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Sample records for led light-curing units

  1. Curing depth of composite resin light cured by LED and halogen light-curing units

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    Calixto, L. R.; Lima, D. M.; Queiroz, R. S.; Rastelli, A. N. S.; Bagnato, V. S.; Andrade, M. F.

    2008-11-01

    The purpose of this study was to evaluate the polymerization effectiveness of a composite resin (Z-250) utilizing microhardness testing. In total, 80 samples with thicknesses of 2 and 4 mm were made, which were photoactivated by a conventional halogen light-curing unit, and light-curing units based on LED. The samples were stored in water distilled for 24 h at 37°C. The Vickers microhardness was performed by the MMT-3 microhardness tester. The microhardness means obtained were as follows: G1, 72.88; G2, 69.35; G3, 67.66; G4, 69.71; G5, 70.95; G6, 75.19; G7, 72.96; and G8, 71.62. The data were submitted to an analysis of variance (ANOVA’s test), adopting a significance level of 5%. The results showed that, in general, there were no statistical differences between the halogen and LED light-curing units used with the same parameters.

  2. Guidelines for the selection, use, and maintenance of LED light-curing units - Part 1.

    Science.gov (United States)

    Shortall, A C; Price, R B; MacKenzie, L; Burke, F J T

    2016-10-21

    Light curing is a critical step in the restorative process when using light-activated resin-based composites, but it is frequently not given the attention it deserves. The selection of a reliable light curing unit (LCU) that meets the practitioner's needs is an important equipment purchase. Using an inappropriate LCU may seriously compromise the quality of care without the practitioner realising their mistake until years later. The importance of the subject is reflected by the rapidly increasing use of light-cured composites and the decline in the use of amalgam. Many changes have occurred in the equipment and materials available for making light-cured restorations in the last twenty years. This article is part of a two-part series that will describe those changes and recommend guidelines for the selection, use, and maintenance of light emitting diode light-curing units (LED LCUs). This paper (Part 1) discusses terminology, clinical studies, the development of LCUs in dentistry, the aims of light-curing, and the need to deliver an adequate amount of energy. The interaction between light source and material is briefly described to demonstrate the complex nature of the resin photopolymerisation process.

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

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    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.

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

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    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.

  5. Effectiveness of composite resin polymerization using light-emitting diodes (LEDs) or halogen-based light-curing units

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    Micali,Bianca; Basting,Roberta Tarkany

    2004-01-01

    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...

  6. Comparison of Bond Strength of Metal and Ceramic Brackets Bonded with Conventional and High-Power LED Light Curing Units

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    Javad Chalipa

    2017-01-01

    Full Text Available Objectives: The aim of this study was to evaluate the effect of conventional and high-power light emitting diode (LED light curing units on shear bond strength (SBS of metal and ceramic brackets to tooth surface.Materials and Methods: Forty sound bovine maxillary central incisors were used for the study. The teeth were divided into four groups (n=10. Teeth surfaces were etched with 37% phosphoric acid for 20 seconds. After applying a uniform layer of adhesive primer on the etched enamel, composite was placed on the base of brackets. The samples were light cured according to the manufacturer’s instructions and thermocycled. The SBS was measured. The failure mode was scored using the adhesive remnant index (ARI.Results: The mean SBS of samples in groups A (high-power LED, metal bracket, B (high-power LED, ceramic bracket, C (conventional LED, metal bracket and D (conventional LED, ceramic bracket was 23.1±3.69, 10.7±2.06, 24.92±6.37 and 10.74±3.18MPa, respectively. The interaction effect of type of LED unit (high-power/conventional and bracket type on SBS was not statistically significant (P=0.483. In general, type of LED unit did not affect SBS. Type of bracket significantly affected SBS (P<0.001. The ARI score was not significantly influenced by the interaction between the type of LED unit and bracket. Conclusions: The obtained SBS is the same for both bracket types by use of high-power and conventional LED light curing units. Regardless of the type of LED unit, SBS of ceramic brackets was significantly lower than that of metal brackets.Keywords: Orthodontic Brackets; Shear Strength; Light-Curing of Dental Adhesives

  7. Comparison of Bond Strength of Metal and Ceramic Brackets Bonded with Conventional and High-Power LED Light Curing Units.

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    Chalipa, Javad; Jalali, Yasamin Farajzadeh; Gorjizadeh, Fatemeh; Baghaeian, Pedram; Hoseini, Mohammad Hashem; Mortezai, Omid

    2016-11-01

    The aim of this study was to evaluate the effect of conventional and high-power light emitting diode (LED) light curing units on shear bond strength (SBS) of metal and ceramic brackets to tooth surface. Forty sound bovine maxillary central incisors were used for the study. The teeth were divided into four groups (n=10). Teeth surfaces were etched with 37% phosphoric acid for 20 seconds. After applying a uniform layer of adhesive primer on the etched enamel, composite was placed on the base of brackets. The samples were light cured according to the manufacturer's instructions and thermocycled. The SBS was measured. The failure mode was scored using the adhesive remnant index (ARI). The mean SBS of samples in groups A (high-power LED, metal bracket), B (high-power LED, ceramic bracket), C (conventional LED, metal bracket) and D (conventional LED, ceramic bracket) was 23.1±3.69, 10.7±2.06, 24.92±6.37 and 10.74±3.18MPa, respectively. The interaction effect of type of LED unit (high-power/conventional) and bracket type on SBS was not statistically significant (P=0.483). In general, type of LED unit did not affect SBS. Type of bracket significantly affected SBS (Punit and bracket. The obtained SBS is the same for both bracket types by use of high-power and conventional LED light curing units. Regardless of the type of LED unit, SBS of ceramic brackets was significantly lower than that of metal brackets.

  8. Robust spectrometer-based methods for characterizing radiant exitance of dental LED light curing units.

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    Shortall, Adrian C; Felix, Christopher J; Watts, David C

    2015-04-01

    Firstly, to assess light output, from a representative range of dental light curing units (LCUs), using a new portable spectrometer based instrument (checkMARC™) compared with a "gold standard" method. Secondly, to assess possible inconsistency between light output measurements using three different laboratory-grade thermopile instruments. The output of four blue-dental LCUs and four polywave blue-and-violet-LCUs was measured with two spectrometer-based systems: a portable spectrometer instrument and a benchtop Integrating Sphere fiber-coupled spectrometer system. Power output was also recorded with three thermopiles according to ISO 10650-2. Beam profile images were recorded of LCU output to assess for spatial and spectral beam uniformity. Power recorded with the portable spectrometer instrument closely matched the 'gold standard' Integrating Sphere apparatus calibrated according to International Standards. Radiant exitance for the eight LCUs differed significantly between the three thermopiles. Light source to thermopile sensor distance influenced recorded power significantly (pSpectrometer-based methods are capable of overcoming the limitations inherent with thermopile-based measurement techniques. Spectrometer based measurements can fulfill the intention of ISO 10650. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  9. Comparison of Surface Hardness of Various Shades of Twinky Star Colored Compomer Light-cured with QTH and LED Units

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    Khodadadi, Effat; Khafri, Soraya; Aziznezhad, Mahdiyeh

    2016-01-01

    Introduction Colored compomers are a group of restorative materials that were introduced in 2002 to repair primary teeth, and they provide attractive color and ease of use in pediatric dentistry. The aim of this study was to evaluate the effect of QTH and LED light-curing units on the surface hardness of different colors of Twinky Star compomers. Methods In this experimental study, a composite resin (Z250, 3M, and USA), an ionosit compomer (DMG, Germany) with A3 shade and 8 different Twinky Star colored compomer (Voco, Germany) samples were used. In all, 100 samples were prepared with 10 samples in each group, i.e., 10 Z250 composite resin, 10 ionosit compomers, and 10 Twinky Star compomer samples of each color. The samples were prepared in a 4×4-mm Teflon mold. Half of the samples were light-cured with QTH and the other half with LED units. Then, the surface microhardness was measured by Vickers hardness test. The data were analyzed with IBM-SPSS version 22, using the t-test and ANOVA. Results Two-way ANOVA showed that the mean surface hardness of the compomer samples cured with the QTH unit was significantly higher than that cured with the LED unit (p curing unit, surface hardness of some materials exhibited significant differences with the highest hardness being observed in the Z250 composite resin (650.35 ± 56.320) and the lowest hardness being detected in the ionosit compomers (461.10 ± 96.170). One-way ANOVA also showed that, among the different colors of the Twinky Star compomer, the lowest hardness with both units (QTH and LED) was observed in the gold color (214.32 ± 22.026 and 175.116 ± 15.918, respectively). Conclusion The colored compomer and the type of light-curing unit affected the microhardnesses of the surfaces. Different colors of Twinky Star compomers exhibited different surface microhardnesses. PMID:27382444

  10. Evaluation of shear bond strength of orthodontic brackets using trans-illumination technique with different curing profiles of LED light-curing unit in posterior teeth

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    Heravi, Farzin; Moazzami, Saied Mostafa; Ghaffari, Negin; Jalayer, Javad; Bozorgnia, Yasaman

    2013-01-01

    Background 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 unit...

  11. Advances in light-curing units: four generations of LED lights and clinical implications for optimizing their use: Part 2. From present to future.

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    Shortall, Adrian C; Palin, Will M; Jacquot, Bruno; Pelissier, Bruno

    2012-01-01

    The first part of this series of two described the history of light curing in dentistry and developments in LED lights since their introduction over 20 years ago. Current second- and third-generation LED light units have progressively replaced their halogen lamp predecessors because of their inherent advantages. The background to this, together with the clinical issues relating to light curing and the possible solutions, are outlined in the second part of this article. Finally, the innovative features of what may be seen as the first of a new fourth-generation of LED lights are described and guidance is given for the practitioner on what factors to consider when seeking to purchase a new LED light activation unit. Adequate curing in depth is fundamental to clinical success with any light-activated restoration. To achieve this goal predictably, an appropriate light source needs to be combined with materials knowledge, requisite clinical skills and attention to detail throughout the entire restoration process. As dentists increasingly use light-cured direct composites to restore large posterior restorations they need to appreciate the issues central to effective and efficient light curing and to know what to look for when seeking to purchase a new light-curing unit.

  12. A comparative study of the effects of QTH and LED light curing units on the surface hardness of colored compomer and Hybrid composites

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    Effat khodadadi

    2015-03-01

    Full Text Available Introduction: One factor affecting the degree of polymerization is the type of light-curing device. The aim of this study was to compare the effects of LED and QTH light curing units on the surface hardness of composite and compomer. Materials & Methods: In this experimental study, 30 samples of composite and compomer were divided into 3 groups of 10 each. One-half of the subgroups in each group were cured with LED and the other half with Halogen light curing units (LCUs. 49 points on the surface were marked and then the hardness of these points was measured by using Vickers hardness test. Results : The mean hardness of composites cured by using LED was more than the Halogen group but in compomer it was reversed and this difference was statistically significant (p<0.001. Z 250 composite had the highest level of hardness and the lowest hardness was related to the Heliomolar composite and had significant difference. (p<0.001  Conclusion :In the present study, the results indicated that LED light curing unit had great effect on the hardness of composites but in compomer, the QTH showed a better result.

  13. In vivo temperature rise in anesthetized human pulp during exposure to a polywave LED light curing unit.

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    Runnacles, Patrício; Arrais, Cesar Augusto Galvão; Pochapski, Marcia Thais; Dos Santos, Fábio André; Coelho, Ulisses; Gomes, João Carlos; De Goes, Mário Fernando; Gomes, Osnara Maria Mongruel; Rueggeberg, Frederick Allen

    2015-05-01

    This in vivo study evaluated pulp temperature (PT) rise in human premolars during exposure to a light curing unit (LCU) using selected exposure modes (EMs). After local Ethics Committee approval, intact first upper premolars, requiring extraction for orthodontic reasons, from 8 volunteers, received infiltrative and intraligamental anesthesia. The teeth (n=15) were isolated using rubber dam and a minute pulp exposure was attained. A sterile probe from a wireless, NIST-traceable, temperature acquisition system was inserted directly into the coronal pulp chamber, and real time PT (°C) was continuously monitored while the buccal surface was exposed to polywave light from a LED LCU (Bluephase 20i, Ivoclar Vivadent) using selected EMs allowing a 7-min span between each exposure: 10-s either in low (10-s/L) or high (10-s/H); 5-s-turbo (5-s/T); and 60-s-high (60-s/H) intensities. Peak PT values and PT increases from baseline (ΔT) after exposure were subjected to one-way, repeated measures ANOVAs, and Bonferroni's post hoc tests (α=0.05). Linear regression analysis was performed to establish the relationship between applied radiant exposure and ΔT. All EMs produced higher peak PT than the baseline temperature (p<0.001). The 60-s/H mode generated the highest peak PT and ΔT (p<0.001), with some teeth exhibiting ΔT higher than 5.5°C. A significant, positive relationship between applied radiant exposure and ΔT (r(2)=0.916; p<0.001) was noted. Exposing intact, in vivo anesthetized human upper premolars to a polywave LED LCU increases PT, and depending on EM and the tooth, PT increase can be higher than the critical ΔT, thought to be associated with pulpal necrosis. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  14. Analysis of temperature increase in swine gingiva after exposure to a Polywave®LED light curing unit.

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    Maucoski, Cristiane; Zarpellon, Driellen Christine; Dos Santos, Fabio Andre; Lipinski, Leandro Cavalcante; Campagnoli, Eduardo Bauml; Rueggeberg, Frederick Allen; Arrais, Cesar Augusto Galvão

    2017-11-01

    This study evaluated the temperature increase in swine gingival temperature after exposure to light emitted by a Polywave ® LED light curing unit (LCU, Bluephase 20i, Ivoclar Vivadent). After local Ethics Committee approval (protocol 711/2015), 40 pigs were subjected to general anesthesia and the LCU tip was placed 5mm from the buccal gingival tissue (GT) close to lower lateral incisors. A thermocouple probe (Thermes WFI, Physitemp) was inserted into the gingival sulcus before and immediately after exposure to light. Real-time temperature (°C) was measured after the following exposure modes were applied: High Power (20s-H, 40s-H, and 60s-H) or Turbo mode (5s-T), either with or without the presence of rubber dam (RD) interposed between the LCU tip and GT (n=10). The presence of gingival lesions after the exposures was also evaluated. Peak temperature (°C) and the temperature increase during exposure over that of the pre-exposure baseline value (ΔT) data were analyzed using 2-way ANOVA followed by Bonferroni's post-hoc test (α=5%). A binary logistic regression analysis determined the risk of gingival lesion development. Without RD, no significant difference in ΔT was observed among 20s-H, 40s-H, and 60s-H groups, which showed the highest temperature values, while the 5s-T exposure showed the lowest ΔT, regardless of RD. RD reduced ΔT only for the 20s-H group (p=0.004). Gingival lesions were predominantly observed using 40s-H, with RD, and 60s-H, with and without RD. Exposure to a LCU light might be harmful to swine gingiva only when high radiant exposure values are delivered, regardless of the use of RD. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  15. Evaluation of shear bond strength of orthodontic brackets using trans-illumination technique with different curing profiles of LED light-curing unit in posterior teeth.

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    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.

  16. Comparison of the Amount of Temperature Rise in the Pulp Chamber of Teeth Treated With QTH, Second and Third Generation LED Light Curing Units: An In Vitro Study.

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    Mahant, Rajesh Harivadanbhai; Chokshi, Shraddha; Vaidya, Rupal; Patel, Pruthvi; Vora, Asima; Mahant, Priyanka

    2016-01-01

    Introduction: This in vitro study was designed to measure and compare the amount of temperature rise in the pulp chamber of the teeth exposed to different light curing units (LCU), which are being used for curing composite restorations. Methods: The study was performed in two settings; first, an in vitro and second was mimicking an in vivo situation. In the first setup of the study, three groups were formed according to the respective three light curing sources. i.e. quartz-tungsten-halogen (QTH) unit and two light-emitting diode (LED) units (second and third generations). In the in vitro setting, direct thermal emission from three light sources at 3 mm and 6 mm distances, was measured with a k-type thermocouple, and connected to a digital thermometer. For a simulation of an in vivo situation, 30 premolar teeth were used. Class I Occlusal cavity of all the teeth were prepared and they were restored with incremental curing of composite, after bonding agent application. While curing the bonding agent and composite in layers, the intrapulpal temperature rise was simultaneously measured with a k-type thermocouple. Results: The first setting of the study showed that the heat produced by irradiation with LCU was significantly less at 6 mm distance when compared to 3 mm distance. The second setting of the study showed that the rise of intrapulpal temperature was significantly less with third generation LED light cure units than with second generation LED and QTH light cure units. Conclusion: As the distance from the light source increases, less irradiation heat is produced. Third generation LED lights cause the least temperature change in the pulp chamber of single rooted teeth.

  17. Evaluation of temperature changes in the pulp chamber during polymerization of light-cured pulp-capping materials by using a VALO LED light curing unit at different curing distances.

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    Savas, Selcuk; Botsali, Murat S; Kucukyilmaz, Ebru; Sari, Tugrul

    2014-01-01

    The aim of this study was to evaluate temperature changes in the pulp chamber during polymerization of four different pulp-capping materials using a LED-light-curing-unit in the contact and noncontact positions. A pulpal circulation mechanism was simulated to measure increases in temperature in four pulp-capping materials that were applied to the occlusal dentin surface. Two different distances were used between the tip of the unit and the material surface during polymerization; 0 and 2 mm. The data were statistically analyzed using factorial-ANOVA, one-way-ANOVA, and Tukey's HSD test. There were statistically differences between contact and noncontact groups (plight curing units from restorations should not be overlooked as well as the types of the materials.

  18. Effects of distance from tip of LED light-curing unit and curing time on surface hardness of nano-filled composite resin

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    Shafadilla, V. A.; Usman, M.; Margono, A.

    2017-08-01

    Polymerization process depends on several variables, including the hue, thickness, and translucency of the composite resin, the size of the filler particles, the duration of exposure to light (the curing time), the intensity of the light, and the distance from the light. This study aimed to analyze the effects of the distance from the tip of the light-emitting diode (LED) light-curing unit and of curing time on the surface hardness of nano-filled composite resin. 60 specimens were prepared in a mold and divided into 6 groups based on various curing distances and times: 2 mm, 5 mm, and 8 mm and 20 seconds and 40 seconds. The highest surface hardness was seen in the group both closest to the tip and having the longest curing time, while the lowest hardness was seen in the group both farthest from the tip and having the shortest curing time. Significant differences were seen among the various tip distances, except for in the two groups that had 8-mm tip distances, which had no significant differences due to curing time. Both decreased distance from the tip of the LED light-curing unit and increased curing time increase the surface hardness of nano-filled composite resin. However, curing time increases the surface hardness only if the tip distance is ≤ 5 mm.

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

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    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 (p<.05). The least temperature increase (11.8+/-1.3 degrees C) occurred with a LED curing unit for each tested period except for the measurement of the temperature rise using the QTH curing unit at the tenth second interval (p<.05). These results indicate the choice of light activation unit and curing time is important when polymerizing light activated resin based restorations to avoid any thermal damage to the pulp.

  20. Comparative evaluation of the effect of Light Emitting Diode (LED and Quartz Tungsten Halogen (QTH light curing units on color stability of Filtek Z350 XT

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    Behnaz Esmaeili

    2014-03-01

    Full Text Available Introduction:Discoloration of the resin-based composites is a common problem in restorative dentistry. There are many factors associated with the discoloration of dental materials in the oral environment. The purpose of this study was to evaluate the color changes in a nano-composite cured with a quartz-tungsten-halogen (QTH and light emitting diode (LED unit. Methods:80 disk-shaped specimens were prepared using Filtek Z350 XT.The specimens were cured with two LED units (Valo and BluephaseC5 and QTH Astralis7 ( with two different energy density (400 & 750 mW/Cm². The color of the materials was measured before and after immersing in tea and artificial saliva. Color change value (ΔE were calculated and analyzed by 2-way ANOVA and Tukey’s test. Results: In artificial saliva group, the composites cured with Astralis7 and BluephaseC5 showed significantly more color stability. In tea group, the composites cured with BluephaseC5 significantly had the least color change. Conclusions: The type of light curing unit does not affect the color stability. Exposure time and interaction between light source and photo initiator content in composite may be the most important factors affecting color stability.

  1. Degree of conversion of micro-hybrid, nano-hybrid and Ormocer composites using LED and QTH light-curing units

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    Seied Mostafa Fatemi

    2012-01-01

    Full Text Available Background and Aims: The aim of this study was to measure the degree of conversion (DC of three types of composite resins (micro-hybrid, nano-hybrid and Ormocer with different light curing units (LED LCU and QTH LCU in two depths.Materials and Methods: Three commercially available dental resin composites were used in this study: (Tetric Ceram, Ivoclar Vivadent, Liechtenstein-A2 shade, (Tetric Evoceram, Ivoclar Vivadent, Liechtenstein-A2 shade, (Ceram X, Dentsply, Germany-M2 shade. Specimens were divided into two groups, 5 specimens were photo-activated by QTH unit (Coltolux 75-Colten and the other five specimens were cured by LED (Demi-Kerr. Then each specimen was sectioned at the top surface and at 2-mm depth. The DC was measured by FT-IR(Bruker-tensor 27. The data were analyzed by 3-way ANOVA test.Results: There was significant difference between tested composite resins (P<0.001. The results of top surfaces were significantly different from those observed at 2-mm depth (P<0.001. The type of curing unit affected the polymerization of Ceram X resin composite.Conclusion: This study showed a significant difference in the degree of conversion in different thicknesses within three groups of resin composites.

  2. Light curing through glass ceramics with a second- and a third-generation LED curing unit: effect of curing mode on the degree of conversion of dual-curing resin cements.

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

    2013-12-01

    The aim of this study was to measure the degree of conversion (DC) of five dual-curing resin cements after different curing modes with a second- and a third-generation light-emitting diode (LED) curing unit. Additionally, irradiance of both light curing units was measured at increasing distances and through discs of two glass ceramics for computer-aided design/manufacturing (CAD/CAM). Irradiance and spectra of the Elipar FreeLight 2 (Standard Mode (SM)) and of the VALO light curing unit (High Power Mode (HPM) and Xtra Power Mode (XPM)) were measured with a MARC radiometer. Irradiance was measured at increasing distances (control) and through discs (1.5 to 6 mm thickness) of IPS Empress CAD and IPS e.max CAD. DC of Panavia F2.0, RelyX Unicem 2 Automix, SpeedCEM, BisCem, and BeautiCem SA was measured with an attenuated total reflectance-Fourier transform infrared spectrometer when self-cured (negative control) or light cured in SM for 40 s, HPM for 32 s, or XPM for 18 s. Light curing was performed directly (positive control) or through discs of either 1.5- or 3-mm thickness of IPS Empress CAD or IPS e.max CAD. DC was analysed with Kruskal-Wallis tests followed by pairwise Wilcoxon rank sum tests (α = 0.05). Maximum irradiances were 1,545 mW/cm(2) (SM), 2,179 mW/cm(2) (HPM), and 4,156 mW/cm(2) (XPM), and all irradiances decreased by >80 % through discs of 1.5 mm, ≥95 % through 3 mm, and up to >99 % through 6 mm. Generally, self-curing resulted in the lowest DC. For some cements, direct light curing did not result in higher DC compared to when light cured through ceramic discs. For other cements, light curing through ceramic discs of 3 mm generally reduced DC. Light curing was favourable for dual-curing cements. Some cements were more susceptible to variations in curing mode than others. When light curing a given cement, the higher irradiances of the third-generation LED curing unit resulted in similar DC compared to the second-generation one, though at shorter

  3. 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.

  4. Changes in the temperature of a dental light-cured composite resin by different light-curing units

    Science.gov (United States)

    Rastelli, A. N. S.; Jacomassi, D. P.; Bagnato, V. S.

