AG, Germany) at the disposed condition modes in vitro. A quartz-tungsten-halogen light source emits radiation of the wavelengths between 400 and 515 nm. This halogen blue light source operates in the three illumination modes, medium (M), exponential (E) and standard (S), and five illumination times. The total irradiance or the light intensity was measured by the light intensity control area on the control panel of device and mean light intensity given by manufacturer was 800 m W/cm 2 . Continuous culture of V79 cells was illuminated in triplicate. The influence of medium mode (M), exponential (E) and standard (S) illumination during 20, 40 and 80 sec on the cell viability, colony forming ability and proliferation of V79 cell culture was investigated. Trypan blue exclusion test was used to determine cell viability, both, in the treated and control cell samples. Colony forming ability was assessed for each exposure time and mode by colony count on post-exposure day 7. Cell proliferation was determined by cell counts for each time and mode of exposure during five post-exposure days. Statistical difference were determined at p<0.05 (Statistica 7.0, StatSoft Inc., USA). Viability of cells was not affected by blue light in view of exposure time and modes. Regardless to exposure or illumination

  8. Luting of CAD/CAM ceramic inlays: direct composite versus dual-cure luting cement.

    Science.gov (United States)

    Kameyama, Atsushi; Bonroy, Kim; Elsen, Caroline; Lührs, Anne-Katrin; Suyama, Yuji; Peumans, Marleen; Van Meerbeek, Bart; De Munck, Jan

    2015-01-01

    The aim of this study was to investigate bonding effectiveness in direct restorations. A two-step self-etch adhesive and a light-cure resin composite was compared with luting with a conventional dual-cure resin cement and a two-step etch and rinse adhesive. Class-I box-type cavities were prepared. Identical ceramic inlays were designed and fabricated with a computer-aided design/computer-aided manufacturing (CAD/CAM) device. The inlays were seated with Clearfil SE Bond/Clearfil AP-X (Kuraray Medical) or ExciTE F DSC/Variolink II (Ivoclar Vivadent), each by two operators (five teeth per group). The inlays were stored in water for one week at 37°C, whereafter micro-tensile bond strength testing was conducted. The micro-tensile bond strength of the direct composite was significantly higher than that from conventional luting, and was independent of the operator (P<0.0001). Pre-testing failures were only observed with the conventional method. High-power light-curing of a direct composite may be a viable alternative to luting lithium disilicate glass-ceramic CAD/CAM restorations.

  9. Effect of Rebonding on the Bond Strength of Orthodontic Tubes: A Comparison of Light Cure Adhesive and Resin-Modified Glass Ionomer Cement In Vitro

    Directory of Open Access Journals (Sweden)

    Monika Aleksiejunaite

    2017-01-01

    Full Text Available The purpose of this study was to determine the impact of different enamel preparation procedures and compare light cure composite (LCC and resin-modified glass ionomer (RMGI on the bond strength of orthodontic metal tubes rebonded to the enamel. Twenty human molars were divided into two groups (n=10. Tubes were bonded using LCC (Transbond XT in group 1 and RMGI (Fuji Ortho LC in group 2. The tubes in each group were bonded following manufacturers’ instructions (experiment I and then debonded using testing machine. Then, the same brackets were sandblasted and rebonded twice. Before the first rebonding, the enamel was cleaned using carbide bur (experiment II and before second rebonding, it was cleaned using carbide bur and soda blasted (experiment III. Mann–Whitney and Wilcoxon signed-rank tests showed no significant difference between RMGI and LCC bond strengths in case of normal bonding and rebonding, when enamel was cleaned using carbide bur before rebonding. Enamel soda blasting before rebonding significantly increased RMGI tensile bond strength value compared to LLC (p<0.05. LCC and RMGI (especially RMGI provide sufficient bond strengths for rebonding of molar tubes, when residual adhesive from previous bonding is removed and enamel soda blasted.

  10. The use of epoxidised palm oil products (EPOP) for the synthesis of radiation curable resins. II. Ultraviolet (UV) curing of epoxidised RBD palm oil acrylate (EPOLA)

    International Nuclear Information System (INIS)

    Mohd Hilmi bin Mahmood; Hussin bin Mohd Nor; Hamirin bin Kifli; Masni bin Abdul Ragman; Azman bin Rafei

    1991-01-01

    Epoxidised RBD palm olein acrylate (EPOLA) and polyurethane acrylate (PUA) prepared at UTN laboratory were used as base polymers or oligomers in the formulations of ultraviolet (UV) curable resins. Mono-, di- and trifunctional monomers were utilized both as crosslinkers as well as for diluents. Curing was done by means of 20 cm wide IST UV machine with the conditions of 8A current and 4m/min conveyor speed. The properties of the cured films were investigated by using pencil hardness tester and gel content analysis

  11. A new fluorinated urethane dimethacrylate with carboxylic groups for use in dental adhesive compositions

    Energy Technology Data Exchange (ETDEWEB)

    Buruiana, Tinca, E-mail: tbur@icmpp.ro [Polyaddition and Photochemistry Department, Petru Poni Institute of Macromolecular Chemistry, 41 A Grigore Ghica Voda Alley, 700487 Iasi (Romania); Melinte, Violeta [Polyaddition and Photochemistry Department, Petru Poni Institute of Macromolecular Chemistry, 41 A Grigore Ghica Voda Alley, 700487 Iasi (Romania); Aldea, Horia [Gr. T. Popa University of Medicine and Pharmacy, Faculty of Dentistry, 16 University Str., 700115 Iasi (Romania); Pelin, Irina M.; Buruiana, Emil C. [Polyaddition and Photochemistry Department, Petru Poni Institute of Macromolecular Chemistry, 41 A Grigore Ghica Voda Alley, 700487 Iasi (Romania)

    2016-05-01

    A urethane macromer containing hexafluoroisopropylidene, poly(ethylene oxide) and carboxylic moieties (UF-DMA) was synthesized and used in proportions varying between 15 and 35 wt.% (F1–F3) in dental adhesive formulations besides BisGMA, triethylene glycol dimethacrylate and 2-hydroxyethyl methacrylate. The FTIR and {sup 1}H ({sup 13}C) NMR spectra confirmed the chemical structure of the UF-DMA. The experimental adhesives were characterized with regard to the degree of conversion, water sorption/solubility, contact angle, diffusion coefficient, Vickers hardness, and morphology of the crosslinked networks and compared with the specimens containing 10 wt.% hydroxyapatite (HAP) or calcium phosphate (CaP). The conversion degree (after 180 s of irradiation with visible light) ranged from 59.5% (F1) to 74.8% (F3), whereas the water sorption was between 23.15 μg mm{sup −3} (F1) and 40.52 μg mm{sup −3} (F3). Upon the addition of HAP or CaP this parameter attained values of 37.82–49.14 μg mm{sup −3} (F1–F3-HAP) and 34.58–45.56 μg mm{sup −3}, respectively. Also, the formation of resin tags through the infiltration of a dental composition (F3) was visualized by SEM analysis. The results suggest that UF-DMA taken as co-monomer in dental adhesives of acrylic type may provide improved properties in the moist environment of the mouth. - Highlights: • Fluorinated urethane dimethacrylate with carboxylic units (UF-DMA) was proposed as co-monomer in dental adhesives. • UF-DMA exhibits good photoreactivity in mixture with commercial dental monomers. • Water sorption/solubility and diffusion coefficient depend on the amount of UF-DMA. • The infiltration of adhesive mixture into the dentin tubules was evidenced by SEM.

  12. Isosorbide as the structural component of bio-based unsaturated polyesters for use as thermosetting resins.

    Science.gov (United States)

    Sadler, Joshua M; Toulan, Faye R; Nguyen, Anh-Phuong T; Kayea, Ronald V; Ziaee, Saeed; Palmese, Giuseppe R; La Scala, John J

    2014-01-16

    In recent years, the development of renewable bio-based resins has gained interest as potential replacements for petroleum based resins. Modified carbohydrate-based derivatives have favorable structural features such as fused bicyclic rings that offer promising candidates for the development of novel renewable polymers with improved thermomechanical properties when compared to early bio-based resins. Isosorbide is one such compound and has been utilized as the stiffness component for the synthesis of novel unsaturated polyesters (UPE) resins. Resin blends of BioUPE systems with styrene were shown to possess viscosities (120-2200 cP) amenable to a variety of liquid molding techniques, and after cure had Tgs (53-107 °C) and storage moduli (430-1650 MPa) that are in the desired range for composite materials. These investigations show that BioUPEs containing isosorbide can be tailored during synthesis of the prepolymer to meet the needs of different property profiles. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Influence of curing protocol on selected properties of light-curing polymers

    DEFF Research Database (Denmark)

    Dewaele, Magali; Asmussen, Erik; Peutzfeldt, Anne

    2009-01-01

    The purpose of this study was to investigate the effect of light-curing protocol on degree of conversion (DC), volume contraction (C), elastic modulus (E), and glass transition temperature (T(g)) as measured on a model polymer. It was a further aim to correlate the measured values with each other....

  14. Studies on chemoviscosity modeling for thermosetting resins

    Science.gov (United States)

    Bai, J. M.; Hou, T. H.; Tiwari, S. N.

    1987-01-01

    A new analytical model for simulating chemoviscosity of thermosetting resins has been formulated. The model is developed by modifying the well-established Williams-Landel-Ferry (WLF) theory in polymer rheology for thermoplastic materials. By introducing a relationship between the glass transition temperature Tg(t) and the degree of cure alpha(t) of the resin system under cure, the WLF theory can be modified to account for the factor of reaction time. Temperature dependent functions of the modified WLF theory constants C sub 1 (t) and C sub 2 (t) were determined from the isothermal cure data. Theoretical predictions of the model for the resin under dynamic heating cure cycles were shown to compare favorably with the experimental data. This work represents progress toward establishing a chemoviscosity model which is capable of not only describing viscosity profiles accurately under various cure cycles, but also correlating viscosity data to the changes of physical properties associated with the structural transformation of the thermosetting resin systems during cure.

  15. Simultaneous determination of components released from dental composite resins in human saliva by liquid chromatography/multiple-stage ion trap mass spectrometry.

    Science.gov (United States)

    Hsu, Wei-Yi; Wang, Ven-Shing; Lai, Chien-Chen; Tsai, Fuu-Jen

    2012-02-01

    Dental composite resins are widely used for fixing teeth; however, the monomers used in dental composite resins have been found to be cytotoxic and genotoxic, namely triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA), and bisphenol A glycol dimethacrylate (Bis-GMA). In this study, we incubated dental composite resins with human saliva for demonstrating the released monomers and biodegradation products. A simple saliva sample dilution method without purification or derivatization was used for quantification. We found that liquid chromatography coupled with multiple-stage ion trap mass spectrometry (LC-MS(n) ) operated in selected reaction monitoring (SRM) mode was able to separate the three monomers within 10 min. The calibration curves were linear (R² >0.996) over a wide range for each monomer in saliva: TEGDMA, 5-500 ppb; UDMA, 5-100 ppb, and Bis-GMA, 5-700 ppb. Furthermore, several biodegradation products were discovered with data-dependent MS/MS scan techniques. Although TEGMA degradation products have previously been reported, we identified two previously unknown UDMA degradation products. The LC-MS/MS method developed in this study was able to successfully quantify monomers and their principal biodegradation products from dental composite resins in human saliva. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Chemoviscosity modeling for thermosetting resins

    Science.gov (United States)

    Tiwari, S. N.; Hou, T. H.; Bai, J. M.

    1985-01-01

    A chemoviscosity model, which describes viscosity rise profiles accurately under various cure cycles, and correlates viscosity data to the changes of physical properties associated with structural transformations of the thermosetting resin system during cure, was established. Work completed on chemoviscosity modeling for thermosetting resins is reported.

  17. Study on the heat-resistant EB curing composites

    International Nuclear Information System (INIS)

    Bao Jianwen; Li Yang; Li Fengmei

    2000-01-01

    There are many advantages in the EB-curing process of composites. Heat-resistant EB-curing composites could substitute for polyimide composites used in aeronautical engine. The effects of catalyst and dose on the cured resin were investigated. The heat-resistance of the resin cured by EB was evaluated by dynamic mechanical thermal analysis (DMTA). The experiment result shows that the mechanical property of the composites cured by EB could meet the needs of the aeronautical engine in 250degC. (author)

  18. Influence of surface roughness on streptococcal adhesion forces to composite resins

    NARCIS (Netherlands)

    Mei, Li; Busscher, Henk J; van der Mei, Henny C; Ren, Yijin

    OBJECTIVE: To determine streptococcal adhesion forces with composite resins with different surface roughness. METHODS: Polishing and grinding were applied to obtain smooth (roughness 20 nm), moderately rough (150 nm) and rough (350 nm) surfaces of two orthodontic, light-cured composites. Adhesion

  19. Evaluation of post-curing and laser manufacturing parameters on the properties of SOMOS 7110 photosensitive resin used in stereolithography

    International Nuclear Information System (INIS)

    Salmoria, G.V.; Ahrens, C.H.; Beal, V.E.; Pires, A.T.N.; Soldi, V.

    2009-01-01

    The degree of cure of parts produced by stereolithography (SL) depends on laser power, manufacturing parameters, resin photosensitivity characteristics, and so on. Usually parts require a post-cure process, such as ultraviolet radiation and/or thermal treatment to improve their degree of cure, and thermal, mechanical and chemical properties. In this study, we evaluated the influence of line hatch spacing, an important manufacturing parameter, in relation to the calorimetric, dilatometric and hardness behavior of SL parts. The post-cure processes of ultraviolet radiation, microwave irradiation and conventional heating were also investigated. A higher degree of cure in green specimens was obtained with a line hatch spacing of 0.05 mm. However, the utilization of line hatch spacings of 0.15 and 0.10 mm induced an inhomogeneous curing process in relation to the internal and surface specimen structure, and remarkable cure shrinkage. The post-cure processes, especially the thermal treatment, improved the degree of cure of green specimens built using line hatch spacing of 0.10 mm, minimizing the anisotropy inherent to this rapid manufacturing method, which permits a better control over the dimensional behavior of SOMOS 7110 parts

  20. Simulation of the Vacuum Assisted Resin Transfer Molding (VARTM) process and the development of light-weight composite bridging

    Science.gov (United States)

    Robinson, Marc J.

    A continued desire for increased mobility in the aftermath of natural disasters, or on the battlefield, has lead to the need for improved light-weight bridging solutions. This research investigates the development of a carbon/epoxy composite bridging system to meet the needs for light-weight bridging. The research focuses on two main topics. The first topic is that of processing composite structures and the second is the design and testing of these structures. In recent years the Vacuum Assisted Resin Transfer Molding (VARTM) process has become recognized as a low-cost manufacturing alternative for large Fiber Reinforced Polymer (FRP) composite structures for civil, military, and aerospace applications. The success of the VARTM process (complete wet-out) is very sensitive to the resin injection strategy used and the proper placement of flow distribution materials and inlet and vacuum ports. Predicting the flow front pattern, the time required for infusing a part with resin, and the time required to bleed excess resin at the end of filling, is critical to ensure that the part will become completely impregnated and desired fiber volume fractions achieved prior to the resin gelling (initiation of cure). In order to eliminate costly trial and error experiments to determine the optimal infusion strategy, this research presents a simulation model which considers in-plane flow as well as flow through the thickness of the preform. In addition to resin filling, the current model is able to simulate the bleeding of resin at the end of filling to predict the required bleeding time to reach desired fiber volume fractions for the final part. In addition to processing, the second portion of the dissertation investigates the design and testing of composite bridge deck sections which also serve as short-span bridging for gaps up to 4 m in length. The research focuses on the design of a light-weight core material for bridge decking as well as proof loading of short-span bridge

  1. Cuspal deflection and microleakage in premolar teeth restored with bulk-fill flowable resin-based composite base materials

    DEFF Research Database (Denmark)

    Moorthy, A; Hogg, C H; Dowling, A H

    2012-01-01

    To assess the cuspal deflection and cervical microleakage of standardised Class II cavities incrementally filled with a dimethacrylate RBC or bulk-fill flowable RBC bases.......To assess the cuspal deflection and cervical microleakage of standardised Class II cavities incrementally filled with a dimethacrylate RBC or bulk-fill flowable RBC bases....

  2. Comparing depth-dependent curing radiant exposure and time of curing of regular and flow bulk-fill composites

    Directory of Open Access Journals (Sweden)

    Jose Augusto RODRIGUES

    2017-08-01

    Full Text Available Abstract The effect of restoration depth on the curing time of a conventional and two bulk-fill composite resins by measuring microhardness and the respective radiosity of the bottom surface of the specimen was investigated. 1-, 3- and 5-mm thick washers were filled with Surefil SDR Flow–U (SDR, Tetric EvoCeram Bulk Fill-IVA (TEC or Esthet-X HD–B1 (EHD, and cured with Bluephase® G2 for 40s. Additional 1-mm washers were filled with SDR, TEC or EHD, placed above the light sensor of MARC®, stacked with pre-cured 1-, 3- or 5-mm washer of respective material, and cured for 2.5~60s to mimic 2-, 4- and 6-mm thick composite curing. The sensor measured the radiosity (EB at the bottom of specimen stacks. Vickers hardness (VH was measured immediately at 5 locations with triplicate specimens. Nonlinear regression of VH vs EB by VH=α[1-exp(-EB/β] with all thickness shows that the values of α, maximum hardness, are 21.6±1.0 kg/mm2 for SDR, 38.3±0.6 kg/mm2 for TEC and 45.3±2.6 kg/mm2 for EHD, and the values of β, rate parameter, are 0.40±0.06 J/cm2 for SDR, 0.77±0.04 J/cm2 for TEC and 0.58±0.09 J/cm2 for EHD. The radiosity of the bottom surface was calculated when the bottom surface of each material attained 80% of α of each material. The curing times for each material are in agreement with manufacturer recommendation for thickness. It is possible to estimate time needed to cure composite resin of known depth adequately by the radiosity and microhardness of the bottom surface.

  3. Comparing depth-dependent curing radiant exposure and time of curing of regular and flow bulk-fill composites.

    Science.gov (United States)

    Rodrigues, Jose Augusto; Tenorio, Ilana Pais; Mello, Ginger Baranhuk Rabello de; Reis, André Figueiredo; Shen, Chiayi; Roulet, Jean-François

    2017-08-21

    The effect of restoration depth on the curing time of a conventional and two bulk-fill composite resins by measuring microhardness and the respective radiosity of the bottom surface of the specimen was investigated. 1-, 3- and 5-mm thick washers were filled with Surefil SDR Flow-U (SDR), Tetric EvoCeram Bulk Fill-IVA (TEC) or Esthet-X HD-B1 (EHD), and cured with Bluephase® G2 for 40s. Additional 1-mm washers were filled with SDR, TEC or EHD, placed above the light sensor of MARC®, stacked with pre-cured 1-, 3- or 5-mm washer of respective material, and cured for 2.5~60s to mimic 2-, 4- and 6-mm thick composite curing. The sensor measured the radiosity (EB) at the bottom of specimen stacks. Vickers hardness (VH) was measured immediately at 5 locations with triplicate specimens. Nonlinear regression of VH vs EB by VH=α[1-exp(-EB/β)] with all thickness shows that the values of α, maximum hardness, are 21.6±1.0 kg/mm2 for SDR, 38.3±0.6 kg/mm2 for TEC and 45.3±2.6 kg/mm2 for EHD, and the values of β, rate parameter, are 0.40±0.06 J/cm2 for SDR, 0.77±0.04 J/cm2 for TEC and 0.58±0.09 J/cm2 for EHD. The radiosity of the bottom surface was calculated when the bottom surface of each material attained 80% of α of each material. The curing times for each material are in agreement with manufacturer recommendation for thickness. It is possible to estimate time needed to cure composite resin of known depth adequately by the radiosity and microhardness of the bottom surface.

  4. Evaluation of degree of conversion and the effect of thermal aging on the color stability of resin cements and flowable composite.

    Science.gov (United States)

    Prieto, Lúcia Trazzi; Pimenta de Araújo, Cíntia Tereza; Araujo Pierote, Josué Junior; Salles de Oliveira, Dayane Carvalho Ramos; Coppini, Erick Kamiya; Sartini Paulillo, Luís Alexandre Maffei

    2018-01-01

    The aim of this in vitro study was to evaluate the color stability and degree of conversion (DC) of dual-cure and light-cure cements and flowable composites after thermal aging. A total of 50 human incisors were prepared and divided into six groups ( n = 10). Veneers were fabricated using IPS Empress Direct composite resin were bonded with three types of luting agents: Light-cured, conventional dual, and flowable composite according to the manufacturer's instructions. The groups were as follows: Filtek Z350XT Flow/Single Bond 2, RelyX ARC/Single Bond 2, RelyX Veneer/Single Bond 2, Tetric N-Flow/Tetric N-Bond, and Variolink II/Tetric N-Bond. Commission Internationale de l'Éclairage L*, a* and b* color coordinates were measured 24 h after cementation procedure with a color spectrophotometer and reevaluated after 10,000 thermal cycles. To evaluate the DC 50 specimens ( n = 10) of each resin material were obtained and Fourier transform infrared spectroscopy was used to evaluate the absorption spectra. Statistical analysis was performed with one-way ANOVA and Tukey's test (α = 0.05). No statistically significant differences in ΔE* occurred after aging. The greatest change in lightness occurred in the Variolink II resin cement. Changes in red-green hue were very small for the same cement and largest in the Tetric N-Flow flowable resin composite, while the greatest change in blue-yellow hue was a yellowing of the RelyX ARC luting cement. RelyX ARC exhibited the highest DC, and there were no statistically significant differences in DC among the other cements. Resin-based luting agent might affect the final of ceramic veneer restorations. The thermal aging affected the final color of the evaluated materials, and these were regarded as clinically unacceptable (ΔE >3.3).

  5. Poly(N-vinylimidazole/ethylene glycol dimethacrylate) for the purification and isolation of phenolic acids

    Energy Technology Data Exchange (ETDEWEB)

    Schemeth, Dieter; Noël, Jean-Christophe [Institute of Analytical Chemistry and Radiochemistry, Leopold-Franzens University of Innsbruck, CCB—Center of Chemistry and Biomedicine, Innrain 80-82, 6020 Innsbruck (Austria); Jakschitz, Thomas [Austrian Drug Screening Institute, Innrain 66a, 6020 Innsbruck (Austria); Rainer, Matthias, E-mail: m.rainer@uibk.ac.at [Institute of Analytical Chemistry and Radiochemistry, Leopold-Franzens University of Innsbruck, CCB—Center of Chemistry and Biomedicine, Innrain 80-82, 6020 Innsbruck (Austria); Tessadri, Richard [Institute of Mineralogy and Petrography, Leopold-Franzens University of Innsbruck, Innrain 52, 6020 Innsbruck (Austria); Huck, Christian W. [Institute of Analytical Chemistry and Radiochemistry, Leopold-Franzens University of Innsbruck, CCB—Center of Chemistry and Biomedicine, Innrain 80-82, 6020 Innsbruck (Austria); Bonn, Günther K. [Institute of Analytical Chemistry and Radiochemistry, Leopold-Franzens University of Innsbruck, CCB—Center of Chemistry and Biomedicine, Innrain 80-82, 6020 Innsbruck (Austria); Austrian Drug Screening Institute, Innrain 66a, 6020 Innsbruck (Austria)

    2015-07-23

    Highlights: • Free-radical polymerization of protonable vinylimidazole with EGMDA. • Polymer-optimization by maximum loading capacity of phenolic acids. • Performs better than SiO{sub 2} and Al{sub 2}O{sub 3} in normal phase mode using acetonitrile. • Performs equal or even better in anion-exchange mode compared to Oasis-MAX. • Efficient purification of phenolic compounds from crude extract. - Abstract: In this study we report the novel polymeric resin poly(N-vinyl imidazole/ethylene glycol dimethacrylate) for the purification and isolation of phenolic acids. The monomer to crosslinker ratio and the porogen composition were optimized for isolating phenolic acids diluted in acetonitrile at normal phase chromatography conditions, first. Acetonitrile serves as polar, aprotic solvent, dissolving phenolic acids but not interrupting interactions with the stationary phase due to the approved Hansen solubility parameters. The optimized resin demonstrated high loading capacities and adsorption abilities particularly for phenolic acids in both, acetonitrile and aqueous solutions. The adsorption behavior of aqueous standards can be attributed to ion exchange effects due to electrostatic interactions between protonated imidazole residues and deprotonated phenolic acids. Furthermore, adsorption experiments and subsequent curve fittings provide information of maximum loading capacities of single standards according to the Langmuir adsorption model. Recovery studies of the optimized polymer in the normal-phase and ion-exchange mode illustrate the powerful isolation properties for phenolic acids and are comparable or even better than typical, commercially available solid phase extraction materials. In order to prove the applicability, a highly complex extract of rosemary leaves was purified by poly(N-vinyl imidazole/ethylene glycol dimethacrylate) and the isolated compounds were identified using UHPLC–qTOF-MS.