    2008-08-01

    The purpose of this study was to evaluate the temperature increase during the polymerization process through the use of three different light-curing units with different irradiation times. One argon laser (Innova, Coherent), one halogen (Optilight 501, Demetron), and one blue LED (LEC 1000, MM Optics) LCU with 500 mW/cm2 during 5, 10, 20, 30, 40, 50, and 60 s of irradiation times were used in this study. The composite resin used was a microhybrid Filtek Z-250 (3M/ESPE) at color A2. The samples were made in a metallic mold 2 mm in thickness and 4 mm in diameter and previously light-cured during 40 s. A thermocouple (Model 120 202 EAJ, Fenwal Electronic, Milford, MA, USA) was introduced in the composite resin to measure the temperature increase during the curing process. The highest temperature increase was recorded with a Curing Light 2500 halogen LCU (5 and 31°C after 5 and 60 s, respectively), while the lowest temperature increase was recorded for the Innova LCU based on an argon laser (2 and 11°C after 5 and 60 s, respectively). The temperature recorded for LCU based on a blue LED was 3 and 22°C after 5 and 60 s, respectively. There was a quantifiable amount of heat generated during the visible light curing of a composite resin. The amount of heat generated was influenced by the characteristics of the light-curing units used and the irradiation times.

  5. 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 ...

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

    Science.gov (United States)

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

    2011-01-01

    Purpose To examine the thermal expansion of resin nanocomposites after light-curing using different light-curing units. Methods 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°C. Results The CTE of the resin nanocomposites tested ranged from 28.5 to 65.8 (×10−6/°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. (Am J Dent 2010;23:331–334). PMID:21344832

  7. Pengaruh Penggunaan Light-Emitting Diode Light Curing Unit Dan Halogen Light Curing Unit Terhadap Microleakage Dengan Jarak Penyinaran 0 MM Dan 5 MM Pada Restorasi Klas V (Penelitian In Vitro)

    OpenAIRE

    Yumira

    2010-01-01

    Kelemahan utama dari resin komposit adalah terjadinya kontraksi polimerisasi selama pengerasan sehingga timbul kebocoran mikro. Kebocoran mikro sering menimbulkan masalah pada kavitas klas V resin komposit seperti hipersensitivitas, karies rekuren, penyakit pulpa, dan diskolorissasi marginal. Penelitian ini bertujuan untuk mengamati dan mengetahui perbedaan kebocoran mikro pada restorasi resin komposit yang dipolimerisasi dengan LED light curing unit dan halogen light curing unit dengan jarak...

  8. Localised irradiance distribution found in dental light curing units.

    Science.gov (United States)

    Michaud, Pierre-Luc; Price, Richard B T; Labrie, Daniel; Rueggeberg, Frederick A; Sullivan, Braden

    2014-02-01

    To measure the localised irradiance and wavelength distributions from dental light curing units (LCUs) and establish a method to characterise their output. Using a laboratory grade integrating sphere spectrometer system (Labsphere and Ocean Optics) the power, irradiance, and spectral emission were measured at the light tips of four LCUs: one plasma-arc (PAC) unit, one single peak blue light-emitting diode (blue-LED) unit, and two polywave LED (poly-LED) units. A beam profiler camera (Ophir Spiricon) was used to record the localised irradiance across the face of the light tips. The irradiance-calibrated beam profile images were then divided into 45 squares, each 1mm(2). Each square contained the irradiance information received from approximately 3200 pixels. The mean irradiance value within each square was calculated, and the distribution of irradiance values among these 45 squares across the tip-ends was examined. Additionally, the spectral emission was recorded at various regions across each light tip using the integrating sphere with a 4-mm diameter entrance aperture. The localised irradiance distribution was inhomogeneous in all four lights. The irradiance distribution was most uniformly distributed across the PAC tip. Both the irradiance and spectral emission from the poly-LED units were very unevenly distributed. Reporting a single irradiance value or a single spectral range to describe the output from a curing light is both imprecise and inappropriate. Instead, an image of both the irradiance distribution and the distribution of the spectral emission across the light tip should be provided. The localised beam irradiance profile at the tip of dental LCUs is not uniform. Poly-LED units may deliver spectrally inhomogeneous irradiance profiles. Depending on the photoinitiator used in the RBC and the orientation of the LCU over the tooth, this non-uniformity may cause inadequate and inhomogeneous resin polymerisation, leading to poor physical properties, and

  9. 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

  10. 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.

  11. Influence of physical assessment of different light-curing units on irradiance and composite microhardness top/bottom ratio.

    Science.gov (United States)

    Morimoto, Susana; Zanini, Renata Aló Maluza; Meira, Josete Barbosa Cruz; Agra, Carlos Martins; Calheiros, Fernanda Calabró; Nagase, Denis Yudi

    2016-09-01

    The aim of this study was to evaluate the influence of the physical assessment of different light-curing units from 55 dental offices on the irradiance and composite microhardness top/bottom ratio, and the influence of the radiometers for LED or QTH light sources on irradiance measurement. The irradiance of each light-curing unit was evaluated with two radiometers, either for LED or QTH light. A questionnaire regarding the type of source (LED or QTH), time of use, date of last maintenance and light-curing performance assessment applied. The physical assessments were evaluated regarding damage or debris on the light tip. For each light-curing unit, three composite specimens were made (diameter = 7 mm; thickness = 2 mm) with polymerizing time of 20 s, in order to perform the microhardness (Knoop) test. Data were analyzed by Kruskal-Wallis and Dunn test (α = 0.01). There was wide variation in irradiance (0-1000 mW/cm(2)). Approximately 50 % of the light-curing units presented radiation lower than 300 mW/cm(2); 10 % of light-curing units, especially those with LED source, presented values higher than 800 mW/cm(2), and 43 % of light-curing units worked with adequate irradiance between 301 and 800 mW/cm(2). In almost 60 % of cases, no maintenance of light-curing units was performed in a period of 3 to 10 years. The age of the light-curing units and the use of inadequate tips interfered negatively in irradiance. The data emphasize the importance of periodic maintenance of light-polymerizing, light-curing units.

  12. LED vs halogen light-curing of adhesive-precoated brackets.

    Science.gov (United States)

    Mirabella, Davide; Spena, Raffaele; Scognamiglio, Giovanni; Luca, Lombardo; Gracco, Antonio; Siciliani, Giuseppe

    2008-09-01

    To test the hypothesis that bonding with a blue light-emitting diode (LED) curing unit produces no more failures in adhesive-precoated (APC) orthodontic brackets than bonding carried out by a conventional halogen lamp. Sixty-five patients were selected for this randomized clinical trial, in which a total of 1152 stainless steel APC brackets were employed. In order to carry out a valid comparison of the bracket failure rate following use of each type of curing unit, each patient's mouth was divided into four quadrants. In 34 of the randomly selected patients, designated group A, the APC brackets of the right maxillary and left mandibular quadrants were bonded using a halogen light, while the remaining quadrants were treated with an LED curing unit. In the other 31 patients, designated group B, halogen light was used to cure the left maxillary and right mandibular quadrants, whereas the APC brackets in the remaining quadrants were bonded using an LED dental curing light. The bonding date, the type of light used for curing, and the date of any bracket failures over a mean period of 8.9 months were recorded for each bracket and, subsequently, the chi-square test, the Yates-corrected chi-square test, the Fisher exact test, Kaplan-Meier survival estimates, and the log-rank test were employed in statistical analyses of the results. No statistically significant difference in bond failure rate was found between APC brackets bonded with the halogen light-curing unit and those cured with LED light. However, significantly fewer bonding failures were noted in the maxillary arch (1.67%) than in the mandibular arch (4.35%) after each light-curing technique. The hypothesis cannot be rejected since use of an LED curing unit produces similar APC bracket failure rates to use of conventional halogen light, with the advantage of a far shorter curing time (10 seconds).

  13. 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.

  14. Hardness of composite resin polymerized with different light-curing units

    Directory of Open Access Journals (Sweden)

    Hengameh Safarcherati

    2012-09-01

    Full Text Available Introduction: The degree of polymerization depends on the type of light-curing unit. The aim of this study was to compare the hardness of composite resin cured by LED and Halogen light curing units. Methods: In this experimental study, 20 cylindrical samples of Tetric Ceram composite were prepared. Half of them were cured with Ultralume 2 LED and the other half with Astralis 7 Halogen light curing unit. In the depths of 0,1,2 and 3 mm from surface, one point in peripheral and one point in central portion were marked ,then the hardness of these points was measured by Vickers test . The data was analyzed by a pvalue less than 0.05 considered as significant. Results: The mean hardness of samples cured by LED was more than halogen group in different depths and this difference was statistically significant in peripheral points (p=.048 but this was not significant in central points (p=0.644. The mean hardness in both groups had a decreasing trend from surface to the deep parts in central and peripheral parts and this was more in the central parts. Conclusions: Composites cured by LED light curing unit showed more hardness in similar depths, besides the hardness of composites in central parts is more than the peripheral ones in both groups.

  15. 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.

  16. Effect of new light curing units on microleakage and microhardness of resin sealants.

    Science.gov (United States)

    Bani, Mehmet; Tirali, Resmiye Ebru

    2016-01-01

    To determine new developed light curing units with shorter curing times effects on microleakage and microhardness values for resin fissure sealants. Resin filled sealant (UltraSeal-XT), resin unfilled sealant (Delton Type-II) and ormocer-based sealant (Admira-Seal) were light cured with a quartz-tungsten-halogen (QTH), two LED light and a high power LED. Two hundred and forty extracted human molars were randomly allocated into four groups according to used light-curing unit and three subgroups were formed for three different fissure sealant materials. Specimens were immersed in 0.5% basic fuchsin for 24 h, sectioned and examined under a stereomicroscope, and scored for marginal microleakage. Knoop hardness number (KHN) readings were measured after 48 h. Statistical analyses of test were found in significant difference both microleakage and microhardness values between the various light curing units. The time saving approaches in the curing light were determined higher microhardness, although it was found in higher microleakage.

  17. Use of light-curing units in orthodontics.

    Science.gov (United States)

    Goyal, Amit; Hurkadle, Jyothikiran; Magegowda, Shivalinga; Bhatia, Pankaj

    2013-08-01

    Because of their wide field of applications, light-curing units are now indispensable for orthodontists and general dentists; thus, it is important to be familiar with the various types of light-curing units, their history, specifications, advantages, and disadvantages. For this review, a search of the PubMed database (from 1966 to March 2010) was conducted using the search term "curing lights orthodontics". Eligibility of the selected studies was determined by reading the abstracts of articles identified by the search. All the articles that met the inclusion criteria were selected, and the articles collected. The reference lists of the retrieved articles were also hand searched for any applicable studies that might have been missed in the database searches. When selecting curing lights for an office, many variables need to be considered. Armed with knowledge about each curing-light category, orthodontists can evaluate their unique practice style and select the appropriate light/lights. © 2013 Wiley Publishing Asia Pty Ltd.

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

    Directory of Open Access Journals (Sweden)

    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.

  19. Comparison of light transmittance in different thicknesses of zirconia under various light curing units.

    Science.gov (United States)

    Cekic-Nagas, Isil; Egilmez, Ferhan; Ergun, Gulfem

    2012-05-01

    The objective of this study was to compare the light transmittance of zirconia in different thicknesses using various light curing units. A total of 21 disc-shaped zirconia specimens (5 mm in diameter) in different thicknesses (0.3, 0.5 and 0.8 mm) were prepared. The light transmittance of the specimens under three different light-curing units (quartz tungsten halogen, light-emitting diodes and plasma arc) was compared by using a hand-held radiometer. Statistical significance was determined using two-way ANOVA (α=.05). ANOVA revealed that thickness of zirconia and light curing unit had significant effects on light transmittance (Plight transmittance. Light-emitting diodes light-curing units might be considered as effective as Plasma arc light-curing units or more effective than Quartz-tungsten-halogen light-curing units for polymerization of the resin-based materials.

  20. Curing efficiency of dual-cure resin cement under zirconia with two different light curing units.

    Science.gov (United States)

    Gultekin, Pınar; Pak Tunc, Elif; Ongul, Deger; Turp, Volkan; Bultan, Ozgur; Karataslı, Burcin

    2015-01-01

    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. 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. 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 (punit produced significantly greater VHN values compared to the QTH unit (pLight 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.

  1. Comparison of temperature rise in the pulp chamber with different light curing units: An in-vitro study

    OpenAIRE

    Rajesh Ebenezar A; Anilkumar R; Indira R; Ramachandran S; Srinivasan M

    2010-01-01

    Aims/Objectives : This in vitro study was designed to measure and compare the temperature rise in the pulp chamber with different light curing units. Materials and Methods : 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...

  2. Comparison of temperature rise in the pulp chamber with different light curing units: An in-vitro study

    OpenAIRE

    Rajesh Ebenezar, A V; Anilkumar, R; Indira, R; Ramachandran, S; Srinivasan, M R

    2010-01-01

    Aims/Objectives: This in vitro study was designed to measure and compare the temperature rise in the pulp chamber with different light curing units. Materials and Methods: 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, th...

  3. Effect of pre-heating resin composite and light-curing units on monomer conversion

    Science.gov (United States)

    Saade, E. G.; Bandéca, M. C.; Saade, J. L.; Rossato, D. M.; Rastelli, A. N. S.; Bagnato, V. S.; Porto-Neto, S. T.

    2010-01-01

    The purpose of this study was to evaluate the effect of pre-heating resin composite photo-cured with light-curing units (LCU) by FT-IR. Twenty specimens were made in a metallic mold (4 mm diameter × 2 mm thick) from composite resin—Tetric Ceram® (Ivoclar/Vivadent) at room temperature (25°C) and pre-heated to 37, 54, and 60°C. The specimens were cured with halogen curing light (QTH) and light emitted by diodes (LED) during 40 s. Then, the specimens were pulverized, pressed with KBr and analyzed with FT-IR. The data were submitted to statistical analysis of variance and Kruskal-Wallis test. Study data showed no statistically significant difference to the degree of conversion for the different light curing units (QTH and LED) ( p > 0.05). With the increase of temperature there was significant increase in the degree of conversion ( p light curing unit and temperature influenced the degree of conversion.

  4. 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

  5. Standardization of distance and angulation of light curing unit tip using distometer

    OpenAIRE

    Radzi, Z.; Abu Kasim, N.H.; Yahya, N. A.; Abu Osman, N.A.; Kassim, N.L.

    2017-01-01

    The purpose of this study was to investigate the light intensity of selected light curing unit with varying distance and angulation of the light curing tip and lightmeter. Four types of light units; Spectrum 800 (Dentsply), Coltulux 3 (Coltene), Elipar FreeLight 2 (3M Espe) and Starlight Pro (Mectron) were evaluated for light intensity at various distance between the light curing tip and the lightometer Cure Rite Denstply (0, 1, 3, 5, 10 and 15 mm). The light curing units were angulated ...

  6. 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

  7. Effect of LED light-curing time for the adhesive resin on the modulus of elasticity.

    Science.gov (United States)

    Senawongse, Pisol; Harnirattisai, Choltacha; Otsuki, Masayuki; Tagami, Junji

    2007-06-01

    To evaluate the elastic modulus of successive layers where an adhesive resin was cured by different light-curing times. Eighty dentin discs which were 2 mm thick were prepared from 40 sound third molars. The dentin discs were further divided into four groups and bonded with 3M Single Bond 2 and cured with an LED for 5, 10, 15 and 20s. Bonded specimens were restored with a microhybrid resin composite. Specimens were cut perpendicular to the resin dentin interface, embedded in epoxy resin, and polished. Polished specimens were evaluated for the elastic modulus at the layer of dentin, hybrid layer, adhesive resin, and resin composite at 24 hours after preparation. Light-curing times influenced the elastic modulus of hybrid layer and adhesive resin. The significant differences of elastic modulus among successive layers were found. The results suggested that extension of light-curing times of adhesive resin from 5 to 20 seconds increased the mechanical properties of the resin dentin interface.

  8. 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.

  9. Temperature Rise Induced by Light Curing Unit Can Shorten Enamel Acid-Etching Time

    Directory of Open Access Journals (Sweden)

    Ahmad Najafi Abrandabadi

    2016-08-01

    Full Text Available Objectives: The aim of this in-vitro study was to assess the thermal effect of light emitting diode (LED light curing unit on the enamel etching time.Materials and Methods: Three treatment groups with 15 enamel specimens each were used in this study: G1: Fifteen seconds of etching, G2: Five seconds of etching, G3: Five seconds of etching plus LED light irradiation (simultaneously. The micro shear bond strength (µSBS of composite resin to enamel was measured.Results: The mean µSBS values ± standard deviation were 51.28±2.35, 40.47±2.75 and 50.00±2.59 MPa in groups 1, 2 and 3, respectively. There was a significant difference between groups 1 and 2 (P=0.013 and between groups 2 and 3 (P=0.032 in this respect, while there was no difference between groups 1 and 3 (P=0.932.Conclusion: Simultaneous application of phosphoric acid gel over enamel surface and light irradiation using a LED light curing unit decreased enamel etching time to five seconds without compromising the µSBS.

  10. Temperature Rise Induced by Light Curing Unit Can Shorten Enamel Acid-Etching Time.

    Science.gov (United States)

    Najafi Abrandabadi, Ahmad; Sheikh-Al-Eslamian, Seyedeh Mahsa; Panahandeh, Narges

    2015-12-01

    The aim of this in-vitro study was to assess the thermal effect of light emitting diode (LED) light curing unit on the enamel etching time. Three treatment groups with 15 enamel specimens each were used in this study: G1: Fifteen seconds of etching, G2: Five seconds of etching, G3: Five seconds of etching plus LED light irradiation (simultaneously). The micro shear bond strength (μSBS) of composite resin to enamel was measured. The mean μSBS values ± standard deviation were 51.28±2.35, 40.47±2.75 and 50.00±2.59 MPa in groups 1, 2 and 3, respectively. There was a significant difference between groups 1 and 2 (P=0.013) and between groups 2 and 3 (P=0.032) in this respect, while there was no difference between groups 1 and 3 (P=0.932). Simultaneous application of phosphoric acid gel over enamel surface and light irradiation using a LED light curing unit decreased enamel etching time to five seconds without compromising the μSBS.

  11. Influence of pre-heat treatment and different light-curing units on Vickers hardness of a microhybrid composite resin

    Science.gov (United States)

    Saade, E. G.; Bandeca, M. C.; Rastelli, A. N. S.; Bagnato, V. S.; Porto-Neto, S. T.

    2009-06-01

    The aim of this study was to evaluate the hardness of a dental composite resin submitted to temperature changes before photo-activation with two light-curing unite (LCUs). Five samples (4 mm in diameter and 2 mm in thickness) for each group were made with pre-cure temperatures of 37, 54, and 60°C. The samples were photo-activated with a conventional quartz-tungsten-halogen (QTH) and blue LED LCUs during 40 s. The hardness Vickers test (VHN) was performed on the top and bottom surfaces of the samples. According to the interaction between light-curing unit and different pre-heating temperatures of composite resin, only the light-curing unit provided influences on the mean values of initial Vickers hardness. The light-curing unit based on blue LED showed hardness mean values more homogeneous between the top and bottom surfaces. The hardness mean values were not statistically significant difference for the pre-cure temperature used. According to these results, the pre-heating of the composite resin provide no influence on Vickers hardness mean values, however the blue LED showed a cure more homogeneous than QTH LCU.

  12. Effect of preheating and light-curing unit on physicochemical properties of a bulk fill composite.

    Science.gov (United States)

    Theobaldo, Jéssica Dias; Aguiar, Flávio Henrique Baggio; Pini, Núbia Inocencya Pavesi; Lima, Débora Alves Nunes Leite; Liporoni, Priscila Christiane Suzy; Catelan, Anderson

    2017-01-01

    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. 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). 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. 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.

  13. The effect of light curing units, curing time, and veneering materials on resin cement microhardness

    Directory of Open Access Journals (Sweden)

    Nurcan Ozakar Ilday

    2013-06-01

    Conclusion: Light-curing units, curing time, and veneering materials are important factors for achieving adequate dual cure resin composite microhardness. High-intensity light and longer curing times resulted in the highest microhardness values.

  14. The cytotoxicity of resin composites cured with three light curing units at different curing distances.

    Science.gov (United States)

    Ergun, Gulfem; Egilmez, Ferhan; Cekic-Nagas, Isil

    2011-03-01

    The purpose of this study was to compare the effect of light curing distance on the cytotoxicity of five resin composites cured with three high-power light curing units. Seven cylindrical discs of each material (Grandio®, Voco; Filtek™ Z250, 3M ESPE; Clearfil™ AP-X, Kuraray Co. Ltd.; Aelite™ LS, Bisco Inc. and Simile®, Pentron) were cured. For curing, soft-up mode of quartz-tungsten-halogen, exponential mode of light emitting diode for 20 s, and ramp-curing mode of plasma arc light curing units for 6 s were used. The curing tip distances were determined as 2 and 9 mm and controlled via the use of metal rings. After ageing the samples for 24 and 72 hours in Dulbecco's Modified Eagle Medium/Ham's F12 (DMEM/F12), cytotoxicity of the extracts to cultured fibroblasts (L 929) was measured by using MTT (tetrazolium salt 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay. The degree of cytotoxicity for each sample was determined according to the reference value represented by the cells in a pure culture medium. Statistical significance was determined using multifactorial analysis of variance. The type of resin composite (p light curing unit (p curing tip distance (p light emitting diode and plasma arc light curing units were used (p=0.184, F=1.448). The results of this study suggest that the light curing units and resin composites should be harmonized to one another and the curing distance between the tip of the light curing unit and the restoration surface should be as close as possible in order to achieve maximal biocompatibility.

  15. 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.

  16. 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

  17. Comparison of light transmittance in different thicknesses of zirconia under various light curing units

    OpenAIRE

    Cekic-Nagas, Isil; Egilmez, Ferhan; Ergun, Gulfem

    2012-01-01

    PURPOSE The objective of this study was to compare the light transmittance of zirconia in different thicknesses using various light curing units. MATERIALS AND METHODS A total of 21 disc-shaped zirconia specimens (5 mm in diameter) in different thicknesses (0.3, 0.5 and 0.8 mm) were prepared. The light transmittance of the specimens under three different light-curing units (quartz tungsten halogen, light-emitting diodes and plasma arc) was compared by using a hand-held radiometer. Statistical...

  18. 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.

  19. Effect of light curing unit on resin-modified glass-ionomer cements: a microhardness assessment.

    Science.gov (United States)

    Cefaly, Daniela Francisca Gigo; de Mello, Liliam Lucia Carrara Paes; Wang, Linda; Lauris, José Roberto Pereira; D'Alpino, Paulo Henrique Perlatti

    2009-01-01

    To evaluate the microhardness of resin-modified glass-ionomer cements (RMGICs) photoactivated with a blue light-emitting diode (LED) curing light. Thirty specimens were distributed in 3 groups: Fuji II LC Improved/GC (RM1), Vitremer/3M ESPE (RM2) and Filtek Z250/3M ESPE (RM3). Two commercial light-curing units were used to polymerize the materials: LED/Ultrablue IS and a halogen light/XL3000 (QTH). After 24 h, Knoop microhardness test was performed. Data were submitted to three-way ANOVA and Tukey's test at a pre-set alpha of 0.05. At the top surface, no statistically significant difference (p>0.05) in the microhardness was seen when the LED and QTH lights were used for all materials. At the bottom surface, microhardness mean value of RM2 was significantly higher when the QTH light was used (plight was used. No statistically significant difference (p>0.05) was seen at the bottom surface for RM3, irrespective of the light used. Top-to-bottom surface comparison showed no statistically significant difference (p>0.05) for both RMGICs, regardless of the light used. For RM3, microhardness mean value at the top was significantly higher (pcuring units were used. The microhardness values seen when a LED light was used varied depending on the restorative material tested.

  20. Effect of light curing unit on resin-modified glass-ionomer cements: a microhardness assessment

    Directory of Open Access Journals (Sweden)

    Daniela Francisca Gigo Cefaly

    2009-06-01

    Full Text Available OBJECTIVE: To evaluate the microhardness of resin-modified glass-ionomer cements (RMGICs photoactivated with a blue light-emitting diode (LED curing light. MATERIAL AND METHODS: Thirty specimens were distributed in 3 groups: Fuji II LC Improved/GC (RM1, Vitremer/3M ESPE (RM2 and Filtek Z250/ 3M ESPE (RM3. Two commercial light-curing units were used to polymerize the materials: LED/Ultrablue IS and a halogen light/XL3000 (QTH. After 24 h, Knoop microhardness test was performed. Data were submitted to three-way ANOVA and Tukey's test at a pre-set alpha of 0.05. RESULTS: At the top surface, no statistically significant difference (p>0.05 in the microhardness was seen when the LED and QTH lights were used for all materials. At the bottom surface, microhardness mean value of RM2 was significantly higher when the QTH light was used (p0.05 was seen at the bottom surface for RM3, irrespective of the light used. Top-to-bottom surface comparison showed no statistically significant difference (p>0.05 for both RMGICs, regardless of the light used. For RM3, microhardness mean value at the top was significantly higher (p<0.05 than bottom microhardness when both curing units were used. CONCLUSION: The microhardness values seen when a LED light was used varied depending on the restorative material tested.

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

    African Journals Online (AJOL)

    2013-09-09

    Sep 9, 2013 ... LEDs produced light of low intensity (2) which resulted in composites of inferior properties than. QTH lamps (9, 11). Newer generations of LEDs try to address these deficits through higher intensities and being of dual spectrum. This allows them to be used with non-CQ composites (7). However, the high.

  2. The cytotoxicity of resin composites cured with three light curing units at different curing distances

    OpenAIRE

    Ergün, Gülfem; Egilmez, Ferhan; Cekic Nagas, Isil

    2011-01-01

    Objective: The purpose of this study was to compare the effect of light curing distance on the cytotoxicity of five resin composites cured with three high-power light curing units. Study design: Seven cylindrical discs of each material (Grandio ®, Voco; Filtek ? Z250, 3M ESPE; Clearfil ? AP-X, Kuraray Co. Ltd.; Aelite ? LS, Bisco Inc. and Simile ®, Pentron) were cured. For curing, soft-up mode of quartz-tungsten-halogen, exponential mode of light emitting diode for 20 s, and ramp-curing m...

  3. Effect of different photo-initiators and light curing units on degree of conversion of composites

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    William Cunha Brandt

    2010-09-01

    Full Text Available The aim of this study was to evaluate: (i the absorption of photo-initiators and emission spectra of light curing units (LCUs; and (ii the degree of conversion (DC of experimental composites formulated with different photo-initiators when activated by different LCUs. Blends of BisGMA, UDMA, BisEMA and TEGDMA with camphorquinone (CQ and/ or 1-phenyl-1,2-propanedione (PPD were prepared. Dimethylaminoethyl methacrylate (DMAEMA was used as co-initiator. Each mixture was loaded with 65 wt% of silanated filler particles. One quartz-tungsten-halogen - QTH (XL 2500, 3M/ESPE and two lightemitting diode (LED LCUs (UltraBlue IS, DMC and UltraLume LED 5, Ultradent were used for activation procedures. Irradiance (mW/cm² was calculated by the ratio of the output power by the area of the tip, and spectral distribution with a spectrometer (USB 2000. The absorption curve of each photo-initiator was determined using a spectrophotometer (Varian Cary 5G. DC was assessed by Fourier transformed infrared spectroscopy. Data were submitted to two-way ANOVA and Tukey's test (5%. No significant difference was found for DC values when using LED LCUs regardless of the photo-initiator type. However, PPD showed significantly lower DC values than composites with CQ when irradiated with QTH. PPD produced DC values similar to those of CQ, but it was dependent on the LCU type.

  4. Effects of Different Light Curing Units/Modes on the Microleakage of Flowable Composite Resins

    Science.gov (United States)

    Yazici, A. Ruya; Celik, Cigdem; Dayangac, Berrin; Ozgunaltay, Gul

    2008-01-01

    Objectives The aim of this in vitro study was to evaluate the influence of different light curing units and modes on microleakage of flowable composite resins. Methods Eighty Class V cavities were prepared in buccal and lingual surfaces of 40 extracted human premolars with cervical wall located in dentin and the occlusal wall in enamel. These teeth were randomly assigned into two groups (n=20) and restored with different flowable composites; Group I: Esthet-X Flow, Group II: Grandio Flow. Each group was randomly divided into four subgroups; while the samples of the first subgroup were polymerized with conventional Halogen light, the rest of them were polymerized with different curing modes of Light Emitting Diode (LED). The second subgroup was polymerized with fast-curing; the third subgroup with pulse-curing and those of the fourth subgroup with step-curing modes of LED. After the samples were thermocycled and immersed in dye, they were longitudinally sectioned. Dye penetration was assessed under a stereomicroscope. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests. Results None of the restorations showed leakage on enamel margins. On dentin margins no significant differences were observed between flowable composite resins polymerized with halogen light (P>.05). While step curing mode of LED presented significant differences between the resins, the difference was insignificant when fast-curing and pulse-curing mode of LED were used. No statistically significant differences were observed between curing units for Esthet-X Flow samples. For Grandio Flow samples, only step-curing mode of LED caused statistically higher leakage scores than halogen and other curing modes of LED (P<.05). Conclusions The effect of curing units’ type and curing mode on flowable composite resin leakage might be material-dependent. PMID:19212529

  5. Effect of three types of light-curing units on 5-year colour changes of light-cured composite.

    Science.gov (United States)

    Tak, Onjen; Altintas, Subutay Han; Ozturk, Nilgun; Usumez, Aslihan

    2009-03-01

    The purpose of this study was to determine colour changes in a composite cured with tungsten-halogen, light-emitting diode (LED) or a plasma arc after 5 years. Five specimens 10 mm in diameter and 2 mm in height were prepared using Hybrid (Clearfil AP-X) composite for each test group. The corresponding specimens were cured with a tungsten-halogen curing light, a LED unit or with a plasma arc. Specimens were stored in light-proof boxes for 5 years after the curing procedure to avoid further exposure to light and stored in 37 degrees C in 100% humidity. Colorimetric values of the specimens immediately after curing and after 5 years were measured using colorimeter. The DeltaE*( ab ) values varied significantly depending on the curing unit used (p Curing time did not affect the colour changes of the specimens (p = 0.4). The results of this study suggest that composite materials undergo measurable changes due to the curing unit exposure.

  6. The Effect of Irradiation Distance on Microhardness of Resin Composites Cured with Different Light Curing Units

    Science.gov (United States)

    Cekic-Nagas, Isil; Egilmez, Ferhan; Ergun, Gulfem

    2010-01-01

    Objectives: The aim of this study was to compare the microhardness of five different resin composites at different irradiation distances (2 mm and 9 mm) by using three light curing units (quartz tungsten halogen, light emitting diodes and plasma arc). Methods: A total of 210 disc-shaped samples (2 mm height and 6 mm diameter) were prepared from different resin composites (Simile, Aelite Aesthetic Enamel, Clearfil AP-X, Grandio caps and Filtek Z250). Photoactivation was performed by using quartz tungsten halogen, light emitting diode and plasma arc curing units at two irradiation distances (2 mm and 9 mm). Then the samples (n=7/per group) were stored dry in dark at 37°C for 24 h. The Vickers hardness test was performed on the resin composite layer with a microhardness tester (Shimadzu HMV). Data were statistically analyzed using nonparametric Kruskal Wallis and Mann-Whitney U tests. Results: Statistical analysis revealed that the resin composite groups, the type of the light curing units and the irradiation distances have significant effects on the microhardness values (P<.05). Conclusions: Light curing unit and irradiation distance are important factors to be considered for obtaining adequate microhardness of different resin composite groups. PMID:20922164

  7. Effect of light-curing units in shear bond strength of metallic brackets: an in vitro study

    Directory of Open Access Journals (Sweden)

    Luciana Borges Retamoso

    2010-02-01

    Full Text Available OBJECTIVES: To determine the influence of the light curing units on the shear bond strength of orthodontic brackets. MATERIAL AND METHODS: Seventy-two premolars were divided into six groups (n=12: Group I: brackets bonded with Transbond and polymerization with halogen light; Group II: Transbond and LED; Group III: Fuji Ortho and halogen light; Group IV: Fuji Ortho and LED; Group V: Fuji Ortho, without acid and halogen light; Group VI: Fuji Ortho, without acid and LED. The groups were tested to shear strength in a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed statistically by ANOVA and Tukey's test. RESULTS: The composite resin presented higher shear bond strength than the resin-modified glass ionomer cement (p0.05. CONCLUSION: The shear bond strength was influenced by the material but not by the light-curing unit. The use of LED reduced the experimental time by approximately 60%, with the same curing efficiency.

  8. A PREP Panel, Practice-Based, Evaluation of the Handling of the Kerr Demi-Ultra Light Curing Unit.

    Science.gov (United States)

    Burke, F J Trevor; Crisp, Russell J

    2015-09-01

    This paper describes the handling evaluation (by a group of practice-based researchers, the PREP Panel) of a recently introduced Light Curing Unit (LCU), the Kerr Demi-Ultra, which possesses a number of novel features such as its ultracapacitor power source, and the Light Emitting Diodes (LEDs) which provide the light output being placed close to the tip of the light guide. CPD/CLINICAL RELEVANCE: Testing of new devices and materials with respect to their handling is of importance, given that an easy to handle device should produce better clinical results than one which is difficult to use.

  9. Power density of various light curing units through resin inlays with modified layer thickness

    Science.gov (United States)

    Hong, Sung-Ok; Oh, Yonghui; Min, Jeong-Bum; Kim, Jin-Woo; Lee, Bin-Na; Hwang, Yun-Chan; Hwang, In-Nam; Oh, Won-Mann

    2012-01-01

    Objectives The purpose of this study was to enhance curing light penetration through resin inlays by modifying the thicknesses of the dentin, enamel, and translucent layers. Materials and Methods To investigate the layer dominantly affecting the power density of light curing units, resin wafers of each layer with 0.5 mm thickness were prepared and power density through resin wafers was measured with a dental radiometer (Cure Rite, Kerr). The dentin layer, which had the dominant effect on power density reduction, was decreased in thickness from 0.5 to 0.1 mm while thickness of the enamel layer was kept unchanged at 0.5 mm and thickness of the translucent layer was increased from 0.5 to 0.9 mm and vice versa, in order to maintain the total thickness of 1.5 mm of the resin inlay. Power density of various light curing units through resin inlays was measured. Results Power density measured through 0.5 mm resin wafers decreased more significantly with the dentin layer than with the enamel and translucent layers (p inlays increased when the dentin layer thickness was reduced and the enamel or translucent layer thickness was increased. The highest power density was recorded with dentin layer thickness of 0.1 mm and increased translucent layer thickness in all light curing units. Conclusions To enhance the power density through resin inlays, reducing the dentin layer thickness and increasing the translucent layer thickness would be recommendable when fabricating resin inlays. PMID:23431061

  10. THE EFFECT OF DIFFERENT LIGHT-CURING UNITS ON TENSILE STRENGTH AND MICROHARDNESS OF A COMPOSITE RESIN

    Science.gov (United States)

    Franco, Eduardo Batista; dos Santos, Patrícia Aleixo; Mondelli, Rafael Francisco Lia

    2007-01-01

    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. PMID:19089182

  11. 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.

  12. Power density of various light curing units through resin inlays with modified layer thickness

    Directory of Open Access Journals (Sweden)

    Sung-Ok Hong

    2012-08-01

    Full Text Available Objectives The purpose of this study was to enhance curing light penetration through resin inlays by modifying the thicknesses of the dentin, enamel, and translucent layers. Materials and Methods To investigate the layer dominantly affecting the power density of light curing units, resin wafers of each layer with 0.5 mm thickness were prepared and power density through resin wafers was measured with a dental radiometer (Cure Rite, Kerr. The dentin layer, which had the dominant effect on power density reduction, was decreased in thickness from 0.5 to 0.1 mm while thickness of the enamel layer was kept unchanged at 0.5 mm and thickness of the translucent layer was increased from 0.5 to 0.9 mm and vice versa, in order to maintain the total thickness of 1.5 mm of the resin inlay. Power density of various light curing units through resin inlays was measured. Results Power density measured through 0.5 mm resin wafers decreased more significantly with the dentin layer than with the enamel and translucent layers (p < 0.05. Power density through 1.5 mm resin inlays increased when the dentin layer thickness was reduced and the enamel or translucent layer thickness was increased. The highest power density was recorded with dentin layer thickness of 0.1 mm and increased translucent layer thickness in all light curing units. Conclusions To enhance the power density through resin inlays, reducing the dentin layer thickness and increasing the translucent layer thickness would be recommendable when fabricating resin inlays.

  13. The effect of light curing units, curing time, and veneering materials on resin cement microhardness

    OpenAIRE

    Nurcan Ozakar Ilday; Yusuf Ziya Bayindir; Funda Bayindir; Aysel Gurpinar

    2013-01-01

    Background/purpose: Several factors may affects microhardness of resin cement under veneering materials. The aim of this study was to evaluate the effect of different veneering materials, light-curing units and curing times (20/3, 40/6) on the microhardness of dual-cured resin cement. Materials and methods: We pressed dual-cured resin cement specimens (Clearfil SA cement, 5 mm diameter, 1 mm thick) between two microscopic glass slides covered with transparent polystyrene matrix strips to r...

  14. Influence of the light-curing unit, storage time and shade of a dental composite resin on the fluorescence

    Science.gov (United States)

    Queiroz, R. S.; Bandéca, M. C.; Calixto, L. R.; Gaiao, U.; Cuin, A.; Porto-Neto, S. T.

    2010-07-01

    The aim of this study was to determine the influence of three light-curing units, storage times and colors of the dental composite resin on the fluorescence. The specimens (diameter 10.0 ± 0.1 mm, thickness 1.0 ± 0.1 mm) were made using a stainless steel mold. The mold was filled with the microhybrid composite resin and a polyethylene film covered each side of the mold. After this, a glass slide was placed on the top of the mold. To standardize the top surface of the specimens a circular weight (1 kg) with an orifice to pass the light tip of the LCU was placed on the top surface and photo-activated during 40 s. Five specimens were made for each group. The groups were divided into 9 groups following the LCUs (one QTH and two LEDs), storage times (immediately after curing, 24 hours, 7 and 30 days) and colors (shades: A2E, A2D, and TC) of the composite resin. After photo-activation, the specimens were storage in artificial saliva during the storage times proposed to each group at 37°C and 100% humidity. The analysis of variance (ANOVA) and Tukey’s posthoc tests showed no significant difference between storage times (immediately, 24 hours and 30 days) ( P > 0.05). The means of fluorescence had difference significant to color and light-curing unit used to all period of storage ( P 0.05).

  15. A survey of power density of light-curing units used in private dental offices in Changchun City, China.

    Science.gov (United States)

    Hao, Xinqing; Luo, Meng; Wu, Jian; Zhu, Song

    2015-02-01

    This study investigated power density and relevant information related to light-curing units used in private dental offices in Changchun City, China. The power density of 196 light-curing units used in private dental offices in Changchun City was measured using a simple random sampling method. Relevant information included the brand, type, years of operation, frequency of use, model numbers and types of light guide, resin buildup on the light guides, damage caused by the light guides, required maintenance of the curing lights, and ratio of the unit and chair number. There were 132 quartz tungsten halogen (QTH) units and 64 light-emitting diode units. The power density range was defined as 0-1,730 mW/cm(2). The mean power density was 453.1 mW/cm(2). The mean years of operation of the light-curing units were 3.96. The majority of dentists never tested the power density of the light-curing units and a considerable number of light guide surfaces showed resin buildup and damage. In Changchun City, the majority of light-curing units were QTH. Some units needed to be replaced due to aging. The majority of dentists were not aware that the light-curing units require periodic testing and maintenance. The data herein indicate the importance of periodic testing of the power density of light-curing units and timely replacement of the components and then guarantee the quality of medical services and their benefits to patients.

  16. Effects of cement-curing mode and light-curing unit on the bond durability of ceramic cemented to dentin

    Directory of Open Access Journals (Sweden)

    Sheila Pestana Passos

    2013-04-01

    Full Text Available The aim of this study was to evaluate the effects of different light-curing units and resin cement curing types on the bond durability of a feldspathic ceramic bonded to dentin. The crowns of 40 human molars were sectioned, exposing the dentin. Forty ceramic blocks of VITA VM7 were produced according to the manufacturer's recommendations. The ceramic surface was etched with 10% hydrofluoric acid / 60s and silanized. The dentin was treated with 37% phosphoric acid / 15s, and the adhesive was applied. The ceramic blocks were divided and cemented to dentin according to resin cement / RC curing type (dual- and photo-cured, light-curing unit (halogen light / QTH and LED, and storage conditions (dry and storage / 150 days + 12,000 cycles / thermocycling. All blocks were stored in distilled water (37°C / 24h and sectioned (n = 10: G1 - QTH + RC Photo, G2 - QTH + RC Dual, G3 - LED + RC Photo, G4 - LED + RC Dual. Groups G5, G6, G7, and G8 were obtained exactly as G1 through G4, respectively, and then stored and thermocycled. Microtensile bond strength tests were performed (EMIC, and data were statistically analyzed by ANOVA and Tukey's test (5%. The bond strength values (MPa were: G1 - 12.95 (6.40ab; G2 - 12.02 (4.59ab; G3 - 13.09 (5.62ab; G4 - 15.96 (6.32a; G5 - 6.22 (5.90c; G6 - 9.48 (5.99bc; G7 - 12.78 (11.30ab; and G8 - 8.34 (5.98bc. The same superscript letters indicate no significant differences. Different light-curing units affected the bond strength between ceramic cemented to dentin when the photo-cured cement was used, and only after aging (LED > QTH. There was no difference between the effects of dual- and photo-cured resin-luting agents on the microtensile bond strength of the cement used in this study.

  17. Effects of cement-curing mode and light-curing unit on the bond durability of ceramic cemented to dentin.

    Science.gov (United States)

    Passos, Sheila Pestana; Souza, Rodrigo Othávio Assunção; Michida, Silvia Masae Araújo; Zamboni, Sandra Costa; Oliveira, Simone Helena Gonçalves de

    2013-01-01

    The aim of this study was to evaluate the effects of different light-curing units and resin cement curing types on the bond durability of a feldspathic ceramic bonded to dentin. The crowns of 40 human molars were sectioned, exposing the dentin. Forty ceramic blocks of VITA VM7 were produced according to the manufacturer's recommendations. The ceramic surface was etched with 10% hydrofluoric acid / 60s and silanized. The dentin was treated with 37% phosphoric acid / 15s, and the adhesive was applied. The ceramic blocks were divided and cemented to dentin according to resin cement / RC curing type (dual- and photo-cured), light-curing unit (halogen light / QTH and LED), and storage conditions (dry and storage / 150 days + 12,000 cycles / thermocycling). All blocks were stored in distilled water (37°C / 24h) and sectioned (n = 10): G1 - QTH + RC Photo, G2 - QTH + RC Dual, G3 - LED + RC Photo, G4 - LED + RC Dual. Groups G5, G6, G7, and G8 were obtained exactly as G1 through G4, respectively, and then stored and thermocycled. Microtensile bond strength tests were performed (EMIC), and data were statistically analyzed by ANOVA and Tukey's test (5%). The bond strength values (MPa) were: G1 - 12.95 (6.40)ab; G2 - 12.02 (4.59)ab; G3 - 13.09 (5.62)ab; G4 - 15.96 (6.32)a; G5 - 6.22 (5.90)c; G6 - 9.48 (5.99)bc; G7 - 12.78 (11.30)ab; and G8 - 8.34 (5.98)bc. The same superscript letters indicate no significant differences. Different light-curing units affected the bond strength between ceramic cemented to dentin when the photo-cured cement was used, and only after aging (LED > QTH). There was no difference between the effects of dual- and photo-cured resin-luting agents on the microtensile bond strength of the cement used in this study.

  18. Effect of light-curing unit and adhesive system on marginal adaptation of class v composite restorations.

    Science.gov (United States)

    Maia-Casseli, Denise S; Faria-e-Silva, André L; Cavalcanti, Andréa N; Romani, Eliene A O N; Martins, Luis R M

    2012-01-01

    The aim of this study was to evaluate the effect of light-curing units (LED or halogen) on the marginal adaptation of composite restorations performed with etch-and-rinse and self-etching adhesive. Class V cavities were prepared on bovine teeth with the gingival margin on dentin and the incisal margin on enamel. The cavities were restored with a micro-hybrid resin composite using an etch-and-rinse (Single Bond 2--SB) or a self-etching adhesive (Clearfil SE Bond--CL). The light-activations were performed using halogen lamp (Optilux 501--QTH) or second-generation light-emitting diode (Radii-Cal--LED) (n = 10). After finishing and polishing the restorations, epoxy replicas were prepared. The marginal adaptation was analyzed under scanning electronic microscopy with 500x of magnification. The greatest gap width at each margin was recorded. Data were submitted to Mann-Whitney and Wilcoxon tests (a = 0.05). SB and CL showed similar behavior of enamel margins when the light-activations were performed with QTH. The same was observed for dentin margins with LED. When the LED was used, higher gap measurements at enamel margins were observed with CL, while higher gap values in dentin were observed for SB within QTH. No significant difference between substrates was found when CL was used. However, SB had significantly higher gap measurements in dentin. The light-curing unit seems to affect the marginal adaptation of resin composite restorations. However this effect was dependent on the adhesive and the location of the margin.

  19. Comparison of the bonding strengths of second- and third-generation light-emitting diode light-curing units.

    Science.gov (United States)

    Lee, Hee-Min; Kim, Sang-Cheol; Kang, Kyung-Hwa; Chang, Na-Young

    2016-11-01

    With the introduction of third-generation light-emitting diodes (LEDs) in dental practice, it is necessary to compare their bracket-bonding effects, safety, and efficacy with those of the second-generation units. In this study, 80 extracted human premolars were randomly divided into eight groups of 10 samples each. Metal or polycrystalline ceramic brackets were bonded on the teeth using second- or third-generation LED light-curing units (LCUs), according to the manufacturers' instructions. The shear bond strengths were measured using the universal testing machine, and the adhesive remnant index (ARI) was scored by assessing the residual resin on the surfaces of debonded teeth using a scanning electron microscope. In addition, curing times were also measured. The shear bond strengths in all experimental groups were higher than the acceptable clinical shear bond strengths, regardless of the curing unit used. In both LED LCU groups, all ceramic bracket groups showed significantly higher shear bond strengths than did the metal bracket groups except the plasma emulation group which showed no significant difference. When comparing units within the same bracket type, no differences in shear bond strength were observed between the second- and third-generation unit groups. Additionally, no significant differences were observed among the groups for the ARI. The bracket-bonding effects and ARIs of second- and third-generation LED LCUs showed few differences, and most were without statistical significance; however, the curing time was shorter for the second-generation unit.

  20. 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.

  1. Effect of cement shade and light-curing unit on bond strength of a ceramic cemented to dentin.

    Science.gov (United States)

    de Castro, Humberto Lago; Passos, Sheila Pestana; Zogheib, Lucas Villaça; Bona, Alvaro Della

    2012-04-01

    To evaluate the effect of cement shade, light-curing unit, and water storage on tensile bond strength (σ) of a feldspathic ceramic resin bonded to dentin. The dentin surface of 40 molars was exposed and etched with 37% phosphoric acid, then an adhesive system was applied. Forty blocks of feldspathic ceramic (Vita VM7) were produced. The ceramic surface was etched with 10% hydrofluoric acid for 60 s, followed by the application of a silane agent and a dual-curing resin cement (Variolink II). Ceramic blocks were cemented to the treated dentin using either A3 or transparent (Tr) shade cement that was activated using either halogen or LED light for 40 s. All blocks were stored in 37°C distilled water for 24 h before cutting to obtain non-trimmed bar-shaped specimens (adhesive area = 1 mm2 ± 0.1) for the microtensile bond strength test. The specimens were randomly grouped according to the storage time: no storage or stored for 150 days in 37°C distilled water. Eight experimental groups were obtained (n = 30). The specimens were submitted to the tensile bond strength test using a universal testing machine at a crosshead speed of 1 mm/min. The data were statistically analyzed using ANOVA and Tukey's posthoc tests (a = 0.05). The mean bond strength values were significantly lower for the corresponding water stored groups, except for the specimens using A3 resin cement activated by halogen light. There was no significance difference in mean bond strength values among all groups after water storage. Water storage had a detrimental effect under most experimental conditions. For both cement shades investigated (Tr and A3) under the same storage condition, the light-curing units (QTH and LED) did not affect the mean microtensile bond strengths of resin-cemented ceramic to dentin.