  6. COMPOSITE RESIN BOND STRENGTH TO ETCHED DENTINWITH ONE SELF PRIMING ADHESIVE

    Directory of Open Access Journals (Sweden)

    P SAMIMI

    2002-09-01

    Full Text Available Introduction. The purpose of this study was to compare shear bond strength of composite resins to etched dentin in both dry and wet dentin surface with active and inactive application of a single-bottle adhesive resin (Single Bond, 3M Dental products. Methods. Fourthy four intact human extracted molars and premolars teeth were selected. The facial surfaces of the teeth were grounded with diamond bur to expose dentin. Then specimens were divided into four groups of 11 numbers (9 Molars and 2 Premolars. All the samples were etched with Phosphoric Acid Gel 35% and then rinsed for 10 seconds. The following stages were carried out for each group: Group I (Active-Dry: After rinsing, air drying of dentin surface for 15 seconds, active priming of adhesive resin for 15 seconds, air drying for 5 seconds, the adhesive resin layer was light cured for 10 seconds. Group III (Inactive-Dry:After rinsing, air drying of dentin surface for 15 seconds, adhesive resin was applied and air dryied for 5 seconds, the adhesive layer was light cured for 10 seconds. Group III (Active-Wet:After rinsing, removal of excess water of dentin surface with a cotton roll, active priming of adhesive resin for 15 seconds and air drying for 5 seconds, the adhesive layer was light cured for 10 seconds. Group IV (Inactive-Wet:After rinsing, removal of excess water of dentin surface with a cotton roll, the adhesive resin was applied and air dryied for 5 seconds and then cured for 10 seconds. After adhesive resin application, composite resin (Z250, 3M Dental products was applied on prepared surface with cylindrical molds (with internal diameter of 2.8mm, & height of 5mm and light-cured for 100 seconds (5x20s. The samples were then thermocycled. They were located in 6±3c water .temperature for 10 seconds and then 15 seconds in inviromental temperature, 10s in 55±3c water temperature and then were located at room temperature for 15s. This test was repeated for 100s. All of the specimens

  7. Comparison of stabilities in translucency, fluorescence and opalescence of direct and indirect composite resins.

    Science.gov (United States)

    Yu, Bin; Lee, Young-Keun

    2013-01-01

    To evaluate translucency, fluorescence and opalescence stabilities of direct and indirect composite resins after aging. One direct (16 shades) and two indirect composite resins (16 and 26 shades) were investigated. Resins were filled in a mold (1 mm thick) and light cured; post-curings were performed for indirect resins. Color was measured before and after 5,000 cycles of thermocycling on a reflection spectrophotometer in reflectance and transmittance modes to calculate parameters for translucency (TP), fluorescence (FL) and opalescence (OP). Differences in the changes of TP, FL and OP after aging by the type of resin were determined by t test, and those were also determined by one-way ANOVA with the factor of the brand or the shade group (P resins; and were -2.0 to 1.8, -0.9 to 0.4 and -2.9 to 3.7, respectively, for indirect resins. Changes in TP were not significantly different by the type of resin, but those in FL and OP were different (P = 0.05). Changes in optical parameters were influenced by the brand or the shade group of the resins (P resins varied depending on type, brand or shade group. Aging significantly affected fluorescence and opalescence, but not translucency, of indirect resins compared to those of direct resins.

  8. Wear Resistance of 3D Printing Resin Material Opposing Zirconia and Metal Antagonists

    Directory of Open Access Journals (Sweden)

    Ji-Man Park

    2018-06-01

    Full Text Available 3D printing offers many advantages in dental prosthesis manufacturing. This study evaluated the wear resistance of 3D printing resin material compared with milling and conventional resin materials. Sixty substrate specimens were prepared with three types of resin materials: 3D printed resin, milled resin, and self-cured resin. The 3D printed specimens were printed at a build angle of 0° and 100 μm layer thickness by digital light processing 3D printing. Two kinds of abraders were made of zirconia and CoCr alloy. The specimens were loaded at 5 kg for 30,000 chewing cycles with vertical and horizontal movements under thermocycling condition. The 3D printed resin did not show significant difference in the maximal depth loss or the volume loss of wear compared to the milled and the self-cured resins. No significant difference was revealed depending on the abraders in the maximal depth loss or the volume loss of wear. In SEM views, the 3D printed resin showed cracks and separation of inter-layer bonds when opposing the metal abrader. The results suggest that the 3D printing using resin materials provides adequate wear resistance for dental use.

  9. Perlekatan koloni Streptococcus mutans pada permukaan resin komposit sinar tampak (The adherence of Streptococcus mutans colony to surface visible light composite resins

    Directory of Open Access Journals (Sweden)

    Ajeng Anggraeni

    2005-03-01

    Full Text Available Visible light composite resins was used to restore anterior and posterior teeth, and it is always covered by saliva pellicle. S. mutans can adhere to all of the surface of oral cavity and visible light composite resins. The aim of this study was to know the amount of S. mutans colony adherence to visible light composite resins surface. The sample of 5 mm diameter and 3 mm in thickness was immersed in saliva for one hour, than the samples were put into bacteria suspension, incubated for 24 hours at 37° C. The amount of S. mutans was determined by direct count using microscope. The data were statistically analyzed by using t test. The result showed a significance difference of S. mutans colony between hybrid and micro fill visible light composite resins. The conclusion was that the amount of S. mutans adherence on the surface of hybrid was higher than the micro fill visible light composite resins.

  10. Effect of Sandblasting on Shear Bond Strength Composite Resin Veneer

    Directory of Open Access Journals (Sweden)

    Octarina Octarina

    2013-07-01

    Full Text Available Attachment between restoration and enamel surface in indirect resin composite veneer restoration (IRCV is obtained using multi-step (MS resin cement. Recently, a one step self-adhesive dual-cured resin cement (SADRC was introduced. Objective: To determine the effect of sandblasting on shear bond strength (SBS of IRCV to enamel using MS resin cement and SADRC. Methods: Forty specimens of buccal surface of enamel human were light-cured in Solidilite chamber and were divided into two groups: IRCV without sandblasting (n=20 and with sandblasting for 10 seconds (n=20 and then bonded to enamel using MS (n=10 and SADRC (n=10, respectively. After 24h SBS of specimens were tested using a Universal Testing Machine. Data were analyzed statistically by one-way ANOVA. Results: The average SBS value of IRCV without SB and bonded with MS was 18.95+7.80MPa and MS with SB was 19.30+ SB (4.85+2.12MPa and SADRC with SB (9.57+3.45MPa(p<0.05. Conclusion: increased SBS VIRK to enamel using MS resin cement than SADRC.  

  11. Evaluation of shear bond strength of orthodontic brackets using trans-illumination technique with different curing profiles of LED light-curing unit in posterior teeth.

    Science.gov (United States)

    Heravi, Farzin; Moazzami, Saied Mostafa; Ghaffari, Negin; Jalayer, Javad; Bozorgnia, Yasaman

    2013-11-21

    Although using light-cured composites for bonding orthodontic brackets has become increasingly popular, curing light cannot penetrate the metallic bulk of brackets and polymerization of composites is limited to the edges. Limited access and poor direct sight may be a problem in the posterior teeth. Meanwhile, effectiveness of the trans-illumination technique is questionable due to increased bucco-lingual thickness of the posterior teeth. Light-emitting diode (LED) light-curing units cause less temperature rise and lower risk to the pulpal tissue. The purpose of this study was to evaluate the clinical effectiveness of trans-illumination technique in bonding metallic brackets to premolars, using different light intensities and curing times of an LED light-curing unit. Sixty premolars were randomly divided into six groups. Bonding of brackets was done with 40- and 80-s light curing from the buccal or lingual aspect with different intensities. Shear bond strengths of brackets were measured using a universal testing machine. Data were analyzed by one-way analysis of variance test and Duncan's post hoc test. The highest shear bond belonged to group 2 (high intensity, 40 s, buccal) and the lowest belonged to group 3 (low intensity, 40 s, lingual). Bond strength means in control groups were significantly higher than those in experimental groups. In all experimental groups except group 6 (80 s, high intensity, lingual), shear bond strength was below the clinically accepted values. In clinical limitations where light curing from the same side of the bracket is not possible, doubling the curing time and increasing the light intensity during trans-illumination are recommended for achieving acceptable bond strengths.

  12. Tunable properties of novel tetra-functional fluorene-based benzoxazines from mixed amines: Synthesis, characterization and curing kinetics

    International Nuclear Information System (INIS)

    Feng, Tiantian; Wang, Jun; Pan, Lan; Derradji, Mehdi; Ramdani, Noureddine; Liu, Wenbin; Zhou, Haoran

    2016-01-01

    Highlights: • Synthesis of tetra-functional fluorene-based benzoxazines with tunable properties. • Cure reaction could be successfully described with the autocatalytic model. • The benzoxazines show an excellent heat resistance with T_g of 291–307 °C. • The benzoxazines exhibit good thermal stability with T_5 over 340 °C. - Abstract: A series of tetra-functional fluorene-based benzoxazines containing both flexible linear aliphatic chain and rigid aromatic structure in their backbones were synthesized using mixed amines such as aniline and n-octylamine, 2,7-dihydroxy-9,9-bis-(4-hydroxyphenyl)fluorene (THPF) and paraformaldehyde as raw materials via Mannich reaction. The prepared benzoxazine monomers were identified by fourier transform infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance ("1H NMR). In addition, the curing behavior, curing kinetics and rheological properties of these monomers as well as the thermal and mechanical properties of their cured resins were studied using a rheometer, differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA), and dynamic thermomechanical analyzer (DMA). The newly developed benzoxazines show good processibility, excellent thermal stability and high glass transition temperature (T_g) values ranging from 291 to 307 °C. By varying the proportion of n-octylamine to aniline, the properties of these resins are tuned.

  13. Roughness comparison of heat cured type of acrylic resin in disinfectant solution immersion (Immersion in a solution of alkaline peroxide and 75% Celery extract (Apium graveolens L

    Directory of Open Access Journals (Sweden)

    Dewi Puspitasari

    2016-08-01

    Full Text Available Acrylic resin denture base has the properties absorbing that affecting physical and mechanical properties. One of the physical properties of acrylic resin is surface roughness. The aim of the study was to find out the roughness effect on heat cured acrylic that was immersed in alkaline peroxide and 75% celery (Apium graveoens L extract as a disinfectant solution. The study was a true experimental and posttest with control group designed with a rectangular shape size 65 x 10 x 3.3 mm based on the ISO standard 1567, six samples were used for alkaline peroxide, celery extract 75% and aquadest group for 5 and 15 days. A Surface Roughness Tester was used for the surface roughness changes observation. The statistical test used One-way ANOVA and post hoc Bonferroni. The results of this study showed the value of roughness on 5 days for alkaline peroxide (1.51 µm is greater than celery extract (0.36µm and aquadest (0.30 µm. The soaking for 15 days in alkaline peroxide (1.52 µm is greater than 75% celery extracts (0.38 µm and aquadest (0.34 µm. Alkaline peroxide caused higher roughness value of heat cured acrylic resin than 75% celery extract.

  14. Temperature rise induced by various light curing units through human dentin.

    Science.gov (United States)

    Dogan, Arife; Hubbezoglu, Ihsan; Dogan, Orhan Murat; Bolayir, Giray; Demir, Hakan

    2009-05-01

    This study investigated temperature rises caused by different light curing units (LCUs) in dentin of different thicknesses. The different LCUs tested in this study were namely: quartz-tungsten-halogen (QTH) (Heliolux DLX) LCU, plasma arc (PAC) (Apollo 95E Elite) LCU, and light emitting diode (LED) (Mini LED) in standard curing mode as well as pulse and soft-start modes. One hundred and forty dentin disks of 0.5, 1, 1.5, and 2 mm thickness were prepared from mandibular molars (n=7). Temperatures were recorded using a L-type thermocouple in direct contact with the light guide tip. For all curing units/modes, dentin thickness was inversely proportional to temperature rise and that QTH light gave significantly higher values compared to PAC and LED in all the test conditions. The highest temperature rise was observed under 0.5-mm-thick dentin disk with QTH, whereas the lowest temperature rise was registered with LED light in pulse mode under 2-mm-thick dentin.

  15. EB/UV curing market in Malaysia

    Energy Technology Data Exchange (ETDEWEB)

    Dahlan, Khairul Zaman; Nik Salleh, Nik Ghazali; Mahmood, Mohd Hilmi [Malaysian Inst. for Nuclear Technology Res. (MINT), Bangi (Malaysia)

    1999-07-01

    Radiation curing of coatings of wood based products is expanding and being used for curing of coatings of table tops, parquet, wood panel, furniture, curtain railing, etc. UV curing of over print varnish is still the main application of UV curing in printing industry. However, curing ofprinting ink has also been extended in the printing of CD and VCD in addition to other printing such as paper, magazine, label on bottles, metal-can, etc. In the electronic industry, the manufacturer of printed circuit board is still the main consumer of UV curable resins. On the other hand, low energy electron beam machine is used mainly for cross-linking of heat shrink films.

  16. EB/UV curing market in Malaysia

    International Nuclear Information System (INIS)

    Khairul Zaman Dahlan; Nik Ghazali Nik Salleh; Mohd Hilmi Mahmood

    1999-01-01

    Radiation curing of coatings of wood based products is expanding and being used for curing of coatings of table tops, parquet, wood panel, furniture, curtain railing, etc. UV curing of over print varnish is still the main application of UV curing in printing industry. However, curing of printing ink has also been extended in the printing of CD and VCD in addition to other printing such as paper, magazine, label on bottles, metal-can, etc. In the electronic industry, the manufacturer of printed circuit board is still the main consumer of UV curable resins. On the other hand, low energy electron beam machine is used mainly for cross-linking of heat shrink films

  17. Implications of resin-based composite (RBC) restoration on cuspal deflection and microleakage score in molar teeth: Placement protocol and restorative material.

    Science.gov (United States)

    McHugh, Lauren E J; Politi, Ioanna; Al-Fodeh, Rami S; Fleming, Garry J P

    2017-09-01

    To assess the cuspal deflection of standardised large mesio-occluso-distal (MOD) cavities in third molar teeth restored using conventional resin-based composite (RBC) or their bulk fill restorative counterparts compared with the unbound condition using a twin channel deflection measuring gauge. Following thermocycling, the cervical microleakage of the restored teeth was assessed to determine marginal integrity. Standardised MOD cavities were prepared in forty-eight sound third molar teeth and randomly allocated to six groups. Restorations were placed in conjunction with (and without) a universal bonding system and resin restorative materials were irradiated with a light-emitting-diode light-curing-unit. The dependent variable was the restoration protocol, eight oblique increments for conventional RBCs or two horizontal increments for the bulk fill resin restoratives. The cumulative buccal and palatal cuspal deflections from a twin channel deflection measuring gauge were summed, the restored teeth thermally fatigued, immersed in 0.2% basic fuchsin dye for 24h, sectioned and examined for cervical microleakage score. The one-way analysis of variance (ANOVA) identified third molar teeth restored using conventional RBC materials had significantly higher mean total cuspal deflection values compared with bulk fill resin restorative restoration (all pmaterial selection is vital in the absence of clinical data. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. Biocompatible Metal-Oxide Nanoparticles: Nanotechnology Improvement of Conventional Prosthetic Acrylic Resins

    Directory of Open Access Journals (Sweden)

    Laura S. Acosta-Torres

    2011-01-01

    Full Text Available Nowadays, most products for dental restoration are produced from acrylic resins based on heat-cured Poly(Methyl MethAcrylate (PMMA. The addition of metal nanoparticles to organic materials is known to increase the surface hydrophobicity and to reduce adherence to biomolecules. This paper describes the use of nanostructured materials, TiO2 and Fe2O3, for simultaneously coloring and/or improving the antimicrobial properties of PMMA resins. Nanoparticles of metal oxides were included during suspension polymerization to produce hybrid metal oxides-alginate-containing PMMA. Metal oxide nanoparticles were characterized by dynamic light scattering, and X-ray diffraction. Physicochemical characterization of synthesized resins was assessed by a combination of spectroscopy, scanning electron microscopy, viscometry, porosity, and mechanical tests. Adherence of Candida albicans cells and cellular compatibility assays were performed to explore biocompatibility and microbial adhesion of standard and novel materials. Our results show that introduction of biocompatible metal nanoparticles is a suitable means for the improvement of conventional acrylic dental resins.

  19. Biocompatible Metal-Oxide Nanoparticles: Nanotechnology Improvement of Conventional Prosthetic Acrylic Resins

    International Nuclear Information System (INIS)

    Acosta-Torres, L.S.; Lopez-Marin, L.M.; Padron, G.H.; Castano, V.M.; Nunez-Anita, R.E.

    2011-01-01

    Nowadays, most products for dental restoration are produced from acrylic resins based on heat-cured Poly(Methyl Methacrylate) (PMMA). The addition of metal nanoparticles to organic materials is known to increase the surface hydrophobicity and to reduce adherence to biomolecules. This paper describes the use of nano structured materials, TiO 2 and Fe 2 O 3 , for simultaneously coloring and/or improving the antimicrobial properties of PMMA resins. Nanoparticles of metal oxides were included during suspension polymerization to produce hybrid metal oxides-alginate-containing PMMA. Metal oxide nanoparticles were characterized by dynamic light scattering, and X-ray diffraction. Physicochemical characterization of synthesized resins was assessed by a combination of spectroscopy, scanning electron microscopy, viscometry, porosity, and mechanical tests. Adherence of Candida albicans cells and cellular compatibility assays were performed to explore biocompatibility and microbial adhesion of standard and novel materials. Our results show that introduction of biocompatible metal nanoparticles is a suitable means for the improvement of conventional acrylic dental resins.

  20. Chemoviscosity modeling for thermosetting resin systems, part 3

    Science.gov (United States)

    Hou, T. H.; Bai, J. M.

    1988-01-01

    A new analytical model for simulating chemoviscosity resin has been formulated. The model is developed by modifying the well established Williams-Landel-Ferry (WLF) theory in polymer rheology for thermoplastic materials. By introducing a relationship between the glass transition temperature (T sub g (t)) and the degree of cure alpha(t) of the resin system under cure, the WLF theory can be modified to account for the factor of reaction time. Temperature-dependent functions of the modified WLF theory parameters C sub 1 (T) and C sub 2 (T) were determined from the isothermal cure data. Theoretical predictions of the model for the resin under dynamic heating cure cycles were shown to compare favorably with the experimental data. This work represents a progress toward establishing a chemoviscosity model which is capable of not only describing viscosity profiles accurately under various cure cycles, but also correlating viscosity data to the changes of physical properties associated with the structural transformations of the thermosetting resin systems during cure.

  1. Thio-urethane oligomers improve the properties of light-cured resin cements.

    Science.gov (United States)

    Bacchi, Ataís; Consani, Rafael L; Martim, Gedalias C; Pfeifer, Carmem S

    2015-05-01

    Thio-urethanes were synthesized by combining 1,6-hexanediol-diissocyante (aliphatic) with pentaerythritol tetra-3-mercaptopropionate (PETMP) or 1,3-bis(1-isocyanato-1-methylethyl)benzene (aromatic) with trimethylol-tris-3-mercaptopropionate (TMP), at 1:2 isocyanate:thiol, leaving pendant thiols. Oligomers were added at 10-30 phr to BisGMA-UDMA-TEGDMA (5:3:2, BUT). 25 wt% silanated inorganic fillers were added. Commercial cement (Relyx Veneer, 3M-ESPE) was also evaluated with 10-20 phr of aromatic oligomer. Near-IR was used to follow methacrylate conversion (DC) and rate of polymerization (Rpmax). Mechanical properties were evaluated in three-point bending (ISO 4049) for flexural strength/modulus (FS/FM, and toughness), and notched specimens (ASTM Standard E399-90) for fracture toughness (KIC). Polymerization stress (PS) was measured on the Bioman. Volumetric shrinkage (VS, %) was measured with the bonded disk technique. Results were analyzed with ANOVA/Tukey's test (α=5%). In general terms, for BUT cements, conversion and mechanical properties in flexure increased for selected groups with the addition of thio-urethane oligomers. The aromatic versions resulted in greater FS/FM than aliphatic. Fracture toughness increased by two-fold in the experimental groups (from 1.17 ± 0.36 MPam(1/2) to around 3.23 ± 0.22 MPam(1/2)). Rpmax decreased with the addition of thio-urethanes, though the vitrification point was not statistically different from the control. VS and PS decreased with both oligomers. For the commercial cement, 20 phr of oligomer increased DC, vitrification, reduced Rpmax and also significantly increased KIC, and reduced PS and FM. Thio-urethane oligomers were shown to favorably modify conventional dimethacrylate networks. Significant reductions in polymerization stress were achieved at the same time conversion and fracture toughness increased. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  2. Stability of the Light Output, Oral Cavity Tip Accessibility in Posterior Region and Emission Spectrum of Light-Curing Units.

    Science.gov (United States)

    André, C B; Nima, G; Sebold, M; Giannini, M; Price, R B

    2018-04-09

    This study evaluated the light output from six light-emitting diode dental curing lights after 25 consecutive light exposures without recharging the battery, tip accessibility in the posterior region, and light beam spread from light-curing units. Irradiance, spectral peak, and radiant exposure were measured with the battery fully charged (Bluephase Style, ESPE Cordless, Elipar S10, Demi Ultra, Valo Cordless, and Radii-Cal) and monitored for 25 light exposures (each lasting 10 seconds). The tip diameter was measured to identify the beam size and the ability of the six light-curing units to irradiate all areas of the lower second molar in the standard output setting. Four curing lights delivered a single peak wavelength from 454 to 462 nm, and two (Bluephase Style and Valo Cordless) delivered multiple emission peaks (at 410 and 458 nm and 400, 450, and 460 nm, respectively). The irradiance and radiant exposure always decreased after 25 exposures by 2% to 8%, depending on the light unit; however, only ESPE Cordless, Valo Cordless, and Radii-Cal presented a statistical difference between the first and the last exposure. The tip diameter ranged from 6.77 mm to 9.40 mm. The Radii-Cal delivered the lowest radiant exposure and irradiance. This light was also unable to access all the teeth with the tip parallel to the occlusal surface of the tooth. Not all of the blue-emitting lights deliver the same emission spectra, and some curing lights delivered a lower irradiance (as much as 8% lower) after the 25th exposure.

  3. Effect of gingival fluid on marginal adaptation of Class II resin-based composite restorations.

    Science.gov (United States)

    Spahr, A; Schön, F; Haller, B

    2000-10-01

    To evaluate in vitro the marginal quality of Class II composite restorations at the gingival enamel margins as affected by contamination of the cavities with gingival fluid (GF) during different steps of resin bonding procedures. 70 Class II cavities were prepared in extracted human molars and restored with composite using a multi-component bonding system (OptiBond FL/Herculite XRV; OPTI) or a single-bottle adhesive (Syntac Sprint/Tetric Ceram; SYN). The cavities were contaminated with human GF: C1 after acid etching, C2 after application of the primer (OPTI) or light-curing of the primer-adhesive (SYN), and C3 after light-curing of the resin adhesive (OPTI). Uncontaminated cavities were used as the control (C0). The restored teeth were subjected to thermocycling (TC) and replicated for SEM analysis of marginal gap formation. Microleakage at the gingival margins was determined by dye penetration with basic fuchsin. non-parametric tests (Kruskal-Wallis test, Mann-Whitney test with Bonferroni correction). In both bonding systems, contamination with GF after acid etching (C1) did not impair the marginal quality; the mean percentages of continuous margin/mean depths of dye penetration were: OPTI: C0: 88.5%/0.10 mm, C1: 95.6%/0.04 mm; SYN: C0: 90.9%/0.08 mm, C1: 97.0%/0.05 mm. Marginal adaptation was adversely affected when GF contamination was performed after

  4. Photocurable bioactive bone cement based on hydroxyethyl methacrylate-poly(acrylic/maleic) acid resin and mesoporous sol gel-derived bioactive glass

    Energy Technology Data Exchange (ETDEWEB)

    Hesaraki, S., E-mail: S-hesaraki@merc.ac.ir

    2016-06-01

    This paper reports on strong and bioactive bone cement based on ternary bioactive SiO{sub 2}-CaO-P{sub 2}O{sub 5} glass particles and a photocurable resin comprising hydroxyethyl methacrylate (HEMA) and poly(acrylic/maleic) acid. The as-cured composite represented a compressive strength of about 95 MPa but it weakened during soaking in simulated body fluid, SBF, qua its compressive strength reached to about 20 MPa after immersing for 30 days. Biodegradability of the composite was confirmed by reducing its initial weight (~ 32%) as well as decreasing the molecular weight of early cured resin during the soaking procedure. The composite exhibited in vitro calcium phosphate precipitation in the form of nanosized carbonated hydroxyapatite, which indicates its bone bonding ability. Proliferation of calvarium-derived newborn rat osteoblasts seeded on top of the composite was observed during incubation at 37 °C, meanwhile, an adequate cell supporting ability was found. Consequently, it seems that the produced composite is an appropriate alternative for bone defect injuries, because of its good cell responses, high compressive strength and ongoing biodegradability, though more in vivo experiments are essential to confirm this assumption. - Highlights: • Light cure cement based on SiO{sub 2}-CaO-P{sub 2}O{sub 5} glass and polymer-like matrix was formed. • The matrix includes poly(acrylic/maleic acid) and poly(hydroxyethyl methacrylate). • The cement is as strong as polymethylmethacrylate bone cement. • The cement exhibits apatite formation ability in simulated body fluid. • The cement is biodegradable and supports proliferation of osteoblastic cells.

  5. Color stability of bulk-fill and incremental-fill resin-based composites polished with aluminum-oxide impregnated disks

    Directory of Open Access Journals (Sweden)

    Uzay Koc-Vural

    2017-05-01

    Full Text Available Objectives This study aimed to evaluate the color stability of bulk-fill and nanohybrid resin-based composites polished with 3 different, multistep, aluminum-oxide impregnated finishing and polishing disks. Materials and Methods Disk-shaped specimens (8 mm in diameter and 4 mm in thickness were light-cured between two glass slabs using one nanohybid bulk-fill (Tetric EvoCeram, Ivoclar Vivadent, one micro-hybrid bulk-fill (Quixfil, Dentsply, and two nanohybrid incremental-fill (Filtek Ultimate, 3M ESPE; Herculite XRV Ultra, Kerr resin-based composites, and aged by thermocycling (between 5 - 55℃, 3,000 cycles. Then, they were divided into subgroups according to the polishing procedure as SwissFlex (Coltène/Whaledent, Optidisc (Kerr, and Praxis TDV (TDV Dental (n = 12 per subgroup. One surface of each specimen was left unpolished. All specimens were immersed in coffee solution at 37℃. The color differences (ΔE were measured after 1 and 7 days of storage using a colorimeter based on CIE Lab system. The data were analyzed by univariate ANOVA, Mann-Whitney U test, and Friedmann tests (α = 0.05. Results Univariate ANOVA detected significant interactions between polishing procedure and composite resin and polishing procedure and storage time (p 0.05. Polishing reduced the discoloration resistance of Tetric EvoCeram/SwissFlex, Tetric EvoCeram/Praxis TDV, Quixfil-SwissFlex, and all Herculite XRV Ultra groups after 7 days storage (p < 0.05. Conclusions Discoloration resistance of bulk-fill resin-based composites can be significantly affected by the polishing procedures.

  6. Do light cured ART conventional high-viscosity glass-ionomer sealants perform better than resin-composite sealants: a 4-year randomized clinical trial

    NARCIS (Netherlands)

    Zhang, W.; Chen, X.; Fan, M.W.; Mulder, J.; Huysmans, M.C.D.N.J.M.; Frencken, J.E.F.M.

    2014-01-01

    OBJECTIVE: The hypotheses tested were: the cumulative survival rates of dentin caries lesion-free pits and fissures of ART conventional high-viscosity glass-ionomer sealants with light-curing (high-intensity LED) and glass-carbomer sealants are higher than those of conventional ART sealants and

  7. Salivary contamination during bonding procedures with a one-bottle adhesive system.

    Science.gov (United States)

    Fritz, U B; Finger, W J; Stean, H

    1998-09-01

    The effect of salivary contamination of enamel and dentin on bonding efficacy of an experimental one-bottle resin adhesive was investigated. The adhesive was a light-curing urethane dimethacrylate/hydroxyethyl methacrylate/4-methacryloxyethyl trimellitate anhydride mixture dissolved in acetone. Evaluation parameters were shear bond strength and marginal gap width in a dental cavity. Apart from a control group without contamination (group 1), etched enamel and dentin were (2) contaminated with saliva and air dried; (3) contaminated, rinsed, and blot dried; (4) coated with adhesive, contaminated, rinsed, and blot dried; (5) coated with adhesive, light cured, contaminated, rinsed, and air dried; or (6) treated as in group 5, with additional adhesive application after air drying. There was no negative effect in groups 3 and 4, compared with control. Air drying after salivary contamination (group 2) resulted in low shear bond strengths and wide marginal gaps. Contamination of the cured adhesive layer (groups 5 and 6) had no adverse effect on enamel shear bond strengths, but resulted in 50% reduced dentin shear bond strengths and wide marginal gaps. The one-bottle adhesive system is relatively insensitive to salivary contamination, provided that the contamination occurs prior to light curing of the adhesive and is carefully rinsed and blot dried. Salivary contact after adhesive curing must be avoided.

  8. Cytotoxic evaluation of hydroxyapatite-filled and silica/hydroxyapatite-filled acrylate-based restorative composite resins: An in vitro study.

    Science.gov (United States)

    Chadda, Harshita; Naveen, Sangeetha Vasudevaraj; Mohan, Saktiswaren; Satapathy, Bhabani K; Ray, Alok R; Kamarul, Tunku

    2016-07-01

    Although the physical and mechanical properties of hydroxyapatite-filled dental restorative composite resins have been examined, the biocompatibility of these materials has not been studied in detail. The purpose of this in vitro study was to analyze the toxicity of acrylate-based restorative composite resins filled with hydroxyapatite and a silica/hydroxyapatite combination. Five different restorative materials based on bisphenol A-glycidyl methacrylate (bis-GMA) and tri-ethylene glycol dimethacrylate (TEGDMA) were developed: unfilled (H0), hydroxyapatite-filled (H30, H50), and silica/hydroxyapatite-filled (SH30, SH50) composite resins. These were tested for in vitro cytotoxicity by using human bone marrow mesenchymal stromal cells. Surface morphology, elemental composition, and functional groups were determined by scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), and Fourier-transformed infrared spectroscopy (FTIR). The spectra normalization, baseline corrections, and peak integration were carried out by OPUS v4.0 software. Both in vitro cytotoxicity results and SEM analysis indicated that the composite resins developed were nontoxic and supported cell adherence. Elemental analysis with EDX revealed the presence of carbon, oxygen, calcium, silicon, and gold, while the presence of methacrylate, hydroxyl, and methylene functional groups was confirmed through FTIR analysis. The characterization and compatibility studies showed that these hydroxyapatite-filled and silica/hydroxyapatite-filled bis-GMA/TEGDMA-based restorative composite resins are nontoxic to human bone marrow mesenchymal stromal cells and show a favorable biologic response, making them potential biomaterials. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  9. Effect of Relining Methods (Cold & Heat Cure On the Accuracy of Posterior

    Directory of Open Access Journals (Sweden)

    Nafiseh AsadzadehOghadaee

    2013-01-01

    Full Text Available Introduction: The posterior palatal area is the most important area for retention of maxillary dentures and must be considered carefully during and after the reline. The purpose of this in vitro study was to compare the posterior palatal seal in relined complete dentures with two different methods.Materials & Methods: An average size of edentulous maxillary acrylic arch without undercuts was selected in this in vitro study. The alginate impression was made of this model ten times and was poured with a type IV gypsum product, and the casts of control groups were prepared. Then 10 definitive bases were created for each cast. For the experimental groups, one relief wax layer with a thickness of 2mm was put in post-dam area for relining processes. Then, 20 alginate impressions were made of this model. On definitive base, clear heat-cured acrylic bases were fabricated. In experimental groups, bases were divided into 2 groups of 10: first group was relined with heat-cured acrylic resin and another one was relined with cold cured acrylic resin. All of the bases were put in distilled water for two weeks and then each of them was placed on the definitive base. One code was considered for each model. The gap in posterior area between acrylic bases and arch was measured in five points (a-b-c-d-e: mid line, two points in hamular notch, and two points between midline and hamular notch by two practicers in two different times (during two weeks with light B×60 microscope. The data were analyzed by Tukey and Kruskal Wallis tests.Results: The results of this study indicated that there was a statistically significant difference in the amount of gap at point A between control (bases without reline and experimental groups (P=0.047. At point D there was no significant difference between experimental groups, but a significant difference was detected between control group and bases relined with cold cure acryl (P<0.05.Conclusion: The results of this laboratory study

  10. Post-irradiation hardness of resin-modified glass ionomer cements and a polyacid-modified composite resin

    International Nuclear Information System (INIS)

    Yap, A.U.J.

    1997-01-01

    This study examined the post-irradiation hardness of resin-modified glass ionomer cements and a polyacid-modified composite resin using a digital microhardness tester. Change in hardness of these materials over a period of 6 months was compared to that of conventional glass ionomer cements and a composite resin. With the exception of the composite resin, all materials showed a significant increase in hardness over 24 h after their initial set. Dual-cure resin-modified glass ionomer cements showed decreased hardness with increased storage time in saline at 37 o C. Results suggest that the addition of resins to glass ionomer cements does not improve initial hardness and does not negate the acid-base reaction of conventional cements. Resin addition may, however, lead to increased water sorption and decreased hardness. (author)

  11. Influence of staining solutions and whitening procedures on discoloration of hybrid composite resins.

    Science.gov (United States)

    Garoushi, Sufyan; Lassila, Lippo; Hatem, Marwa; Shembesh, Muneim; Baady, Lugane; Salim, Ziad; Vallittu, Pekka

    2013-01-01

    The aim was to evaluate the color stability and water uptake of two hybrid composite resins polymerized in two different conditions after exposure to commonly consumed beverages. In addition, the effect of repolishing and bleaching on the stained composite was evaluated. Eighty specimens (12 mm × 12 mm × 3 mm) were made from two hybrid composite resins of shade A2. Forty specimens of each composite were divided into two groups (n = 20 per each) according to the curing method used (hand light cure HLC or oven light cure OLC). Then each group (HLC or OLC) was sub-divided randomly into four sub-groups (n = 5), which were immersed for 60 days in different beverages (distal water, coffee, tea and pepsi) and incubated at 37°C. Water uptake was measured during this time and followed by measurement of color difference (ΔE) by using a spectrophotometer. After complete staining, repolishing (grit 4000 FEPA at 300 rpm under water) and bleaching (40% hydrogen peroxide bleaching gel) were conducted. The repolished and bleached specimens were submitted to new color measurements. Color value of the specimens immersed in tea displayed the highest statistically significant (p pepsi was significantly lower than the others. After staining of the composite resins, both the bleaching and repolishing were able to reduce the ΔE value. All beverages used affected the color stability of tested composite resins. The effect of beverages on color change of composites depends on type of beverage and water uptake value of resins used. A superior whitening effect was obtained with repolishing technique compared to bleaching.

  12. Effect of preheating and light-curing unit on physicochemical properties of a bulk fill composite

    Directory of Open Access Journals (Sweden)

    Theobaldo JD

    2017-05-01

    Full Text Available Jéssica Dias Theobaldo,1 Flávio Henrique Baggio Aguiar,1 Núbia Inocencya Pavesi Pini,2 Débora Alves Nunes Leite Lima,1 Priscila Christiane Suzy Liporoni,3 Anderson Catelan3 1Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, 2Ingá University Center, Maringá, 3Departament of Dentistry, University of Taubaté, Taubaté, Brazil Objective: The aim of this study is to evaluate the effect of composite preheating and polymerization mode on degree of conversion (DC, microhardness (KHN, plasticization (P, and depth of polymerization (DP of a bulk fill composite.Methods: Forty disc-shaped samples (n = 5 of a bulk fill composite were prepared (5 × 4 mm thick and randomly divided into 4 groups according to light-curing unit (quartz–tungsten–halogen [QTH] or light-emitting diode [LED] and preheating temperature (23 or 54 °C. A control group was prepared with a flowable composite at room temperature. DC was determined using a Fourier transform infrared spectrometer, KHN was measured with a Knoop indenter, P was evaluated by percentage reduction of hardness after 24 h of ethanol storage, and DP was obtained by bottom/top ratio. Data were statistically analyzed by analysis of variance and Tukey’s test (α = 0.05.Results: Regardless of light-curing, the highest preheating temperature increased DC compared to room temperature on bottom surface. LED showed a higher DC compared to QTH. Overall, DC was higher on top surface than bottom. KHN, P, and DP were not affected by curing mode and temperature, and flowable composite showed similar KHN, and lower DC and P, compared to bulk fill.Conclusion: Composite preheating increased the polymerization degree of 4-mm-increment bulk fill, but it led to a higher plasticization compared to the conventional flowable composite evaluated. Keywords: composite resins, physicochemical phenomena, polymerization, hardness, heating

  13. Evaluation of mechanical properties of Z250 composite resin light-cured by different methods Avaliação de propriedades mecânicas da resina composta Z250 fotoativada com diferentes métodos

    Directory of Open Access Journals (Sweden)

    Andresa Carla Obici

    2005-12-01

    Full Text Available This study evaluated some mechanical parameters of Z250 composite resin using different light-curing methods. Ten specimens were prepared for each mechanical test group with different dimensions according to the test. Light-curing was performed by: a. continuous light (800mW/cm²-40s; b. exponential light (0-800mW/cm²-40s; c. intermittent light (2s-600mW/cm²; 2s without light-80s; d. stepped light (10s-150mW/cm²; 30s-650mW/cm²; e. PAC (1320mW/cm²-3s; f. LED (350mW/cm²-40s. After 24 ± 1 h, the specimens were loaded at a crosshead speed of 0.5 mm/min until fracture. The mechanical properties were calculated and analyzed by ANOVA and Tukey test (5%. The results showed that the highest compressive strength values were found for the continuous, exponential, intermittent and stepped light methods, whereas PAC and LED obtained the lowest values. LED, stepped light, PAC, exponential and continuous light presented the highest values for diametral tensile strength. The intermittent light showed the lowest value, which was significantly lower than the value obtained for LED only. Flexural strength results were not significantly different between all light-curing methods. Finally, the highest modulus of elasticity values were obtained for LED, exponential, continuous and intermittent light, whereas PAC and stepped light showed the lowest values. The mechanical properties were affected by light-curing methods employed.Este estudo avaliou algumas propriedades mecânicas da resina composta Z250 usando diferentes métodos de fotoativação. Dez amostras foram preparadas para cada grupo, com diferentes dimensões de acordo com o ensaio. Os métodos de fotoativação foram: a luz contínua (800mW/cm²-40s; b luz exponencial (0-800mW/cm²-40s; c luz intermitente (2s-600mW/cm²; 2s sem luz-80s; d dupla intensidade (10s-150mW/cm²; 30s-650mW/cm²; e PAC (1320mW/cm²-3s; f LED (350mW/cm²-40s. Após 24 ± 1 h, as amostras foram carregadas até fraturar (v=0

  14. Paramagnetic epoxy resin

    Directory of Open Access Journals (Sweden)

    E. C. Vazquez Barreiro

    2017-01-01

    Full Text Available This work illustrates that macrocycles can be used as crosslinking agents for curing epoxy resins, provided that they have appropriate organic functionalities. As macrocycles can complex metal ions in their structure, this curing reaction allows for the introduction of that metal ion into the resin network. As a result, some characteristic physical properties of the metallomacrocycle could be transferred to the new material. The bisphenol A diglycidyl ether (BADGE, n = 0 and hemin (a protoporphyrin IX containing the Fe(III ion, and an additional chloride ligand have been chosen. The new material has been characterized by differential scanning calorimetry (DSC, thermogravimetric analysis (TGA, Fourier Transform Infrared (FT-IR, Nuclear Magnetic Resonance (NMR, Transmission Electron Microscopy (TEM, and magnetic susceptibility measurements. Fe(III remains in the high-spin state during the curing process and, consequently, the final material exhibits the magnetic characteristics of hemin. The loss of the chlorine atom ligand during the cure of the resin allows that Fe(III can act as Lewis acid, catalyzing the crosslinking reactions. At high BADGE n = 0/hemin ratios, the formation of ether and ester bonds occurs simultaneously during the process.

  15. Comparison of temperature rise in the pulp chamber with different light curing units: An in-vitro study.

    Science.gov (United States)

    Rajesh Ebenezar, A V; Anilkumar, R; Indira, R; Ramachandran, S; Srinivasan, M R

    2010-07-01

    This in vitro study was designed to measure and compare the temperature rise in the pulp chamber with different light curing units. The study was done in two settings-in-vitro and in-vivo simulation. In in-vitro setting, 3mm and 6mm acrylic spacers with 4mm tip diameter thermocouple was used and six groups were formed according to the light curing source- 3 Quartz-Tungsten-Halogen (QTH) units and 3 Light-Emitting-Diode (LED) units. For the LED units, three modes of curing like pulse-cure mode, fast mode and ramp mode were used. For in-vivo simulation, 12 caries free human third molar tooth with fused root were used. K-type thermocouple with 1 mm tip diameter was used. Occlusal cavity was prepared, etched, rinsed with water and blot dried; bonding agent was applied and incremental curing of composite was done. Thermal emission for each light curing agent was noted. Temperature rise was very minimal in LED light cure units than in QTH light cure units in both the settings. Temperature rise was minimal at 6mm distance when compared to 3 mm distance. Among the various modes, fast mode produces the less temperature rise. Temperature rise in all the light curing units was well within the normal range of pulpal physiology. Temperature rise caused due to light curing units does not result in irreversible pulpal damage.

  16. Design And Implementation of Microcontroller Based Curing Light Control of Dental System.

    OpenAIRE

    Ali hussein hamed

    2006-01-01

    In this paper, a microcontroller-based electronic circuit have been designed and implemented for dental curing system using 8-bit MCS-51 microcontroller. Also a new control card is designed while considering advantages of microcontroller systems the time of curing was controlled automatically by preset values which were input from a push-button switch. An ignition based on PWM technique was used to reduce the high starting current needed for the halogen lamp. This paper and through the test r...

  17. Photoacoustic study of curing time by UV laser radiation of a photoresin with different thickness

    Energy Technology Data Exchange (ETDEWEB)

    Pincel, P. Vieyra [UPIITA IPN, Avenida Instituto Politécnico Nacional, No. 2580, Col. Barrio la Laguna Ticomán, Delegación Gustavo A. Madero, C.P. 07340 México, D.F. (Mexico); Jiménez-Pérez, J.L., E-mail: jimenezp@fis.cinvestav.mx [UPIITA IPN, Avenida Instituto Politécnico Nacional, No. 2580, Col. Barrio la Laguna Ticomán, Delegación Gustavo A. Madero, C.P. 07340 México, D.F. (Mexico); Cruz-Orea, A. [Departamento de Física, CINVESTAV-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, C.P. 07360 México, D.F. (Mexico); Correa-Pacheco, Z.N. [Instituto Politécnico Nacional-Centro de Desarrollo de Productos Bióticos (CEPROBI). Carr. Yautepec–Jojutla, km 6. San Isidro, C.P. 62730 Yautepec, Morelos (Mexico); Rosas, J. Hernández [UPIITA IPN, Avenida Instituto Politécnico Nacional, No. 2580, Col. Barrio la Laguna Ticomán, Delegación Gustavo A. Madero, C.P. 07340 México, D.F. (Mexico)

    2015-04-20

    Highlights: • The curing of a resin in the presence of a UV laser radiation was studied. • Open photoacoustic cell technique was used to characterize the curing of the resin. • The curing of the resin as a function of time was studied. • A parabolic behavior of the resin thickness, as a function of time was observed. • UV–vis and FTIR spectroscopy were employed to characterize the resin. - Abstract: This paper deals with the study of the cure of a resin in the presence of a UV laser radiation used as the excitation source, operated at λ = 405 nm, with an output power of 20 mW. The open photoacoustic cell (OPC) technique was used to study the curing of the resins as a function of time. The curing characteristic time values were τ = 10.43, 20.99, 30.18, 45.84, 67.59 and 89.55 s for the resin thicknesses of 1000, 2000, 3000, 4000, 5000 and 6000 μm, respectively. A parabolic behavior of the resin thickness, as a function of the curing characteristic time, was obtained. UV–vis spectroscopy and infrared Fourier transform spectroscopy (FTIR) techniques were employed to characterize the resin in order to study the optical absorption and the chemical bonds, respectively. Our work has applications in the manufacture of 3D printing parts for applications, among others, in medicine.

  18. Photoacoustic study of curing time by UV laser radiation of a photoresin with different thickness

    International Nuclear Information System (INIS)

    Pincel, P. Vieyra; Jiménez-Pérez, J.L.; Cruz-Orea, A.; Correa-Pacheco, Z.N.; Rosas, J. Hernández

    2015-01-01

    Highlights: • The curing of a resin in the presence of a UV laser radiation was studied. • Open photoacoustic cell technique was used to characterize the curing of the resin. • The curing of the resin as a function of time was studied. • A parabolic behavior of the resin thickness, as a function of time was observed. • UV–vis and FTIR spectroscopy were employed to characterize the resin. - Abstract: This paper deals with the study of the cure of a resin in the presence of a UV laser radiation used as the excitation source, operated at λ = 405 nm, with an output power of 20 mW. The open photoacoustic cell (OPC) technique was used to study the curing of the resins as a function of time. The curing characteristic time values were τ = 10.43, 20.99, 30.18, 45.84, 67.59 and 89.55 s for the resin thicknesses of 1000, 2000, 3000, 4000, 5000 and 6000 μm, respectively. A parabolic behavior of the resin thickness, as a function of the curing characteristic time, was obtained. UV–vis spectroscopy and infrared Fourier transform spectroscopy (FTIR) techniques were employed to characterize the resin in order to study the optical absorption and the chemical bonds, respectively. Our work has applications in the manufacture of 3D printing parts for applications, among others, in medicine

  19. Effect of energy density and delay time on the degree of conversion and Knoop microhardness of a dual resin cement.

    Science.gov (United States)

    Mainardi, Maria do Carmo A J; Giorgi, Maria Cecília C; Lima, Débora A N L; Marchi, Giselle M; Ambrosano, Gláucia M; Paulillo, Luiz A M S; Aguiar, Flávio H B

    2015-02-01

    In the present study, we evaluated the influence of the photo-curing delay time and energy density on the degree of conversion and the Knoop microhardness of a resin cement. Seventy-eight samples were assigned to 13 groups (n = 6), one of which received no light curing (control). The samples were made of a dual-cured resin cement (RelyX ARC) with the aid of a Teflon matrix, submitted to one of the following energy densities (J/cm²): 7, 14, 20, and 28. Delay times were immediate (0), 1 min, or 2 min. After 24 h, the degree of conversion and microhardness were measured at three segments: cervical, medium, and apical. Data were submitted to three-way anova and Tukey's and Dunnett's tests, the latest of which was used to compare the control to the experimental groups. No interaction was observed between delay time and energy density regarding the degree of conversion. The cervical segment showed the highest values, while the apical showed the lowest. Microhardness values concerning the cervical segment in all groups were statistically different from that obtained for the control. A high-irradiance light-curing unit allows for a reduced irradiation exposure time with a short delay time, aimed at tooth restorations using a dual-cured resin cement. © 2014 Wiley Publishing Asia Pty Ltd.

  20. Chemoviscosity modeling for thermosetting resin systems, 4

    Science.gov (United States)

    Hou, T. H.; Huang, Joan Y. Z.

    1989-01-01

    An experimental study on the changes of chemorheological properties has been conducted and analyzed on commercial Hercules 3501-6 resin system cured under several isothermal conditions between 375 and 435 K. For the cure temperatures equal to or greater than 385 K, the storage modulus curing curves, G prime (t), exhibited abrupt changes in slope which occurred at various times depending on the curing temperatures and were attributed to the onset of gelation reactions. The crossover points between G prime (t) and G double prime (t) curves were observed for curing temperatures equal to or greater than 400 K. The gelation and the crossover points obtained from the chemorheological measurements, therefore, defined two characteristic resin states during cure. Approximately the same value for the degree of cure was reached by the advancement of the reaction at each of these states. The temperature dependency of the viscosities for the characteristic resin states and the rate constants of increase in moduli at different stages of curing were analyzed. Various G prime (t) and G double prime (t) isothermal curing curves were also shown to be capable of being superimposed on one another by the principle of time-temperature superposition. The resultant shift factors a sub t(t) and a Eta(T) were shown to follow the Arrhenius type relationship. Values of the activation energy suggested that the reaction kinetics, instead of the diffusion mechanism, was the limiting step in the overall resin advancement for the cure at temperatures equal to or greater than 385 K.

  1. Formulation of eb-curable epoxy resin : some important parameters

    International Nuclear Information System (INIS)

    Dahlan bin Haji Mohd; Hosoi, Fumio; Sasaki, Takashi

    1989-01-01

    The works on the electron-beam curing of surface coatings using epoxy acrylic-based resins were discussed. The works covered among other things the effect of molecular weights of the resins on the physical properties of coatings and their physical and chemical characterizations. The emphasis was given to formulating the resins applicable to surface coatings. Curings were done on a low-energy electron beam accelerator operating at 250 kV. A number of parameters deemed important to formulations, such as the molecular weights of the oligomers and monomers, monomer ratios, and HEA additions were explored. It was found that one could modify the physical properties of the coatings by changing or adjusting those parameters. (author)

  2. Synthesis of non-ionic and ionic resins for BEP intaglio inks curing by electron-beam radiation. Annual report

    International Nuclear Information System (INIS)

    Bauer, B.J.; Dickens, B.

    1992-01-01

    The inks currently used to print US postage stamps on web presses are dried by heat evaporation of solvents. Emission of solvents into the atmosphere is governed by Local and Federal Government Regulations. Reduction of these emissions to acceptable levels can be accomplished by either of two methods available to the BEP. The work was part of a continuing effort to produce resins for use in formulation of intaglio inks for the printing of postage stamps and security documents. The inks are to be cured by exposure to an electron beam. The uncured inks are cleaned from the roller and wiping blade by washing the wiping blade with neutral water or with caustic water. Laboratory scale work on the urethane/polyethylene oxide/methacrylate resins has now been concluded and information on the synthesis has been provided to BEP for patenting and scaleup. Some effort on nonionic resins continued into FY88

  3. Efficient composite fabrication using electron-beam rapidly cured polymers engineered for several manufacturing processes

    International Nuclear Information System (INIS)

    Walton, T.C.; Crivello, J.V.

    1995-01-01

    Low cost, efficiently processed ultra high specific strength and stiffness graphite fiber reinforced polymeric composite materials are of great interest to commercial transportation, construction and aerospace industries for use in various components with enhanced degrees of weight reduction, corrosion/erosion resistance and fatigue resistance. 10 MeV Electron Beam cure processing has been found to increase the cure rate by an order of magnitude over thermally cured systems yet provide less molded in stresses and high T g s. However, a limited range of resins are available which are easily processed with low shrinkage and with performance properties equal or exceeding those of state of the art toughened epoxies and BMI's. The technology, introduced by an academia-industry partnership sparked by Langley Research Center utilizes a cost effective, rapid curing polymeric composite processing technique which effectively reduces the need for expensive tooling and energy inefficient autoclave processing and can cure the laminate in seconds (compared to hours for thermal curing) in ambient or sub-ambient conditions. The process is based on electron beam (E-Beam) curing of a new series of (65 to 1,000,000 cPs.) specially formulated resins that have been shown to exhibit excellent mechanical and physical properties once cured. Fabrication processes utilizing these specially formulated and newly commercialized resins, (e.g. including Vacuum Assist Resin Transfer molding (VARTM), vacuum bag prepreg layup, pultrusion and filament winding grades) are engineered to cure with low shrinkage, provide excellent mechanical properties, be processed solventless (environmentally friendly) and are inherently non toxic

  4. Preparation and characterization of silane-modified SiO2 particles reinforced resin composites with fluorinated acrylate polymer.

    Science.gov (United States)

    Liu, Xue; Wang, Zengyao; Zhao, Chengji; Bu, Wenhuan; Na, Hui

    2018-04-01

    A series of fluorinated dental resin composites were prepared with two kinds of SiO 2 particles. Bis-GMA (bisphenol A-glycerolate dimethacrylate)/4-TF-PQEA (fluorinated acrylate monomer)/TEGDMA (triethylene glycol dimethacrylate) (40/30/30, wt/wt/wt) was introduced as resin matrix. SiO 2 nanopartices (30nm) and SiO 2 microparticles (0.3µm) were silanized with 3-methacryloxypropyl trimethoxysilane (γ-MPS) and used as fillers. After mixing the resin matrix with 0%, 10%, 20%, 30% SiO 2 nanopartices and 0%, 10%, 20%, 30%, 40%, 50% SiO 2 microparticles, respectively, the fluorinated resin composites were obtained. Properties including double bond conversion (DC), polymerization shrinkage (PS), water sorption (W p ), water solubility (W y ), mechanical properties and cytotoxicity were investigated in comparison with those of neat resin system. The results showed that, filler particles could improve the overall performance of resin composites, particularly in improving mechanical properties and reducing PS of composites along with the addition of filler loading. Compared to resin composites containing SiO 2 microparticles, SiO 2 nanoparticles resin composites had higher DC, higher mechanical properties, lower PS and lower W p under the same filler content. Especially, 50% SiO 2 microparticles reinforced resins exhibited the best flexural strength (104.04 ± 7.40MPa), flexural modulus (5.62 ± 0.16GPa), vickers microhardness (37.34 ± 1.13 HV), compressive strength (301.54 ± 5.66MPa) and the lowest polymerization (3.42 ± 0.22%). Copyright © 2018 Elsevier Ltd. All rights reserved.