  2. Odontological light-emitting diode light-curing unit beam quality

    Science.gov (United States)

    de Magalhães Filho, Thales Ribeiro; Weig, Karin de Mello; Werneck, Marcelo Martins; da Costa Neto, Célio Albano; da Costa, Marysilvia Ferreira

    2015-05-01

    The distribution of light intensity of three light-curing units (LCUs) to cure the resin-based composite for dental fillings was analyzed, and a homogeneity index [flat-top factor (FTF)] was calculated. The index is based on the M2 index, which is used for laser beams. An optical spectrum analyzer was used with an optical fiber to produce an x-y power profile of each LCU light guide. The FTF-calculated values were 0.51 for LCU1 and 0.55 for LCU2, which was the best FTF, although it still differed greatly from the perfect FTF=1, and 0.27 for LCU3, which was the poorest value and even lower than the Gaussian FTF=0.5. All LCUs presented notably heterogeneous light distribution, which can lead professionals and researchers to produce samples with irregular polymerization and poor mechanical properties.

  3. Changes on degree of conversion of dual-cure luting light-cured with blue LED

    Science.gov (United States)

    Bandéca, M. C.; El-Mowafy, O.; Saade, E. G.; Rastelli, A. N. S.; Bagnato, V. S.; Porto-Neto, S. T.

    2009-05-01

    The indirect adhesive procedures constitute recently a substantial portion of contemporary esthetic restorative treatments. The resin cements have been used to bond tooth substrate and restorative materials. Due to recently introduction of the self-bonding resin luting cement based on a new monomer, filler and initiation technology has become important to study the degree of conversion of these new materials. In the present work the polymerization reaction and the filler content of dual-cured dental resin cements were studied by means of infra-red spectroscopy (FT-IR) and thermogravimetry (TG). Twenty specimens were made in a metallic mold (8 mm diameter × 1 mm thick) from each of 2 cements, Panavia® F2.0 (Kuraray) and RelyX™ Unicem Applicap (3M/ESPE). Each specimen was cured with blue LED with power density of 500 mW/cm2 for 30 s. Immediately after curing, 24 and 48 h, and 7 days DC was determined. For each time interval 5 specimens were pulverized, pressed with KBr and analyzed with FT-IR. The TG measurements were performed in Netzsch TG 209 under oxygen atmosphere and heating rate of 10°C/min from 25 to 700°C. A two-way ANOVA showed DC (%) mean values statistically significance differences between two cements ( p cements ( p > 0.05). The Relx-Y™ Unicem mean values were significantly higher than Panavia® F 2.0. The degree of conversion means values increasing with the storage time and the filler content showed similar for both resin cements.

  4. A comparative evaluation of curing depth and compressive strength of dental composite cured with halogen light curing unit and blue light emitting diode: an in vitro study.

    Science.gov (United States)

    Kumar, C N Vijaya; Gururaj, M; Paul, Joseph

    2012-11-01

    To evaluate the curing depth and compressive strength of dental composite using halogen light curing unit and light emitting diode light curing unit. Eighty cylindrical composite specimens were prepared using posterior composite P60(3M). Forty specimens, out of which 20 samples (group A) cured with halogen light and 20 samples (group B) cured using light emitting diode (LED) light were checked for curing depth according to ISO 4049. Remaining 40 samples out of which 20 samples (group I) cured using halogen light and 20 samples (group II) cured using LED light were checked for compressive strength using Instron universal testing machine. Twenty samples (group A) cured with halogen light showed better curing depth than 20 samples (group B) cured with LED light. Twenty samples (group I) cured with halogen light showed almost similar results as 20 samples (group II) cured with LED light for compressive strength. Halogen light commonly used to cure composite resin have greater depth of cure, when compared to LED light, while both the lights produced compressive strength which is almost similar. Lower depth of cure with the LED unit, compared to the QTH unit, is associated with different light scattering due to differences in spectral emission. LED technology differs from QTH by the spectral emission that favorably matches the absorption spectrum of camphorquinone.

  5. Effect of light-activation with different light-curing units and time intervals on resin cement bond strength to intraradicular dentin.

    Science.gov (United States)

    Miguel-Almeida, Maria Eleonora; Azevedo, Mario Lucio da Costa; Rached-Júnior, Fuad Abi; Oliveira, Camila Favero; Silva, Ricardo Gariba; Messias, Danielle Cristine

    2012-01-01

    The aim of this study was to assess the bond strength of a resin cement to intraradicular dentin varying the light-curing unit and the moment at which the light was applied. Post spaces of endodontically treated canines were prepared. The roots were distributed into 6 groups (n=10) according to the light-curing unit and the moment of light exposure: I) Quartz tungsten halogen-600 mW/cm² (QTH) + immediate light activation (t0); II) QTH + light activation after 10 min (t10); III) Light-emitting diodes (LED)-800 mW/cm² (LED-800)+ t0; IV) LED-800 + t10; V) LED-1,500 mW/cm² (LED-1500)+ t0; VI) LED-1500 + t10. After post cementation, slices from coronal, middle and apical post/root regions were submitted to the push-out test and failure evaluation. It was verified that LED-800 (4.40 ± 3.00 MPa) and LED-1500 (4.67 ± 3.04 MPa) provided bond strength statistically superior to QTH (3.13 ± 1.76 MPa) (p0.05). There was no significant difference between t0 and t10 (p>0.05). Coronal post/root region (4.75 ± 3.10 MPa) presented significantly higher bond strength than the apical (3.32 ± 2.30 MPa) (plight-activation, regardless of the moment of light exposure.

  6. Prototype of a new tip developed to be coupled to dental light-curing units for optimizing bonding of orthodontic brackets and accessories.

    Science.gov (United States)

    Mota Júnior, Sergio Luiz; Campos, Márcio José da Silva; Gravina, Marco Abdo; Fraga, Marcelo Reis; Vitral, Robert Willer Farinazzo

    2013-01-01

    Development of a new device to be coupled to light-curing units for bonding orthodontic brackets and accessories, and test its efficacy in an in vitro mechanical trial. The inner surface of the device is mirrored and is based on physical concepts of light refraction and reflection. The main advantage of such device is the reduced clinical time needed for bonding and the low possibility of contamination during the process. One hundred and twenty specimens were used for testing the shear bond strength of brackets bonded with the device. The Adhesive Remnant Index (ARI) was also determined. The sample was divided into 2 groups. In group 1 a halogen light-curing unit was used while in group 2 a led light-curing unit was used. Each group was then subdivided. In subgroups H1 and L1, a conventional light guide rod was used while in subgroups H2 and L2 bonding was performed with the mirrored device coupled to the tip of the guide light rod. The values obtained for the shear bond strength and the ARI in the subgroups were compared. Results showed that there was no statistically significant difference for the shear strength (p > 0.05) and the ARI (p > 0.05) between the subgroups. The tests of mechanical trials and the ARI analysis showed that the new device fulfilled the requirements for bonding orthodontic accessories, and that the time for bonding was reduced to half, being necessary only one light exposure.

  7. 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.

  8. Influence of cavity preparation, light-curing units, and composite filling on intrapulpal temperature increase in an in vitro tooth model.

    Science.gov (United States)

    Choi, S H; Roulet, J F; Heintze, S D; Park, S H

    2014-01-01

    This study examined the effect of both the tooth substance and restorative filling materials on the increase in pulp chamber temperature when using light-curing units with different power densities. The tip of a temperature sensor was positioned on the pulpal dentinal wall of the buccal side of a maxillary premolar. Metal tubes were inserted in the palatal and buccal root of the tooth, one for water inflow and the other for water outflow. Polyethylene tubes were connected from the metal tubes to a pump to control the flow rate. For the unprepared tooth group (group 1), the tooth was light-cured from the buccal side using two light-curing units (three curing modes): the VIP Junior (QTH, BISCO, Schaumburg, IL, USA) and the Bluephase LED light-curing units (two modes: LEDlow and LEDhigh; Ivoclar Vivadent, Schaan, Liechtenstein). The power densities of each light-curing unit for the LEDlow, QTH, and LEDhigh modes were 785 mW/cm(2), 891 mW/cm(2), and 1447 mW/cm(2), respectively. All light-curing units were activated for 60 seconds. For the prepared tooth group (group 2), a Class V cavity, 4.0 mm in width by 4.0 mm in height by 1.8 mm in depth in size, was prepared on the buccal surface of the same tooth for the temperature measurement. The light-curing and temperature measurements were performed using the same methods used in group 1. The cavity prepared in group 2 was filled with a resin composite (Tetric N Ceram A3 shade, Ivoclar Vivadent) (group 3) or a flowable composite (Tetric N Flow with A3 shade, Ivoclar Vivadent) (group 4). The light-curing and temperature measurements were performed for these groups using the same methods used for the other groups. The highest intrapulpal temperature (TMAX) was measured, and a comparison was conducted between the groups using two-way analysis of variance with a post hoc Tukey test at the 95% confidence level. The TMAX values were as follows: 38.4°C (group 1), 39.0°C (group 2), 39.8°C (group 3), and 40.3°C (group 4) for the

  9. Light-Curing Units: A Review of What We Need to Know.

    Science.gov (United States)

    Price, R B; Ferracane, J L; Shortall, A C

    2015-09-01

    For improved interstudy reproducibility, reduced risk of premature failures, and ultimately better patient care, researchers and dentists need to know how to accurately characterize the electromagnetic radiation (light) they are delivering to the resins they are using. The output from a light-curing unit (LCU) is commonly characterized by its irradiance. If this value is measured at the light tip, it describes the radiant exitance from the surface of the light tip, and not the irradiance received by the specimen. The value quoted also reflects only an averaged value over the total measurement area and does not represent the irradiance that the resin specimen is receiving locally or at a different moment in time. Recent evidence has reported that the spectral emission and radiant exitance beam profiles from LCUs can be highly inhomogeneous. This can cause nonuniform temperature changes and uneven photopolymerization within the resin restoration. The spectral radiant power can be very different between different brands of LCUs, and the use of irradiance values derived from dental radiometers to describe the output from an LCU for research purposes is discouraged. Manufacturers should provide more information about the light output from the LCU and the absorption spectrum of their resin-based composite (RBC). Ideally, future assessments and research publications should include the following information about the curing light: 1) radiant power output throughout the exposure cycle and the spectral radiant power as a function of wavelength, 2) analysis of the light beam profile and spectral emission across the light beam, and 3) measurement and reporting of the light the RBC specimen received as well as the output measured at the light tip. © International & American Associations for Dental Research 2015.

  10. Effect of light-curing units on push-out fiber post bond strength in root canal dentin

    Science.gov (United States)

    Calixto, L. R.; Bandéca, M. C.; Silva, F. B.; Rastelli, A. N. S.; Porto-Neto, S. T.; Andrade, M. F.

    2009-08-01

    The purpose of this study was to evaluate the effectiveness of different light-curing units on the bond strength (push-out) of glass fiber posts in the different thirds of the root (cervical, middle and apical) with different adhesive luting resin systems (dual-cure total-etch; dual-cured and self-etch bonding system; and dual-cure self-adhesive cements), Disks of the samples ( n = 144) were used, with approximately 1 mm of thickness of 48 bovine roots restored with glass fiber posts, that were luted with resin cements photo-activated by halogen LCU (QTH, Optilux 501) and blue LED (Ultraled), with power densities of 600 and 550 mW/cm2, respectively. A universal testing machine (MTS 810 Material Test System) was used with a 1 mm diameter steel rod at cross-head speed of 0.5 mm/min until post extrusion, with load cell of 50 kg, for evaluation of the push-out strength in the different thirds of each sample. The push-out strength values in kgf were converted to MPa and analyzed through Analysis of Variance and Tukey’s test, at significance level of 5%. The results showed that there were no statistical differences between the QTH and LED LCUs. The self-adhesive resin cement had lower values of retention. The total-etch and self-adhesive system resin cements seem to be a possible alternative for glass fiber posts cementation into the radicular canal and the LED LCU can be applied as an alternative to halogen light on photo-activation of dual-cured resin cements.

  11. General dental practitioners' knowledge of polymerisation of resin-based composite restorations and light curing unit technology.

    Science.gov (United States)

    Santini, A; Turner, S

    2011-09-23

    Clinical successful use of resin-based composite restorations (RBCs) depends on knowledge of material and light curing unit (LCU) related factors. The purpose of this study was to evaluate general dental practitioners' knowledge of polymerisation of RBCs and LCU technology. Members of the Active Research Group of the Faculty of General Dental Practice (UK) in England, Scotland and Wales engaged in primary dental care were sent a letter introducing the study and asking for their cooperation, followed by an email containing a link to the online survey questionnaire, hosted on Surveymonkey.com. The questionnaire enquired about current LCUs, and asked a series of questions on material science. Sixty-six percent of the 274 members contacted responded. Fifty-seven percent used LED units, 25% quartz tungsten halogen (QTH), and 1% plasma arc (missing: 17%). Thirty percent reported having access to a radiometer. Appropriate responses regarding the degree of conversion of composite and adhesive materials were given by 32% and 23% respectively, and 22% agreed that LED and QTH LCUs had comparable efficiency in polymerising composites. Thirty-three percent were aware that RBCs eluted substances that may have adverse local or systemic consequences. Fifty-eight percent stated that if polymerisation of RBC is slowed down, polymerisation stress will be lower, and 43% said that polymerisation shrinkage will be reduced if the degree of conversion is reduced. Knowledge (measured by appropriate responses to these questions) was not related to years since qualification (r=-0.05, n=168, p=0.53). The study suggests that dentists' knowledge of curing RBC restorations and LCUs is poor. This indicates that there is a need for training and guidance in this aspect of primary dental care.

  12. Comparison of curing depth of a colored polyacid-modified composite resin with different light-curing units.

    Science.gov (United States)

    Vandenbulcke, Jeroen D E; Marks, Luc A M; Martens, Luc C; Verbeeck, Ronald M H

    2010-10-01

    To compare the depth of cure (DoC) of a colored polyacid-modified composite resin (PAM-C) with a traditional PAM-C and a fine hybrid composite resin using different light-curing units and different radiant energies. The DoC of the PAM-C Twinky Star (Voco, all shades), the PAM-C Glasiosite (Voco), and the composite resin Z100 (3M ESPE) shades A2 and A4 was determined using a penetrometer test method. The materials were cured in bulk using a halogen-based unit (Elipar Trilight, E = 18 J/cm2 and E = 32 J/cm2; 3M ESPE) and an LED curing unit (Elipar Freelight 2, E = 20 J/cm2; 3M ESPE) in split stainless steel molds. Immediately after curing, the height (mm) of the cured material was measured and taken as the DoC. Ranking of means was performed by Student-Newman-Keuls multiple comparison test, and statistically significant differences among mean values were detected with ANOVA. Mean DoC for all materials and shades varied as follows: 4.705 to 8.870 mm (E = 32 J/cm2); 3.672 to 8.050 mm (E = 20 J/cm2); and 4.090 to 7.357 mm (E = 18 J/cm2). Two-way ANOVA revealed that the DoC depended significantly (P curing device. Moreover, there was a significant interaction (P curing device with the highest energy density exhibited the highest curing depths.

  13. Prototype of a new tip developed to be coupled to dental light-curing units for optimizing bonding of orthodontic brackets and accessories

    Directory of Open Access Journals (Sweden)

    Sergio Luiz Mota Júnior

    2013-12-01

    Full Text Available OBJECTIVE: development of a new device to be coupled to light-curing units for bonding orthodontic brackets and accessories, and test its efficacy in an in vitro mechanical trial. The inner surface of the device is mirrored and is based on physical concepts of light refraction and reflection. The main advantage of such device is the reduced clinical time needed for bonding and the low possibility of contamination during the process. METHODS: One hundred and twenty specimens were used for testing the shear bond strength of brackets bonded with the device. The Adhesive Remnant Index (ARI was also determined. The sample was divided into 2 groups. In group 1 a halogen light-curing unit was used while in group 2 a led light-curing unit was used. Each group was then subdivided. In subgroups H1 and L1, a conventional light guide rod was used while in subgroups H2 and L2 bonding was performed with the mirrored device coupled to the tip of the guide light rod. RESULTS: The values obtained for the shear bond strength and the ARI in the subgroups were compared. Results showed that there was no statistically significant difference for the shear strength (p > 0.05 and the ARI (p > 0.05 between the subgroups. CONCLUSION: The tests of mechanical trials and the ARI analysis showed that the new device fulfilled the requirements for bonding orthodontic accessories, and that the time for bonding was reduced to half, being necessary only one light exposure.

  14. Effect of instruction, light curing unit, and location in the mouth on the energy delivered to simulated restorations.

    Science.gov (United States)

    Samaha, Sara; Bhatt, Sapan; Finkelman, Matthew; Papathanasiou, Aikaterini; Perry, Ronald; Strassler, Howard; Kugel, Gerard; Garcia-Godoy, Franklin; Price, Richard

    2017-12-01

    To determine the amount of energy (Joules/cm²) delivered by students to simulated restorations in a patient simulator based on the restoration location, the curing light unit used, and before vs. after instruction on how to improve their light curing technique. 30 dental students "light cured" two simulated restorations (that were 1-mm deep anterior and 4-mm deep posterior) using three light-curing units (LCUs) : VALO, Bluephase G2, and Optilux 401. A MARC Patient Simulator was used to measure the irradiance (mW/cm²) received by the restorations in real-time to calculate the radiant exposure (J/cm²) delivered during a 20-second exposure. At first, students were asked to use the light curing technique that they had been previously taught. They were then given 5 minutes of additional verbal instructions and a practical demonstration on proper curing technique using the patient simulator. They then light cured the restorations again. Based on a literature review, 16 J/cm² was considered the minimum acceptable radiant exposure. Before receiving instruction using the simulator, some students delivered as little as 4 J/cm² to the restoration. A mixed model test determined that the radiant exposure delivered to the anterior restoration was significantly greater than that delivered to the posterior restoration (Plt; 0.001). Additionally, when the locations were compared for each LCU individually, a paired t-test determined that before the students received the additional instruction, the anterior restoration received a significantly greater radiant exposure than the posterior restoration, for all three LCUs. Further paired t-tests and Wilcoxon signed-rank tests determined that after instruction, the radiant exposure improved significantly at both the anterior and posterior locations, for all three LCUs. The Bluephase G2 and the VALO each individually delivered 45% more radiant exposure than the Optilux 401 (Plights delivered similar mean radiant exposures (25.4 J

  15. Degree of conversion and hardness of a silorane-based composite resin: effect of light-curing unit and depth.

    Science.gov (United States)

    Torres, S A S; Silva, G C; Maria, D A; Campos, W R C; Magalhães, C S; Moreira, A N

    2014-01-01

    To investigate the effect of different light-curing units and depths on the degree of conversion (DC) through Fourier transform infrared spectroscopy (FTIR) and Knoop Hardness Number (KHN) of a silorane-based composite resin (Filtek LS, 3M ESPE, St Paul, MN, USA) (LS). LS specimens mounted in a particular designed matrix were photoactivated by three light-cure units (LCUs) at depths of 2, 3, 4, and 5 mm. The DC was determined in a FTIR spectrometer with an attenuated total reflectance accessory. The KHN was measured in an automatic microhardness tester. The results were analyzed using the Friedman and Spearman statistical tests (α=0.05). There was no effect of LCUs on the DC (p=0.472) or KHN (p=0.174) for all of the studied depths. The highest DC and KHN means were found at 2-mm depth, which were not statistically different from 3-mm depth, but were higher than 4-mm and 5-mm depths (p=0.007). Spearman analysis found a positive linear correlation between the variables KHN and DC (r=0.858, p<0.000). The LCUs' effect was not verified. Values of DC and KHN for LS decreased with increasing depth. The highest values for both DC and KHN were obtained at depths of 2-3 mm.

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

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    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.

  17. 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.

  18. Influence of light-curing unit systems on shear bond strength and marginal microleakage of composite resin restorations

    Directory of Open Access Journals (Sweden)

    Juliano Fernandes Sassi

    2008-03-01

    Full Text Available The aim of the present study was to evaluate the influence of different photopolymerization (halogen, halogen soft-start and LED systems on shear bond strength (SBS and marginal microleakage of composite resin restorations. Forty Class V cavities (enamel and dentin margins were prepared for microleakage assessment, and 160 enamel and dentin fragments were prepared for the SBS test, and divided into 4 groups. Kruskal-Wallis and Wilcoxon tests showed statistically significant difference in microleakage between the margins (p 0.05 neither between substrates nor among groups. It was concluded that Soft-Start technique with high intensity end-light influenced negatively the cervical marginal sealing, but the light-curing systems did not influence adhesion.

  19. 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.

  20. Degree of conversion and temperature increase of a composite resin light cured with an argon laser and blue LED

    Science.gov (United States)

    Rastelli, A. N. S.; Jacomassi, D. P.; Bagnato, V. S.

    2008-12-01

    Different light sources and power densities used on the photoactivation process may provide changes in the degree of conversion (DC%) and temperature ( T) of the composite resins. Thus, the purpose of this study was to evaluate the DC (%) and T (°C) of the microhybrid composite resin (Filtek™ Z-250, 3M/ESPE) photoactivated with one argon laser and one LED (light-emitting diode) with different power densities. For the KBr pellet technique, the composite resin was placed into a metallic mould (2-mm thickness, 4-mm diameter) and photoactivated as follows: a continuous argon laser (CW) and LED LCUs with power density values of 100, 400, 700, and 1000 mW/cm2 for 20 s. The measurements for DC (%) were made in a FTIR spectrometer Bomen (model MB 102, Quebec, Canada). Spectroscopy (FTIR) spectra for both uncured and cured samples were analyzed using an accessory of the reflectance diffusion. The measurements were recorded in absorbance operating under the following conditions: 32 scans, 4 cm-1 resolution, 300 to 4000-cm-1 wavelength. The percentage of unreacted carbon double bonds (% C=C) was determined from the ratio of absorbance intensities of aliphatic C=C (peak at 1638 cm-1) against an internal standard before and after the curing of the specimen: aromatic C-C (peak at 1608 cm-1). For T (°C), the samples were created in a metallic mould (2-mm thickness, 4-mm diameter) and photoactivated for 20 s. The thermocouple was attached to the multimeter allowing temperature readings. The DC (%) and T (°C) were submitted to ANOVA and Tukey’s test ( p units.

  1. Comparison of hardness of three temporary filling materials cured by two light-curing devices.

    Science.gov (United States)

    Bodrumlu, E; Koçak, M M; Hazar Bodrumlu, E; Ozcan, S; Koçak, S

    2014-01-01

    Polymerization ability of light-curing devices can affect the light-cured material hardness. The purpose of the present study was to evaluate and compare the hardness of three temporary filling materials that had been light-cured by either a light emitting diode (LED) or a halogen light-curing unit. The temporary filling materials, First Fill, Voco Clip and Bioplic, were placed in wells in a Teflon plate. The 24 specimens of each material were divided into two groups (N.=12/group) for photo-activation by either of the two light-curing units. The LED or halogen device was applied for 40s to the top surface of each specimen. A Knoop hardness test was performed on the top and bottom surface of each specimen, with five measurements per specimen. The highest hardness values for both the LED and halogen treated groups were observed for First Fill and the lowest values were for Voco Clip in top and bottom surfaces. The hardness obtained for the three materials with the halogen unit were significantly higher than the values obtained with the LED unit in both surfaces (Plight-cured temporary material exhibited the highest hardness values on the top and bottom surfaces than Voco Clip and Bioplic temporary materials. The hardness of light-cured temporary filling materials can be affected by the type of light-curing unit.

  2. Micro-leakage of a Fissure Sealant Cured Using Quartz-tungsten-halogen and Plasma Arc Light Curing Units.

    Science.gov (United States)

    Bahrololoomi, Zahra; Soleimani, Ali Asghar; Jafari, Najmeh; Varkesh, Bentolhoda

    2014-01-01

    Background and aims. Newer curing units such as plasma arc can polymerize the sealants in much shorter curing times. The aim of this study was to compare the effect of two different curing units on the micro-leakage of a fissure sealant material. Materials and methods. Sixty two extracted premolars without caries were randomly divided into two groups of 31 samples. Occlusal surfaces of all teeth were cleansed. Then, teeth surfaces were etched by 37% phosphoric acid. After rinsing and drying, occlusal surfaces of teeth were sealed by a fissure sealant. The sealant was then cured using either a halogen light curing unit or a plasma arc curing light. After sealing, the teeth were thermocycled for 500 cycles. The teeth were then sectioned and examined for micro-leakage. Statistical analyses were performed with Mann-Whitney test. Results. There was no significant difference between two groups regarding micro-leakage (P = 0.42). Conclusion. Results showed that there was no significant difference between two different curing units. Therefore, plasma arc unit might be a useful alternative for sealant polymerization.