  5. Degree of conversion of nanofilled and microhybrid composite resins photo-activated by different generations of LEDs

    Directory of Open Access Journals (Sweden)

    Benicia Carolina Iaskieviscz Ribeiro

    2012-04-01

    Full Text Available OBJECTIVE:This study aimed at evaluating the degree of conversion (DC of four composite resins, being one nanofilled and 3 microhybrid resins, photo-activated with second- and third-generation light-emitting diodes (LEDs. MATERIAL AND METHODS: Filtek TM Z350 nanofilled composite resins and Amelogen® Plus, Vit-l-escenceTM and Opallis microhybrid resins were photo-activated with two second-generation LEDs (Radii-cal and Elipar Free LightTM 2 and one third-generation LED (Ultra-Lume LED 5 by continuous light mode, and a quartz halogen-tungsten bulb (QHT, control. After 24 h of storage, the samples were pulverized into fine powder and 5 mg of each material were mixed with 100 mg of potassium bromide (KBr. After homogenization, they were pressed, which resulted in a pellet that was evaluated using an infrared spectromer (Nexus 470, Thermo Nicolet equipped with TGS detector using diffuse reflectance (32 scans, resolution of 4 cm-1 coupled to a computer. The percentage of unreacted carbon-carbon double bonds (% C=C was determined from the ratio of absorbance intensities of aliphatic C=C (peak at 1637 cm-1 against internal standard before and after curing of the specimen: aromatic C-C (peak at 1610 cm-1. RESULTS: The ANOVA showed a significant effect on the interaction between the light-curing units (LCUs and the composite resins (p<0.001. The Tukey’s test showed that the nanofilled resin (FiltekTM Z350 and Opallis when photo-activated by the halogen lamp (QTH had the lowest DC compared with the other microhybrid composite resins. The DC of the nanofilled resin (FiltekTM Z350 was also lower using LEDs. The highest degrees of conversion were obtained using the third-generation LED and one of second-generation LEDs (Elipar Free LightTM 2. CONCLUSIONS: The nanofilled resin showed the lowest DC, and the Vit-l-escenceTM microhybrid composite resin showed the highest DC. Among the LCUs, it was not possible to establish an order, even though the second

  6. Full in-vitro analyses of new-generation bulk fill dental composites cured by halogen light.

    Science.gov (United States)

    Tekin, Tuçe Hazal; Kantürk Figen, Aysel; Yılmaz Atalı, Pınar; Coşkuner Filiz, Bilge; Pişkin, Mehmet Burçin

    2017-08-01

    The objective of this study was to investigate the full in-vitro analyses of new-generation bulk-fill dental composites cured by halogen light (HLG). Two types' four composites were studied: Surefill SDR (SDR) and Xtra Base (XB) as bulk-fill flowable materials; QuixFill (QF) and XtraFill (XF) as packable bulk-fill materials. Samples were prepared for each analysis and test by applying the same procedure, but with different diameters and thicknesses appropriate to the analysis and test requirements. Thermal properties were determined by thermogravimetric analysis (TG/DTG) and differential scanning calorimetry (DSC) analysis; the Vickers microhardness (VHN) was measured after 1, 7, 15 and 30days of storage in water. The degree of conversion values for the materials (DC, %) were immediately measured using near-infrared spectroscopy (FT-IR). The surface morphology of the composites was investigated by scanning electron microscopes (SEM) and atomic-force microscopy (AFM) analyses. The sorption and solubility measurements were also performed after 1, 7, 15 and 30days of storage in water. In addition to his, the data were statistically analyzed using one-way analysis of variance, and both the Newman Keuls and Tukey multiple comparison tests. The statistical significance level was established at pfill, resin-based dental composites. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Effect of Curing Direction on Microtensile Bond Strength of Fifth and Sixth Generation Dental Adhesives

    Directory of Open Access Journals (Sweden)

    Ali Nadaf

    2012-09-01

    Full Text Available Background and Aims: Composite restorative materials and dental adhesives are usually cured with light sources. The light direction may influence the bond strength of dental adhesives. The aim of this study was to evaluate the effect of light direction on the microtensile bond strength of fifth and sixth generation dental adhesives.Materials and Methods: Prime & Bond NT and Clearfil SE bond were used with different light directions.Sixty human incisor teeth were divided into 4 groups (n=15. In groups A and C, Clearfil SE bond with light curing direction from buccal was used for bonding a composite resin to dentin. In groups B and D, Prime & Bond NT with light curing direction from composite was used. After thermocycling the specimens were subjected to tensile force until debonding occurred and values for microtensile bond strength were recorded. The data were analyzed using two-way ANOVA and Tukey post hoc test.Results: The findings showed that the bond strength of Clearfil SE bond was significantly higher than that of Prime&Bond NT (P<0.001. There was no significant difference between light curing directions (P=0.132.Conclusion: Light curing direction did not have significant effect on the bond strength. Sixth generation adhesives was more successful than fifth generation in terms of bond strength to dentin.

  8. Viscoelastic properties of graphene-based epoxy resins

    Science.gov (United States)

    Nobile, Maria Rossella; Fierro, Annalisa; Rosolia, Salvatore; Raimondo, Marialuigia; Lafdi, Khalid; Guadagno, Liberata

    2015-12-01

    In this paper the viscoelastic properties of an epoxy resin filled with graphene-based nanoparticles have been investigated in the liquid state, before curing, by means of a rotational rheometer equipped with a parallel plate geometry. Exfoliated graphite was prepared using traditional acid intercalation followed by a sudden treatment at high temperature (900°C). The percentage of exfoliated graphite was found to be 56%. The epoxy matrix was prepared by mixing a tetrafunctional precursor with a reactive diluent which produces a significant decrease in the viscosity of the epoxy precursor so that the dispersion step of nanofillers in the matrix can easily occur. The hardener agent, the 4,4-diaminodiphenyl sulfone (DDS), was added at a stoichiometric concentration with respect to all the epoxy rings. The inclusion of the partially exfoliated graphite (pEG) in the formulated epoxy mixture significantly modifies the rheological behaviour of the mixture itself. The epoxy mixture, indeed, shows a Newtonian behaviour while, at 3 wt % pEG content, the complex viscosity of the nanocomposite clearly shows a shear thinning behaviour with η* values much higher at the lower frequencies. The increase in complex viscosity with the increasing of the partially exfoliated graphite content was mostly caused by a dramatic increase in the storage modulus. All the graphene-based epoxy mixtures were cured by a two-stage curing cycles: a first isothermal stage was carried out at the lower temperature of 125°C for 1 hour while the second isothermal stage was performed at the higher temperature of 200°C for 3 hours. The mechanical properties of the cured nanocomposites show high values in the storage modulus and glass transition temperature.

  9. Cork-resin ablative insulation for complex surfaces and method for applying the same

    Science.gov (United States)

    Walker, H. M.; Sharpe, M. H.; Simpson, W. G. (Inventor)

    1980-01-01

    A method of applying cork-resin ablative insulation material to complex curved surfaces is disclosed. The material is prepared by mixing finely divided cork with a B-stage curable thermosetting resin, forming the resulting mixture into a block, B-stage curing the resin-containing block, and slicing the block into sheets. The B-stage cured sheet is shaped to conform to the surface being insulated, and further curing is then performed. Curing of the resins only to B-stage before shaping enables application of sheet material to complex curved surfaces and avoids limitations and disadvantages presented in handling of fully cured sheet material.

  10. Microarray analysis of the gene expression profile in triethylene glycol dimethacrylate-treated human dental pulp cells.

    Science.gov (United States)

    Torun, D; Torun, Z Ö; Demirkaya, K; Sarper, M; Elçi, M P; Avcu, F

    2017-11-01

    Triethylene glycol dimethacrylate (TEGDMA) is an important resin monomer commonly used in the structure of dental restorative materials. Recent studies have shown that unpolymerized resin monomers may be released into the oral environment and cause harmful biological effects. We investigated changes in the gene expression profiles of TEGDMA-treated human dental pulp cells (hDPCs) following short- (1-day) and long-term (7-days) exposure. HDPCs were exposed to a noncytotoxic concentration of TEGDMA, and gene expression profiles were evaluated by microarray analysis. The results were confirmed by quantitative reverse-transcriptase PCR (qRT PCR). In total, 1282 and 1319 genes (up- or down-regulated) were differentially expressed compared with control group after the 1- and 7-day incubation periods, respectively. Biological ontology-based analyses revealed that metabolic, cellular, and developmental processes constituted the largest groups of biological functional processes. qRT-PCR analysis on bone morphogenetic protein-2 (BMP-2), BMP-4, secreted protein, acidic, cysteine-rich, collagen type I alpha 1, oxidative stress-induced growth inhibitor 1, MMP3, interleukin-6, and heme oxygenase-1 genes confirmed the changes in expression observed in the microarray analysis. Our results suggest that TEGDMA can change the many functions of hDPCs through large changes in gene expression levels and complex interactions with different signaling pathways.

  11. Development of AlGaN-based deep-ultraviolet (DUV) LEDs focusing on the fluorine resin encapsulation and the prospect of the practical applications

    Science.gov (United States)

    Hirano, Akira; Nagasawa, Yosuke; Ippommatsu, Masamichi; Aosaki, Ko; Honda, Yoshio; Amano, Hiroshi; Akasaki, Isamu

    2016-09-01

    AlGaN-based LEDs are expected to be useful for sterilization, deodorization, photochemical applications such as UV curing and UV printing, medical applications such as phototherapy, and sensing. Today, it has become clear that efficient AlGaN-based LED dies are producible between 355 and 250 nm with an external quantum efficiency (EQE) of 3% on flat sapphire. These dies were realized on flat sapphire without using a special technique, i.e., reduction in threading dislocation density or light extraction enhancement techniques such as the use of a photonic crystal or a patterned sapphire substrate. Despite the limited light extraction efficiency of about 8% owing to light absorption at a thick p-GaN contact layer, high EQEs of approximately 6% has been reproducible between 300 and 280 nm without using special techniques. Moreover, an EQE of 3.9% has been shown at 271 nm, despite the smaller current injection efficiency (CIE). The high EQEs are thought to correspond to the high internal quantum efficiency (IQE), indicating a small room for improving IQE. Accordingly, resin encapsulation on a simple submount is strongly desired. Recently, we have succeeded in demonstrating fluorine resin encapsulation on a ceramic sheet (chip-on-board, COB) that is massproducible. Furthermore, the molecular structure of a resin with a durability of more than 10,000 h is explained in this paper from the photochemical viewpoint. Thus, the key technologies of AlGaN-based DUV-LEDs having an EQE of 10% within a reasonable production cost have been established. The achieved efficiency makes AlGaN-based DUVLEDs comparable to high-pressure mercury lamps.

  12. Microhardness of light- and dual-polymerizable luting resins polymerized through 7.5-mm-thick endocrowns.

    Science.gov (United States)

    Gregor, Ladislav; Bouillaguet, Serge; Onisor, Ioana; Ardu, Stefano; Krejci, Ivo; Rocca, Giovanni Tommaso

    2014-10-01

    The complete polymerization of luting resins through thick indirect restorations is still questioned. The purpose of this study was to evaluate the degree of polymerization of light- and dual-polymerizable luting resins under thick indirect composite resin and ceramic endocrowns by means of Vickers microhardness measurements. The Vickers microhardness measurements of a light-polymerizable microhybrid composite resin and a dual-polymerizable luting cement directly polymerized in a natural tooth mold for 40 seconds with a high-power light-emitting diode lamp (control) were compared with measurements after indirect irradiation through 7.5-mm-thick composite resin and ceramic endocrowns for 3 × 90 seconds. A test-to-control microhardness values ratio of 0.80 at a depth of 0.5 mm below the surface was assumed as the criterion for adequate conversion. For the Vickers microhardness measurements of a dual-polymerizable luting cement, no differences (P>.05) were found between Vickers microhardness control values and values reported after polymerization through composite resin and ceramic endocrowns. For The Vickers microhardness measurements (±SD) of a light-polymerizable microhybrid composite resin, control values were significantly (P.05). Under the conditions of this in vitro study, Vickers microhardness values of the dual-polymerizable resin cement and the light-polymerizable restorative composite resin irradiated for 3 × 90 seconds with a high irradiance light-emitting diode lamp through 7.5-mm-thick endocrowns reached at least 80% of the control Vickers microhardness values, which means that both materials can be adequately polymerized when they are used for luting thick indirect restorations. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  13. Bond Strength of Silorane- and Methacrylate-Based Composites to Resin-Modified Glass Ionomers

    Science.gov (United States)

    2012-01-13

    genre was given the name of resin-modified glass ionomers (RMGI) (Antonucci et al., 1988). The addition of resin improved many of the drawbacks of...entire surface for 15 seconds then gentle air was used to create an even film over the sample. This layer was cured for 10 seconds using the Bluephase

  14. Biological behaviour of buccal cells exposed to blue light

    International Nuclear Information System (INIS)

    Gritsch, Kerstin; Ponsonnet, Laurence; Schembri, Catherine; Farge, Pierre; Pourreyron, Laurence; Grosgogeat, Brigitte

    2008-01-01

    Blue light is used in dental practise to cure resin-based materials, but the path of the light often includes oral tissues such as gingival tissues. While adverse effects of blue light exposure on cells - such as retina cells - are well known, few studies have investigated the impact of blue light exposure on oral cells. The aim of the present in vitro study was to assess the biological effects of blue light emitted by two dental curing devices (a plasma-arc and a light-emitting diode curing unit) on human gingival fibroblasts. Light intensities and light-induced temperature rise were respectively measured with a radiometer and a thermocouple. Cellular response to blue light exposure was assessed by the observation of cell morphology (scanning electron microscopy) and the estimation of cell mitochondrial activity (MTT assay). Light intensities measured at the clinical distance were 488 ± 42 mW/cm 2 for the plasma-arc unit and ranged from 61 ± 5 to 140 ± 16 mW/cm 2 for the light-emitting diodes unit, according to the curing program used. The highest temperature rise was 0.5 and 3.5 deg. C for exposure to the plasma-arc light and to the light-emitting diodes light, respectively. Results showed no differences between exposed- and non-exposed cells in regards to cell morphology. However, cells exposed to blue light presented an increased mitochondrial activity compared to control cells (non-exposed), and mostly those exposed to plasma-arc light

  15. Bulk fill restoratives: to cap or not to cap--that is the question?

    Science.gov (United States)

    Tomaszewska, Iwona M; Kearns, Jennifer O; Ilie, Nicoleta; Fleming, Garry J P

    2015-03-01

    To assess the cuspal deflection and cervical microleakage scores of standardised large mesio-occlusal-distal (MOD) cavities filled with different restoration protocols: (1) conventional resin restoratives, (2) bulk fill flowable base materials 'capped' with a conventional dimethacrylate resin-based composite (RBC) or (3) bulk fill resin restorative materials. Standardised MOD cavities were prepared in sixty-four sound maxillary premolar teeth and randomly allocated to eight groups. Restorations were placed in conjunction with a universal bonding system and resin restorative materials were irradiated with a quartz-tungsten-halogen light-curing-unit. Restoration protocol (eight oblique increments of conventional resin restorative, bulk fill flowable base and two occlusal 'capping' RBC increments (three increments in total) or bulk fill resin restorative (two increments)) was the dependent variable. A twin channel deflection measuring gauge measured the buccal and palatal cuspal deflections. Teeth were thermally fatigued, immersed in a 0.2% basic fuchsin dye for 24h, sectioned and examined for cervical microleakage score. Post hoc Tukey's tests highlighted significant differences in the mean total cuspal deflection values between resin restoratives (p fill flowable base materials with occlusal 'capping' RBC increments (restoration protocol 2) compared with bulk fill resin restoratives (restoration protocol 3). Not all bulk fill flowable materials or bulk fill resin restoratives behave in a similar fashion when used to restore standardised MOD cavities in maxillary premolar teeth and material selection is vital in the absence of clinical data. Poorly performing bulk fill flowable materials or bulk fill restoratives can be identified using the cuspal deflection and cervical microleakage protocol which could save the complications encountered clinically when restoring Class II restorations. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. TiO2-Nanofillers Effects on Some Properties of Highly- Impact Resin Using Different Processing Techniques.

    Science.gov (United States)

    Aziz, Hawraa Khalid

    2018-01-01

    The criteria of conventional curing of polymethyl methacrylate do not match the standard properties of the denture base materials. This research was conducted to investigate the addition of TiO 2 nano practical on impact strength, thermal conductivity and color stability of acrylic resin cured by microwave in comparison to the conventional cured of heat-polymerized acrylic resin. 120 specimens made of high impact acrylic resin were divided into two main groups according to the type of curing (water bath, microwave), then each group was subdivided into two groups according to the addition of 3% TiO 2 nano-fillers and control group (without the addition of TiO 2 0%). Each group was subdivided according to the type of test into 3 groups with 10 specimens for each group. Data were statistically analyzed using Student t-test to detect the significant differences between tested and control groups at significance level ( P <0.05). According to curing type methods, the results showed that there was a significant decrease in impact strength of microwaved cured resin, but there was no significant difference in the thermal conductivity and color stability of resin. In addition, by using nanofiller, there was a significant increase in the impact strength and color stability with the addition of 3% TiO 2 nanofillers, but no significant difference was found in the thermal conductivity of the acrylic resin. The microwave curing of acrylic resin had no change in the color stability and thermal conductivity in comparison to the water bath, but the impact strength was decreased. The addition of 3% TiO 2 improved the impact and the color stability, but the thermal conductivity did not change.

  17. A comparative study to determine strength of autopolymerizing acrylic resin and autopolymerizing composite resin influenced by temperature during polymerization: An In Vitro study

    Directory of Open Access Journals (Sweden)

    Anuj Chhabra

    2017-01-01

    Full Text Available Aim: Temporary coverage of a prepared tooth is an important step during various stages of the fixed dental prosthesis. Provisional restorations should satisfy proper mechanical requirements to resist functional and nonfunctional loads. A few studies are carried out regarding the comparison of the effect of curing environment, air and water, on mechanical properties of autopolymerizing acrylic and composite resin. Hence, the aim of this study was to compare the transverse strength of autopolymerizing acrylic resin and autopolymerizing composite resin as influenced by the temperature of air and water during polymerization. Materials and Methods: Samples of autopolymerizing acrylic resin and composite resin were prepared by mixing as per manufacturer's instructions and were placed in a preformed stainless steel mold. The mold containing the material was placed under different controlled conditions of water temperature and air at room temperature. Polymerized samples were then tested for transverse strength using an Instron universal testing machine. Results: Alteration of curing condition during polymerization revealed a significant effect on the transverse strength. The transverse strength of acrylic resin specimens cured at 60°C and composite resin specimens cured at 80°C was highest. Polymerizing the resin in cold water at 10°C reduced the mechanical strength. Conclusions: Polymerization of the resin in hot water greatly increased its mechanical properties. The method of placing resin restoration in hot water during polymerization may be useful for improving the mechanical requirements and obtaining long-lasting performance.

  18. Effect of mode of polymerization of bonding agent on shear bond strength of autocured resin composite luting cements.

    Science.gov (United States)

    Dong, Cecilia C S; McComb, Dorothy; Anderson, James D; Tam, Laura E

    2003-04-01

    There have been anecdotal reports of low bond strength with autocured resin composite materials, particularly when light-cured bonding agents that combine primer and adhesive in a 1-bottle preparation are used. The objective of this study was to determine if the mode of polymerization of the bonding agent influences the strength of the attachment of autocured resin composite luting cements to dentin. The shear bond strength of 2 resin luting cements, Calibra and RelyX ARC, polymerized by autocuring, in combination with 4 different bonding agents, Scotchbond Multipurpose Plus, Prime & Bond NT, IntegraBond and Single Bond, polymerized to bovine dentin by light-curing, autocuring or dual-curing, was determined. The pH of each bonding agent and its components was measured. Two-way analysis of variance was used to test the effect of cement and adhesive on shear bond strength. For each bonding agent, the adhesive variable combined the factors product brand and mode of polymerization. With significant interaction among the above variables, the least square means of the 16 combinations of resin cement and adhesive were compared. There was no consistent relationship between shear bond strength and mode of polymerization of the bonding agent. Significant differences in bond strength were specific to the proprietary brand of bonding agent. The pH of the bonding agent depends on the manufacturer's formulation, and low pH may contribute to low bond strength. The low in vitro bond strength occurring with some combinations of bonding agent and resin cement could be clinically significant.

  19. Electron beam-cured coating

    International Nuclear Information System (INIS)

    Kishi, Naoyuki

    1976-01-01

    The method for hardening coatings by the irradiation with electron beams is reviewed. The report is divided into seven parts, namely 1) general description and characteristics of electron beam-cured coating, 2) radiation sources of curing, 3) hardening conditions and reaction behaviour, 4) uses and advantages, 5) latest trends of the industry, 6) practice in the field of construction materials, and 7) economy. The primary characteristics of the electron beam hardening is that graft reaction takes place between base resin and coating to produce strong adhesive coating without any pretreatment. A variety of base resins are developed. High class esters of acrylic acid monomers and methacrylic acid monomers are mainly used as dilutants recently. At present, scanning type accelerators are used, but the practical application of the system producing electron beam of curtain type is expected. The dose rate dependence, the repetitive irradiation and the irradiation atmosphere are briefly described. The filed patent applications on the electron beam hardening were analyzed by the officer of Japan Patent Agency. The production lines for coatings by the electron beam hardening in the world are listed. In the electron beam-cured coating, fifty percent of given energy is consumed effectively for the electron beam hardening, and the solvents discharged from ovens and polluting atmosphere are not used, because the paints of high solid type is used. The running costs of the electron beam process are one sixth of the thermal oven process. (Iwakiri, K.)

  20. The effect of cure conditions on the stability of cement waste forms after immersion in water

    International Nuclear Information System (INIS)

    Siskind, B.; Adams, J.W.; Clinton, J.H.; Piciulo, P.L.; McDaniel, K.

    1988-01-01

    We investigated the effects of curing conditions on the stability of cement-solidified ion-exchange resins after immersion in water. The test specimens consisted of partially depleted mixed-bed bead resins solidified in one of three vendor-supplied Portland I cement formulations, in a reference cement formulation, or in a gypsum-based binder formulation. We cured samples prepared using each formulation in sealed containers for periods of 7, 14, or 28 days as well as in air or with an accelerated heat cure prior to 90-day immersion in water. Two cement formulations exhibited apparent Portland-cement-like behavior, i.e., compressive strength increased or stabilized with increasing cure time. Two cement formulations exhibited behavior apparently unlike that of Portland cement, i.e., compressive strength decreased with increasing cure time. Such non-Portland-cement-like behavior is correlated with higher waste loadings. The gypsum-based formulation exhibited approximately constant compressive strength with cure time. Accelerated heat cures may not give compressive strengths representative of real-time cures. Some physical deterioration (cracking, spalling) of the waste form occurs during immersion

  1. The effect of cure conditions on the stability of cement waste forms after immersion in water

    International Nuclear Information System (INIS)

    Siskind, B.; Adams, J.W.; Clinton, J.H.; Piciulo, P.L.

    1988-01-01

    The authors investigated the effects of curing conditions on the stability of cement-solidified ion-exchange resins after immersion in water. The test specimens consisted of partially depleted mixed-bed bead resins solidified in one of three vendor-supplied Portland I cement formulations, in a reference cement formulation, or in a gypsum-based binder formulation. They cured samples prepared using each formulation in sealed containers for periods of 7, 14, or 28 days as well as in air or with an accelerated heat cure prior to 90-day immersion in water. Two cement formulations exhibited apparent Portland-cement-like behavior, i.e., compressive strength increased or stabilized with increasing cure time. Two cement formulations exhibited behavior apparently unlike that of Portland cement, i.e. compressive strength decreased with increasing cure time. Such non-Portland-cement-like behavior is correlated with higher waste loadings. The gypsum-based formulation exhibited approximately constant compressive strength with cure time. Accelerated heat cures may not give compressive strengths representative of real-time cures. Some physical deterioration (cracking, spalling) of the waste form occurs during immersion

  2. Effect of repair resin type and surface treatment on the repair strength of heat-polymerized denture base resin.

    Science.gov (United States)

    Alkurt, Murat; Yeşil Duymuş, Zeynep; Gundogdu, Mustafa

    2014-01-01

    Acrylic resin denture fracture is common in prosthodontic practice. When fractured denture bases are repaired, recurrent fractures frequently occur at the repair surface interface or adjacent areas. The purpose of this study was to evaluate the effect of different surface treatments on the flexural strength of the acrylic resin denture base repaired with heat-polymerized acrylic resin, autopolymerizing resin, and light-polymerized acrylic resin. Ninety-six specimens of heat-polymerized acrylic resin were prepared according to the American Dental Association Specification No. 12 (65.0 × 10.0 × 2.5 mm) and sectioned into halves to create a repair gap (3.0 × 10 × 2.5 mm). The sectioned specimens were divided into 3 groups according to their repair materials. The specimens from each group were divided into 4 subgroups according to their surface treatments: a control group without any surface treatment; an experimental group treated with methyl methacrylate monomer (MMA group); an experimental group treated with airborne-particle abrasion with aluminum oxide particles of 250-μm particle size (abrasion group); and an experimental group treated with erbium:yttrium-aluminum-garnet laser (laser group). After the surface treatments, the 3 materials were placed into the repair gaps and then polymerized. After all of the specimens had been ground and polished, they were stored in distilled water at 37°C for 1 week and subjected to a 3-point bend test. Data were analyzed with a 2-way analysis of variance, and the Tukey honestly significant difference test was performed to identify significant differences (α=.05). The effects of the surface treatments and repair resins on the surface of the denture base resin were examined with scanning electron microscopy. Significant differences were found among the groups in terms of repair resin type (P<.001). All surface-treated specimens had higher flexural strength than controls, except the surface treated with the methyl

  3. Influence of Al2O3 nanoparticles on the isothermal cure of an epoxy resin

    International Nuclear Information System (INIS)

    Sanctuary, R; Baller, J; Zielinski, B; Becker, N; Krueger, J K; Philipp, M; Mueller, U; Ziehmer, M

    2009-01-01

    The influence of Al 2 O 3 nanoparticles on the curing of an epoxy thermoset based on diglycidyl ether of bisphenol A was investigated using temperature-modulated differential scanning calorimetry (TMDSC) and rheology. Diethylene triamine was used as a hardener. TMDSC not only allows for a systematic study of the kinetics of cure but simultaneously gives access to the evolution of the specific heat capacities of the thermosets. The technique thus provides insight into the glass transition behaviour of the nanocomposites and hence makes it possible to shed some light on the interaction between the nanoparticles and the polymer matrix. The Al 2 O 3 fillers are shown to accelerate the growth of macromolecules upon isothermal curing. Several mechanisms which possibly could be responsible for the acceleration are described. As a result of the faster network growth chemical vitrification occurs at earlier times in the filled thermosets and the specific reaction heat decreases with increasing nanoparticle concentration. Rheologic measurements of the zero-shear viscosity confirm the faster growth of the macromolecules in the presence of the nanoparticles.