  3. Micro-leakage of a Fissure Sealant Cured Using Quartz-tungsten-halogen and Plasma Arc Light Curing Units

    Directory of Open Access Journals (Sweden)

    Zahra Bahrololoomi

    2014-12-01

    Full Text Available Background and aims. Newer curing units such as plasma arc can polymerize the sealants in much shorter curing times. The aim of this study was to compare the effect of two different curing units on the micro-leakage of a fissure sealant material. Materials and methods. Sixty two extracted premolars without caries were randomly divided into two groups of 31 samples. Occlusal surfaces of all teeth were cleansed. Then, teeth surfaces were etched by 37% phosphoric acid. After rinsing and drying, occlusal surfaces of teeth were sealed by a fissure sealant. The sealant was then cured using either a halogen light curing unit or a plasma arc curing light. After sealing, the teeth were thermocycled for 500 cycles. The teeth were then sectioned and examined for micro-leakage. Statistical analyses were performed with Mann-Whitney test. Results. There was no significant difference between two groups regarding micro-leakage (P = 0.42. Conclusion. Results showed that there was no significant difference between two different curing units. Therefore, plasma arc unit might be a useful alternative for sealant polymerization.

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

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    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.

  5. The effects of light curing units and environmental temperatures on C 000000000000 000000000000 000000000000 111111111111 000000000000 111111111111 000000000000 000000000000 000000000000 C conversion of commercial and experimental bonding agents.

    Science.gov (United States)

    Jafarzadeh-Kashi, Tahereh Sadat; Erfan, Mohmmad; Kalbasi, Salmeh; Ghadiri, Malihe; Rakhshan, Vahid

    2014-10-01

    Polymerization of bonding agents (BA) is a critical factor in determining the success of bonded restorations. We aimed to assess the effects of two light curing units and two temperatures on the extent of polymerization (EP) of a commercial BA and an experimental BA. Forty BA specimens were randomly divided into 8 subgroups of n = 5 to compare the polymerization of two BAs (experimental/Scotchbond) based on the variables: temperature (23/37 °C) and light-curing unit (quartz-tungsten-halogen/light-emitting diode). The EP (%) was measured using differential scanning calorimetry, and analyzed using the t-test, two- and three-way analyses of variance (ANOVA), and the Bonferroni test (α = 0.05). There were significant differences between the EP results between the two BAs (P = 0.012) and due to the different temperatures (P = 0.001), but not between the different light-curing units (P = 0.548). The interaction between BA and temperature was significant (P light-curing units had similar effects on the EP. The EP values were better when curing was performed at human body temperature.

  6. EFFECT OF LIGHT CURING UNIT CHARACTERISTICS ON LIGHT INTENSITY OUTPUT, DEPTH OF CURE AND SURFACE MICRO-HARDNESS OF DENTAL RESIN COMPOSITE.

    Science.gov (United States)

    Kassim, B A; Kisumbi, B K; Lesan, W R; Gathece, L W

    2013-09-01

    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. To determine the characteristics of light curing units (LCUs) in dental clinics in Nairobi and their effect on light intensity output, depth of cure (DOC) and surface micro-hardness (SMH) of dental resin composite. Laboratory based, cross-sectional analytical study. Public and private dental clinics in Nairobi, Kenya. Eighty three LCUs which were in use in private and public dental health facilities in Nairobi, Kenya and resin composite specimens. Of the 83 LCUs studied, 43 (51.8%) were Light Emitting Diodes (LEDs) and 39(47.0%) were Quartz-Tungsten-Halogen (QTH) and 1 (1.2%) was Plasma Arc Curing (PAC) light. Mean light intensity for QTH and LED lights was 526.59 mW/cm2 and 493.67 mW/cm2 respectively (p=0.574), while the mean DOC for QTH lights was 1.71 mm and LED was 1.67 mm (p=0.690). Mean Vickers Hardness Number (VHN) for LED was 57.44 and for QTH was 44.14 (p=0.713). Mean light intensity for LCUs units > 5 years old (p=0.024). The mean DOC for the two age groups was 1.74 mm and 1.57 mm respectively (p=0.073). For SMH, the 5 years age groups gave a mean VHN of 58.81 and 51.46 respectively (p=0.1). On maintenance history, the frequency of routine inspection, duration since the last repair/replacement of a part or other maintenance activity and the nature of the last maintenance activity were determined and were not found to have influenced the light intensity, DOC and SMH. The LCU age has a statistically significant influence on its light intensity (p=0.024) while the type and maintenance history have no significant influence on its light intensity and composite DOC and SMH (p=0.574, p=0.690, p=0.713 respectively).

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

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    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.

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

    Science.gov (United States)

    Lima, Adriano Fonseca; Formaggio, Stephanie Ellen Ferreira; Zambelli, Lígia França Aires; Palialol, Alan Rodrigo Muniz; Marchi, Giselle Maria; Saraceni, Cintia Helena Coury; de Oliveira, Marcelo Tavares

    2016-11-01

    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. 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/cm 2 ) 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. 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. 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.

  9. Kinetics of pulpal temperature rise during light curing of 6 bonding agents from different generations, using light emitting diode and quartz-tungsten-halogen units: An in-vitro simulation

    Science.gov (United States)

    Khaksaran, Najmeh Khatoon; Kashi, Tahereh Jafarzadeh; Rakhshan, Vahid; Zeynolabedin, Zahra Sadat; Bagheri, Hossein

    2015-01-01

    Background: Application of bonding agents (BA) into deep cavities and light curing them might increase pulpal temperature and threaten its health. The purpose of this study was to evaluate temperature rise of pulp by light curing six BA using two different light curing units (LCU), through a dent in wall of 0.5 mm. Materials and Methods: This in vitro experiment was carried out on 96 slices of the same number of human third molars (6 BAs × 2 LCUs × 8 specimens in each group). There were 6 groups of BAs: N Bond, G-Bond, OptiBond XTR, Clearfil SE, Adper Single Bond 2 and V Bond. Each group of BA (n = 16) had two subgroups of light emitting diode (LED) and quartz-tungsten-halogen light cure units (n = 8). Each of these 16 specimens were subjected to light emitting for 20 s, once without any BAs (control) and later when a BA was applied to surface of disk. Temperature rises in 140 s were evaluated. Their mean temperature change in first 20 s were calculated and analyzed using two-way repeated-measures and one-way analysis of variance (ANOVA) and Tukey (α = 0.05). Furthermore rate of temperature increase was calculated for each material and LCU. Results: Minimum and maximum temperature rises in all subgroups were 1.7 and 2.8°C, respectively. Repeated measures ANOVA showed that both of adhesive and LCU types had significant effect on temperature rise after application of adhesives. Tukey post-hoc analysis showed Clearfil SE showed significantly higher temperature rise in comparison with Adper Single bond 2 (P = 0.047) and N Bond (P = 0.038). Temperature rose in a linear fashion during first 30-40 s and after that it was non-linear. Conclusion: 20 s of light curing seems safe for pulpal health (with critical threshold of 5.5°C). However, in longer durations and especially when using LED units, the process should be broken to two sessions. PMID:25878684

  10. Impact of Material Shade and Distance from Light Curing Unit Tip on the Depth of Polymerization of Composites.

    Science.gov (United States)

    Faria-E-Silva, André L; Fanger, Christopher; Nguyen, Lillian; Howerton, Demetri; Pfeifer, Carmem S

    2017-01-01

    This study aimed to evaluate the effect of the composite shade and distance from the light-curing unit (LCU) tip on the irradiance reaching the bottom of composite disks and on the depth of polymerization. Composites of three shades (opaque - OXDC, bleach - BXL, and A2) were inserted into molds with 3-mm of thickness positioned over a spectrometer and photo-activated with the LCU (Bluephase) tip placed at 0 or 1 cm from the composite surface. The mean irradiance reaching the bottom of composite was recorded during the entire photo-activation (30 s). Specimens (2 x 2 x 4 mm) were polymerized and used to map the degree of conversion achieved in different depths from irradiated surface. Specimens were sectioned into slices that were positioned over the platform of the infra-red microscope connected to the spectrometer to map the conversion. The conversion was measured in eight different depths every 500-µm. Increasing the distance of LCU tip reduced the irradiance only for A2. Interposing OXDC disks resulted in lowest values of irradiance and A2 the highest one. A tendency to decrease the conversion was observed towards the bottom of specimens for all experimental conditions, and the slope was more accentuated for OXDC. Differences among shades and distances from LCU tip were evident only beyond 1.5-2.0 mm of depth. In conclusion, both composite shade and distance from LCU tip might affect the light-transmission and depth of polymerization, while the effect of last was more pronounced.

  11. 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.

  12. Effect of thickness of indirect restoration and distance from the light-curing unit tip on the hardness of a dual-cured resin cement.

    Science.gov (United States)

    de Paula, Andréia Bolzan; Tango, Rubens Nisie; Sinhoreti, Mário Alexandre Coelho; Alves, Marcelo Corrêa; Puppin-Rontani, Regina M

    2010-01-01

    This study evaluated the Knoop hardness and polymerization depth of a dual-cured resin cement, light-activated at different distances through different thicknesses of composite resin. One bovine incisor was embedded in resin and its buccal surface was flattened. Dentin was covered with PVC film where a mold (0.8-mm-thick and 5 mm diameter) was filled with cement and covered with another PVC film. Light curing (40 s) was carried out through resin discs (2, 3, 4 or 5 mm) with a halogen light positioned 0, 1, 2 or 3 mm from the resin surface. After storage, specimens were sectioned for hardness measurements (top, center, and bottom). Data were subjected to split-plot ANOVA and Tukey's test (alpha=0.05). The increase in resin disc thickness decreased cement hardness. The increase in the distance of the light-curing tip decreased hardness at the top region. Specimens showed the lowest hardness values at the bottom, and the highest at the center. Resin cement hardness was influenced by the thickness of the indirect restoration and by the distance between the light-curing unit tip and the resin cement surface.

  13. Effects of radiant exposure values using second and third generation light curing units on the degree of conversion of a lucirin-based resin composite

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    Kelly Antonieta Oliveira Rodrigues de Faria CARDOSO

    Full Text Available Abstract Alternative photoinitiators with different absorption wavelengths have been used in resin composites (RCs, so it is crucial to evaluate the effectiveness of light-curing units (LCUs on these products. Objective 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. Material and Methods 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. Results 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. Conclusions 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

  14. The effects of Exposure Times and Light Curing Sources on Surface Micro-Hardness of a Resin Modified Glass Ionomer

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    Iman Parisay

    2014-06-01

    Full Text Available Introduction: The aim of this study was to evaluate the influenceof different light curing systems and curing times on the micro-hardness of aresin modified glass ionomer. Methods: Forty two samples of ResinModified Glass Ionomer (RMGI were prepared using stainless steel cylindrical mold(8 × 2 mm and randomly divided into six groups of seven. Three groups werecured with a Quartz Tungsten Halogen (QTH light cure unit and the other threegroups were polymerized with LED unit for 20, 30 and 40 seconds. All sampleswere stored in distilled water for 24 hours. The micro-hardness was measured onthe top and bottom surfaces of the samples by Vickers hardness tester. Datawere analyzed by two–way ANOVA and Tukey’s post-hoc tests. Results: Two-wayANOVA showed that QTH light-cure unit had higher percentage in depth of curethan LED light-curing unit in both surfaces; whereas, the application time hasno significant effect on it. There was no interaction between two variables. Inboth light-curing groups, the values of top and bottom surfaces micro-hardnesswere increased as the application time increased, but there was not anystatistically significant difference among these groups except for 40-second groupof LED light-curing unit which was significantly higher than 20-second and30-second groups (P

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

    Science.gov (United States)

    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

  16. Effect of energy density on low-shrinkage composite resins: diode-pumped solid state laser versus quartz-tungsten-halogen light-curing unit.

    Science.gov (United States)

    Heo, Young-Joon; Lee, Geun-Ho; Park, Jeong-Kil; Ro, Jung-Hoon; García-Godoy, Franklin; Kim, Hyung-Il; Kwon, Yong Hoon

    2013-01-01

    The purpose of the present study was to evaluate the effect of energy density on the polymerization of low-shrinkage composite resins. The number of photons needs to initiate the polymerization process can be controlled by light intensity and curing time through the form of energy density. For the study, two methacrylate-based (Premise [PR] and Venus Diamond [VE]) and one silorane-based (Filtek LS [LS]) composite resins were light cured using a quartz-tungsten-halogen (QTH) light-curing unit (LCU) and a 473 nm diode-pumped solid state (DPSS) laser. Degree of conversion (DC), microhardness, refractive index, and polymerization shrinkage were evaluated under different energy densities. Through the study, the feasibility of DPSS laser as a light source was tested as well. LS showed the highest DC and refractive index both on the top and bottom surfaces, and the least polymerization shrinkage among the tested specimens. For the same or similar energy density, QTH and DPSS showed insignificant DC difference (p>0.05). On the other hand, for microhardness, except for one case at the bottom surface, QTH and DPSS showed significant difference (punit.

  17. Surface energy and wettability of polymers light-cured by two different systems.

    Science.gov (United States)

    Namen, Fatima Maria; Ferrandini, Eduardo; Galan Junior, João

    2011-10-01

    This study evaluated the surface energy and wettability of composite resins polymerized by different light-curing units to ascertain the good wetting of tooth surfaces to achieve adhesion. Filtek Z350 (3M ESPE), Admira (VOCO) and Grandio (VOCO) resins were selected for the testing procedures. The resins were light cured using LED and Halogen devices. Contact angles were measured goniometrically (Ramé-Hart F100) using water and glycerol as test liquids. Surface energy values were calculated with a software program (DROPimage Standard) that uses the harmonic mean method applied to the acid-base theory. The data were analyzed statistically by ANOVA and Tukey's test with a significance of 0.05. No statistically significant differences were found between the values of surface energy. The measured wettability differed statistically in most combinations as a function of the type of composite resin, type of light-curing unit, and the test liquid.

  18. The effect of interincisal opening, cavity location and operator experience on the energy delivered by a light-curing unit to a simulated dental restoration.

    Science.gov (United States)

    Harun, Nor Asilah; Santini, Ario; Roebuck, Elizabeth M

    2014-05-01

    Curing of resin-based composites depends on the delivery of adequate total energy, which may be operator dependent. Aim To determine the effect of interincisal opening, cavity location and operator experience on the total energy delivered to simulated cavity preparation sites. Three cohorts were included: junior dental nurses, senior dental nurses and qualified dentists (N=5, each cohort). Each operator (participant) followed the same procedure and light-cured two simulated restorations in a MARC patient simulator using a Demi light-curing unit for 20 seconds in each of the following situations: left upper second molar (UL7), interincisal opening at both 25 mm and 45 mm; upper central incisor (UR1), interincisal opening at 45mm. The light energy delivered by each operator in each situation was recorded. Five readings for each operator were taken at each interincisal distance. Statistical comparisons of delivered energy (J/cm2) between interincisal openings, location and groups in the total energy delivered were performed using the Kruskal-Wallis nonparametric test: alpha = 0.05. Less total energy was delivered to the posterior cavity at 25mm (12.0 +/- 5.3 J/cm2) than at 45mm (16.9 +/- 5.6 J/cm2) by all operators (P 0.05) but there was a significant difference in the total energy delivered between senior nurses (20.1 +/- 7.8 J/cm2) and junior nurses (17.5 +/- 7.6 J/cm2) and between senior nurses and qualified dentists (16.6 +/- 8.7 J/cm2) (P < 0.05). Interincisal mouth opening, location of the cavity and operator experience affected the total energy delivered to cavities in a simulated clinical environment.

  19. Degree of conversion of three fissure sealants cured by different light curing units using micro-Raman spectroscopy

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    Ario Santini

    2012-03-01

    Conclusion: Higher DC is achieved with the LED with less exposure time compared with the conventional QTH at top and bottom surfaces of the three fissure sealants, although a lower conversion may be expected in opaque materials.

  20. Vickers Hardness of Composite Resins Cured with LED and QTH Units

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    Alaghemand H

    2016-03-01

    Full Text Available Statement of Problem: One of the factors affecting the degree of polymerization of light-cured composites is the type of light-curing unit used. In addition, physicomechanical properties of the composite resins depend on the degree of conversion and polymerization. Objectives: Since the type of initiator in new composite resins is not explained by manufacturers, this study is an attempt to compare the depth of hardening, with two LED and QTH light-curing units. Materials and Methods: Fifteen samples prepared from Gradia Direct and Filtek Z250, both of which being universal, were cured with QTH (Astralis 7 and LED (Bluephase C8 light-curing units. All the samples were molded in polyester resin and cut from the middle by a disk. The hardness of the cut area was evaluated at 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5 and 4-mm depth intervals and also at the same interval as the width of the sample, with Vickers hardness machine, while the samples were placed in a darkroom. Data were statistically analyzed using one-way ANOVA, two-way ANOVA, t-test and post Hoc Tukey’s tests in SPSS, version 16. Results: Filtek Z250 was harder than Gradia Direct at all the depth with both light-curing units. The hardness of Filtek Z250 sample cured with Astralis 7 was higher than that cured with LED, but with Gradia Direct the LED unit resulted in higher hardness. Curing depth was not significantly different between the groups (p = 0.109. Conclusions: Vickers hardness number for both composites used in this study is in an acceptable range for clinical implications. The composites’ composition is important to be considered for selection of light unit. Based on the findings of the present study, LED did not present more curing depth compared with QTH.

  1. 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

  2. Evaluation of effect of different disposable infection control barriers on light intensity of light-curing unit and microhardness of composite - An in vitro study.

    Science.gov (United States)

    Khode, Rajiv Tarachand; Shenoi, Pratima Ramakrishna; Kubde, Rajesh R; Makade, Chetana S; Wadekar, Kanchan D; Khode, Priyanka Tarachand

    2017-01-01

    This study evaluated effect of infection control barriers on light intensity (LI) of light-curing unit (LCU) and microhardness of composite. Four different disposable barriers ( n = 30) were tested against the control. LI for each barrier was measured with Lux meter. One hundred and fifty Teflon molds were equally divided into five groups of thirty each. Composite was filled in bulk in these molds and cured without and with barrier. Microhardness was evaluated on top and bottom surface of composite specimen with microhardness testing machine and hardness ratio (HR) was derived. One-way analysis of variance, Tukey's honestly significant difference test, and paired t -test using SPSS version 18 software. All barriers had significantly reduced the baseline LI of LCU ( P glove pieces (LCGP) significantly reduced the microhardness of the composite ( P < 0.05). However, HR determined inadequate curing only with LCGP. Although entire tested barrier significantly reduced the LI; none, except LCGP markedly affected the degree of cure of the composite.

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

    Science.gov (United States)

    Peutzfeldt, Anne; Lussi, Adrian; Flury, Simon

    2016-01-01

    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/cm 2 ; HPM: 15.0 and 30.4 J/cm 2 ; XPM: 9.5, 19.3, and 29.7 J/cm 2 ) ( n = 17). Vickers hardness ( H V ) and indentation modulus ( E IT ) 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 H V and E IT significantly ( p ≤ 0.0001). Statistically significant correlations between radiant exposure and H V or E IT 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.

  4. 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.

  5. Dental light curing and its effects on color perception.

    Science.gov (United States)

    McCusker, Neil; Bailey, Clare; Robinson, Stephen; Patel, Naresh; Sandy, Jonathan R; Ireland, Anthony J

    2012-09-01

    Light curing has become increasingly popular for orthodontic bonding, partly as a result of improvements in light-curing unit technology and higher light intensities. The aim of this study was to determine orthodontists' knowledge of dental light-curing units, their safety aspects, and the possible effects on color perception. Questionnaires were administered to 120 specialists or trainees to assess their knowledge of light curing and safety issues. In addition, 15 orthodontists and 15 nonorthodontists were asked to complete the Farnsworth Munsell 100 hue test to assess color perception. One hundred four questionnaires were returned, giving a response rate of 86.6%. Light-emitting diode lights were the most popular (73.4%), followed by quartz-halogen (9.2%) and plasma lights (5.5%); 11.9% were unsure of the type of light used, 84% did not know the intensity, and 67% did not know the wavelength of the lights. Although most used safety equipment-eg, paddles-7% used no safety measures. Seventy-six percent were either unsure or took no precautions during light curing for staff or patients who had previous cataract surgery, and up to 99% were either unsure or took no precautions during light curing for staff or patients taking photosensitizing medications. With the Farnsworth Munsell test, 28 participants had average color discrimination, with 2 demonstrating superior discrimination. There were no differences between the orthodontists and the controls, or between men and women. Orthodontists' knowledge of dental light-curing units and hazards is poor. Although potential risks are associated with the long-term use of these light-curing units, no effect on color discrimination was detected. Copyright © 2012 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  6. Effect of light curing protocol on degree of conversion of composites.

    Science.gov (United States)

    Catelan, Anderson; Mainardi, Maria do Carmo Aguiar Jordão; Soares, Giulliana Panfiglio; de Lima, Adriano Fonseca; Ambrosano, Gláucia Maria Bovi; Lima, Débora Alves Nunes Leite; Marchi, Giselle Maria; Aguiar, Flávio Henrique Baggio

    2014-11-01

    To evaluate the degree of conversion (DC) of two light-cured composites with different protocols of light curing. One hundred and ninety two specimens (n = 8) were prepared (5 mm × 2 mm) according to experimental groups: two composite resins (Filtek Supreme and four seasons); three light curing protocols [20 s with the tip of the light curing unit (LCU) device touching composite surface (C); 20 s with the tip of the LCU at 8 mm distant from composite surface (D); and tip of the LCU at 8 mm distant from composite surface and polymerization time required to obtain a radiant exposure of 16 J/cm(2) (DS)]. Four LCUs (Bluephase 16i, Ultralume LED 5, XL 3000 and Optilux 501C) were used. DC of the bottom and top surface of specimens were measured using a FTIR spectrometer. Data were statistically analyzed by 3-way split splot ANOVA and Tukey's test (alpha = 0.05). The results showed that DC of the top surface was higher than the bottom at all experimental conditions (p curing at 8 mm of distance did not affect conversion rate on the top surface (p > 0.05), but bottom surfaces showed DC reduction (p curing units with higher light power and/or extended exposure time.

  7. Glass transition and degree of conversion of a light-cured orthodontic composite

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    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.

  8. Study of energy transfer by different light curing units into a class III restoration as a function of tilt angle and distance, using a MARC Patient Simulator (PS).

    Science.gov (United States)

    Konerding, Katharina L; Heyder, Markus; Kranz, Stefan; Guellmar, Andre; Voelpel, Andrea; Watts, David C; Jandt, Klaus D; Sigusch, Bernd W

    2016-05-01

    The MARC Patient Simulator (MARC PS) enables researchers to observe the influence of handling errors on the radiant exposure that is delivered by light curing units (LCUs). Changes in the tilt angle and distance of the light guide exit face in relation to the surface of the composite increment have a distinct effect on the total amount of light delivered during polymerization and may cause insufficient conversion of the material. Therefore, the aim of the present study was to determine the influence of the tilt angle and distance of irradiance on the efficiency of light application by recording the total amount of energy using the anterior tooth sensor of the MARC PS. The influence of the tilt angle and distance of the light guide to the sensor surface on the delivered radiant exposure was examined for three different LCUs (Celalux 2 [C2], Bluephase [BP] and Translux Powerblue [TPB]). The measurements were performed for 20 s each with five different tilt angles (α=0°, 5°, 10°, 15°, 20°) and nine different distances (L=1, 2, 3, 4, 5, 6, 7, 8, 9 mm). For all LCUs, a distinct influence of the tilt angle on the delivered amount of fluence was found. At 0° tilt the C2 delivered a total light energy of 38.55 J/cm(2). By increasing the tilt of the light guide the amount of energy applied significantly decreased. At 20° tilt a reduction by 31.2% of the original light fluence was recorded. However, the C2 was the most powerful LCU measured. Even under optimum measurement conditions, the BP delivered a fluence of only 14.8 J/cm(2). At a tilt angle of 20°, though, the light sensor still registered 92.7% of the original output power. Under the same conditions, the TPB delivered 81.4%. With increasing distance of the light guide exit face to the surface of the sensor all LCUs showed a significant loss in delivered light energy. At a distance of 2mm the C2 showed a reduction by 46.7%, whereas total fluence of BP and TPB were reduced by 3.8% and 4.8%, respectively. The

  9. Light curing in orthodontics; should we be concerned?

    Science.gov (United States)

    McCusker, Neil; Lee, Siu Man; Robinson, Stephen; Patel, Naresh; Sandy, Jonathan R; Ireland, Anthony J

    2013-06-01

    Light cured materials are increasingly used in orthodontic clinical practice and concurrent with developments in materials have been developments in light curing unit technology. In recent years the irradiances of these units have increased. The aim of this study was to determine the safe exposure times to both direct and reflected light. The weighted irradiance and safe exposure times of 11 dental curing lights (1 plasma arc, 2 halogen and 8 LED lights) were determined at 6 distances (2-60 cm) from the light guide tip using a spectroradiometer. In addition, using the single most powerful light, the same two parameters were determined for reflected light. This was done at a distance of 10 cm from the reflected light, but during simulated bonding of 8 different orthodontic brackets of three material types, namely stainless steel, ceramic and composite. The results indicate that the LED Fusion lamp had the highest weighted irradiance and the shortest safe exposure time. With this light the maximum safe exposure time without additional eye protection for the patient (at 10 cm), the operator (at 30 cm) and the assistant (at 60 cm) ranged from 2.5 min, 22.1 min and 88.8 min respectively. This indicates a relatively low short term risk during normal operation of dental curing lights. For reflected light at a distance of 10 cm the risk was even lower, but was affected by the material and shape of the orthodontic bracket under test. The short term risks associated with the use of dental curing lights, halogen, LED or plasma, appear to be low, particularly if as is the case adequate safety precautions are employed. The same is true for reflected light from orthodontic brackets during bonding. What is still unclear is the potential long term ocular effects of prolonged exposure to the blue light generated from dental curing lights. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  10. Influence of light curing and sample thickness on microhardness of a composite resin

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    Flávio HB Aguiar

    2009-05-01

    Full Text Available Flávio HB Aguiar1, Kelly RM Andrade1, Débora AN Leite Lima1, Gláucia MB Ambrosano2, José R Lovadino11Department of Restorative Dentistry; 2Department of Social Dentistry/Statistics, Piracicaba Dental School, State University of Campinas, SP, BrazilAbstract: The aim of this in vitro study was to evaluate the influence of light-curing units and different sample thicknesses on the microhardness of a composite resin. Composite resin specimens were randomly prepared and assigned to nine experimental groups (n = 5: considering three light-curing units (conventional quartz tungsten halogen [QTH]: 550 mW/cm2 – 20 s; high irradiance QTH: 1160 mW/cm2 – 10 s; and light-emitting diode [LED]: 360 mW/cm2 – 40 s and three sample thicknesses (0.5 mm, 1 mm, and 2 mm. All samples were polymerized with the light tip 8 mm away from the specimen. Knoop microhardness was then measured on the top and bottom surfaces of each sample. The top surfaces, with some exceptions, were almost similar; however, in relation to the bottom surfaces, statistical differences were found between curing units and thicknesses. In all experimental groups, the 0.5-mm-thick increments showed microhardness values statistically higher than those observed for 1- and -2-mm increments. The conventional and LED units showed higher hardness mean values and were statistically different from the high irradiance unit. In all experimental groups, microhardness mean values obtained for the top surface were higher than those observed for the bottom surface. In conclusion, higher levels of irradiance or thinner increments would help improve hybrid composite resin polymerization.Keywords: photo-polymerization, light-curing distance, light-curing units, composite resin, composite thickness, microhardness

  11. The applicability of DPSS laser for light curing of composite resins.

    Science.gov (United States)

    Kwon, Yong Hoon; Jang, Chang-Min; Shin, Dong-Hee; Seol, Hyo-Joung; Kim, Hyung-Il

    2008-10-01

    The applicability of diode-pumped solid state (DPSS) laser for light curing the composite resins was tested with a quartz-tungsten-halogen lamp-based unit and a light emitting diode unit. The emission spectra of the light-curing systems used match with the absorption spectrum of camphorquinone. Among the light-curing systems, DPSS laser showed the narrowest emission bandwidth. The light intensity of DPSS laser was approximately 64% of the other two light-curing units. In most specimens, DPSS laser showed the least attenuation of the number of incident photons. On the top surface, specimens cured with DPSS laser showed similar microhardness values compared to the specimens cured with the other two light-curing units. During the light curing, DPSS laser induced the lowest temperature rise (25.5-35.5 degrees C) in the specimens compared to the other two light-curing units (34.2-41.7 degrees C). In conclusion, DPSS laser has high potential to be an alternative to the other light-curing units or a new light-curing unit.

  12. How visible light curing came into dentistry.

    Science.gov (United States)

    Wilson, N H F

    2016-01-01

    The present paper details the history of the introduction of visible light curing into dentistry. This history provides an excellent example of 'out of the box', lateral thinking translation of innovative scientific technology into dentistry. Visible light curing is an important UK contribution to the recent history and current practice of dentistry, with several million visible light curing procedures being carried out globally on a daily basis.

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

    Science.gov (United States)

    Voltarelli, Fernanda Regina; dos Santos-Daroz, Claudia Batitucci; Alves, Marcelo Corrêa; Peris, Alessandra Rezende; Marchi, Giselle Maria

    2009-01-01

    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.

  14. 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.

  15. Surface energy and wettability of polymers light-cured by two different systems

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    Fatima Maria Namen

    2011-10-01

    Full Text Available OBJECTIVE: This study evaluated the surface energy and wettability of composite resins polymerized by different light-curing units to ascertain the good wetting of tooth surfaces to achieve adhesion. MATERIAL AND METHOD: Filtek Z350 (3M ESPE, Admira (VOCO and Grandio (VOCO resins were selected for the testing procedures. The resins were light cured using LED and Halogen devices. Contact angles were measured goniometrically (Ramé-Hart F100 using water and glycerol as test liquids. Surface energy values were calculated with a software program (DROPimage Standard that uses the harmonic mean method applied to the acid-base theory. The data were analyzed statistically by ANOVA and Tukey's test with a significance of 0.05. RESULTS AND CONCLUSIONS: No statistically significant differences were found between the values of surface energy. The measured wettability differed statistically in most combinations as a function of the type of composite resin, type of light-curing unit, and the test liquid.

  16. Effect of different blue light-curing systems on the polymerization of nanocomposite resins.

    Science.gov (United States)

    Jang, Chang-Min; Seol, Hyo-Joung; Kim, Hyung-Ii; Kwon, Yong Hoon

    2009-12-01

    To examine the degree of polymerization of nanocomposite resins to test the possibility of using a diode-pumped solid state (DPSS) laser as a light-curing source on behalf of the argon laser. DPSS lasers emitting light at 473 nm have many advantages over argon lasers on account of their compactness, efficiency, and price. A 473-nm DPSS laser (LAS) was used with three other light-curing units (a quartz-tungsten-halogen lamp-based unit, a light emitting diode-based unit, and a xenon lamp-based plasma arc unit) to polymerize dental nanocomposite resins. The degree of polymerization was determined by measuring the microhardness, maximum polymerization shrinkage, and increase in temperature during and after light curing. The results were analyzed statistically. The specimens light cured with LAS showed a microhardness that was similar or superior to the values obtained from the specimens cured with the other light-curing units and maximum polymerization shrinkage values. The maximum increase in temperature by LAS was much lower than that induced by the other light-curing units. LAS effectively polymerizes dental nanocomposite resins to an extent similar to that of recently available light-curing units. The results suggest that LAS has good potential as a light source for light curing of dental nanocomposite resins.

  17. The effects of halogen and light-emitting diode light curing on the depth of cure and surface microhardness of composite resins

    Science.gov (United States)

    Yaman, Batu Can; Efes, Begüm Güray; Dörter, Can; Gömeç, Yavuz; Erdilek, Dina; Büyükgökçesu, Sami

    2011-01-01

    Aim: Light-emitting diode light curing units (LED LCUs) have become more popular than halogen LCUs in routine dental restorative treatment. The aim of the study was to compare the effects of two conventional halogen (Hilux Plus and VIP) and two LED (Elipar FreeLight 2 and Smart Lite) light curing units on the depth of cure and the microhardness of various esthetic restorative materials. Materials and Methods: The curing depth and microhardness of a compomer (Dyract Extra), a resin-modified glass ionomer (Vitremer), a packable composite (Sculpt It), an ormocer (Admira), a hybrid composite (Tetric Ceram), two microhybrid composites (Miris and Clearfil Photo Posterior) and, a nanofil composite (Filtek Supreme) were determined using a scraping method and a hardness tester. A total of 320 samples were prepared using the eight different materials (n = 10 samples for each subgroup). The scraping test was based on ISO 4049:2000. Vicker's microhardness testing was carried out using hardness tester (Zwick 3212). Data were analyzed using one-way analysis of variance (ANOVA), Bonferroni and the Kolmogorov–Smirnov tests. Results: Best microhardness results were obtained with the LED light curing units and Tetric EvoCeram and Filtek Supreme achieved the highest hardness values. The nanofil composite, Filtek Supreme, showed the best curing depth results in all the tested light curing systems. Conclusions: The LEDs were found to be more successful than the halogen units with respect to both curing depth and microhardness properties. PMID:21814353

  18. Effect of Dental Chair Light on Enamel Bonding of Orthodontic Brackets Using Light Cure Based Adhesive System: An In-Vitro Study.

    Science.gov (United States)

    Tiwari, Anil; Shyagali, Tarulatha; Kohli, Sarvraj; Joshi, Rishi; Gupta, Abhishek; Tiwari, Rana

    2016-10-01

    The aim of this in vitro study was to evaluate the influence of the Dental chair light on the bond strength of light cured composite resin. Sixty therapeutically extracted human premolar teeth were randomly allocated to two groups of 30 specimens each. In both groups light cured composite resin (Transbond XT) and MBT premolar metal brackets (3M Unitek) was used to bond brackets. In group I and II light curing was done using Light-emitting diode light curing units without and with the dental chair light respectively. After bonding, all samples were stored in distilled water at room temperature for 24 hours and subsequently tested for shear bond strength and Adhesive Remnant Index (ARI) scores. Data was subjected to Mann Whitney U statistical test. Results indicated that there was significantly higher shear bond strength (7.71 ± 1.90) for the Group II (composite cured with LED and dental chair light) compared with Group I (composite cured with LED LCU only) (5.74 ± 1.13).the obtained difference was statistically significant. There was no statistical significant difference between ARI scores in between the groups. light cure bonding with dental chair light switched on will produce greater bond strength than the conventional bonding. However, the ARI score were similar to both the groups. It is advised that the inexperienced orthodontist should always switch off the dental chair light while bonding for enough working time during the bracket placement.

  19. 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.

  20. 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.

  1. 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 (Pcured with the dual-wave 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 (Plight energy 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.

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

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    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.

  3. 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.

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

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    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.

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

    Science.gov (United States)

    Chang, Hoon-Sang; Cho, Kyu-Jeong; Park, Su-Jung; Lee, Bin-Na; Hwang, Yun-Chan; Oh, Won-Mann; Hwang, In-Nam

    2013-01-01

    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. 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. 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. 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.

  6. 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.

  7. Light-curing efficiency of dental adhesives by gallium nitride violet-laser diode determined in terms of ultimate micro-tensile strength.

    Science.gov (United States)

    Kameyama, Atsushi; Kato, Junji; De Munck, Jan; Hatayama, Hitoshi; Haruyama, Akiko; Yoshinari, Masao; Takase, Yasuaki; Van Meerbeek, Bart; Tsunoda, Masatake

    2011-01-01

    The purpose of this study was to evaluate whether violet-laser diode (VLD) can be used as light-curing source. The ultimate (micro-)tensile strength (μTS) of three adhesives was determined when cured by VLD in comparison with curing by two different types of commercial LED light-curing units. One VLD (VLM 500) and two LED units (Curenos and G-Light Prima) were used to cure the adhesive resin of the two-step self-etch adhesives Clearfil SE Bond, Tokuso Mac Bond II, and FL-Bond II. A 0.6-mm thick acrylic mould was filled with adhesive resin and cured for 60 s. After 24-h water storage, specimens were trimmed into an hourglass shape with a width of 1.2 mm at the narrowest part, after which the μTS was determined (n=10). In addition, the light transmittance of each adhesive was characterized using a UV-vis-NIR spectrometer. No significant difference in curing efficiency between VLD and LED were observed for both Tokuso Mac Bond II and FL-Bond II (p>0.05). For Clearfil SE Bond, the μTS of VLD-cured specimens was higher than that of the specimens cured by the LED Curenos unit (plight transmittance of Clearfil SE Bond for visible blue light versus for the lower area of UV and visible violet light. In conclusion, A GaN-based violet laser diode can be used as light-curing source to initiate polymerization of dental resins.

  8. Effect of light curing sources on microhardness of different composite resins

    Science.gov (United States)

    Valentino, T. A.; Calabrez-Filho, S.; de Menezes, F. C. H.; Cavalcante, L. M. A.; Pimenta, L. A. F.; de Andrade, M. F.; Dantas, A. A. R.; Rastelli, A. N. S.

    2011-06-01

    This study evaluated the influence of light-curing units (LCUs) on Knoop microhardness (KHN) of different composite resins formulations. Four LCUs, one Quartz-Tungsten-Halogen (QTH) for 20 s, one Argon-Ion-Laser (AL) for 10 s, one Plasma-Arc-Curing (PAC) for 9 s, and one Light-Emitting-Diode (LED) for 20 s, and three composite resins, nanofill and easy cure (Filtek™ Supreme), microhybrid and medium cure (Herculite XRV), and microfill and difficult cure (Heliomolar) were used. Discs (4 × 2 mm2) of each composite resin were divided in 12 Groups and KHN was measured at the top (T) and bottom (B) surfaces. Data were analyzed using two-way ANOVA and Tukey's test ( p < 0.05). Top presented significantly higher KHN than bottom surface for all composite resins and LCUs tested. Statistical significant differences were observed among the LCUs. At the bottom surface QTH and LED presented higher KHN than PAC and LA. However, at the top surface PAC and LA presented similar results than QTH for nanofill and microhybrid composite resins. Different LCUs play an important effect on Knoop microhardness and the composite resin formulations were significant factor on the photosensitivity.

  9. Temperature changes caused by light curing of fiber-reinforced composite resins

    Science.gov (United States)

    Ilday, Nurcan Ozakar; Sagsoz, Omer; Karatas, Ozcan; Bayindir, Yusuf Ziya; Çelik, Neslihan

    2015-01-01

    Objective: The aim of the study is to evaluate temperature change in fiber-reinforced composite (FRC) resin photopolymerized with a light-emitting diode (LED) light-curing unit (LCU). Materials and Methods: Forty dentine disks (1 mm thick and 8 mm diameter) were prepared from human molars. The FRC specimens (2 mm thickness and 8 mm diameter) consisted of polyethylene fiber (Construct (CT)) products or glass fiber (ever Stick (ES)) and one hybrid composite bonded to the dentin disks and polymerized with an LED LCU. Control groups were prepared using the hybrid composite. Temperature rise in dentine samples under the FRC bonded disks was measured using a K-type thermocouple, and data were recorded. Temperature change data were subjected to analysis of variance (ANOVA) and Duncan's test. Results: The results show that addition of fiber (one or two layers) did not change temperature rise values at any of the exposure times (P > 0.05). The CT fiber/two layer/40 s group exhibited the greatest temperature rise (5.49 ± 0.62) and the ES/one layer/10 s group the lowest rise (1.75 ± 0.32). A significant difference was observed in temperature rise measured during 10 and 20 s exposures (P < 0.05). Conclusion: Maximal temperature rise determined in all groups was not critical for pulpal health, although clinicians need to note temperature rises during polymerization. PMID:26069409

  10. Light-curing considerations for resin-based composite materials: a review. Part II.

    Science.gov (United States)

    Malhotra, Neeraj; Mala, Kundabala

    2010-10-01

    As discussed in Part I, the type of curing light and curing mode impact the polymerization kinetics of resin-based composite (RBC) materials. Major changes in light-curing units and curing modes have occurred. The type of curing light and mode employed affects the polymerization shrinkage and associated stresses, microhardness, depth of cure, degree of conversion, and color change of RBCs. These factors also may influence the microleakage in an RBC restoration. Apart from the type of unit and mode used, the polymerization of RBCs is also affected by how a light-curing unit is used and handled, as well as the aspects associated with RBCs and the environment. Part II discusses the various clinical issues that should be considered while curing RBC restorations in order to achieve the best possible outcome.

  11. The effect of light-cured nanofilled composite resin shades on their under-surface temperature

    Science.gov (United States)

    Hanum, U. A.; Herda, E.; Indrani, D. J.

    2017-08-01

    The objective of this study was to observe the effect of shades of light-cured nanofilled composite resins on their under-surface temperature. Resin composites specimens of shades bright, medium, and dark shade were obtained from a cylindrical mold. While polymerizing using a curing unit, the under-surface temperature was determined at the bottom of the specimens using a thermocouple wire 20 sec after the start. Results showed that the under-surface temperature of the darker shade specimens were relatively higher that those of the brighter shades with significant diffferences between the resin composites of different shades. To conlude, the under-surface temperature of the light-cured nanofilled resin composites raised from the brighter to the darker shades.

  12. 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.

  13. ANALYSIS OF GAP FORMATION AT TOOTH-COMPOSITE RESIN INTERFACE: EFFECT OF C-FACTOR AND LIGHT-CURING PROTOCOL

    Science.gov (United States)

    dos Santos, Gustavo Oliveira; da Silva, Antônio Henrique Monteiro da Fonseca Thomé; Guimarães, José Guilherme Antunes; Barcellos, Alexandre de Araújo Lima; Sampaio, Eduardo Martins; da Silva, Eduardo Moreira

    2007-01-01

    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 (α=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. PMID:19089143

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

    Directory of Open Access Journals (Sweden)

    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.

  15. Hardness Evaluation of Composite Resins Cured with QTH and LED

    Directory of Open Access Journals (Sweden)

    Behnaz Esmaeili

    2014-03-01

    Full Text Available Background and aims. Today light cured composites are widely used. Physical and mechanical properties of composites are related to the degree of conversion. Light curing unit (LCU is an important factor for composite polymerization. Aim of this study is evaluation of composite resins hardness using halogen and LED light curing units. Materials and methods. In this study, 30 samples of Filtek Z250 and C-Fill composite resins were provided. Samples were light cured with Ultralume2, Valo and Astralis7. Vickers hardness number (VHN was measured in 0, 1, 2 mm depth. Statistical analysis used: Data were analysed by SPSS software and compared with each other by T-test, one-way and twoway ANOVA and Post-hoc Tukey test. Results. In Filtek Z250, at top surface, VHN of Ultralume2 was higher than VHN of Valo (P = 0.02 and Astralis7 (P = 0.04, but in depth of 1, 2 mm, VHN of Ultralume2 and Astralis7 were almost the same and both LCUs were more than Valo which the difference between Ultralume2 and Valo was significant in depth of 1mm (0.05 and 2mm (0.02. In C-Fill composite, at top surface, Astralis7 showed higher VHN, but in depth of 2 mm, performance of all devices were rather similar. Conclusion. In Z250, which contains camphorquinone initiator, light cure LED Ultra-lume2 with narrow wavelength showed higher hardness number than Valo. In C-fill, in top surface, Astralis7 with more exposure time, resulted higher VHN. But In depth of 2 mm, various light curing devices had rather similar hardness number.

  16. Curing performance of a new-generation light-emitting diode dental curing unit.

    Science.gov (United States)

    Wiggins, Kim M; Hartung, Martin; Althoff, Olaf; Wastian, Christine; Mitra, Sumita B

    2004-10-01

    BACKGROUND; Recent technological advances have resulted in the marketing of high-powered, or HP, battery-operated light-emitting diode, or LED, dental curing lights. The authors examine the curing efficiency and peak polymerization temperature, or Tp, of a new HP LED curing light. The authors studied four visible light-curing, or VLC, units: HP LED (A), first-generation LED (B), conventional halogen (C) and high-intensity halogen (D). They determined the depth of cure, or DOC; adhesion; and Tp of three types of VLC resin-based composites after exposure to each light. The exposure times for units A and D were one-half those for units B and C. The power density of unit A was 1,000 milliwatts per square centimeter, which was comparable to that of unit D with turbo charge. The DOC and adhesion attained for all three resin-based composites after being light cured by unit A for a 10-second exposure time were equivalent to those after being light cured by unit D for a 10-second exposure time and to those after being light cured by units B and C for 20-second exposure times. The resin-based composites light cured by unit A attained significantly lower Tps than did those light cured by unit D at equivalent cure, or exposure, times and by unit C at twice the cure time. The authors found that Unit A effectively cured the resin-based composites at one-half the cure time of units B and C and at the same time as unit D, while maintaining low Tp. The battery-operated HP LED curing light might be an effective, time-saving alternative for clinicians to use in light curing resin-based composites.

  17. [The development of light-curing soft denture liner].

    Science.gov (United States)

    Zhao, X; Shi, C

    1997-07-01

    In this study, a visible light-curing soft denture liner was developed, and 6 methacrylate polyurethane elastomer and a diluent were synthesised, their effect on tensile strength, compression set, Shore A hardness, absorption and solubility were also investigated. The results showed that the elastomer made of polyethylene adipate or polybutylene ether glycol possessed the highest tensile strength and hardness, the elastomer made of polypropylene ether glycol showed low tensile strength and low shore A hardness, the elastomer made of hydroxyl-terminated liquid polybutadiene rubber had a moderate tensile strength and hardness.

  18. Influence of prolonged light-curing time on the shear bonding strength of resin to bleached enamel.

    Science.gov (United States)

    Hussain, Manal; Wang, Yining

    2010-01-01

    This study evaluated the effect of prolonged light-curing time using a light-emitting diode unit (LED) on the shear bond strength of a resin composite to enamel immediately after bleaching. The enamel surfaces of human molars were divided into four groups: one control and three bleaching groups. One bleaching group (CP) was exposed to a 10% carbamide peroxide bleaching agent and bonded after 24 hours. The other two bleaching groups (HP) were bleached with a 38% hydrogen peroxide bleaching agent, then bonded either within one hour (HPA) or after 24 hours (HPB). All groups were subdivided into two subgroups and cured for two different times (20 or 40 seconds) with an LED unit. Shear bond strength (SBS) was tested with a universal-testing machine and the data were analyzed by ANOVA and post-hoc tests. Scanning electron micrographs of representative specimens were taken. A significant difference was seen between the control and HPA groups for both curing times (p = 0.000). However, neither the CP nor HPB groups showed any significant differences compared with the control groups (p > 0.05). Two-way ANOVA showed that a significant effect of the curing time factor was recorded for all groups (p = 0.000). Prolonged curing time, using an LED unit with a light intensity of 500 mW/cm2, increased resin-enamel bonding strengths for the control and bleached groups when bonding was performed after 24 hours of immersion in deionized water. However, the SBS was still compromised when bonding was performed immediately to enamel bleached with 38% HP.

  19. Photothermal radiometry monitoring of light curing in resins

    Science.gov (United States)

    Zambrano-Arjona, M. A.; Medina-Esquivel, R.; Alvarado-Gil, J. J.

    2007-10-01

    Real time measurement of thermal diffusivity during the evolution of the light curing process in dental resins is reported using photothermal radiometry. The curing is induced by a non-modulated blue light beam, and at the same time, a modulated red laser beam is sent onto the sample, generating a train of thermal waves that produce modulated infrared radiation. The monitoring of this radiation permits to follow the time evolution of the process. The methodology is applied to two different commercially available light curing resin-based composites. In all cases thermal diffusivity follows a first order kinetics with similar stabilization characteristic times. Analysis of this kinetics permits to exhibit the close relationship of increase in thermal diffusivity with the decrease in monomer concentration and extension of the polymerization in the resin, induced by the curing light. It is also shown that the configuration in which the resin is illuminated by the modulated laser can be the basis for the development of an in situ technique for the determination of the degree of curing.