  4. Possible preparation of wood-plastic materials based on unsaturated polyester resins and methyl metacrylate, by radiation and chemical methods in combination

    International Nuclear Information System (INIS)

    Pesek, M.

    1982-01-01

    The preparation of wood-plastic combinations (WPC) using combined methods for curing intermediate products and final products is described. In the first step, impregnated wood was irradiated using doses of 1 to 10 kGy in the presence of chemical initiators of polymerization. Thereafter, curing of this partly cured impregnating mixture was accomplished in the wood at elevated temperatures with the aid of chemical initiators of polymerization. Impregnation mixtures based on unsaturated polyester resins and methyl methacrylate, and the wood species European Beech (Fagus silvatica) and Black Alder (Alnus glutinosa) were used. The results indicate that this method of preparing WPC allows substantially lower radiation doses to be used, i.e., doses in the range of 1 to 2.5 kGy. These doses gelatinate the impregnation mixture in the wood so that the subsequent curing by chemical polymerization initiators proceeds without the impregnation mixture flowing out of the wood, and without forming bosses and incrustations. Intermediate products and wood products needing no further finish may thus be prepared: in some cases regrinding or repolish is sufficient. The possibility of using impregnation mixtures based on various unsaturated polyester resins was investigated, and the influence on the curing process of temperature, polymerization initiator concentration, methyl methacrylate concentration, inhibitor concentration, and other factors affecting curing was evaluated. (author)

  5. Optical emission behavior and radiation resistance of epoxy resins

    International Nuclear Information System (INIS)

    Kawanishi, Shunichi; Udagawa, Akira; Hagiwara, Miyuki

    1987-11-01

    To make clear a mechanism of radiation resistance of epoxy resin systems, a role of energy trapping site induced in bisphenol A type epoxy resins cured with 4 kinds of aromatic amines (Φ N ) was studied in comparison with the case of aliphatic amine curing system through a measurement of optical emission. In the system of the epoxy resin cured with DETA, the optical emission from an excited state of bisphenol A unit of epoxy resin and a charge transfer complex was observed. On the other hand, the optical emission from Φ N was observed in the aromatic amine curing system. Their excitation spectrum consists of peaks of absorption spectrum of BA and those of Φ N , showing that the excited state of Φ N is formed through the excitation of both BA and Φ N . Therefore, the excited energy of BA transfers to the excited state of Φ N . Emission intensity of Φ N band was 20 ∼ 100 times as large as that of BA. These results indicate that the radiation energy is effectively released as an optical emission from excited state of Φ N in the epoxy resin when cured with aromatic amine. It can be concluded from the above results that aromatic amine hardeners contribute to enhancement of the radiation resistance of epoxy resin by acting as an energy transfer agent. (author)

  6. [Comparative evaluation of physical-mechanical properties and surface morphology of the samples of base self cured acrylic resin "Redont-kolir" polymerized in the silicone and alginate matrixes].

    Science.gov (United States)

    2014-01-01

    Determination of advantages of using silicone or alginate impression material as a matrix is decisive for quality of immediate and transitional dentures manufactured by the direct method using self-cured acrylic resins. The aim of this study was a comparative evaluation of physical-mechanical properties and surface morphology of the samples of base self-cured acrylic resin "Redont-kolir" polymerized in the silicone and alginate matrix. The samples were polymerized in the C-silicone - "Zeta plus-putty" ("Zhermack", Italy) and alginate -"Ypeen" ("Spofa Dental", Czech Republic) matrixes under different regimes: 1) in the pneumopolymerizer "Averon" at an air pressure of 3 atm., a temperature of 450C for 15 minutes, and 2) polymerization in water at 450C for 15 minutes. We determined the following physical and mechanical properties: bending load, toughness, bending stress at break, hardness by Heppler, conical point of fluidity and water absorption. Electron microscopy studies of the samples have been conducted on electronic raster microscope JSM-840 ("Jeol", Japan). As a result of studies, it was found that the optimum regime of polymerization for acrylate "Redont-kolir" is in the pneumopolymerizer "Averon" at an air pressure of 3 atm., a temperature of 450 C for 15 minutes. By the results of studying the surface morphology of the samples we can draw a conclusion that the use of an alginate impression material as matrix allows to obtain a qualitatively better surface of denture. But taking into account the technological properties of the alginate impression materials, namely an expressed shrinkage, their use for this purpose must be limited by the time during which the impression matrix remain stable in size, which is specified by manufacturer's recommendations.

  7. Composite Cure Process Modeling and Simulations using COMPRO(Registered Trademark) and Validation of Residual Strains using Fiber Optics Sensors

    Science.gov (United States)

    Sreekantamurthy, Thammaiah; Hudson, Tyler B.; Hou, Tan-Hung; Grimsley, Brian W.

    2016-01-01

    Composite cure process induced residual strains and warping deformations in composite components present significant challenges in the manufacturing of advanced composite structure. As a part of the Manufacturing Process and Simulation initiative of the NASA Advanced Composite Project (ACP), research is being conducted on the composite cure process by developing an understanding of the fundamental mechanisms by which the process induced factors influence the residual responses. In this regard, analytical studies have been conducted on the cure process modeling of composite structural parts with varied physical, thermal, and resin flow process characteristics. The cure process simulation results were analyzed to interpret the cure response predictions based on the underlying physics incorporated into the modeling tool. In the cure-kinetic analysis, the model predictions on the degree of cure, resin viscosity and modulus were interpreted with reference to the temperature distribution in the composite panel part and tool setup during autoclave or hot-press curing cycles. In the fiber-bed compaction simulation, the pore pressure and resin flow velocity in the porous media models, and the compaction strain responses under applied pressure were studied to interpret the fiber volume fraction distribution predictions. In the structural simulation, the effect of temperature on the resin and ply modulus, and thermal coefficient changes during curing on predicted mechanical strains and chemical cure shrinkage strains were studied to understand the residual strains and stress response predictions. In addition to computational analysis, experimental studies were conducted to measure strains during the curing of laminated panels by means of optical fiber Bragg grating sensors (FBGs) embedded in the resin impregnated panels. The residual strain measurements from laboratory tests were then compared with the analytical model predictions. The paper describes the cure process

  8. Elastic properties, reaction kinetics, and structural relaxation of an epoxy resin polymer during cure

    Science.gov (United States)

    Heili, Manon; Bielawski, Andrew; Kieffer, John

    The cure kinetics of a DGEBA/DETA epoxy is investigated using concurrent Raman and Brillouin light scattering. Raman scattering allows us to monitor the in-situ reaction and quantitatively assess the degree of cure. Brillouin scattering yields the elastic properties of the system, providing a measure of network connectivity. We show that the adiabatic modulus evolves non-uniquely as a function of cure degree, depending on the cure temperature and the molar ratio of the epoxy. Two mechanisms contribute to the increase in the elastic modulus of the material during curing. First, there is the formation of covalent bonds in the network during the curing process. Second, following bond formation, the epoxy undergoes structural relaxation toward an optimally packed network configuration, enhancing non-bonded interactions. We investigate to what extent the non-bonded interaction contribution to structural rigidity in cross-linked polymers is reversible, and to what extent it corresponds to the difference between adiabatic and isothermal moduli obtained from static tensile, i.e. the so-called relaxational modulus. To this end, we simultaneously measure the adiabatic and isothermal elastic moduli as a function of applied strain and deformation rate.

  9. Accompanying of parameters of color, brightness and hardness on polymeric films coated with pigmented inks cured by different radiation doses of ultraviolet light

    International Nuclear Information System (INIS)

    Bardi, M.A.G.; Machado, L.D.B.

    2011-01-01

    Complete text of publication follows. In the search for alternatives to traditional paint systems containing solvents, the curing process of polymer coatings by ultraviolet (UV) light has been widely studied and discussed, specially because of their high content of solids and null emission of VOCs. Radiation curing is defined as the conversion of a reactive liquid into a solid through polymerization and crosslinking reactions between the species, promoted by the interaction of the chemical system with the incident ionizing radiation. The appearance of the coated object (e.g., color, gloss) is a complex function of the light incident on the object, the optical scattering characteristic of the material, and human perception. Pigments are very fine powders being nearly insoluble in binders and solvents, but provide color and the ability to hide the underlying surface. In this context, this paper aims to investigate variations on color, brightness and hardness of UV-cured pigmented coatings by different doses. When it comes to irradiation exposition, the incorporation of pigments can preferentially cause its reflection or absorption of the incident radiation. Reflection usually occurs at the pigment surface within the resin so that the radiation has to pass through the top layers twice. Some degradation can, therefore, occur at the surface, and this is why materials frequently lose gloss on exposure.

  10. Development of new and improved polymer matrix resin systems, phase 1

    Science.gov (United States)

    Hsu, M. S.

    1983-01-01

    Vinystilbazole (vinylstryrylpyridine) and vinylpolystyrulpyridine were prepared for the purpose of modifying bismaleimide composite resins. Cure studies of resins systems were investigated by differential scanning calorimetry. The vinylstyrylpyridine-modified bismaleimide composite resins were found to have lower cure and gel temperatures, and shorter cure times than the corresponding unmodified composite resins. The resin systems were reinforced with commercially avialable satin-weave carbon cloth. Prepregs were fabricated by solvent or hot melt techniques. Thermal stability, flammability, moisture absorption, and mechanical properties of the composites (such as flexural strength, modulus, tensile and short beam shear strength) were determined. Composite laminates showed substantial improvements in both processability and mechanical properties compared to he bismaleimide control systems. The vinylstyrylpyridine modified bismaleimide resins can be used as advanced matrix resins for graphite secondary structures where ease of processing, fireworthiness, and high temperature stability are required for aerospace applications.

  11. Relative biocompatibility of micro-hybrid and nano-hybrid light-activated composite resins.

    Science.gov (United States)

    Olabisi Arigbede, Abiodun; Folasade Adeyemi, Bukola; Femi-Akinlosotu, Omowumi

    2017-01-01

    Background. In vitro studies have revealed a direct association between resin content and cytotoxicity of composite resins; however, implantation studies in this regard are sparse. This study investigates the relationship between filler content of composite resins and biocompatibility. Methods. This research employed twelve 180‒200-gr male Wistar rats, 1 nano-hybrid (Prime-Dent Inc.) and 1 micro-hybrid (Medental Inc.) composite resins containing 74% and 80‒90% filler content, respectively. The samples were assessed on the 2nd, 14th and 90th day of implantation. Four rats were allocated to each day in this experimental study. A section of 1.5mm long cured nano-hybrid and micro-hybrid materials were implanted into the right and left upper and lower limbs of the rats, respectively. Eight samples were generated on each day of observation. Inflammation was graded according to the criteria suggested by Orstavik and Major. Pearson's chi-squared test was employed to determine the relationship between the tissue responses of the two materials. Statistical significance was set at P resin had a score of 3.0 for cellular inflammation. On the 14th day, the micro-hybrid resin also exhibited a lower average grade for cellular inflammation. On the 90th day, the micro-hybrid resin had a higher grade of inflammation (0.9) compared to 0.3 recorded for nano-hybrid. The composite resins with higher filler content elicited a significantly lower grade of inflammation irrespective of the duration (χ=20.000, df=8, P=0.010) while the composite resins with lower filler content elicited a significantly lower inflammatory response on the 90th day (χ=4.000, df=1, P=0.046). Conclusion. The composite resins with higher filler content generally elicited significantly lower grades of inflammation, and the composite resins with lower filler content exhibited significantly lower inflammatory response on the 90th day of implantation.

  12. Chemoviscosity modeling for thermosetting resins - I

    Science.gov (United States)

    Hou, T. H.

    1984-01-01

    A new analytical model for chemoviscosity variation during cure of thermosetting resins was developed. This model is derived by modifying the widely used WLF (Williams-Landel-Ferry) Theory in polymer rheology. Major assumptions involved are that the rate of reaction is diffusion controlled and is linearly inversely proportional to the viscosity of the medium over the entire cure cycle. The resultant first order nonlinear differential equation is solved numerically, and the model predictions compare favorably with experimental data of EPON 828/Agent U obtained on a Rheometrics System 4 Rheometer. The model describes chemoviscosity up to a range of six orders of magnitude under isothermal curing conditions. The extremely non-linear chemoviscosity profile for a dynamic heating cure cycle is predicted as well. The model is also shown to predict changes of glass transition temperature for the thermosetting resin during cure. The physical significance of this prediction is unclear at the present time, however, and further research is required. From the chemoviscosity simulation point of view, the technique of establishing an analytical model as described here is easily applied to any thermosetting resin. The model thus obtained is used in real-time process controls for fabricating composite materials.

  13. Degree of conversion of nanofilled and microhybrid composite resins photo-activated by different generations of LEDs.

    Science.gov (United States)

    Ribeiro, Benicia Carolina Iaskieviscz; Boaventura, Juliana Maria Capelozza; Brito-Gonçalves, Joel de; Rastelli, Alessandra Nara de Souza; Bagnato, Vanderlei Salvador; Saad, José Roberto Cury

    2012-01-01

    This study aimed at evaluating the degree of conversion (DC) of four composite resins, being one nanofilled and 3 microhybrid resins, photo-activated with second- and third-generation light-emitting diodes (LEDs). Filtek™ Z350 nanofilled composite resins and Amelogen® Plus, Vit-l-escence™ and Opallis microhybrid resins were photo-activated with two second-generation LEDs (Radii-cal and Elipar Free Light™ 2) and one third-generation LED (Ultra-Lume LED 5) by continuous light mode, and a quartz halogen-tungsten bulb (QHT, control). After 24 h of storage, the samples were pulverized into fine powder and 5 mg of each material were mixed with 100 mg of potassium bromide (KBr). After homogenization, they were pressed, which resulted in a pellet that was evaluated using an infrared spectromer (Nexus 470, Thermo Nicolet) equipped with TGS detector using diffuse reflectance (32 scans, resolution of 4 cm(-1)) coupled to a computer. The percentage of unreacted carbon-carbon double bonds (% C=C) was determined from the ratio of absorbance intensities of aliphatic C=C (peak at 1637 cm-1) against internal standard before and after curing of the specimen: aromatic C-C (peak at 1610 cm-1). The ANOVA showed a significant effect on the interaction between the light-curing units (LCUs) and the composite resins (presin (Filtek™ Z350) and Opallis when photo-activated by the halogen lamp (QTH) had the lowest DC compared with the other microhybrid composite resins. The DC of the nanofilled resin (Filtek™ Z350) was also lower using LEDs. The highest degrees of conversion were obtained using the third-generation LED and one of second-generation LEDs (Elipar Free Light™ 2). The nanofilled resin showed the lowest DC, and the Vit-l-escence™ microhybrid composite resin showed the highest DC. Among the LCUs, it was not possible to establish an order, even though the second-generation LED Radii-cal provided the lowest DC.

  14. Shear force bond analysis between acrylic resin bases and retention framework (open- and mesh-type)

    Science.gov (United States)

    Royhan, A.; Indrasari, M.; Masulili, C.

    2017-08-01

    Occlusions between teeth and the activity of the muscles around an artificial tooth during mastication create a force on dentures. This force causes friction between acrylic resin bases and retention frameworks that can lead to the complete loss of the acrylic resin base from the framework. The purpose of this study was to analyze the design of retention frameworks and determine which ones have a better resistance to shear forces in order to prevent the loss of heat cured acrylic resin base (HCARB). Six samples each of open-and mesh-type retention frameworks, both types made of Co-Cr material, and HCARB, were shear tested by means of a universal testing machine. The average shear force required to release the HCARB for mesh-type retention frameworks was 28.84 kgf, and the average for the open-type was 26.52 kgf. There was no significant difference between the shear forces required to remove HCARB from open- and mesh-type retention frameworks.

  15. Effect of light aging on silicone-resin bond strength in maxillofacial prostheses.

    Science.gov (United States)

    Polyzois, Gregory; Pantopoulos, Antonis; Papadopoulos, Triantafillos; Hatamleh, Muhanad

    2015-04-01

    The aim of this study was to investigate the effect of accelerated light aging on bond strength of a silicone elastomer to three types of denture resin. A total of 60 single lap joint specimens were fabricated with auto-, heat-, and photopolymerized (n = 20) resins. An addition-type silicone elastomer (Episil-E) was bonded to resins treated with the same primer (A330-G). Thirty specimens served as controls and were tested after 24 hours, and the remaining were aged under accelerated exposure to daylight for 546 hours (irradiance 765 W/m(2) ). Lap shear joint tests were performed to evaluate bond strength at 50 mm/min crosshead speed. Two-way ANOVA and Tukey's test were carried out to detect statistical significance (p Accelerated light aging for 546 hours affects the bond strength of an addition-type silicone elastomer to three different denture resins. The bond strength significantly increased after aging for photo- and autopolymerized resins. All the bonds failed adhesively. © 2014 by the American College of Prosthodontists.

  16. Influence of increment thickness on dentin bond strength and light transmission of composite base materials.

    Science.gov (United States)

    Omran, Tarek A; Garoushi, Sufyan; Abdulmajeed, Aous A; Lassila, Lippo V; Vallittu, Pekka K

    2017-06-01

    Bulk-fill resin composites (BFCs) are gaining popularity in restorative dentistry due to the reduced chair time and ease of application. This study aimed to evaluate the influence of increment thickness on dentin bond strength and light transmission of different BFCs and a new discontinuous fiber-reinforced composite. One hundred eighty extracted sound human molars were prepared for a shear bond strength (SBS) test. The teeth were divided into four groups (n = 45) according to the resin composite used: regular particulate filler resin composite: (1) G-ænial Anterior [GA] (control); bulk-fill resin composites: (2) Tetric EvoCeram Bulk Fill [TEBF] and (3) SDR; and discontinuous fiber-reinforced composite: (4) everX Posterior [EXP]. Each group was subdivided according to increment thickness (2, 4, and 6 mm). The irradiance power through the material of all groups/subgroups was quantified (MARC® Resin Calibrator; BlueLight Analytics Inc.). Data were analyzed using two-way ANOVA followed by Tukey's post hoc test. SBS and light irradiance decreased as the increment's height increased (p composite used. EXP presented the highest SBS in 2- and 4-mm-thick increments when compared to other composites, although the differences were not statistically significant (p > 0.05). Light irradiance mean values arranged in descending order were (p composites. Discontinuous fiber-reinforced composite showed the highest value of curing light transmission, which was also seen in improved bonding strength to the underlying dentin surface. Discontinuous fiber-reinforced composite can be applied safely in bulks of 4-mm increments same as other bulk-fill composites, although, in 2-mm thickness, the investigated composites showed better performance.

  17. The Effect of Simplified Bonding Agents on the Bond Strength to Dentin of Self-Activated Dual-Cure Resin Cements

    Science.gov (United States)

    2013-04-26

    steps that included an acidic conditioner, primer, and adhesive monomer. Examples include Optibond FL (Kerr) and Adper Scotchbond MultiPurpose ( 3M ESPE...Bond NT (Dentsply) and Adper Prompt L-Pop ( 3M /ESPE); and two non-simplified adhesives , Optibond FL (Kerr) and Clearfil SE (Kuraray). The four...presentation at the 2013 IADR by Bisco Inc. compared their simplified adhesive and self-cure resin combination All-Bond Universal and Duolink with

  18. Development of an extractive-scintillating chromatographic resin for the detection of radioactive isotopes

    International Nuclear Information System (INIS)

    Vincze, A.; Halasz, L.; Solymosi, J.; Molnar, A.; Safrany, A.

    2007-01-01

    In this paper, the development of a new-type of resin is presented, which contains selective complexing and scintillating molecules in a chemically bonded form. The resin material is produced via radiation polymerization of a solution of 2-(4-allyloxy-phenyl)-5-phenyl oxazole, 5-(allyloxyphenyl)- 2-[4-(5-phenyl-oxazole-2-il)-phenyl] oxazole, diethylene glycol dimethacrylate (DEGMA), styrene and the allyl derivative of a 18C6 crown ether-dicarbolic acid complexing agent. The product is a macroporous polymer matrix that shows fluorescent properties and ion binding capacity excellent for radioanalytical purposes. (author)

  19. Synthesis and Thermal Properties of a Novel Nitrogen-containing Epoxy Resin

    Institute of Scientific and Technical Information of China (English)

    Xing Hong ZHANG; Hong Mei WAN; Yu Qin MIN; Zuo FANG; Guo Rong QI

    2005-01-01

    A new nitrogen-containing epoxy resin (XT resin) was synthesized from chain extension of xylenephenolformaldehyde resin (XPF) and triglycidyl isocyanurate (TGIC) in the presence of base catalyst. FT-IR and 1H-NMR analysis confirmed the chemical structure of XT resin. It was cured with dicyandiamide (DICY) and diaminodiphenyl sulfone (DDS). Dynamic mechanical analysis (DMA) results showed that the introduction of triazine ring provides epoxy polymer with good thermal stability. Furthermore, high char yields at 800℃ in thermogravimetric (TGA)analysis indicated that XT resin had potential flame retardance.

  20. Retention of a resin-based sealant and a glass ionomer used as a fissure sealant: A comparative clinical study

    Directory of Open Access Journals (Sweden)

    Subramaniam P

    2008-09-01

    Full Text Available Sealing occlusal pits and fissures with resin-based sealants is a proven method of preventing occlusal caries. Retention of the sealant is very essential for its efficiency. This study evaluated the retention of glass ionomer used as a fissure sealant when compared to a self-cure resin-based sealant. One hundred and seven children between the ages of 6-9 years, with all four newly erupted permanent first molars were selected. Two permanent first molars on one side of the mouth were sealed with Delton, a resin-based sealant, and the contralateral two permanent first molars were sealed with Fuji VII glass ionomer cement. Evaluation of sealant retention was performed at regular intervals over 12 months, using Simonsen′s criteria. At the end of the study period, the retention of the resin sealant was seen to be superior to that of the glass ionomer sealant.

  1. Effect of cavity preparation on the flexural strengths of acrylic resin repairs

    Science.gov (United States)

    ELHADIRY, Safa Salim; YUNUS, Norsiah; ARIFFIN, Yusnidar Tajul

    2010-01-01

    Objective To investigate the effect of cavity preparation on the flexural strength of heat-curing denture resin when repaired with an auto-curing resin. Material and methods Ninety-six rectangular specimens (64x10x2.5 mm) prepared from heat-curing denture base resin (Meliodent) were randomly divided into four groups before repair. One group was left intact as control. Each repair specimen was sectioned into two; one group was repaired using the conventional repair method (Group 1). Two groups had an additional transverse cavity (2x3.5x21.5 mm) prepared prior to the repair; one repaired with (Group 2) and one without glass-fiber reinforcement (Group 3). A three-point flexural bending test according to the ISO 1567:1999 specification8 for denture base polymers was carried out on all groups after 1, 7 and 30 days of water immersion. Statistical analysis was carried out using two-way ANOVA, Kruskal Wallis and post-hoc Mann Whitney tests. Results The highest flexural strength was observed in the control group. Control and conventional repairs group (Group 1) showed reduction in the flexural strength 30 days after water immersion. No significant change in the strength was observed for Groups 2 and 3 where the repair joints were similarly prepared with additional transverse cavity. Conclusion Repaired specimens showed lower flexural strength values than intact heat-curing resin. Cavity preparation had no significant effect on the flexural strength of repair with water immersion. PMID:21308283

  2. Synthesis and Mechanism of Metal-Mediated Polymerization of Phenolic Resins

    Directory of Open Access Journals (Sweden)

    Zhao Yi

    2016-04-01

    Full Text Available Phenol-formaldehyde (PF resin is a high performance adhesive, but has not been widely developed due to its slow curing rate and high curing temperature. To accelerate the curing rate and to lower the curing temperature of PF resin, four types of metal-mediated catalysts were employed in the synthesis of PF resin; namely, barium hydroxide (Ba(OH2, sodium carbonate (Na2CO3, lithium hydroxide (LiOH, and zinc acetate ((CH3COO2Zn. The cure-acceleration effects of these catalysts on the properties of PF resins were measured, and the chemical structures of the PF resins accelerated with the catalysts were investigated by using Fourier transform infrared (FT-IR spectroscopy and quantitative liquid carbon-13 nuclear magnetic resonance (13C NMR. The results showed that the accelerated efficiency of these catalysts to PF resin could be ordered in the following sequence: Na2CO3 > (CH3COO2Zn > Ba(OH2 > LiOH. The catalysts (CH3COO2Zn and Na2CO3 increased the reaction activity of the phenol ortho position and the condensation reaction of ortho methylol. The accelerating mechanism of (CH3COO2Zn on PF resin is probably different from that of Na2CO3, which can be confirmed by the differences in the differential thermogravimetric (DTG curve and thermogravimetric (TG data. Compared to the Na2CO3-accelerated PF resin, the (CH3COO2Zn-accelerated PF resin showed different peaks in the DTG curve and higher weight residues. In the synthesis process, the catalyst (CH3COO2Zn may form chelating compounds (containing a metal-ligand bond, which can promote the linkage of formaldehyde to the phenolic hydroxyl ortho position.

  3. Analytical methods for the measurement of polymerization kinetics and stresses of dental resin-based composites: A review

    Directory of Open Access Journals (Sweden)

    Mehrsima Ghavami-Lahiji

    2017-01-01

    Full Text Available Resin-based composites are commonly used restorative materials in dentistry. Such tooth-colored restorations can adhere to the dental tissues. One drawback is that the polymerization shrinkage and induced stresses during the curing procedure is an inherent property of resin composite materials that might impair their performance. This review focuses on the significant developments of laboratory tools in the measurement of polymerization shrinkage and stresses of dental resin-based materials during polymerization. An electronic search of publications from January 1977 to July 2016 was made using ScienceDirect, PubMed, Medline, and Google Scholar databases. The search included only English-language articles. Only studies that performed laboratory methods to evaluate the amount of the polymerization shrinkage and/or stresses of dental resin-based materials during polymerization were selected. The results indicated that various techniques have been introduced with different mechanical/physical bases. Besides, there are factors that may contribute the differences between the various methods in measuring the amount of shrinkages and stresses of resin composites. The search for an ideal and standard apparatus for measuring shrinkage stress and volumetric polymerization shrinkage of resin-based materials in dentistry is still required. Researchers and clinicians must be aware of differences between analytical methods to make proper interpretation and indications of each technique relevant to a clinical situation.

  4. Study on curing reaction of 4-aminophenoxyphthalonitrile/bisphthalonitrile

    Institute of Scientific and Technical Information of China (English)

    Xiao

    2010-01-01

    A series of phthalonitrile blending resins were prepared from 4-aminophenoxyphthalonitrile (APN) and 4,4'-bis (3,4-dicyanophenoxy)biphenyl (BPH) by directly powder-mixing and copolymerization. Differential scanning calorimeter (DSC) and dynamic rheology were used to study the curing reaction behaviors of APN/BPH blends, and the results indicated that the introduction of APN accelerated the curing rate of BPH, and the existence of BPH decreased the curing temperature of APN/BPH systems. The thermal stability of postcured APN/BPH resins was investigated by thermogravimetric analysis (TGA), and the TGA results indicated that the crosslinked polymers of APN/BPH systems possessed good thermal stability.

  5. Conversion degrees of resin composites using different light sources.

    Science.gov (United States)

    Ozturk, Bora; Cobanoglu, Nevin; Cetin, Ali Rıza; Gunduz, Beniz

    2013-01-01

    The objective of this study was to compare the conversion degree of six different composite materials (Filtek Z 250, Filtek P60, Spectrum TPH, Pertac II, Clearfil AP-X, and Clearfil Photo Posterior) using three different light sources (blue light-emitting diode [LED], plasma arc curing [PAC], and conventional halogen lamp [QTH]). Composites were placed in a 2 mm thick and 5 mm diameter Teflon molds and light cured from the top using three methods: LED for 40 s, PAC for 10 s, and QTH for 40 s. A Fourier Transform Infrared Spectroscopy (FTIR) was used to evaluate the degree of conversion (DC) (n=5). The results were analyzed with two-way analysis of variance and Tukey HSD test. DC was significantly influenced by two variables, light source and composite (PDC values than LED (PDC values of QTH and PAC or between DC values of LED and PAC (P>.05). The highest DC was observed in the Z 250 composite specimens following photopolymerization with QTH (70%). The lowest DC was observed in Clearfil Photo Posterior composite specimens following photo-polymerization with LED (43%). The DC was found to be changing according to both light sources and composite materials used. Conventional light halogen (QTH) from light sources and Filtek Z 250 and Filtek P 60 among composite materials showed the most DC performance.

  6. Non-isothermal curing kinetics and physical properties of MMT-reinforced unsaturated polyester (UP) resins

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, María A., E-mail: angelesvh@yahoo.com [Tecnológico de Estudios Superiores de Ecatepec, Av. Tecnológico S/N, Valle de Anáhuac, 55210 Ecatepec de Morelos (Mexico); Vázquez, H. [Universidad Autónoma Metropolitana-Iztapalapa, Departamento de Física, Av. San Rafael Atlixco 186, col. Vicentina, Mexico, D.F. 09340 (Mexico); Guthausen, G. [KIT, Pro2NMR at MVM and IBG, Karlsruhe (Germany)

    2015-07-10

    Highlights: • Non-isothermal DSC analysis results have shown that the addition of MMT to a UP resin produces a delay in the cure reaction. • The shape of experimental heat-flow DSC curves showed two exothermic peaks for all the samples at different heating rates. • The overall kinetic analysis was performed by isoconversional methods. • It was found that the dependence of the activation energy (E{sub a}) on degree of reaction (α) is complex. - Abstract: Cure behavior of unsaturated polyester (UP)/montmorillonite (MMT)/methyl ethyl ketone peroxide (MEKP)/cobalt octoate intercalated nanocomposites with various MMT loadings was investigated by dynamic differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). UP/MMT nanocomposites were prepared by sequential mixing. Non-isothermal DSC curves were obtained by applying heating rates ranging from 5 to 20 °C/min. They presented two exothermic peaks, which should correspond to two independent cure reactions. The effective activation energy E{sub a}, was determined by applying both the Kissinger’s and Starink’s methods. The results showed slightly higher activation energy for nanocomposites, except for UP/10-MMT. It was found that the dependence of E{sub a} on α is complex. All the systems in this study fitted Sesták–Berggren (SB) model in overall reaction controlled kinetics and the corresponding model parameters, n, m, A were obtained, but it was insufficient in depicting the complex reaction kinetics. Transmission electron microscopy data support the formation of a partially delaminated nanocomposite material. UP and nanocomposites showed similar behavior on thermal stability.

  7. Effects of molecular structure of the resins on the volumetric shrinkage and the mechanical strength of dental restorative composites.

    Science.gov (United States)

    Kim, L U; Kim, J W; Kim, C K

    2006-09-01

    To prepare a dental composite that has a low amount of curing shrinkage and excellent mechanical strength, various 2,2-bis[4-(2-hydroxy-3-methacryloyloxy propoxy) phenyl] propane (Bis-GMA) derivatives were synthesized via molecular structure design, and afterward, properties of their mixtures were explored. Bis-GMA derivatives, which were obtained by substituting methyl groups for hydrogen on the phenyl ring in the Bis-GMA, exhibited lower curing shrinkage than Bis-GMA, whereas their viscosities were higher than that of Bis-GMA. Other Bis-GMA derivatives, which contained a glycidyl methacrylate as a molecular end group exhibited reduced curing shrinkage and viscosity. Methoxy substitution for hydroxyl groups on the Bis-GMA derivatives was performed for the further reduction of the viscosity and curing shrinkage. Various resin mixtures, which had the same viscosity as the commercial one, were prepared, and their curing shrinkage was examined. A resin mixture containing 2,2-bis[3,5-dimethyl, 4-(2-methoxy-3-methacryloyloxy propoxy) phenyl] propane] (TMBis-M-GMA) as a base resin and 4-tert-butylphenoxy-2-methyoxypropyl methacrylate (t-BP-M-GMA) as a diluent exhibited the lowest curing shrinkage among them. The composite prepared from this resin mixture also exhibited the lowest curing shrinkage along with enhanced mechanical properties.

  8. Effect of different curing modes on the degree of conversion and the microhardness of different composite restorations

    Directory of Open Access Journals (Sweden)

    Reem Ali Ajaj

    2015-01-01

    Full Text Available Introduction: This study aims to evaluate the effects of different curing units and modes on the degree of conversion (DC and microhardness (MH of two different resin composites [ESTELITE ∑ QUICK (EQ, and Z350 XT (Z3]. Materials and Methods: One hundred (100 discs of each tested material were made and divided into two subgroups (n = 50 according to the discs′ dimensions: 5 mm diameter × 2 mm thickness, and 2 mm diameter × 2 mm thickness. Each subgroup was further subdivided into the following five classes (n = 10: I cured with halogen light curing-unit; II cured with light-emitting diode (LED unit; III cured with argon laser; IV cured with halogen light-curing unit for 5 s, 10 s rest followed by 20 s curing; and V cured with halogen light-curing unit for 10 s, then 10 s rest, followed by 10 s curing. The first subgroup was tested for MH using the Vickers Microhardness tester and the second subgroup was tested for DC using Fourier transform infrared spectroscopy (FTIR. Data were statistically analyzed using two-way analysis of variance (ANOVA and Tukey′s post hoc test P < 0.05. Results: Specimens in class IV showed the highest mean DC and MH, followed by class III, then class II. Class I showed significantly lower mean values for both DC and MH. On the other hand, Z3 showed statistically significantly higher mean DC and MH than EQ. Conclusion: Although the two tested composites did not perform similarly under the test conditions, curing with halogen unit for 5 s, then 10 s rest, followed by 10 s curing improved the DC and the MH of both the tested materials.

  9. Conventional dual-cure versus self-adhesive resin cements in dentin bond integrity

    Directory of Open Access Journals (Sweden)

    Renata Andreza Talaveira da Silva

    2011-08-01

    Full Text Available During post preparation, the root canal is exposed to the oral cavity, and endodontic treatment may fail because of coronal leakage, bacterial infection and sealing inability of the luting cement. OBJECTIVE: this study quantified the interfacial continuity produced with conventional dual-cure and self-adhesive resin cements in the cervical (C, medium (M and apical (A thirds of the root. MATERIAL AND METHODS: Forty single-rooted human teeth were restored using Reforpost # 01 conical glass-fiber posts and different materials (N=10 per group: group AC=Adper™ ScotchBond™ Multi-purpose Plus + AllCem; group ARC=Adper™ ScotchBond™ Multi-purpose Plus + RelyX ARC; group U100=RelyX U100; and group MXC=Maxcem Elite. After being kept in 100% humidity at 37°C for 72 hours, the samples were sectioned parallel to their longitudinal axis and positive epoxy resin replicas were made. The scanning electron micrographs of each third section of the teeth were combined using Image Analyst software and measured with AutoCAD-2002. We obtained percentage values of the interfacial continuity. RESULTS: Interfacial continuity was similar in the apical, medium and cervical thirds of the roots within the groups (Friedman test, p>0.05. Comparison of the different cements in a same root third showed that interfacial continuity was lower in MXC (C=45.5%; M=48.5%; A=47.3% than in AC (C=85.9%, M=81.8% and A=76.0%, ARC (C=83.8%, M=82.4% and A=75.0% and U100 (C=84.1%, M=82.4% and A=77.3% (Kruskal-Wallis test, p<0.05. CONCLUSIONS: Allcem, Rely X ARC and U100 provide the best cementation; cementation was similar among root portions; in practical terms, U100 is the best resin because it combines good cementation and easy application and none of the cements provides complete interfacial continuity.

  10. Conventional dual-cure versus self-adhesive resin cements in dentin bond integrity

    Science.gov (United States)

    da SILVA, Renata Andreza Talaveira; COUTINHO, Margareth; CARDOZO, Pedro Igor; da SILVA, Larissa Alves; ZORZATTO, José Roberto

    2011-01-01

    During post preparation, the root canal is exposed to the oral cavity, and endodontic treatment may fail because of coronal leakage, bacterial infection and sealing inability of the luting cement. Objective this study quantified the interfacial continuity produced with conventional dual-cure and self-adhesive resin cements in the cervical (C), medium (M) and apical (A) thirds of the root. Material and methods Forty single-rooted human teeth were restored using Reforpost # 01 conical glass-fiber posts and different materials (N=10 per group): group AC=Adper™ ScotchBond™ Multi-purpose Plus + AllCem; group ARC=Adper™ ScotchBond™ Multi-purpose Plus + RelyX ARC; group U100=RelyX U100; and group MXC=Maxcem Elite. After being kept in 100% humidity at 37ºC for 72 hours, the samples were sectioned parallel to their longitudinal axis and positive epoxy resin replicas were made. The scanning electron micrographs of each third section of the teeth were combined using Image Analyst software and measured with AutoCAD-2002. We obtained percentage values of the interfacial continuity. Results Interfacial continuity was similar in the apical, medium and cervical thirds of the roots within the groups (Friedman test, p>0.05). Comparison of the different cements in a same root third showed that interfacial continuity was lower in MXC (C=45.5%; M=48.5%; A=47.3%) than in AC (C=85.9%, M=81.8% and A=76.0%), ARC (C=83.8%, M=82.4% and A=75.0%) and U100 (C=84.1%, M=82.4% and A=77.3%) (Kruskal-Wallis test, p<0.05). Conclusions Allcem, Rely X ARC and U100 provide the best cementation; cementation was similar among root portions; in practical terms, U100 is the best resin because it combines good cementation and easy application and none of the cements provides complete interfacial continuity. PMID:21710099

  11. Surface discoloration of composite resins: Effects of staining and bleaching.

    Science.gov (United States)

    Poggio, Claudio; Beltrami, Riccardo; Scribante, Andrea; Colombo, Marco; Chiesa, Marco

    2012-09-01

    The purpose of this in vitro study was to evaluate surface discoloration of three microhybrid composite resins (Esthet•X HD, Clearfil AP-X, Gradia Direct) and five nanohybrid composite resins (Ceram•X, GC Kalore, G-aenial, Grandio, GrandioSO), after staining and bleaching procedures. The composite resins were polymerized with a curing light (Celalux II, Voco, Cuxhaven, Germany) into 160 silicon molds (6,4 mm in diameter and 2 mm in thickness) to obtain identical specimens. Twenty samples for each composite resin were prepared. The specimens were polished using an automated polishing machine with the sequence of 600-, 800-, 1000-grit abrasive paper under water irrigation. The specimens were immersed in tea and distilled water: the specimens were dipped for 20 min, once a day (every 24 h), for 14 days into the drinks. The specimens were then bleached with carbamide peroxide at 17% (Perfect Bleach-Voco). The color of specimens was measured with a spectrophotometer according to the CIE L(*)a(*)b(*) system after light-polymerization of composite resin specimens, after 7 days, after 14 days, and after bleaching. The color difference h index (DEab(*)) between each measurement was calculated. Statistical analysis was made using analysis of variance (ANOVA). All specimens showed a significant increase in staining with a similar trend and no significant differences between microhybrid and nanohybrid composite resins. After whitening procedures, materials tested showed both significant and unsignificant differences of the h index. Microhybrid and nanohybrid composite resins had similar in vitro surface discoloration in tea. After bleaching, discoloration was removed from some composite resins tested.

  12. Correlations of norbornenyl crosslinked polyimide resin structures with resin thermo-oxidative stability, resin glass transition temperature and composite initial mechanical properties

    Science.gov (United States)

    Alston, William B.

    1988-01-01

    PMR (polymerization of monomeric reactants) methodology was used to prepare 70 different polyimide oligomeric resins and 30 different unidirectional graphite fiber/polyimide composites. Monomeric composition as well as chain length between sites of crosslinks were varied to examine their effects on resin thermo-oxidative stability and glass transition temperature (Tg) of the cured/postcured resins. A linear correlation of decreasing 316 C resin weight loss/surface area versus (1) decreasing aliphatic content, or (2) increasing benzylic/aliphatic content stoichiometry ratio over a wide range of resin compositions was observed. An almost linear correlation of Tg versus molecular distance between the crosslinks was also observed. An attempt was made to correlate Tg with initial composite mechanical properties (flexural strength and interlaminar shear strength). However, the scatter in mechanical strength data prevented obtaining a clear correlation. Instead, only a range of composite mechanical properties was obtained at 25, 288, and 316 C. Perhaps more importantly, what did become apparent during the correlation study was (1) the PMR methodology could be used to prepare composites from resins containing a wide variety of monomer modifications, (2) that these composites almost invariably provided satisfactory initial mechanical properties as long as the resins formulated exhibited satisfactory processing flow, and (3) that PMR resins exhibited predictable rates of 316 C weight loss/surface area based on their benzylic/aliphatic stoichiometery ratio.

  13. A New Epoxy-Based Layered Silicate Nanocomposite Using a Hyperbranched Polymer: Study of the Curing Reaction and Nanostructure Development.

    Science.gov (United States)

    Cortés, Pilar; Fraga, Iria; Calventus, Yolanda; Román, Frida; Hutchinson, John M; Ferrando, Francesc

    2014-03-04

    Polymer layered silicate (PLS) nanocomposites have been prepared with diglycidyl ether of bisphenol-A (DGEBA) epoxy resin as the matrix and organically modified montmorillonite (MMT) as the clay nanofiller. Resin-clay mixtures with different clay contents (zero, two, five and 10 wt%) were cured, both isothermally and non-isothermally, using a poly(ethyleneimine) hyperbranched polymer (HBP), the cure kinetics being monitored by differential scanning calorimetry (DSC). The nanostructure of the cured nanocomposites was characterized by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM), and their mechanical properties were determined by dynamic mechanical analysis (DMA) and impact testing. The results are compared with an earlier study of the structure and properties of the same DGEBA-MMT system cured with a polyoxypropylene diamine, Jeffamine. There are very few examples of the use of HBP as a curing agent in epoxy PLS nanocomposites; here, it is found to enhance significantly the degree of exfoliation of these nanocomposites compared with those cured with Jeffamine, with a corresponding enhancement in the impact energy for nanocomposites with the low clay content of 2 wt%. These changes are attributed to the different cure kinetics with the HBP, in which the intra-gallery homopolymerization reaction is accelerated, such that it occurs before the bulk cross-linking reaction.

  14. A New Epoxy-Based Layered Silicate Nanocomposite Using a Hyperbranched Polymer: Study of the Curing Reaction and Nanostructure Development

    Directory of Open Access Journals (Sweden)

    Pilar Cortés

    2014-03-01

    Full Text Available Polymer layered silicate (PLS nanocomposites have been prepared with diglycidyl ether of bisphenol-A (DGEBA epoxy resin as the matrix and organically modified montmorillonite (MMT as the clay nanofiller. Resin-clay mixtures with different clay contents (zero, two, five and 10 wt% were cured, both isothermally and non-isothermally, using a poly(ethyleneimine hyperbranched polymer (HBP, the cure kinetics being monitored by differential scanning calorimetry (DSC. The nanostructure of the cured nanocomposites was characterized by small angle X-ray scattering (SAXS and transmission electron microscopy (TEM, and their mechanical properties were determined by dynamic mechanical analysis (DMA and impact testing. The results are compared with an earlier study of the structure and properties of the same DGEBA-MMT system cured with a polyoxypropylene diamine, Jeffamine. There are very few examples of the use of HBP as a curing agent in epoxy PLS nanocomposites; here, it is found to enhance significantly the degree of exfoliation of these nanocomposites compared with those cured with Jeffamine, with a corresponding enhancement in the impact energy for nanocomposites with the low clay content of 2 wt%. These changes are attributed to the different cure kinetics with the HBP, in which the intra-gallery homopolymerization reaction is accelerated, such that it occurs before the bulk cross-linking reaction.

  15. Comparative evaluation of different mechanical modifications of denture teeth on bond strength between high-impact acrylic resin and denture teeth: An in vitro study.

    Science.gov (United States)

    Phukela, Sumit Singh; Chintalapudi, Siddesh Kumar; Sachdeva, Harleen; Dhall, Rupinder Singh; Sharma, Neeraj; Prabhu, Allama

    2016-01-01

    Acrylic teeth separates from the denture base and remains a major worry in day-to-day routine dental procedure. The present study was conducted to comparatively evaluate different mechanical modifications of acrylic teeth on bond strength between Lucitone 199 heat cure resin and cross-linked teeth. The test specimens, central incisors (21) were demarcated into four groups. Group 1 was the control group, whereas Group 2, Group 3, and Group 4 were experimental groups modified with round groove, vertical groove, and T-shaped groove, respectively. The preparation of masterpiece was done by aligning the long axis of the central incisor teeth at 45° to the base of a wax block (8 mm × 10 mm × 30 mm), with ridge lap surface contacting the base. These test specimen (21) was prepared by Lucitone 199 heat cure resin. Evaluation of bond strength of all the specimens was done using universal tester (materials testing machine). Shapiro-Wilk Test, one-way analysis of variance (ANOVA), and Bonferroni test were done to do statistical investigation. Group 1 specimens prepared by Lucitone 199 heat cure resin showed the lowest bond strength and Group 4 specimens prepared with T-shaped groove packed with Lucitone 199 exhibited the highest bond strength. The bond strength between Lucitone 199 heat cure resin and cross-linked teeth was increased when mechanical modifications was done on denture teeth. The specimens prepared with T-shaped groove packed with Lucitone 199 heat cure resin showed the highest bond strength followed by Group 3, Group 2, and lastly Group 1 prepared by Lucitone 199 heat cure resin.

  16. Influence of Al{sub 2}O{sub 3} nanoparticles on the isothermal cure of an epoxy resin

    Energy Technology Data Exchange (ETDEWEB)

    Sanctuary, R; Baller, J; Zielinski, B; Becker, N; Krueger, J K; Philipp, M; Mueller, U; Ziehmer, M [University of Luxembourg, 162a avenue de la Faiencerie, L-1511 (Luxembourg)], E-mail: roland.sanctuary@uni.lu

    2009-01-21

    The influence of Al{sub 2}O{sub 3} nanoparticles on the curing of an epoxy thermoset based on diglycidyl ether of bisphenol A was investigated using temperature-modulated differential scanning calorimetry (TMDSC) and rheology. Diethylene triamine was used as a hardener. TMDSC not only allows for a systematic study of the kinetics of cure but simultaneously gives access to the evolution of the specific heat capacities of the thermosets. The technique thus provides insight into the glass transition behaviour of the nanocomposites and hence makes it possible to shed some light on the interaction between the nanoparticles and the polymer matrix. The Al{sub 2}O{sub 3} fillers are shown to accelerate the growth of macromolecules upon isothermal curing. Several mechanisms which possibly could be responsible for the acceleration are described. As a result of the faster network growth chemical vitrification occurs at earlier times in the filled thermosets and the specific reaction heat decreases with increasing nanoparticle concentration. Rheologic measurements of the zero-shear viscosity confirm the faster growth of the macromolecules in the presence of the nanoparticles.

  17. Differences in interfacial bond strengths of graphite fiber-epoxy resin composites

    Science.gov (United States)

    Needles, H. L.

    1985-01-01

    The effect of epoxy-size and degree of cure on the interfacial bonding of an epoxy-amine-graphite fiber composite system is examined. The role of the fiber-resin interface in determining the overall mechanical properties of composites is poorly understood. A good interfacial adhesive bond is required to achieve maximum stress transfer to the fibers in composites, but at the same time some form of energy absorbing interfacial interaction is needed to achieve high fracture toughening. The incompatibility of these two processes makes it important to understand the nature and basic factors involved at the fiber-resin interface as stress is applied. The mechanical properties including interlaminar shear values for graphite fiber-resin composites are low compared to glass and boron-resin composites. These differences have been attributed to poor fiber-matrix adhesion. Graphite fibers are commonly subjected to post-treatments including application of organic sizing in order to improve their compatibility with the resin matrix and to protect the fiber tow from damage during processing and lay-up. In such processes, sized graphite fiber tow is impregnated with epoxy resin and then layed-up i nto the appropriate configuration. Following an extended ambient temperature cure, the graphite-resin composite structure is cured at elevated temperature using a programmed temperature sequence to cure and then cool the product.

  18. Studies on the structural changes during curing of epoxy and its blend with CTBN

    Science.gov (United States)

    Srivastava, Kavita; Rathore, Ashwani Kumar; Srivastava, Deepak

    2018-01-01

    Cashew nut shell liquid (CNSL), an agricultural renewable resource material, produces natural phenolic distillates such as cardanol. Cardanol condenses with formaldehyde at the ortho- and para-position of the phenolic ring under acidic or alkaline condition to yield a series of polymers of novolac- or resol-type phenolic resins. These phenolic resins may further be modified by epoxidation with epichlorohydrin to duplicate the performance of such phenolic-type novolacs (CFN). The structural changes during curing of blend samples of epoxy and carboxyl terminated poly (butadiene-co-acrylonitrile) (CTBN) were studies by Fourier-transform infrared (FTIR) spectrophotometer. The epoxy samples were synthesized by biomass material, cardanol. Blend sample was prepared by physical mixing of CTBN ranging between 0 and 20 weight percent CTBN liquid rubber into cardanol-based epoxidized novolac (CEN) resin. The FTIR spectrum of uncured blend sample clearly indicated that there appeared a band in the region of 3200-3500 cm- 1 which might be due to the presence of phenolic hydroxyl group and sbnd OH group of the opened epoxide. Pure epoxy resin showed peaks near 856 cm- 1 which might be due to oxirane functionality of the epoxidized novolac resin. Both epoxy and its blend sample was cured with polyamine. The cure temperature of CEN resin was found to be decreased by the incorporation of CTBN. The decomposition behavior was also studied by thermogravimetric analyzer (TGA). Two-step decomposition behavior was observed in both epoxy and its blend samples.

  19. Radiation cured polyester compositions containing metal-properties

    Science.gov (United States)

    Szalińska, H.; Pietrzak, M.; Gonerski, A.

    The subject of the studies was unsaturated polyester resin, Polimal-109 and its compositions containing acrylates of: sodium, potassium, calcium, magnesium, barium, manganese, iron, cobalt, copper and acrylic acid. Polyester resin modified with acrylic acid salts was cured with 60Co gamma radiation. Measurements of Vicat softening temperature, water absorption, creep current resistance, volume and surface resistivity, the tangent of dielectric loss angle and permittivity of radiation cured compositions were carried out. The results of the studies presented testify to the fact that the properties of cross-linked polymers alter after ionogenic compounds have been introduced into them.

  20. Radiation cured polyester compositions containing metal-properties

    International Nuclear Information System (INIS)

    Szalinska, H.; Pietrzak, M.; Gonerski, A.

    1987-01-01

    The subject of the studies was unsaturated polyester resin, Polimal-109 and its compositions containing acrylates of: sodium, potassium, calcium, magnesium, barium, manganese, iron, cobalt, copper and acrylic acid. Polyester resin modified with acrylic acid salts was cured with 60 Co gamma radiation. Measurements of Vicat softening temperature, water absorption, creep current resistance, volume and surface resistivity, the tangent of dielectric loss angle and permittivity of radiation cured compositions were carried out. The results of the studies presented testify to the fact that the properties of cross-linked polymers alter after ionogenic compounds have been introduced into them. (author)

  1. Monitoring Prepregs As They Cure

    Science.gov (United States)

    Young, P. R.; Gleason, J. R.; Chang, A. C.

    1986-01-01

    Quality IR spectra obtained in dynamic heating environment. New technique obtains quality infrared spectra on graphite-fiber-reinforced, polymeric-matrix-resin prepregs as they cure. Technique resulted from modification of diffuse reflectance/Fourier transform infrared (DR/FTIR) technique previously used to analyze environmentally exposed cured graphite composites. Technique contribute to better understanding of prepreg chemistry/temperature relationships and development of more efficient processing cycles for advanced materials.

  2. FTIR analysis and the effects of alkyd/melamine resin ratio on the properties of the coatings

    Directory of Open Access Journals (Sweden)

    Cakić Suzana M.

    2009-01-01

    Full Text Available Alkyd/melamine resin mixtures are mainly used in industrial baking enamels. The effects of the alkyd/butylated melamine resin ratio (from 90/10 to 50/50 and curing temperature (from 110 to 180°C on the crosslinking and properties of the coating are presented in this paper. The curing reactions through functional groups of resins were monitored by FT-IR spectroscopy. The hardness, elasticity, degree of adherence and gloss were also determined. Optimal coating properties could be achieved with an alkyd/melamine resin ratio of 80/20, a curing temperature of 150°C and a curing time of 20 min.