  20. 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

  1. Biaxial flexural strength of high-viscosity glass-ionomer cements heat-cured with an LED lamp during setting

    NARCIS (Netherlands)

    Molina, G. Fabian; Cabral, R.J.; Mazzola, I.; Lascano, L. Brain; Frencken, J.E.F.M.

    2013-01-01

    Adding heat to glass ionomers during setting might improve mechanical properties. The aim was to compare the biaxial flexural strength (BFS) between and within four glass ionomers, by time of exposure to a high-intensity LED light-curing unit. Materials and methods. Samples of Fuji 9 Gold Label,

  2. Pharmacist-led medication review in an acute admissions unit

    DEFF Research Database (Denmark)

    Hansen, Trine Graabæk; Bonnerup, Dorthe Krogsgaard; Kjeldsen, Lene Juel

    2015-01-01

    of principles and methodologies, and the practical procedure is seldom described in detail, which makes reproducing study findings difficult. The objective of this paper is to provide a detailed description of a procedure developed and used for pharmacist-led medication review in acute admissions units......) collection of information about the patient's medical treatment, (3) patient interview, (4) critical examination of the patient's medications and (5) recommendations for the hospital physician.Conclusions We have provided a detailed description of a procedure for pharmacist-led medication review. We do so...

  3. Effect of different light-curing modes on degree of conversion, staining susceptibility and stain's retention using different beverages in a nanofilled composite resin.

    Science.gov (United States)

    Aguiar, Flávio Henrique Baggio; Georgetto, Matheus Henrique; Soares, Giulliana Panfiglio; Catelan, Anderson; Dos Santos, Paulo Henrique; Ambrosano, Glaucia Maria Bovi; Figueroba, Sidney Raimundo; Lovadino, José Roberto

    2011-04-01

    It is unknown whether the staining pigment concentration would affect the color of composite resin and whether the absorption of the staining pigment is related to the degree of conversion (DC). The purpose of this study was to evaluate the effect of light-curing units (LCUs) on DC, superficial staining (ΔE), and pigment concentration (PC) in a nanofilled composite resin (Z350, 3M ESPE) using different beverages. Specimens were polymerized for 20 seconds using four LCUs (N=50): quartz-tungsten-halogen (QTH)--450 mW/cm(2); laser (LAS)--300 mW/cm(2); second-generation light-emitting diode (LED)-1100 mW/cm(2); and third generation LED--700 mW/cm(2). DC (%) was measured using Fourier transform infrared spectroscopy. Specimens concerning each group (N=10) were then immersed in one of the solutions (distilled water, red wine, whisky, coffee, and cola--40 min/day, for 40 days). Specimen's color was measured before and after exposure to solutions using a colorimeter (Commission Internacionale de I'Eclairaga L*a*b* color scale), and ΔE was calculated. Specimens were then prepared for the spectrophotometric analysis to measure PC. Data were submitted to two-way analysis of variance and Tukey's test (p=0.05). DC: QTH presented the lowest DC, with statistical differences for LAS, LED 2, and LED 3. Whisky and wine showed lower PC mean values than cola and coffee. No statistical difference was observed for LCUs regarding PC and all staining solutions, except cola. Whisky showed the highest values for ΔE regarding all LCUs. Wine showed statistically lower ΔE than whisky, with water presenting the lowest ΔE. LAS and QTH showed higher values than LED 2 concerning ΔE.   LCUs interfered with DC and altered the PC and ΔE of the composite resin submitted to different staining solutions. There was no correlation among DC, PC, and ΔE. Light-curing modes might interfere with staining susceptibility, stain's retention, and DC of a composite resin, compromising the clinical

  4. 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

  5. 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 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.

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

    Science.gov (United States)

    Cekic-Nagas, Isil; Ergun, Gulfem

    2011-08-01

    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. 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. Resin cement and light-curing unit had significant effects (p0.05) were obtained with different modes of LCUs. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  8. Effect of light curing methods on microleakage and microhardness of different resin sealants.

    Science.gov (United States)

    Duangthip, Duangporn; Ballungpattama, Suda; Sitthisettapong, Thanya

    2011-07-01

    This study's purpose was to evaluate the effect of light curing methods on the microleakage and microhardness of sealants. The Elipar Free Light 2 light emitting diode (LED) with 10- and 20-second curing times, and the Elipar 2500 halogen light with a 20-second curing time were compared. Four different sealants were used: (1) Delton Clear; (2) Delton Opaque; (3) UltraSeal XT Clear; and (4) UltraSeal XT Opaque. Specimens were fabricated in a silicone mold (2-mm thick) and cured. Knoop hardness was measured at the bottom and top surfaces. For the microleakage evaluation, 120 human molars were divided into 12 groups and sealed with the sealants and curing methods, as stated previously. The teeth were thermocycled and immersed in 2% methylene blue for 24 hours. Each tooth was sectioned and examined for dye penetration. There were no statistically significant differences in the microleakage of sealants polymerized by either the halogen or LED curing methods. The microhardness of sealants varied according to the type of material and curing method. A 10-second polymerization time with light emitting diodes was not sufficient to cure the 2-mm-thick opaque or high filler loaded sealants. Decreasing the curing time, however, had no effect on the microleakage of the sealants.

  9. 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

  10. [Improvement of light-cured indirect inlays durability by means of electromagnetic field].

    Science.gov (United States)

    Nidzel'skiĭ, M Ia; Korotetskaia-Zinkevich, V L

    2014-01-01

    The main strength characteristics of light-cured resins used for replacement of dental hard tissues defects are destructive stress by compression, microhardness, resistance to abrasion, impact and water absorption. The study focuses on some strength features of composite materials for inlays processed by electromagnetic field. Four sample series of light cured resin (Charisma, Heraus Kulzer, Germany) were used to assess strength features changes in various curing methods: 10 control samples were polymerized by conventional light-curing device, while 30 were additionally processed by electromagnetic field of various intensity (60, 80 and 100 Oe, 10 samples for each group). The obtained results confirm the positive effects of electromagnetic field on strength features of light-cured resins which improves the quality of inlays.

  11. Comparative evaluation of sealing ability of light cure glass ionomer cement and light cure composite as coronal sealing material: An in vitro study

    Directory of Open Access Journals (Sweden)

    Pragya Jaiswal

    2017-01-01

    Full Text Available Aim: To compare and evaluate the sealing ability of light cure composite and light cure GIC as coronal sealing materials. Materials and Methods: 30 extracted human teeth were divided into three experimental groups of 10 teeth each. The teeth in group I are obturated without coronal seal, teeth in group II are obturated with light cure GIC (3M ESPE VITREMER as coronal seal and teeth in group III are obturated with light cure composite(3M ESPE filtek z250 as coronal seal, after removing 2mm of coronal gutta percha. These teeth (crown portion are then suspended in methylene blue, sealed and kept for 72 hours, to observe the amount of dye penetration. After 72 hours teeth were removed, washed under running water, dried and sectioned longitudinally, separating buccal and lingual halves. The linear extent of dye penetration was measured from cavosurface margin of the access cavity to the most apical extent of dye penetration point. The length from the cavosurface margin to the apex of the tooth was also measured and percentage linear micro leakage was estimated. Statistical Analysis: Data was statistically analyzed using one-way ANOVA followed by Post-Hoc Multiple comparison (Bonferroni. Results: In the present study specimens in group I showed the maximum percentage of linear microleakage of 31.51 percent. The specimens in group II showed the minimal amount of linear micro leakage of 6.49 percent. Conclusion: It can be concluded coronal seal reduces the micro leakage, and light cure GIC has better coronal sealing ability.

  12. Temperature increase at the light guide tip of 15 contemporary LED units and thermal variation at the pulpal floor of cavities: an infrared thermographic analysis.

    Science.gov (United States)

    Gomes, M; DeVito-Moraes, A; Francci, C; Moraes, R; Pereira, T; Froes-Salgado, N; Yamazaki, L; Silva, L; Zezell, D

    2013-01-01

    In this study, a comprehensive investigation on the temperature increase at the light guide tip of several commercial light-emitting diode (LED) light-curing units (LCUs) and the associated thermal variation (ΔT) at the pulpal floor of dental cavities was carried out. In total, 15 LEDs from all generations were investigated, testing a quartz-tungsten-halogen (QTH) unit as a reference. The irradiance level was measured with a power meter, and spectral distribution was analyzed using a spectrometer. Temperature increase at the tip was measured with a type-K thermocouple connected to a thermometer, while ΔT at the pulpal floor was measured by an infrared photodetector in class V cavities, with a 1-mm-thick dentin pulpal floor. The relationship among measured irradiance, ΔT at the tip, and ΔT at the pulpal floor was investigated using regression analyses. Large discrepancies between the expected and measured irradiances were detected for some LCUs. Most of the LCUs showed an emission spectrum narrower than the QTH unit, with emission peaks usually between 450 and 470 nm. The temperature increase at the tip followed a logarithmic growth for LCUs with irradiance ≥1000 mW/cm(2), with ΔT at the tip following the measured irradiance linearly (R(2)=0.67). Linear temperature increase at the pulpal floor over the 40-second exposure time was observed for several LCUs, with linear association between ΔT at the pulpal floor and measured irradiance (R(2)=0.39) or ΔT at the tip (R(2)=0.28). In conclusion, contemporary LED units show varied irradiance levels that affect the temperature increase at the light guide tip and, as a consequence, the thermal variation at the pulpal floor of dental cavities.

  13. Impact of the distance of light curing on the degree of conversion and microhardness of a composite resin.

    Science.gov (United States)

    Catelan, Anderson; de Araújo, Larissa Sgarbosa Napoleão; da Silveira, Bruna Cilene Martins; Kawano, Yoshio; Ambrosano, Gláucia Maria Bovi; Marchi, Giselle Maria; Aguiar, Flávio Henrique Baggio

    2015-05-01

    This study evaluated the impact of the distance between the light guide tip of the curing unit and material surface on the degree of conversion and Knoop microhardness of a composite resin. Circular samples were carried out of a methacrylate micro-hybrid resin-based composite and light cured at 0, 2 and 4 mm distance. Monomer conversion rate was measured using a Fourier-transform Raman spectrometer and Knoop hardness number was obtained using a microhardness tester on the top and bottom surfaces. Data were statistically analyzed by analysis of variance and Tukey's test (α=0.05). Overall, the increase of curing distance reduced the microhardness (p≤0.05), but did not influence the carbon double bond conversion rate (p>0.05) of the composite resin tested; and the top surface showed better properties compared to the bottom (p≤0.05). The light curing at distance can reduce mechanical properties and could affect long-term durability of the composite restorations. Thus, the use of a curing device with high irradiance is recommended.

  14. Environmental SEM and dye penetration observation on resin-tooth interface using different light curing method.

    Science.gov (United States)

    Yoshikawa, Takako; Morigami, Makoto; Sadr, Alireza; Tagami, Junji

    2016-01-01

    The aim of this study was the effects of different light curing methods on marginal sealing and resin composite adaptation to the cavity wall using the dye penetration test and environmental scanning electron microscope (SEM) observations. Cylindrical cavities were prepared on cervical regions. The teeth were restored with Clearfil Liner Bond 2 V adhesive and filled with Clearfil Photo Bright or Palfique Estelite resin composites. These resins were cured with a conventional light-curing method or a slow-start curing method. After thermal cycling, the specimens were subjected to the dye penetration test to evaluate marginal sealing and adaptation of the resin composites to the cavity walls. These resin-tooth interfaces were then observed using environmental SEM. The light-cured resin composite, which exhibited increased contrast ratios during polymerization, suggests high compensation for polymerization stress using the slow-start curing method. There was a high correlation between dye penetration test and environmental SEM observation.

  15. Effects of ceramic shade and thickness on the micro-mechanical properties of a light-cured resin cement in different shades.

    Science.gov (United States)

    Öztürk, Elif; Bolay, Şükran; Hickel, Reinhard; Ilie, Nicoleta

    2015-01-01

    The aim of this study was to evaluate the micro-mechanical properties of a light-cured resin cement in four different shades when polymerized through a leucite-reinforced glass-ceramic in different shades and thicknesses. A light-cured resin cement in four different shades (HV+1, HV+3, LV-1 and LV-3) was selected for this study. The specimens were cured by using a LED-unit (Bluephase®, IvoclarVivadent) for 20 s under a leucite-reinforced glass-ceramic (IPS Empress® CAD, IvoclarVivadent) in two different shades (A1 and A3) of different thicknesses (1 and 2 mm). Specimens cured directly, without an intermediate ceramic, served as control. The specimens were stored after curing for 24 h at 37°C by maintaining moisture conditions with distilled water. Micro-mechanical properties (indentation modulus, E; Hardness, HV; creep, Cr) of the resin cements were measured with an automatic microhardness indenter (Fisherscope H100C, Germany). Twenty groups were included (n = 3), while 10 measurements were performed on each specimen. Data were statistically analyzed by using one-way ANOVA and Tukey's post-hoc test, as well as a multivariate analysis to test the influence of the study parameters. Significant differences were observed between the micromechanical properties of the tested resin cements (p resin cement shade showed the highest effect on the micromechanical properties (Partial-eta squared (ηP(2))-E = 0.45, ηP(2)-HV = 0.59, ηP(2)-Cr = 0.29) of the resin cement, followed by ceramic thickness (ηP(2)-E = 0.38, ηP(2)-HV = 0.3, ηP(2)-Cr = 0.04) and ceramic shade (ηP(2)-E = 0.2, ηP(2)-HV = 0.26). Resin cement shade is an important factor influencing the mechanical properties of the material. Light shades of a resin cement express higher E and HV as well as lower Cr values compared with the darker ones.

  16. 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

  17. 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....

  18. Evaluation of microleakage of class II dental composite resin restorations cured with LED or QTH dental curing light; Blind, Cluster Randomized, In vitro cross sectional study.

    Science.gov (United States)

    Zakavi, Faramarz; Golpasand Hagh, Leila; Sadeghian, Soheila; Freckelton, Virginia; Daraeighadikolaei, Arash; Ghanatir, Elham; Zarnaghash, Najmeh

    2014-07-03

    The aim of this study is to compare the microleakage of Class II dental composite resin restorations which have been cured by three different LED (light emitting diode) light curing modes compared to control samples cured by QTH (quartz tungsten halogen) light curing units (LCUs), to determine the most effective light curing unit and mode of curing. In this experimental study, class II cavities were prepared on 100 sound human premolars which have been extracted for orthodontic treatment. The teeth were randomly divided into four groups; three experimental and one control group of 25 teeth each. Experimental groups were cured by either conventional, pulse-delay, or ramped curing modes of LED. The control group was cured for 20 seconds by QTH. The restorations were thermocycled (1000 times, between 5 and 55°C, for 5 seconds dwell time), dyed, sectioned mesio-distally and viewed under stereo-microscope (40×) magnification. Teeth were then scored on a 0 to 4 scale based on the amount of microleakage. The data were analyzed by Chi-square test.No significant difference was demonstrated between the different LCUs (light curing units), or modes of curing, at the enamel side (p > 0.05). At the dentin side, all modes of LED curing could significantly reduce microleakage (p curing improves marginal integrity and seal. High intense curing endangers those aims. Comparison between the three LED mode cured composite resin restorations and QTH curing showed LED curing in all modes is more effective than QTH for reducing microleakage. Both LED and QTH almost completely eliminate the microleakage on the enamel side, however none of them absolutely eliminated microleakage on the dentin side.

  19. Effect of light-emitting diode and halogen light curing on the micro-hardness of dental composite and resin-modified glass ionomer cement: an in vitro study.

    Science.gov (United States)

    Bhalla, M; Patel, D; Shashikiran, N D; Mallikarjuna, R M; Nalawade, T M; Reddy, H K

    2012-01-01

    This in vitro study was conducted to evaluate and compare the micro-hardness of composite resin and resin-modified glass ionomer cement using light-emitting diode (LED) and halogen curing and also to inter-compare the effect of LED and halogen curing. The study sample comprised of 4 stainless steel plates with a thickness of 2 mm. For these stainless steel plates, holes were made to a diameter of 3 mm. The samples were divided into 4 groups of 8 each and labeled as group I, group II, group III, group IV, thus making provision for the two different modes of light exposure. In each group, the hole was restored with its respective restorative material and cured with light-curing unit according to manufacturer instructions. The results were statistically analyzed using Mann-Whitney test. It was concluded that the curing efficacy of the LED lamp was comparable to that of conventional halogen lamp, even with a 50% reduction in cure time, and resin composite (Filtek Z-250) presented the highest hardness values, whereas complete hardening of resin-modified glass ionomer cement (RMGIC) (Vitremer) was observed because of its self-curing system even after the removal of light source.

  20. Effect of light-emitting diode and halogen light curing on the micro-hardness of dental composite and resin-modified glass ionomer cement: An in vitro study

    Directory of Open Access Journals (Sweden)

    M Bhalla

    2012-01-01

    Full Text Available Aims : This in vitro study was conducted to evaluate and compare the micro-hardness of composite resin and resin-modified glass ionomer cement using light-emitting diode (LED and halogen curing and also to inter-compare the effect of LED and halogen curing. Materials and Methods : The study sample comprised of 4 stainless steel plates with a thickness of 2 mm. For these stainless steel plates, holes were made to a diameter of 3 mm. The samples were divided into 4 groups of 8 each and labeled as group I, group II, group III, group IV, thus making provision for the two different modes of light exposure. In each group, the hole was restored with its respective restorative material and cured with light-curing unit according to manufacturer instructions. The results were statistically analyzed using Mann-Whitney test. Results and conclusion: It was concluded that the curing efficacy of the LED lamp was comparable to that of conventional halogen lamp, even with a 50% reduction in cure time, and resin composite (Filtek Z-250 presented the highest hardness values, whereas complete hardening of resin-modified glass ionomer cement (RMGIC (Vitremer was observed because of its self-curing system even after the removal of light source.

  1. [Experimental study on the reinforced effect of light curing composite resins used for crowns and bridges].

    Science.gov (United States)

    Sun, J; Zhang, J Z

    2001-03-01

    To evaluate the reinforced effect of the light curing composite resins used for crowns and bridges. Three light curing composite resins which were used for crowns and bridges were chosen, and three polyester fiber sieves and three stainless steel sieves in different mesh were used as the additional reinforced materials. Compressive strength and three point flexural strength of test bars made of those materials were evaluated. The reinforced bridges with special fibers were used as control groups. (1)There was significant increase in the stainless steel sieves groups. Nevertheless, there was some decrease after use of the polyester fibers as the additional reinforced material. (2)The increase of the reinforced crowns was especially obvious. (3)Among the three resins, the property of Targis was better than that of Arglass and Solidex. The properties of the whole composite material were closely correlated with the additional reinforced materials, the resistance to compression of the sieves are better than its resistance to bend.

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

    Science.gov (United States)

    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.

  3. Effect of Shade and Light Curing Mode on the Degree of Conversion of Silorane-Based and Methacrylate-Based Resin Composites.

    Science.gov (United States)

    Sm, Mousavinasab; M, Atai; N, Salehi; A, Salehi

    2016-12-01

    The degree of conversion depends on the material composition, light source properties, distance from light source, light intensity, curing time, and other factors such as shade and translucency. In the present study, we evaluated the effects of different light-curing modes and shades of methacrylate and silorane-based resin composites on the degree of conversion of resin composites (DC). The methacrylate-based (Filtek Z250, 3M, ESPE) and low-shrinkage silorane-based (Filtek P90, 3M, ESPE) resin composites were used in three groups as follows: group 1-Filtek Z250 (shade A3), group 2-Filtek Z250 (shade B2), and group 3-Filtek P90 (shade A3). We used a light-emitting diode (LED) curing unit for photopolymerization. 10 samples were prepared in each group to evaluate the degree of conversion; 5 samples were cured using soft-start curing mode, and the other 5 were cured using standard curing mode. The DC of the resin composites was measured using Fourier Transform Infrared Spectroscopy (FTIR). The data were analyzed using Kruskal Wallis and one-way ANOVA statistical tests. The degree of conversion of silorane-based resin composite was 70 - 75.8% and that of methacrylate-based resin composites was 60.2 - 68.2% (p = 0.009). The degree of conversion of the composite with brighter colour (B2) was statistically more than the darker composite (A3). Higher degree of conversion was achieved applying the standard curing mode. The results of the study showed that the colour and type of the resin composite and also the curing mode influence the degree of conversion of resin composites.

  4. Histological Study of Open Wound Healing with a Light Cure Instrument

    Directory of Open Access Journals (Sweden)

    Vahid Changizi

    2010-09-01

    Full Text Available Introduction: In the present study, the effects of light cure on wound healing of mice’s skin with complete thickness were studied. Materials and Methods: Forty male mice of NMRI race were placed randomly into two groups of examination and control. Under aseptic and unconscious conditions, a circular wound of 6 mm width with complete thickness of skin was made on the back of each mice. The surgery day was established as day zero. Blue light of wavelength 420-500 nm from a light cure instrument was shined onto all the mice from the first day. Over the 3rd, 7th, 10th, 15th and 21st days after curing, four kinds of wound and healthy skins were taken from each mice. The practical procedures of general histology were applied on the samples, then slices of 5 micron thickness were taken from them and finally, they were colored with Hematoxline Eosin. The cell population of wound bed including fibroblast cells, macrophages, neutrophils and endothelia of vessels were studied. Results: The examination group showed significantly increased fibrosis and decreased inflammation (p≤0.05. Conclusion: Halogen blue light (light cure causes significant early open wound healing of skin with complete thickness.

  5. 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.

  6. Time reduction of light curing: Influence on conversion degree and microhardness of orthodontic composites.

    Science.gov (United States)

    Amato, Patrícia Alves Ferreira; Martins, Renato Parsekian; dos Santos Cruz, Carlos Alberto; Capella, Marisa Veiga; Martins, Lídia Parsekian

    2014-07-01

    The aim of this study was to assess the influence of curing time and power on the degree of conversion and surface microhardness of 3 orthodontic composites. One hundred eighty discs, 6 mm in diameter, were divided into 3 groups of 60 samples according to the composite used-Transbond XT (3M Unitek, Monrovia, Calif), Opal Bond MV (Ultradent, South Jordan, Utah), and Transbond Plus Color Change (3M Unitek)- and each group was further divided into 3 subgroups (n = 20). Five samples were used to measure conversion, and 15 were used to measure microhardness. A light-emitting diode curing unit with multiwavelength emission of broad light was used for curing at 3 power levels (530, 760, and 1520 mW) and 3 times (8.5, 6, and 3 seconds), always totaling 4.56 joules. Five specimens from each subgroup were ground and mixed with potassium bromide to produce 8-mm tablets to be compared with 5 others made similarly with the respective noncured composite. These were placed into a spectrometer, and software was used for analysis. A microhardness tester was used to take Knoop hardness (KHN) measurements in 15 discs of each subgroup. The data were analyzed with 2 analysis of variance tests at 2 levels. Differences were found in the conversion degree of the composites cured at different times and powers (P light cured at 8.5 seconds (80.7%) and 6 seconds (79.0%), but not at 3 seconds (75.0%). The conversion degrees of the composites were different, with group 3 (87.2%) higher than group 2 (83.5%), which was higher than group 1 (64.0%). Differences in microhardness were also found (P Curing time can be reduced up to 6 seconds by increasing the power, with a slight decrease in the degree of conversion at 3 seconds; the decrease has a positive effect on the surface microhardness. Copyright © 2014 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  7. Determining the dimensional stability, fracture toughness and flexural strength of light-cured acrylic resin custom tray material.

    Science.gov (United States)

    Khan, S B; Geerts, G

    2009-06-01

    Light-cured acrylic resin custom tray material is used in commercial dental laboratories but little evidence-based scientific information on its physical properties is available. This study investigates the dimensional stability of light-cured acrylic resin custom tray material and compares its fracture toughness and flexural strength to a chemically-cured acrylic material. For dimensional stability, 20 light-cured specimens were fabricated and measured 3 times at regular time intervals over 48 hours. Mean shrinkage was calculated for each time interval and the mean values were compared to the standard using the Wilcoxon Rank Sum test. A p-value of materials with a single-edge notch were subjected to a compressive load using the 3-point bending technique. For flexural strength, 1 group (n=20) of each material was subjected to a compressive load using 3-point bending. The highest load before failure was used to calculate the fracture toughness and flexural strength. Differences in fracture toughness and flexural strength values between the 2 groups were compared using ANOVA testing. A p-value of 0.05). The fracture toughness and flexural strength were significantly higher for the light-cured material. Trays made from light-cured acrylic resin can be used immediately following polymerization. The light-cured material is more resistant to bending and crack propagation than the chemically-cured type.