  3. In vitro biofilm formation on resin-based composites after different finishing and polishing procedures.

    Science.gov (United States)

    Cazzaniga, Gloria; Ottobelli, Marco; Ionescu, Andrei C; Paolone, Gaetano; Gherlone, Enrico; Ferracane, Jack L; Brambilla, Eugenio

    2017-12-01

    To evaluate the influence of surface treatments of different resin-based composites (RBCs) on S. mutans biofilm formation. 4 RBCs (microhybrid, nanohybrid, nanofilled, bulk-filled) and 6 finishing-polishing (F/P) procedures (open-air light-curing, light-curing against Mylar strip, aluminum oxide discs, one-step rubber point, diamond bur, multi-blade carbide bur) were evaluated. Surface roughness (SR) (n=5/group), gloss (n=5/group), scanning electron microscopy morphological analysis (SEM), energy-dispersive X-ray spectrometry (EDS) (n=3/group), and S. mutans biofilm formation (n=16/group) were assessed. EDS analysis was repeated after the biofilm assay. A morphological evaluation of S. mutans biofilm was also performed using confocal laser-scanning microscopy (CLSM) (n=2/group). The data were analyzed using Wilcoxon (SR, gloss) and two-way ANOVA with Tukey as post-hoc tests (EDS, biofilm formation). F/P procedures as well as RBCs significantly influenced SR and gloss. While F/P procedures did not significantly influence S. mutans biofilm formation, a significant influence of RBCs on the same parameter was found. Different RBCs showed different surface elemental composition. Both F/P procedures and S. mutans biofilm formation significantly modified this parameter. The tested F/P procedures significantly influenced RBCs surface properties but did not significantly affect S. mutans biofilm formation. The significant influence of the different RBCs tested on S. mutans biofilm formation suggests that material characteristics and composition play a greater role than SR. F/P procedures of RBCs may unexpectedly play a minor role compared to that of the restoration material itself in bacterial colonization. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. High conversion self-curing sealer based on a novel injectable polyurethane system for root canal filling

    International Nuclear Information System (INIS)

    Sun, Bin; Zuo, Yi; Li, Jidong; Wang, Li; Tang, Kuangyun; Huang, Di; Du, Jingjing; Luo, Peipei; Li, Yubao

    2013-01-01

    Low monomer–polymer conversion is the key factor leading to cytotoxicity for resin-containing restorative materials. This paper provides a new root canal filling system based on self-curing injectable polyurethane which can achieve high conversion in a short time. Traced FTIR spectra show more than 90% NCO group participated in the curing reaction after 4 h, and only about 5% remained after 24 h. The calculated data also testified the curing process supports a third-order reaction, and this efficient and sufficient reaction is postulated to weaken the toxic stimulation. By culturing with L929 murine fibroblasts, the PU sealer is shown to be favorable for cell attachment and proliferation. Then physicochemical properties of the injectable PU-based sealer were evaluated according to the Standard [ISO 6876:2001 (E)] for clinical application. A series of physicochemical properties of PU sealer have been tested comparing with AH Plus and Apexit Plus. And the results present that the self-curing PU sealer could not only match the clinic requirements, but even has better properties than the other two commercial sealers. We expect the high conversion PU sealer has a tremendous potential in the field of root canal filling after further biological evaluation. - Highlights: • A new root canal sealer based on self-curing injectable polyurethane was provided. • More than 90% NCO group reacted after 4h, and only about 5% remained after 24 h. • By culturing with L929 murine fibroblasts, the PU sealer showed perfect cytocompatibility. • Volumetric dilatancy after curing will make the sealer achieve a tight seal

  5. High conversion self-curing sealer based on a novel injectable polyurethane system for root canal filling

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Bin [Research Center for Nano-Biomaterials, Analytical and Testing Center, Sichuan University, Chengdu 610064 (China); Zuo, Yi, E-mail: zoae@scu.edu.cn [Research Center for Nano-Biomaterials, Analytical and Testing Center, Sichuan University, Chengdu 610064 (China); Li, Jidong; Wang, Li [Research Center for Nano-Biomaterials, Analytical and Testing Center, Sichuan University, Chengdu 610064 (China); Tang, Kuangyun [The State Key Laboratory of Oral Diseases and Orthognathic Surgery, Sichuan University West China College of Stomatology, Chengdu 610064 (China); Huang, Di; Du, Jingjing; Luo, Peipei; Li, Yubao [Research Center for Nano-Biomaterials, Analytical and Testing Center, Sichuan University, Chengdu 610064 (China)

    2013-08-01

    Low monomer–polymer conversion is the key factor leading to cytotoxicity for resin-containing restorative materials. This paper provides a new root canal filling system based on self-curing injectable polyurethane which can achieve high conversion in a short time. Traced FTIR spectra show more than 90% NCO group participated in the curing reaction after 4 h, and only about 5% remained after 24 h. The calculated data also testified the curing process supports a third-order reaction, and this efficient and sufficient reaction is postulated to weaken the toxic stimulation. By culturing with L929 murine fibroblasts, the PU sealer is shown to be favorable for cell attachment and proliferation. Then physicochemical properties of the injectable PU-based sealer were evaluated according to the Standard [ISO 6876:2001 (E)] for clinical application. A series of physicochemical properties of PU sealer have been tested comparing with AH Plus and Apexit Plus. And the results present that the self-curing PU sealer could not only match the clinic requirements, but even has better properties than the other two commercial sealers. We expect the high conversion PU sealer has a tremendous potential in the field of root canal filling after further biological evaluation. - Highlights: • A new root canal sealer based on self-curing injectable polyurethane was provided. • More than 90% NCO group reacted after 4h, and only about 5% remained after 24 h. • By culturing with L929 murine fibroblasts, the PU sealer showed perfect cytocompatibility. • Volumetric dilatancy after curing will make the sealer achieve a tight seal.

  6. Evaluating resin-enamel bonds by microshear and microtensile bond strength tests: effects of composite resin

    Science.gov (United States)

    de ANDRADE, Andrea Mello; MOURA, Sandra Kiss; REIS, Alessandra; LOGUERCIO, Alessandro Dourado; GARCIA, Eugenio Jose; GRANDE, Rosa Helena Miranda

    2010-01-01

    Objectives The aims of this study were to evaluate the effect of resin composite (Filtek Z250 and Filtek Flow Z350) and adhesive system [(Solobond Plus, Futurabond NR (VOCO) and Adper Single Bond (3M ESPE)] on the microtensile (µTBS) and microshear bond strength (µSBS) tests on enamel, and to correlate the bond strength means between them. Material and methods Thirty-six extracted human molars were sectioned to obtain two tooth halves: one for µTBS and the other one for µSBS. Adhesive systems and resin composites were applied to the enamel ground surfaces and light-cured. After storage (37ºC/24 h) specimens were stressed (0.5 mm/ min). Fracture modes were analyzed under scanning electron microscopy. The data were analyzed using two-way ANOVA and Tukey's test (α=0.05). Results The correlation between tests was estimated with Pearson's product-moment correlation statistics (α =0.05). For both tests only the main factor resin composite was statistically significant (padhesives. Both microbond tests seem to be positive and linearly correlated and can therefore lead to similar conclusions. PMID:21308290

  7. Heat-cured Acrylic Resin versus Light-activated Resin: A Patient ...

    African Journals Online (AJOL)

    The second questionnaire (professional dentist evaluation) was based on a clinical evaluation of soft tissues, complications, and the applied technique. The third questionnaire (technician evaluation) involved ranking the different manufacturing steps of the denture and overall preferences. The obtained data was statistically ...

  8. The effects of different polishing techniques on the staining resistance of CAD/CAM resin-ceramics

    Science.gov (United States)

    Demirci, Tevfik; Demirci, Gamze; Sagsoz, Nurdan Polat; Yildiz, Mehmet

    2016-01-01

    PURPOSE The purposes of this study were to evaluate the staining resistance of CAD/CAM resin-ceramics polished with different techniques and to determine the effectiveness of the polishing techniques on resin-ceramics, comparing it with that of a glazed glass-ceramic. MATERIALS AND METHODS Four different CAD/CAM ceramics (feldspathic ceramic: C-CEREC Blocs, (SIRONA) and three resin-ceramics: L-Lava Ultimate, (3M ESPE), E-Enamic, (VITA) and CS-CeraSmart, (GC)) and one light cure composite resin: ME-Clearfil Majesty Esthetic (Kuraray) were used. Only C samples were glazed (gl). Other restorations were divided into four groups according to the polishing technique: nonpolished control group (c), a group polished with light cure liquid polish (Biscover LV BISCO) (bb), a group polished with ceramic polishing kit (Diapol, EVE) (cd), and a group polished with composite polishing kit (Clearfil Twist Dia, Kuraray) (kc). Glazed C samples and the polished samples were further divided into four subgroups and immersed into different solutions: distilled water, tea, coffee, and fermented black carrot juice. Eight samples (8 × 8 × 1 mm) were prepared for each subgroup. According to CIELab system, four color measurements were made: before immersion, immersion after 1 day, after 1 week, and after 1 month. Data were analyzed with repeated measures of ANOVA (α=.05). RESULTS The highest staining resistance was found in gl samples. There was no difference among gl, kc and cd (P>.05). Staining resistance of gl was significantly higher than that of bb (PCeramic and composite polishing kits can be used for resin ceramics as a counterpart of glazing procedure used for full ceramic materials. Liquid polish has limited indications for resin ceramics. PMID:28018558

  9. Photothermal radiometric determination of thermal diffusivity depth profiles in a dental resin

    International Nuclear Information System (INIS)

    MartInez-Torres, P; Alvarado-Gil, J J; Mandelis, A

    2010-01-01

    The depth of curing due to photopolymerization in a commercial dental resin is studied using photothermal radiometry. The sample consists of a thick layer of resin on which a thin metallic layer is deposited guaranteeing full opacity of the sample. In this case, purely thermal-wave inverse problem techniques without the interference of optical profiles can be used. Thermal profiles are obtained by heating the coating with a modulated laser beam and performing a modulation frequency scan. Before each frequency scan, photopolymerization was induced using a high power blue LED. However due to the fact that dental resins are highly light dispersive materials, the polymerization process depends strongly on the optical absorption coefficient inducing a depth dependent thermal diffusion in the sample. It is shown that using a robust depth profilometric inverse method one can reconstruct the thermal diffusivity profile of the photopolymerized resin.

  10. Micro-shear bond strength of different resin cements to ceramic/glass-polymer CAD-CAM block materials.

    Science.gov (United States)

    Cekic-Nagas, Isil; Ergun, Gulfem; Egilmez, Ferhan; Vallittu, Pekka Kalevi; Lassila, Lippo Veli Juhana

    2016-10-01

    The aim of this study was to evaluate the effects of hydrofluoric acid treatment on bond strength of resin cements to three different types of ceramic/glass containing CAD-CAM block composite materials. CAD-CAM block materials of polymer infiltrated (Vita Enamic), resin nanoceramic (Lava Ultimate) and nanoceramic (Cerasmart) with a thickness of 1.5mm were randomly divided into two groups according to the surface treatment performed. In Group 1, specimens were wet-ground with silicon carbide abrasive papers up to no. 1000. In Group 2, 9.6% hydrofluoric acid gel was applied to ceramics. Three different resin cements (RelyX, Variolink Esthetic and G-CEM LinkAce) were applied to the tubes in 1.2-mm thick increments and light-cured for 40s using LED light curing unit. Half of the specimens (n=10) were submitted to thermal cycling (5000 cycles, 5-55°C). The strength measurements were accomplished with a universal testing machine (Lloyd Instruments) at a cross-head speed of 0.5mm/min until the failure occurs. Failure modes were examined using a stereomicroscope and scanning electron microscope. The data were analyzed with multivariate analysis of variance (MANOVA) and Tukey's post hoc tests (α=0.05). There were significant differences between ceramics and resin cements (pceramics (pceramic/glass-polymer materials might promote the bonding capacity of these systems. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  11. Depth of Cure of New Flowable Composite Resins

    Science.gov (United States)

    2012-03-30

    we met. His encouragement and undiminished love for the past 20 years has been my motivation. This thesis is also dedicated to my four children ...assessed to be the most commonly used by dentists. Therefore, the depths of cure data from this study are pertinent to the practice of dentistry ...Continuing Education in Dentistry . Http://cde.dentalaegis.com Dai Q, Bertrand S. Wear resistance of Surefil SDR Flow posterior flowable base. JDR

  12. Evaluation of Flexural Strength of Polymethyl Methacrylate modified with Silver Colloidal Nanoparticles subjected to Two Different Curing Cycles: An in vitro Study.

    Science.gov (United States)

    Munikamaiah, Ranganath L; Jain, Saket K; Pal, Kapil S; Gaikwad, Ajay

    2018-03-01

    Silver colloidal nanoparticles have been incorporated into acrylic resins to induce antimicrobial properties. However, as additives, they can influence the mechanical properties of the final product. Mechanical properties are also dependent on different curing cycles. The aim of this study was to evaluate flexural strength of a denture base resin incorporated with different concentrations of silver colloidal nanoparticles subjected to two different curing cycles. Lucitone 199 denture base resin was used into which silver colloidal nanoparticles were incorporated at 0.5 and 5% by polymer mass. Specimens devoid of nanoparticles were used as controls. A total of 60 specimens were fabricated and divided into two groups. Each group was divided into three subgroups consisting of 10 specimens each. The specimens were fabricated according to American Dental Association (ADA) specification No. 12 and tested for flexural strength using universal testing machine. Silver colloidal nanoparticle incorporation at 0.5% concentration increased the mean flexural strength in both curing cycles by 7.5 and 4.4%, respectively, when compared with the control group. The study suggested that the mean flexural strength value of 0.5% silver colloidal nanoparticles in denture base resin was above the value of the control group both in short and long curing cycles, which makes it clinically suitable as a denture base material. However, at 5% concentration, the statistically significant amount of decrease in flexural strength compared with the value of control group both in short and long curing cycles gives it a questionable prognosis. The specimens incorporated with the antimicrobial agent 0.5% silver colloidal nanoparticles and processed by long curing cycles showed significant increase in its flexural strength compared with the control group, which makes it clinically suitable as a denture base material.

  13. BOND STRENGTH DURABILITY OF SELF-ETCHING ADHESIVES AND RESIN CEMENTS TO DENTIN

    Science.gov (United States)

    Chaves, Carolina de Andrade Lima; de Melo, Renata Marques; Passos, Sheila Pestana; Camargo, Fernanda Pelógia; Bottino, Marco Antonio; Balducci, Ivan

    2009-01-01

    Objectives: To evaluate the microtensile bond strength (μTBS) of one- (Xeno III, Dentsply) and two-step (Tyrian-One Step Plus, Bisco) self-etching adhesive systems bonded to dentin and cemented to chemically cured (C&B Metabond) or light-cured paste of a dual-cure resin cement (Variolink II, Ivoclar) within a short (24 h) and long period of evaluation (90 days). Material and Methods: Forty recently extracted human molars had their roots removed and their occlusal dentin exposed and ground wet with 600-grit SiC paper. After application of one of the adhesives, the resin cement was applied to the bonded surface and a composite resin block was incrementally built up to a height of 5 mm (n=10). The restored teeth were stored in distilled water at 37°C for 7 days. The teeth were then cut along two axes (x and y), producing beam-shaped specimens with 0.8 mm2 cross-sectional area, which were subjected to μTBS testing at a crosshead speed of 0.05 mm/min and stressed to failure after 24 h or 90 days of storage in water. The μTBS data in MPa were subjected to three-way analysis of variance and Tukey's test (α= 0.05). Results: The interaction effect for all three factors was statistically significant (three-way ANOVA, padhesive combination that provided the most promising bond strength after 90 days of storage in water. PMID:19466243

  14. Effect of resin shades on opacity of ceramic veneers and polymerization efficiency through ceramics.

    Science.gov (United States)

    Öztürk, Elif; Chiang, Yu-Chih; Coşgun, Erdal; Bolay, Şükran; Hickel, Reinhard; Ilie, Nicoleta

    2013-11-01

    The aim of this study was to assess the effect of different resin cement shades on the opacity and color difference of ceramics and to determine the polymerization efficiency of the resin cement at different shades after curing through ceramics. Two different ceramics (IPS e.max Press and IPS Empress(®)CAD, Ivoclar Vivadent) were used for this study. A light-cured veneer luting resin (Variolink Veneer, Ivoclar Vivadent) in four different shades of HV+1, HV+3, LV-1, and LV-3 was used for the colorimetric measurements. The color and spectral reflectance of the ceramics were measured according to the CIELab color scale relative to the standard illuminant D65 on a reflection spectrophotometer (ColorEye7000A, USA). Color differences (ΔE values) and the contrast ratios (CR) of the different groups of samples were calculated. In order to analyse the polymerization efficiency of the resin cements, the micromechanical properties of the resins were measured with an automatic microhardness indenter (Fisherscope H100C, Germany). The results were analysed using one-way ANOVA and Tukey's HSD post hoc tests (SPSS 18.0). The one-way ANOVA test showed that the values of ΔE and CR of the different specimen groups were significantly different (p<0.05). Group 1 (20.7 ± 0.5) (IPS-CAD without resin cement) exhibited the highest and group 10 (14.8 ± 0.5) (e.max:HV+3) exhibited the lowest ΔE value. Significant differences in the micromechanical properties were identified among the tested resin cements in different shades (p<0.05). Resin cement shade is an important factor for the opacity of a restoration. Furthermore, the resin shade affects the micromechanical properties of the underlying resin cement. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Influence of light intensity and curing cycle on microleakage of Class V composite resin restorations Influência da intensidade de luz e métodos de fotoativação no selamento marginal de restaurações classe V em resina composta

    Directory of Open Access Journals (Sweden)

    Maria Jacinta M. Coelho Santos

    2005-06-01

    Full Text Available The aim of this study was to determine the effect of a softstart polymerization method from Quartz-Tungsten-Halogen (QTH and Plasma Arc (PAC curing units on microleakage of Class V composite resin restorations with dentin cavosurface margins. Seventy-five bovine incisors received standardized class V cavities in all dentin margins. Teeth were divided into 5 equal groups according to the curing cycle. The cavities were incrementally restored with a composite resin (Single Bond/Z-100, 3M. Light curing was applied as follows: Group I: PAC light continuous-cycle curing at 1600 mW/cm² for 3s; Group II: PAC light step-cycle curing (2s at 800 mW/cm² then 4s at 1600 mW/cm²; Group III: QTH light continuous-cycle curing at 400 mW/cm² for 40s; Group IV: QTH light ramp-cycle curing (from 100 to 600 mW/cm² in 15s followed by 25s at 600 mW/cm²; Group V: QTH light pulse-delay curing (200 mW/cm² for 3s followed by 3 min delay then 600 mW/cm² for 30s. Teeth were stored in distilled water at 37ºC for 30 days and then subjected to thermocycling for 500 cycles at 5 and 55ºC. Root apices were sealed and teeth coated with nail varnish before they were immersed in 0.5% fuchsine red dye solution. Teeth were then sectioned and slices were scanned with a computer scanner to determine the area of dye leakage using a computer program (Image Tools. Images of tooth slices were also visually examined under magnification and dye penetration along the tooth/restoration interface was scored. Significant differences in the degree of dye penetration and leakage were detected between groups (pO objetivo deste estudo foi determinar o efeito da polimerização gradual, mediante a utilização de aparelhos de Quartzo-Tungustênio-Halógena (QTH e Arco de Plasma de Xenônio (PAC, no selamento marginal de restaurações classe V em resina composta com margens localizadas em dentina. Setenta e cinco incisivos bovinos receberam preparos de cavidades classe V, na raiz, com o

  16. Accompanying of parameters of color, gloss and hardness on polymeric films coated with pigmented inks cured by different radiation doses of ultraviolet light

    International Nuclear Information System (INIS)

    Gonçalves Bardi, Marcelo Augusto; Brocardo Machado, Luci Diva

    2012-01-01

    In the search for alternatives to traditional paint systems solvent-based, the curing process of polymer coatings by ultraviolet light (UV) has been widely studied and discussed, especially because of their high content of solids and null emission of VOC. In UV-curing technology, organic solvents are replaced by reactive diluents, such as monomers. This paper aims to investigate variations on color, gloss and hardness of print inks cured by different UV radiation doses. The ratio pigment/clear coating was kept constant. The clear coating presented higher average values for König hardness than pigmented ones, indicating that UV-light absorption has been reduced by the presence of pigments. Besides, they have indicated a slight variation in function of cure degree for the studied radiation doses range. The gloss loss related to UV light exposition allows inferring that some degradation occurred at the surface of print ink films. - Highlights: ► Color, gloss and hardness are directly influenced by the different pigments. ► Clear coating analysis indicates reduction on UV-light absorption. ► Color and gloss indices indicated aeration in function of cure degree.

  17. Short and long term behaviour of externally bonded fibre reinforced polymer laminates with bio-based resins for flexural strengthening of concrete beams

    Science.gov (United States)

    McSwiggan, Ciaran

    The use of bio-based resins in composites for construction is emerging as a way to reduce of embodied energy produced by a structural system. In this study, two types of bio-based resins were explored: an epoxidized pine oil resin blend (EP) and a furfuryl alcohol resin (FA) derived from corn cobs and sugar cane. Nine large-scale reinforced concrete beams strengthened using externally bonded carbon and glass fibre reinforced bio-based polymer (CFRP and GFRP) sheets were tested. The EP resin resulted in a comparable bond strength to conventional epoxy (E) when used in wet layup, with a 7% higher strength for CFRP. The FA resin, on the other hand, resulted in a very weak bond, likely due to concrete alkalinity affecting curing. However, when FA resin was used to produce prefabricated cured CFRP plates which were then bonded to concrete using conventional epoxy paste, it showed an excellent bond strength. The beams achieved an increase in peak load ranging from 18-54% and a 9-46% increase in yielding load, depending on the number of FRP layers and type of fibres and resin. Additionally, 137 concrete prisms with a mid-span half-depth saw cut were used to test CFRP bond durability, and 195 CFRP coupons were used to examine tensile strength durability. Specimens were conditioned in a 3.5% saline solution at 23, 40 or 50°C, for up to 240 days. Reductions in bond strength did not exceed 15%. Bond failure of EP was adhesive with traces of cement paste on CFRP, whereas that of FA was cohesive with a thicker layer of concrete on CFRP, suggesting that the bond between FA and epoxy paste is excellent. EP tension coupons had similar strength and modulus to E resin, whereas FA coupons had a 9% lower strength and 14% higher modulus. After 240 days of exposure, maximum reductions in tensile strength were 8, 19 and 10% for EP, FA and E resins, respectively. Analysis of Variance (ANOVA) was also performed to assess the significance of the reductions observed. High degrees of

  18. Nanomechanical properties of dental resin-composites.

    Science.gov (United States)

    El-Safty, S; Akhtar, R; Silikas, N; Watts, D C

    2012-12-01

    To determine by nanoindentation the hardness and elastic modulus of resin-composites, including a series with systematically varied filler loading, plus other representative materials that fall into the categories of flowable, bulk-fill and conventional nano-hybrid types. Ten dental resin-composites: three flowable, three bulk-fill and four conventional were investigated using nanoindentation. Disc specimens (15mm×2mm) were prepared from each material using a metallic mold. Specimens were irradiated in the mold at top and bottom surfaces in multiple overlapping points (40s each) with light curing unit at 650mW/cm(2). Specimens were then mounted in 3cm diameter phenolic ring forms and embedded in a self-curing polystyrene resin. After grinding and polishing, specimens were stored in distilled water at 37°C for 7 days. Specimens were investigated using an Agilent Technologies XP nanoindenter equipped with a Berkovich diamond tip (100nm radius). Each specimen was loaded at one loading rate and three different unloading rates (at room temperature) with thirty indentations, per unloading rate. The maximum load applied by the nanoindenter to examine the specimens was 10mN. Dependent on the type of the resin-composite material, the mean values ranged from 0.73GPa to 1.60GPa for nanohardness and from 14.44GPa to 24.07GPa for elastic modulus. There was a significant positive non-linear correlation between elastic modulus and nanohardness (r(2)=0.88). Nonlinear regression revealed a significant positive correlation (r(2)=0.62) between elastic moduli and filler loading and a non-significant correlation (r(2)=0.50) between nanohardness and filler loading of the studied materials. Varying the unloading rates showed no consistent effect on the elastic modulus and nanohardness of the studied materials. For a specific resin matrix, both elastic moduli and nanohardness correlated positively with filler loading. For the resin-composites investigated, the group-average elastic

  19. Thermogravimetric Characterization of the Microstructui Composition of Polyamide Injection Molded Denture Base Material vs Conventional Compression Molded Heat-cured Denture Base Material.

    Science.gov (United States)

    Al-Dharrab, Ayman; Shinawi, Lana

    2016-02-01

    Thermoplastic resin polymers are widely used in medicine due to their biostability and hypoallergenic properties, making them a possible alternative to poly-methylmethacrylate (PMMA). The current research examined the microstructure of a rapid injection molding system thermoplastic resin for construction of flexible denture compared with that of heat-cured PMMA. A total of 40 disk-shaped specimens (25 mm in diameter and 3 mm in thickness) were prepared and divided into two groups of 20 disks each (group I samples were of thermoplastic acrylic resin while group II was heat-cured PMMA resin). In group I, thermogravimetric analyzer showed that increasing the temperature up to 169°C resulted in about 1.3% of the material loss, and after that the material remains thermally stable up to 200°C. Group 11 showed 2.24% weight loss at 171°C, and further weight loss (12.025%) was observed on heating to 230°C. Fourier transform infrared (FTIR) spectrophotometer analysis in the range of 400-4000 cm(-1) detected the presence of an amine group (N-H) in group I samples and the presence of methylene group attached to inorganic Si as reinforcement filler (Si-CH3). Thermoplastic resin displayed excellent thermal stability and the absence of residual monomer within the polymerized material, suggesting its suitability for the fabrication dentures.

  20. Manufacturing of kevlar/polyester composite by resin transfer moulding using conventional and microwave heating

    International Nuclear Information System (INIS)

    Abdullah, I.

    2015-01-01

    Microwave heating was incorporated into the resin transfer moulding technique. Polytetrafluoroethylene (PTFE) mould was used to cure the composite panel. Through the use of microwave heating, the mechanical and physical properties of produced Kevlar fibre/polyester composites were compared to those manufactured by conventional resin transfer moulding. The flexural modulus and flexural strength of 6-ply conventionally cured composites was 45% and 9% higher than the flexural modulus and flexural strength of 6-ply microwaved cured composites, respectively. However, 19% increase in interlaminar shear strength (ILSS) and 2% increase in compressive strength was observed in 6-ply microwave cured composites. This enhancement in ILSS and compressive strength is attributed to the better interfacial bonding of polyester resin with Kevlar fibres in microwaved cured composite, which was also confirmed via electron microscopy scanning. Furthermore, the microwave cured composite yielded maximum void contents (3%). (author)

  1. Fabrication of high-brightness GaN-based light-emitting diodes via thermal nanoimprinting of ZnO-nanoparticle-dispersed resin

    International Nuclear Information System (INIS)

    Byeon, Kyeong-Jae; Cho, Joong-Yeon; Jo, Han-Byeol; Lee, Heon

    2015-01-01

    Highlights: • A various high-refractive-index ZnO patterns were formed on LED using imprinting. • Mechanism of light extraction enhancement was demonstrated by simulation and EL. • Light output power of patterned LED was improved up 19.6% by light waveguide effect. - Abstract: We fabricated high-brightness GaN-based light-emitting diodes (LEDs) with highly refractive patterned structures by using a thermal nanoimprint lithography (NIL). A highly refractive ZnO-nanoparticle-dispersed resin (ZNDR) was used in NIL, and a submicron hole, a submicron high-aspect-ratio pillar, and microconvex arrays were fabricated on the indium tin oxide (ITO) top electrode of GaN-based LED devices. We analyzed the light extraction mechanism for each of the three types of patterns by using a finite element method simulation, and found that the high-aspect-ratio pillar had a great ability to improve light extraction owing to its waveguide effect and prominent scattering effect. As a result, the light output power, which was measured in an integrating sphere, of the LED device was enhanced by up to 19.6% when the high-aspect-ratio pillar array was formed on the top ITO electrode of the device. Further, the electrical properties of none of the patterned LED devices fabricated using ZNDR degraded in comparison to those of bare LED devices

  2. Evaluating resin-enamel bonds by microshear and microtensile bond strength tests: effects of composite resin

    Directory of Open Access Journals (Sweden)

    Andrea Mello de Andrade

    2010-12-01

    Full Text Available OBJECTIVES: The aims of this study were to evaluate the effect of resin composite (Filtek Z250 and Filtek Flow Z350 and adhesive system [(Solobond Plus, Futurabond NR (VOCO and Adper Single Bond (3M ESPE] on the microtensile (μTBS and microshear bond strength (μSBS tests on enamel, and to correlate the bond strength means between them. MATERIAL AND METHODS: Thirty-six extracted human molars were sectioned to obtain two tooth halves: one for μTBS and the other one for μSBS. Adhesive systems and resin composites were applied to the enamel ground surfaces and light-cured. After storage (37(0C/24 h specimens were stressed (0.5 mm/min. Fracture modes were analyzed under scanning electron microscopy. The data were analyzed using two-way ANOVA and Tukey's test (α=0.05. RESULTS: The correlation between tests was estimated with Pearson's product-moment correlation statistics (α =0.05. For both tests only the main factor resin composite was statistically significant (p<0.05. The correlation test detected a positive (r=0.91 and significant (p=0.01 correlation between the tests. CONCLUSIONS: The results were more influenced by the resin type than by the adhesives. Both microbond tests seem to be positive and linearly correlated and can therefore lead to similar conclusions.

  3. Development of palm oil-based UV-curable epoxy acrylate and urethane acrylate resins for wood coating application

    International Nuclear Information System (INIS)

    Rida Tajau; Nurulhuda Mohd Yunus; Mohd Hilmi Mahmood; Mek Zah Salleh; Nik Ghazali Nik Salleh

    2013-01-01

    Full-text: The trend of using renewable sources such as palm oil as raw material in radiation curing is growing due to the demand from the market to produce a more environmental friendly product. In this study, the radiation curable process was done using epoxy acrylate and urethane acrylate resins which are known as epoxidized palm olein acrylate (EPOLA) and palm oil based urethane acrylate (POBUA), respectively. The purpose of the study was to investigate curing properties and the application of this UV-curable palm oil resins for wood coating. Furthermore, the properties of palm oil based coatings are compared with the petrochemical-based compound such as ebecryl (EB) for example EB264 and EB830. From the experiment done, the resins from petrochemical-based compounds resulted higher degree of crosslinking (up to 80 %) than the palm oil based compounds (up to 70 %), where the different is around 10-15 %. The hardness property from this two type coatings can reached until 50 % at the lower percentage of the oligomer. However, the coatings from petrochemical-based have a high scratch resistance as it can withstand at least up to 3.0 Newton's (N) compared to the palm oil-based compounds which are difficult to withstand the load up to 1.0 N. Finally, the test on the rubber wood substrate showed that the coatings containing benzophenone photo initiator give higher adhesion property and their also showed a higher glossiness property on the glass substrate compared to the coatings containing irgacure-819 photo initiator. This study showed that the palm oil coatings can be a suitable for the replacement of petrochemicals compound for wood coating. The palm oil coatings can be more competitive in the market if the problems of using high percentage palm oil oligomer can be overcome as the palm oil price is cheap enough. (author)

  4. Development of palm oil-based UV-curable epoxy acrylate and urethane acrylate resins for wood coating application

    International Nuclear Information System (INIS)

    Tajau, Rida; Mahmood, Mohd Hilmi; Salleh, Mek Zah; Salleh, Nik Ghazali Nik; Ibrahim, Mohammad Izzat; Yunus, Nurulhuda Mohd

    2014-01-01

    The trend of using renewable sources such as palm oil as raw material in radiation curing is growing due to the demand from the market to produce a more environmental friendly product. In this study, the radiation curable process was done using epoxy acrylate and urethane acrylate resins which are known as epoxidised palm olein acrylate (EPOLA) and palm oil based urethane acrylate (POBUA), respectively. The purpose of the study was to investigate curing properties and the application of this UV-curable palm oil resins for wood coating. Furthermore, the properties of palm oil based coatings are compared with the petrochemical-based compound such as ebecryl (EB) i.e. EB264 and EB830. From the experiment done, the resins from petrochemical-based compounds resulted higher degree of crosslinking (up to 80%) than the palm oil based compounds (up to 70%), where the different is around 10-15%. The hardness property from this two type coatings can reached until 50% at the lower percentage of the oligomer. However, the coatings from petrochemical-based have a high scratch resistance as it can withstand at least up to 3.0 Newtons (N) compared to the palm oil-based compounds which are difficult to withstand the load up to 1.0 N. Finally, the test on the rubber wood substrate showed that the coatings containing benzophenone photoinitiator give higher adhesion property and their also showed a higher glosiness property on the glass substrate compared to the coatings containing irgacure-819 photoinitiator. This study showed that the palm oil coatings can be a suitable for the replacement of petrochemicals compound for wood coating. The palm oil coatings can be more competitive in the market if the problems of using high percentage palm oil oligomer can be overcome as the palm oil price is cheap enough

  5. Development of palm oil-based UV-curable epoxy acrylate and urethane acrylate resins for wood coating application

    Energy Technology Data Exchange (ETDEWEB)

    Tajau, Rida; Mahmood, Mohd Hilmi; Salleh, Mek Zah; Salleh, Nik Ghazali Nik [Radiation Processing Technology Division, Malaysian Nuclear Agency (Nuclear Malaysia), Bangi, 43000 Kajang, Selangor (Malaysia); Ibrahim, Mohammad Izzat [Faculty of Science, University of Malaya (UM), 50603 Kuala Lumpur (Malaysia); Yunus, Nurulhuda Mohd [Faculty of Science and Technology, National University Malaysia (UKM), 43600 Bangi, Selangor (Malaysia)

    2014-02-12

    The trend of using renewable sources such as palm oil as raw material in radiation curing is growing due to the demand from the market to produce a more environmental friendly product. In this study, the radiation curable process was done using epoxy acrylate and urethane acrylate resins which are known as epoxidised palm olein acrylate (EPOLA) and palm oil based urethane acrylate (POBUA), respectively. The purpose of the study was to investigate curing properties and the application of this UV-curable palm oil resins for wood coating. Furthermore, the properties of palm oil based coatings are compared with the petrochemical-based compound such as ebecryl (EB) i.e. EB264 and EB830. From the experiment done, the resins from petrochemical-based compounds resulted higher degree of crosslinking (up to 80%) than the palm oil based compounds (up to 70%), where the different is around 10-15%. The hardness property from this two type coatings can reached until 50% at the lower percentage of the oligomer. However, the coatings from petrochemical-based have a high scratch resistance as it can withstand at least up to 3.0 Newtons (N) compared to the palm oil-based compounds which are difficult to withstand the load up to 1.0 N. Finally, the test on the rubber wood substrate showed that the coatings containing benzophenone photoinitiator give higher adhesion property and their also showed a higher glosiness property on the glass substrate compared to the coatings containing irgacure-819 photoinitiator. This study showed that the palm oil coatings can be a suitable for the replacement of petrochemicals compound for wood coating. The palm oil coatings can be more competitive in the market if the problems of using high percentage palm oil oligomer can be overcome as the palm oil price is cheap enough.

  6. Preparation and characterization of a novel epoxy based nanocomposite using tryptophan as an eco-friendly curing agent

    International Nuclear Information System (INIS)

    Motahari, Ahmad; Omrani, Abdollah; Rostami, Abbas Ali; Ehsani, Morteza

    2013-01-01

    Highlights: • Epoxy cured with tryptophan in the presence of 2,4,5-triphenylimidazole. • Kinetic study on the epoxy nanocomposite using advanced isoconversional method. • Structural study and characterization of nanocomposite using SEM, XRD, AFM and DMTA. - Abstract: In this study, kinetics of the curing reaction between DGEBA epoxy resin and tryptophan as an environmentally friendly curing agent in the presence of 2,4,5-triphenylimidazole was reported. The role of silica nanoparticles (SiNP) in changing the mechanism of the curing reaction was also studied. The optimum molar ratio of DGEBA/tryptophan and the optimum content of SiNP were determined by calorimetry analyses. Kinetic analysis using the advanced isoconversional method revealed that the system undergoes the vitrification. Thermogravimetric analysis demonstrated that addition of SiNP does not improve the thermal stability of the tryptophan based thermosets. Impedance spectroscopy and also the standard four-probe method were performed to investigate the effect of curing agent and SiNP loading level on the electrical properties of the cured epoxy. The structure and morphology of the nanocomposite were studied by X-ray diffraction analysis, atomic force microscopy and scanning electron microscopy imaging. Dynamic mechanical thermal analysis revealed that the crosslinking density cannot be significantly affected with the addition of SiNP

  7. Aspects of bonding between resin luting cements and glass ceramic materials.

    Science.gov (United States)

    Tian, Tian; Tsoi, James Kit-Hon; Matinlinna, Jukka P; Burrow, Michael F

    2014-07-01

    The bonding interface of glass ceramics and resin luting cements plays an important role in the long-term durability of ceramic restorations. The purpose of this systematic review is to discuss the various factors involved with the bond between glass ceramics and resin luting cements. An electronic Pubmed, Medline and Embase search was conducted to obtain laboratory studies on resin-ceramic bonding published in English and Chinese between 1972 and 2012. Eighty-three articles were included in this review. Various factors that have a possible impact on the bond between glass ceramics and resin cements were discussed, including ceramic type, ceramic crystal structure, resin luting cements, light curing, surface treatments, and laboratory test methodology. Resin-ceramic bonding has been improved substantially in the past few years. Hydrofluoric acid (HF) etching followed by silanizaiton has become the most widely accepted surface treatment for glass ceramics. However, further studies need to be undertaken to improve surface preparations without HF because of its toxicity. Laboratory test methods are also required to better simulate the actual oral environment for more clinically compatible testing. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  8. Computerized mathematical model for prediction of resin/fiber composite properties

    International Nuclear Information System (INIS)

    Lowe, K.A.

    1985-01-01

    A mathematical model has been developed for the design and optimization of resin formulations. The behavior of a fiber-reinforced cured resin matrix can be predicted from constituent properties of the formulation and fiber when component interaction is taken into account. A computer implementation of the mathematical model has been coded to simulate resin/fiber response and generate expected values for any definable properties of the composite. The algorithm is based on multistage regression techniques and the manipulation of n-order matrices. Excellent correlation between actual test values and predicted values has been observed for physical, mechanical, and qualitative properties of resin/fiber composites. Both experimental and commercial resin systems with various fiber reinforcements have been successfully characterized by the model. 6 references, 3 figures, 2 tables

  9. Development of new addition-type composite resins

    Science.gov (United States)

    Kray, R. J.

    1981-01-01

    The most promising of a number of new addition type polyimides and polyaromatic melamine (NCNS) resins for use in high performance composite materials. Three different cure temperature ranges were of interest: 530-560 K (500-550 F), 475-530 K (400-500 F), and 450 K (350 F). Examined were a wide variety of polyimide precursors terminated with 5 norbornene groups and addition polymerized at 560 K similar to PMR-15 and LARC-160 polyimides. In addition, a number of lower curing cinnamal end capped polyimides and a bismaleimide were investigated but were not found promising. A group of NCNS resins were investigated and some were found to be superior to current epoxy resins in moisture resistance, oxidative aging and flame and smoke properties.

  10. Influence of curing agents on gelation and exotherm behaviour of an ...

    Indian Academy of Sciences (India)

    Unsaturated polyester resin; resin curing; gel time; exotherm behaviour; peroxide initiator. 1. Introduction ... process cycle to manufacture a composite part. The magni- ... work, which makes sudden irreversible transformation from a liquid resin to a ... anistic models attempt to quantify the balance of chemical species taking ...

  11. Characterization of solid UV curable 3D printer resins for biological applications

    KAUST Repository

    Sivashankar, Shilpa

    2016-12-19

    In this paper, we report a simple method to evaluate biocompatibility of solid UV cross-linked resin as a material for microfluidic devices that can be used for biological applications. We evaluated the biocompatibility of the material in two different ways (1) determining if the UV cured resin inhibits the polymerase chain reaction (PCR) and (2) observing agglutination complex formed on the surface of the UV cured resin when anti-CRP antibodies and C- reactive protein (CRP) proteins were allowed to agglutinate. Six different types of 3D printer resins were compared to test the biocompatibility. The study showed that only few among them could be used for fabrication of micro channels and that had least effect on biological molecules that could be used for PCR and protein interactions. Through these studies it is possible to estimate the curing time of various resin and their type of interaction with biomolecules. This study finds importance in on-chip tissue engineering and organ-on-chip applications.

  12. Proton-Transfer Polymerization by N-Heterocyclic Carbenes: Monomer and Catalyst Scopes and Mechanism for Converting Dimethacrylates into Unsaturated Polyesters

    KAUST Repository

    Hong, Miao

    2016-01-18

    This contribution presents a full account of experimental and theoretical/computational investigations into the N-heterocyclic carbene (NHC)-catalyzed proton-transfer polymerization (HTP) that converts common dimethacrylates (DMAs) containing no protic groups into unsaturated polyesters. This new HTP proceeds through the step-growth propagation cycles via enamine intermediates, consisting of the proposed conjugate addition–proton transfer–NHC release fundamental steps. This study examines the monomer and catalyst scopes as well as the fundamental steps involved in the overall HTP mechanism. DMAs having six different types of linkages connecting the two methacrylates have been polymerized into the corresponding unsaturated polyesters. The most intriguing unsaturated polyester of the series is that based on the biomass-derived furfuryl dimethacrylate, which showed a unique self-curing ability Four MeO– and Cl–substituted TPT (1,3,4-triphenyl-4,5-dihydro-1H-1,2,4-triazol-5-ylidene) derivatives as methanol insertion products, RxTPT(MeO/H) (R = MeO, Cl; x = 2, 3), and two free carbenes (catalysts), OMe2TPT and OMe3TPT, have been synthesized, while OMe2TPT(MeO/H) and OMe2TPT have also been structurally characterized. The structure/reactivity relationship study revealed that OMe2TPT, being both a strong nucleophile and a good leaving group, exhibits the highest HTP activity and also produced the polyester with the highest Mn, while the Cl–substituted TPT derivatives are least active and efficient. Computational studies have provided mechanistic insights into the tail-to-tail dimerization coupling step as a suitable model for the propagation cycle of the HTP. The extensive energy profile was mapped out and the experimentally observed unicity of the TPT-based catalysts was satisfactorily explained with the thermodynamic formation of key spirocyclic species.

  13. Influence of CuO nanoparticle on palm oil based alkyd resin preparation and its antimicrobial activity

    Science.gov (United States)

    Ruey Ong, Huei; Maksudur Rahman Khan, Md.; Ramli, Ridzuan; Shein Hong, Chi; Yunus, Rosli Mohd

    2018-03-01

    An alkyd resin has been synthesized from palm oil that reacted with glycerol and phthalic anhydride by alcoholysis-polyesterification process and co-catalyzed by CuO nanoparticle. The CuO nanoparticle was pre-prepared in the glycerol via sol gel method, which creates a new reaction condition for resin preparation. The resins were characterized by fourier transform infrared spectroscopy (FTIR), where a new ester linkage bond (C-O-C) was noticed for resin sample. The antimicrobial activity and the curing behaviour of the resin were determined by Kirby-Bauer and differential scanning calorimeter technique. It was found that, the addition of CuO speeded up the reaction rate and played antimicrobial role. Moreover, it shortens the reaction time of alcoholysis and polyesterification process.

  14. Relationship between Color and Translucency of Multishaded Dental Composite Resins

    Directory of Open Access Journals (Sweden)

    Homan Naeimi Akbar

    2012-01-01

    Full Text Available The aim of the present study was to compare the translucency of different shades of two highly aesthetic multilayered restorative composite resins. In total nine shades from Esthet.X and ten shades from Filtek Supreme composite resins were chosen. Discs of each shade were prepared (N=3 and light-cured. Total and diffuse transmittance values for each sample were measured. Statistical analysis showed that the opaque dentine shades of both composites were the least translucent and the enamel shades had the highest translucency. There was a significant decrease in translucency from A2 to C2 of regular body shades and also from A4 to C4 of opaque dentine shades of Esthet.X composite resin. Grey enamel shade had a significantly higher diffuse translucency compared to clear and yellow enamel shades. There was a significant decrease in translucency from A2B to D2B and also in diffuse translucency from A4D to C6D shades of Filtek Supreme composite resin. It can be concluded that the color of the composite resins tested in this study had a significant effect on their translucency. Information on the translucency of different shades of composite resins can be very useful for the clinicians in achieving optimal esthetic restorative outcome.

  15. Resins for combined light and electron microscopy: a half century of development.

    Science.gov (United States)

    Newman, G R; Hobot, J A

    1999-08-01

    The last fifty years have seen enormous improvements in the way biological specimens are prepared for microscopy. The Fifties produced the essential groundwork upon which many of our current methodologies are based. Acrylic resin embedding was introduced in 1949, with subsequent publications seeking improvements to resin formulations, embedding protocols, and modes of polymerisation. Procedures for progressive lowering of temperature processing, cryosubstitution, freeze-drying and polymerisation by ultra-violet light at low temperatures, all had their genesis in this decade of great innovation. The Sixties marked the period when the acrylics were eclipsed by the more stable and reliable epoxy resins, and much of our present-day understanding of ultrastructure was elucidated. The Seventies carried on this work with advances in technical developments concerned mainly with freezing methodologies. The beginning of the Eighties saw a resurrection of the acrylic resins, with new formulations of these resins giving reliable and stable embeddings. The low temperature and freezing methodologies pioneered in the Fifties, backed up by recent improvements to low temperature technologies, were used to further our understanding of ultrastructure and breathe new life into the science of immunocytochemistry. The remainder of the Eighties and Nineties has seen the ever increasing application of these various microscopical techniques to a wide range of biological studies. The flexibility offered by the acrylic resins in choosing between different processing, embedding and polymerisation methods has provided the impetus for detailed studies to bring to the attention of microscopists the underlying trends governing specimen preparation. Therefore, looking forward to the new Millennium, this has allowed for a more reasoned choice in organising a strategy to deal with a variety of microscopical requirements and for planning an appropriate protocol.

  16. Knowledge Gaps Exist Among Dentists Regarding Curing Lights and Personal Protection.

    Science.gov (United States)

    Wright, Wanda G

    2017-09-01

    Light curing procedures - performance, knowledge level and safety awareness among dentists. Kopperud SE, Rukke HV, Kopperud HM, Bruzell EM. J Dent 2017;58:67-73. Information not available TYPE OF STUDY/DESIGN: Cross-sectional study. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Cytoxicity, dynamic and thermal properties of bio-based rosin-epoxy resin/ castor oil polyurethane/ carbon nanotubes bio-nanocomposites.

    Science.gov (United States)

    Huo, Li; Wang, Dan; Liu, Hongmei; Jia, Pan; Gao, Jungang

    2016-08-01

    In order to prepare bio-nanocomposites with no-cytotoxicity, the rosin-based epoxy resin (MPAER) and castor oil-based polyurethane (COPU) were synthesized and carbon nanotubes (CNTs) was used to enhance the properties of curing MPAER/COPU materials. The curing reaction, dynamic mechanical and thermal properties of this system were characterized by FTIR, NMR, DMA, TG et al. The cytotoxicity of materials is evaluated for HeLa cells using a MTT cell-viability assay. The results showed that COPU can cure MPAER and CNTs can increase effectively the properties of MPAER/COPU nanocomposites. The Tg of MPAER/COPU/CNTs has the highest value when CNTs content is 0.4 wt%, which is 52.4 °C higher than the pure MPAER/COPU. Thermal stability of the nanocomposites is enhanced by the addition of CNTs, the initial decomposition temperature Td5 of the sample No. 0.4 has increased from 284.5 to 305.2 °C, which is 20.7 °C higher than No. 0. The impact strength of the No. 0.4 film is 15 kg cm higher than the pure resin system. The survival rate of HeLa cells to the products is greater than 90% within 48 and 72 h, which demonstrate that this material has excellent biocompatibility and no obvious cytotoxicity for HeLa cells, which may be used in the medical treatment.

  18. Radiation Supporting Synthezis and Curing of Composites Suitable for Practical Applications

    International Nuclear Information System (INIS)

    Przybytniak, G.; Antoniak, M.; Nowicki, A.; Mirkowski, K.; Walo, M.

    2011-01-01

    Epoxy resins (ER) due to favorable combination of superior mechanical and thermal properties with unusual radiation resistance play an important role in some nuclear and aerospace industries. They are also widely used as matrices of reinforced composites since the homogeneous dissipation of fillers in the non-cured material is uncomplicated and efficient. Curing procedure is a very important factor determining final features of the epoxy resin and its composite. It was confirmed that irradiation facilitates molecular mobility and decreases glass transition as a result of chain scission. On the other hand, the increase in local mobility accelerates crosslinking thus the total effect is dependent on the relation between these two processes. Larieva reported that the ratio between degradation and crosslinking is 0.43, thus under selected conditions yield of curing more than twice prevails over yield of decomposition. The nature of hardener and its radiosensitivity also significantly influence the radiation induced curing. During exposure to ionizing radiation the binders participate in the processes initiated both by radiation and by heating, as curing is highly exothermic and considerably increases temperature of the system. Application of radiation treatment lowers energy consumption, shortens curing time and decreases curing temperature enhancing dimensional stability. In the past some attempts were made to improve heat resistance and strength of epoxy resins by the incorporation of various particles, e.g. silica, carbon nanotubes, montmorillonite, etc, however the results were unambiguous. In the reported studies the effects of radiation and thermal curing were investigated for ER and its composites either in the presence of cationic initiator or amine hardener

  19. Radiation Supporting Synthezis and Curing of Composites Suitable for Practical Applications

    Energy Technology Data Exchange (ETDEWEB)

    Przybytniak, G.; Antoniak, M.; Nowicki, A.; Mirkowski, K.; Walo, M. [Institute of Nuclear Chemistry and Technology, Dorodna 16 Str., 03-195 Warsaw (Poland)

    2011-07-01

    Epoxy resins (ER) due to favorable combination of superior mechanical and thermal properties with unusual radiation resistance play an important role in some nuclear and aerospace industries. They are also widely used as matrices of reinforced composites since the homogeneous dissipation of fillers in the non-cured material is uncomplicated and efficient. Curing procedure is a very important factor determining final features of the epoxy resin and its composite. It was confirmed that irradiation facilitates molecular mobility and decreases glass transition as a result of chain scission. On the other hand, the increase in local mobility accelerates crosslinking thus the total effect is dependent on the relation between these two processes. Larieva reported that the ratio between degradation and crosslinking is 0.43, thus under selected conditions yield of curing more than twice prevails over yield of decomposition. The nature of hardener and its radiosensitivity also significantly influence the radiation induced curing. During exposure to ionizing radiation the binders participate in the processes initiated both by radiation and by heating, as curing is highly exothermic and considerably increases temperature of the system. Application of radiation treatment lowers energy consumption, shortens curing time and decreases curing temperature enhancing dimensional stability. In the past some attempts were made to improve heat resistance and strength of epoxy resins by the incorporation of various particles, e.g. silica, carbon nanotubes, montmorillonite, etc, however the results were unambiguous. In the reported studies the effects of radiation and thermal curing were investigated for ER and its composites either in the presence of cationic initiator or amine hardener.

  20. Non-hydrolytic sol-gel synthesis of epoxysilane-based inorganic-organic hybrid resins

    International Nuclear Information System (INIS)

    Jana, Sunirmal; Lim, Mi Ae; Baek, In Chan; Kim, Chang Hae; Seok, Sang Il

    2008-01-01

    A silica-based inorganic-organic hybrid resins (IOHR) were synthesized by non-hydrolytic sol-gel process from 3-glycidoxypropyltrimethoxysilane (GLYMO) and diphenylsilanediol (DPSD) at a fixed amount of (20 mol%) phenyltrimethoxysilane using barium hydroxide as a catalyst. The confirmation of condensation reaction in the IOHR was done by liquid state 29 Si NMR (Nuclear Magnetic Resonance) spectroscopy, measurement of viscosity as well as weight average molecular weight (W m ) of the IOHR. The W m of the IOHR was varied from 1091 to 2151, depending upon the DPSD content. Fourier transform infrared (FTIR) spectroscopic measurements were performed to investigate the details of vibrational absorption bands in the IOHR. It was seen that up to 50 mol% of DPSD there were no absorption peaks in the region of 3000-3600 cm -1 responsible for O-H groups and it reappeared at 60 mol% of DPSD due to some unreacted OH groups present in the resin. The IOHR at all the compositions was oily transparent liquid, miscible with various organic solvents like toluene, cyclohexanone, chloroform, tehrahydrofuran (THF), etc., and also commercial epoxy resins but immiscible with water. The color of the IOHR was pale yellow, which lightened with increasing DPSD content. The IOHR having 40-50 mol% of DPSD were storable. The refractive index at 632.8 nm of the resin films varied from 1.556 to 1.588, depending upon the resin composition. Physico-chemical properties such as the thermal stability, visible transparency, etc. after curing were investigated as a function of the chemical composition