  8. Bonding of acrylic denture teeth to MMA/PMMA and light-curing denture base materials: the role of conditioning liquids.

    Science.gov (United States)

    Palitsch, Anne; Hannig, Matthias; Ferger, Paul; Balkenhol, Markus

    2012-03-01

    The connection between resin denture teeth and the denture base is essential for the integrity of partial and full dentures. The aim of the present study was to analyse the bond strength of acrylic denture teeth to two light curing denture base materials compared to the gold-standard (MMA/PMMA) using different conditioning liquids. The ridge laps of 220 identical denture teeth were ground and pre-treated using different conditioning liquids (MMA, an experimental conditioning liquid as well as the two commercially available liquids Palabond and Versyo.bond). The denture base materials (PalaXpress, Versyo.com, Eclipse) were applied using a split mould to obtain tensile bond strength specimens of identical shape. Ten specimens per test group were either stored in water for 24h or thermocycled (5000×, 5-55°C) prior to tensile bond strength testing (cross-head speed 10mm/min). Data was subjected to parametric statistics (α=0.05). The three-way ANOVA revealed a significant influence of the material, pre-treatment as well as the storage. PalaXpress showed the highest bond strength (24.3MPa) of all materials tested after TC, whereas the use of MMA led to the most constant results. Lower values were recorded for Versyo.com (17.5MPa) and Eclipse (10.4MPa) bonded with Versyo.bond. The results indicate that MMA/PMMA based denture base resins provide reliable and durable bond strength to acrylic denture teeth. Using light-curing denture base materials requires the application of appropriate conditioning liquids to obtain acceptable bond strength. The use of MMA affects bond strength to light-curing denture base materials. The pre-treatment of denture teeth is critical regarding their bond-strength to denture base materials and in turn for the integrity of removable full and partial dentures. Light-curing denture base resins are more sensitive to the correct tooth pre-treatment compared to conventional MMA/PMMA materials, requiring specific conditioning liquids. Copyright

  9. 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.

  10. 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.

  11. Measurement of linear polymerization shrinkage in light cure Ideal Makoo composite resin

    Directory of Open Access Journals (Sweden)

    Ghavam M.

    2001-09-01

    Full Text Available "nAbstract: Polymerization shrinkage of light cure composite resins causes many complications in conservative and esthetic restorations. The objective of this in-vitro study was to evaluate the polymerization shrinkage, degree of conversion and the amount of filler in IDM and tetric ceram composites. Ten disk shaped, uncured specimens (8mm×1.547mm of each composite were placed on glass slide in the center of the metal attached to it. Then specimens were light cured for 60s from underneath. After 30 minutes, the thickness of specimens, using a micrometer and the percent of the polymerization shrinkage of each sample were measured. Statistical analysis was carried out by t-test (P<0.05. Also the degree of conversion of specimens was evaluated with FTIR and the mineral filler content was measured by burning in electric oven. Polymerization shrinkage in IDM and tetric ceram was not significantly different. Degree of conversion and mineral filler content in tetric ceram was greater than that of IDM. "nIt is assumed that the low degree of conversion in IDM is due to its chemical composition and filler content. Also, the similarity in linear polymerization shrinkage between IDM and tetric ceram may be caused by the low degree of conversion in IDM.

  12. Degree of conversion of a resin cement light-cured through ceramic veneers of different thicknesses and types.

    Science.gov (United States)

    Runnacles, Patrício; Correr, Gisele Maria; Baratto Filho, Flares; Gonzaga, Carla Castiglia; Furuse, Adilson Yoshio

    2014-01-01

    During the cementation of ceramic veneers the polymerization of resin cements may be jeopardized if the ceramics attenuate the irradiance of the light-curing device. The aim of this study was to evaluate the effect of different types and thicknesses of ceramic veneers on the degree of conversion of a light-cured resin-based cement (RelyX Veneer). The cement was light-cured after interposing ceramic veneers [IPS InLine, IPS Empress Esthetic, IPS e.max LT (low translucency) and IPS e.max HT (high translucency) - Ivoclar Vivadent] of four thicknesses (0.5 mm, 1.0 mm, 1.5 mm and 2.0 mm). As control, the cement was light-cured without interposition of ceramics. The degree of conversion was evaluated by FTIR spectroscopy (n=5). Data were analyzed with one-way ANOVA and Tukey's test (α=0.05). Significant differences were observed among groups (pceramics of 0.5 mm and 1.0 mm (p>0.05). Among 1.5-mm-thick veneers, IPS e.max LT was the only one that showed different results from the control (p0.05). The degree of conversion of the evaluated light-cured resin cement depends on the thickness and type of ceramics employed when veneers thicker than 1.5 mm are cemented.

  13. Young's modulus and degree of conversion of different combination of light-cure dental resins.

    Science.gov (United States)

    Emami, N; Söderholm, Kj

    2009-10-01

    To evaluate Young's modulus and degree of conversion of several combinations of bisGMA, UEDMA, TEGDMA light-cure dental resin. Young's modulus and DC% were studied for 21 different resin combinations of bisGMA, TEGDMA and UEDMA. Small universal testing machine and photo-calorimetry were used for the tests. The results were evaluated using ANOVA and Duncan's multiple range tests and regular t-test. Young's modulus varied between 2.37±0.2 GPa (100% TEGDMA) and 4.15±0.2 GPa (100% bisGMA). By adding TEGDMA to bisGMA or UEDMA, the Young's modulus decreased significantly (pphysical properties of the mixtures.

  14. 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.

  15. [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.

  16. Light-cured calcium hydroxide vs formocresol in human primary molar pulpotomies: a randomized controlled trial.

    Science.gov (United States)

    Zurn, Derek; Seale, N Sue

    2008-01-01

    The purpose of this prospective study was to compare light-cured calcium hydroxide (Ca(OH)2) with diluted formocresol (FC) for its success as a primary molar pulpotomy medicament Selection criteria included at least 2 matching, asymptomatic, contralateral primary molars requiring vital pulpotomies. Matched teeth in each patient were randomized to receive either Ca(OH)2 or FC as a pulpotomy medicament. All teeth were restored with prefabricated metal crowns. Twenty patients (34 pairs of teeth) were followed clinically and radiographically for > or =1 year. Two blinded, standardized, and calibrated examiners evaluated and scored each radiograph for signs of pathology, based upon a modified scale previously proposed. Findings were grouped in: (a) 0 - 6; (b) 7 - 12; and (c) 13 - 24 month intervals. Radiographic scoring favored the FC group of the 7- to 12- and 13- to 24-month intervals (Pformocresol as a pulpotomy agent.

  17. Color stability of visible light cured composite resin after soft drink immersion

    Directory of Open Access Journals (Sweden)

    Alizatul Khairani Hasan

    2009-09-01

    Full Text Available Background: Composite resin is a tooth-colored filling material containing Bis-GMA which exhibits water sorption properties. People tend to consume soft drink with various colors. Water sorption properties can alter the color stability of composite resin purpose. Purpose: This study was to determine the influence of immersion durations of composite resin in soft drink on color stability. Methods: The visible-light cured hybrid composite resin and soft drink were used. Ten disk specimens (2.5 mm thickness and 15 mm diameter of composite resin were prepared and light cured for 20 seconds, then stored in distilled water for 24 hours at 37° C. The initial color of specimens were measured by Chromameter. After that, each specimen was immersed in 30 ml of soft drink up to 48, 72, and 96 hours at 37° C. The specimens’ color were measured again after each immersion. The color changes were calculated by CIE L*a*b* system formula. The data was analyzed by One-Way ANOVA and LSD (α = 0.05. Result: The ANOVA showed that the immersion durations of composite resin in soft drinks had significant influence on the color stability (p < 0.05. The LSD0.05 tests showed significant differences among all groups. The least color change was detected from the group of 48 hours immersion, while the greatest color change was from the group of 96 hours immersion. Conclusions: The immersion of composite resin in soft drinks influenced the color stability (began after 48 hours immersion.

  18. Do light cured ART conventional high-viscosity glass-ionomer sealants perform better than resin-composite sealants: a 4-year randomized clinical trial.

    Science.gov (United States)

    Zhang, WeiWei; Chen, Xi; Fan, Ming-Wen; Mulder, Jan; Huysmans, Marie-Charlotte C D N J M; Frencken, Jo E

    2014-05-01

    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 resin-composite sealants after 4 years. The randomized controlled clinical trial covered 405 children (mean age 8-years). Three dentists placed sealants in pits and fissures of high caries-risk children. Evaluation by two independent evaluators was conducted after 0.5, 1, 2, 3 and 4 years. The Kaplan-Meier survival method, ANOVA and t-test were used in data analyses. 1304 first permanent molars were sealed. 12.3% of children and 15.4% of sealants dropped out. 46 re-exposed pits and fissures, 39 (occlusal) 7 (free smooth surfaces), in 42 children developed a dentin carious lesion. The cumulative survival of dentin caries lesion-free occlusal pits and fissures in ART plus LED group (98%) was statistically significantly higher than in the resin-composite group (96.4%) and in the glass-carbomer group (94.5%). The cumulative survival of dentin caries lesion-free occlusal pits and fissures in the glass-carbomer group was statistically significantly lower than that in the conventional ART group (97.3%). For the free smooth surfaces, there was no statistically significantly difference among the four sealant groups. Light-cured ART conventional high-viscosity glass-ionomer sealants prevented the occurrence of dentin cavities best. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  19. Midwives' experiences of facilitating normal birth in an obstetric-led unit: a feminist perspective.

    LENUS (Irish Health Repository)

    Keating, Annette

    2012-01-31

    OBJECTIVE: to explore midwives\\' experiences of facilitating normal birth in an obstetric-led unit. DESIGN: a feminist approach using semi-structured interviews focusing on midwives\\' perceptions of normal birth and their ability to facilitate this birth option in an obstetric-led unit. SETTING: Ireland. PARTICIPATION: a purposeful sample of 10 midwives with 6-30 years of midwifery experience. All participants had worked for a minimum of 6 years in a labour ward setting, and had been in their current setting for the previous 2 years. FINDINGS: the midwives\\' narratives related to the following four concepts of patriarchy: \\'hierarchical thinking\\

  20. 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 ...

  1. CARIOSTATIC EFFECT AND FLUORIDE RELEASE FROM A VISIBLE LIGHT-CURING ADHESIVE FOR BONDING OF ORTHODONTIC BRACKETS

    NARCIS (Netherlands)

    OGAARD, B; REZKLEGA, F; RUBEN, J; ARENDS, J

    This study was designed to investigate the cariostatic potential in vivo of a visible light-curing adhesive for the bonding of orthodontic brackets. The fluoride release of the adhesive in water and saliva was also measured. Ten orthodontic patients with premolars to be extracted participated. One

  2. Evaluation of rat alveolar bone response to Angelus MTA or experimental light-cured mineral trioxide aggregate using fluorochromes.

    Science.gov (United States)

    Gomes-Filho, João Eduardo; de Moraes Costa, Mariana Machado Teixeira; Cintra, Luciano Tavares Angelo; Duarte, Paulo Carvalho Tobias; Takamiya, Aline Satie; Lodi, Carolina Simonetti; Bernabé, Pedro Felício Estrada

    2011-02-01

    The aim of this study was to evaluate the rat alveolar bone response after the implantation of experimental light-cured mineral trioxide aggregate (MTA) or Angelus MTA (Angelus, Londrina, Paraná, Brazil) by histological and fluorescence analysis. Thirty Wistar Albino rats were divided into three groups. In the control group, empty polyethylene tubes were inserted into the rat alveolar sockets immediately after extraction. In the other groups, the tubes were filled with light-cured MTA or Angelus MTA. Five animals from each group were injected with calcein on day 7, alizarin on day 14, and oxytetracycline on day 21. On day 30, these animals were killed, and the right hemimaxillas were removed and histologically processed. Half of the maxillas were processed and stained with hematoxylin and eosin. The remaining maxillas were processed for fluorescence analysis and stained with Stevenel blue and alizarin red. New bone was histomorphometrically evaluated using a Merz grid. The light-cured MTA presented a similar response when compared with Angelus MTA; it was characterized by a mild inflammatory response and complete bone healing. In the light-cured MTA group, the fluorescence areas were more evident at 21 days, showing an increase in bone formation. However, dystrophic mineralization was observed only with Angelus MTA. It was concluded that both materials present a similar inflammatory response and bone healing, but dystrophic mineralization was observed only with Angelus MTA. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  3. CALiPER Application Summary Report 14. LED Downlight Retrofit Units

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2012-03-01

    This CALiPER report analyzes the independently tested performance of 11 anonymously purchased LED downlight retrofit units—referred to as the Series 14 products. All the units were tested in a 6-inch insulation contact (IC) rated downlight housing mounted in a 24-inch by 24-inch insulated enclosure.

  4. 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

  5. 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.

  6. In vivo wear pattern of experimental light-cured hybrid composite resins.

    Science.gov (United States)

    Okamoto, A; Sekiya, K; Fukushima, M; Iwaku, M

    1993-12-01

    This study evaluated the effect of various types of microfiller on the in vivo wear resistance of composite resins. Experimental light-cured composites with two different microfiller systems were prepared: (1) 56 wt % fine quartz filler, 21 wt% organic filler and 3 wt% colloidal silica filler (Hybrid type 1), and (2) 64 wt% fine quartz filler and 21 wt% colloidal silica filler (Hybrid type 2). The resin monomer consisted of 50 wt % Bis-GMA and 50 wt% TEGDMA. These materials were placed in 2 mm diameter cylindrical cavities located in the OCA (occlusal contact area) or the CFA (contact free area) in cast gold-silver-palladium alloy full coverage crowns, which were temporarily set in a volunteer patient's mouth. The crowns were removed at monthly intervals for SEM observation. Hybrid type 1, which contained organic fillers, showed bulk fractures in the OCA, by the second month of the experiment. However, reinforcement of the resin matrix by dispersion of microfiller provided Hybrid type 2 with superior wear resistance for up to two months.

  7. Volumetric dimensional changes of dental light-cured dimethacrylate resins after sorption of water or ethanol.

    Science.gov (United States)

    Sideridou, Irini D; Karabela, Maria M; Vouvoudi, Evagelia Ch

    2008-08-01

    This study evaluated the influence of water and ethanol sorption on the volumetric dimensional changes of resins prepared by light curing of Bis-GMA, Bis-EMA, UDMA, TEGDMA or D(3)MA. The resin specimens (15mm diameterx1mm height) were immersed in water or ethanol 37+/-1 degrees C for 30 days. Volumetric changes of specimens were obtained via accurate mass measurements using Archimedes principle. The specimens were reconditioned by dry storage in an oven at 37+/-1 degrees C until constant mass was obtained and then immersed in water or ethanol for 30 days. The volumetric changes of specimens were determined and compared to those obtained from the first sorption. Resins showed similar volume increase during the first and second sorptions of water or ethanol. The volume increase due to water absorption is in the following order: poly-TEGDMA>poly-Bis-GMA>poly-UDMA>poly-Bis-EMA>poly-D(3)MA. On the contrary, the order in ethanol is poly-Bis-GMA>poly-UDMA>poly-TEGDMA>poly-Bis-EMA approximately poly-D(3)MA. The volume increase was found to depend linearly on the amount of water or ethanol absorbed. In the choice of monomers for preparation of composite resin matrix the volume increase in the resin after immersion in water or ethanol must be taken into account. Resins of Bis-EMA and D(3)MA showed the lowest values.

  8. Physical properties of self-, dual-, and light-cured direct core materials.

    Science.gov (United States)

    Rüttermann, Stefan; Alberts, Ian; Raab, Wolfgang H M; Janda, Ralf R

    2011-08-01

    The objective of this study is to evaluate flexural strength, flexural modulus, compressive strength, curing temperature, curing depth, volumetric shrinkage, water sorption, and hygroscopic expansion of two self-, three dual-, and three light-curing resin-based core materials. Flexural strength and water sorption were measured according to ISO 4049, flexural modulus, compressive strength, curing temperature, and curing depth according to well-proven, literature-known methods, and the volumetric behavior was determined by the Archimedes' principle. ANOVA was calculated to find differences between the materials' properties, and correlation of water sorption and hygroscopic expansion was analysed according to Pearson (p hygroscopic expansion (0.0 ± 0.2 vol.%). Clearfil Photo Core and Encore SuperCure Contrast demonstrated the lowest shrinkage (≈2.1 ± 0.1 vol.%). Water sorption and hygroscopic expansion had a very strong positive correlation. The investigated core materials significantly differed in the tested properties. The performance of the materials depended on their formulation, as well as on the respective curing process.

  9. 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.

  10. Effect of Enamel Preparation and Light Curing Methods on Microleakage under Orthodontic Brackets

    Directory of Open Access Journals (Sweden)

    Hamidreza Pakshir

    2015-11-01

    Full Text Available Objectives: This study aimed to compare the microleakage beneath metallic brackets following two different methods of enamel preparation and light curing.Materials and Methods: A total of 120 bovine deciduous lower incisors were randomly divided into four groups of 30 teeth. The preparations were as follows: Group I: Acid etching + Transbond XT primer + direct illumination, group II: acid etching + Transbond XT primer + transillumination, group III: Transbond XT self-etching primer + direct illumination and Group IV: Transbond XT self-etching primer + transillumination. Dye penetration was used as the method of microleakage evaluation. Sections made at the enamel-adhesive and adhesive-bracket interfaces were evaluated under a stereomicroscope. The Kruskal-Wallis and Mann-Whitney U tests were used for statistical analysis. The level of significance was set at P<0.05.Results: All groups showed greater microleakage at the gingival in comparison to the incisal margin and the differences were significant among groups with transillumination (P<0.001. No significant differences were observed in the microleakage scores at the gingival and incisal margins in any of the interfaces (P>0.05. Mesiodistal margins of the self-etching group with direct illumination showed significantly lower scores in comparison with acid etched group (P<0.05.Conclusion: Use of self-etching primers for bonding of orthodontic brackets yields acceptable results if all bracket margins are cured directly.

  11. Current status of visible light activation units and the curing of light-activated resin-based composite materials.

    Science.gov (United States)

    Santini, Ario

    2010-05-01

    Light activation units are standard items of equipment in dental practice. It is essential to understand the many factors which affect the polymerization of light-activated resin composite materials and the choice of a light curing unit. In this respect, the development of high-intensity halogen and light-emitting diode (LED) light curing units (LCUs), many with multiple curing modes, has revolutionized light curing techniques. This article reviews visible light activation unit design and development. Factors influencing the effective use of LCUs and polymerization of resin-based composite materials are discussed, as are the steps which should be taken to maintain the efficiency of units in clinical use. Many LCUs produce lower output intensities than stated by the manufacturer. Newer high power LEDs may present as much of a heat problem as high power quartz tungsten halogen lamps (QTHs).The manufacturer's data should be followed to ensure that the emission spectra of the unit is compatible with the photo-initiator in the resin-based composite material.

  12. Comparison of shear bond strength of stainless steel brackets bonded with three light- cured adhesives

    Directory of Open Access Journals (Sweden)

    Zahra Minaei Basharik

    2015-09-01

    Full Text Available Introduction: The bonding process of the brackets to enamel has been a critical issue in orthodontic research. The purpose of this study was to evaluate the shear bond strength of 3 light-cured adhesives (transbond XT, Z250, light bond. Materials &Methods: In this study sixty extracted human premolars were collected and randomly divided into 3 test groups. All teeth were etched by 37% phosphoric acid. In first group brackets were bonded by Transbond XT adhesive, in group two brackets were bonded by Light bond adhesive and in third group were bonded by filtek Z250 composite. All of them were cured with Ortholux xt for 40 seconds.24 hours after thermocycling, Shear Bond Strength (SBS values of these brackets were recorded using a Universal Testing Machine. Adhesive Remnant Index (ARI scores were determined after the failure of the brackets, using Stereo Microscope the data were analyzed using ANOVA and Chi-square tests. Results: Mean shear bond strength of Transbond XT, light bond and Z250 were 28.9±2.25 MPa, 25.06±1.98 MPa and 26.8±2.57 MPa, respectively. No significant difference was observed in the SBS among the groups and a clinically acceptable SBS was found for the three adhesives. ARI scores were not significantly different between the various groups (P>0.05. Conclusion: This study showed that the Z250 can be used as light bond and transbond xt to bond orthodontic brackets and ARI and SBS scores were not significantly different.

  13. Physical properties of current dental nanohybrid and nanofill light-cured resin composites.

    Science.gov (United States)

    Sideridou, Irini D; Karabela, Maria M; Vouvoudi, Evangelia Ch

    2011-06-01

    The purpose of this work was the detailed study of sorption characteristics of water or artificial saliva, the determination of flexural strength and the flexural modulus, and the study of the thermal stability of some current commercial dental light-cured nanocomposites containing nano-sized filler particles. Three nanohydrid dental composites (Tetric EvoCeram (TEC), Grandio (GR) and Protofill-nano (PR)) and two nanofill composites (Filtek Supreme Body (FSB) and the Filtek Supreme Translucent (FST)) were used in this work. The volumetric shrinkage due to polymerization was first determined. Also the sorption, solubility and volumetric increase were measured after storage of composites in water or artificial saliva for 30 days. The flexural strength and flexural modulus were measured using a three-point bending set-up according to the ISO-4049 specification, after immersion of samples in water or artificial saliva for 1 day or 30 days. Thermal analysis technique TGA method was used to investigate the thermal stability of composites. GR and TEC composites showed statistically no difference in volumetric shrinkage (%) which is lower than the other composites, which follow the order PRGrandio had the lowest polymer matrix content, consisting mainly of Bis-GMA. It showed the lowest polymerization shrinkage and water sorption and the highest flexural strength and flexural modulus after immersion in water or artificial saliva for 30 days. The water and artificial saliva generally showed the same effect on physical properties of the studied composites. Thermogravimetric analysis gave good information about the structure and the amount of organic polymer matrix of composites. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  14. The effect of exposure time on diametral tensile strength of light-cured resin composite

    Directory of Open Access Journals (Sweden)

    Marzia M Tetelepta

    2016-06-01

    Full Text Available Repetition or extend the exposure time in using light-cured resin composite are often done by practitioners in order to get a higher mechanical strength. Nevertheless, failure still can occur. Therefore, the aim of this study was to evaluate the effect of exposure time on Diametral Tensile Strength (DTS of two different resin composite used for provisional crown and bridge restoration and filling materials. A total of 60 cylindrical specimens (6mm diameter x 3mm thickness were divided into three groups (n=10. The first group was cured as recommended by the manufacturer, the second group were cured two times, and the third group were cured three times. Furthermore, specimens were immersed in distilled water for 24 hours at a temperature of 37 °C. DTS were tested by universal testing machine and the results were analyzed by one-way ANOVA continued with Post Hoc Tamhane to see the difference between the groups. The results showed DTS composite as filling materials was significantly higher compared with the resin composite  for provisional crown and bridge restoration. DTS of composite as filling materials in first group had a higher value than first  and third groups. The composite for the provisional crown and bridge restoration in second group had a lower DTS value than in first and third groups. In third group, DTS increased but not significantly. DTS also could be influenced by the composition of filler content and type of matrix. The conclusion of this study was to extend the exposure time can weaken the DTS resin composite.

  15. Effect of Layering Methods, Composite Type, and Flowable Liner on the Polymerization Shrinkage Stress of Light Cured Dental Composites

    Science.gov (United States)

    2011-08-01

    18 TH INTERNATIONAL CONFERENCE ON COMPOSITE MATERIALS 1 Introduction Composite restoration has become an essential part of everyday dental ...thickness of flowable liner, use of RMGI (resin modified glass ionomer ) liner, and light curing methods on the cuspal deflection should be...polymerization shrinkage stress in polymer-based restoratives . J Dent, Vol. 25, pp 435-440, 1997. [4] J. Ferracane. Placing dental composites-A stressful

  16. Hardening of a dual-cure resin cement using QTH and LED curing units

    Science.gov (United States)

    SANTOS, Maria Jacinta Moraes Coelho; PASSOS, Sheila Pestana; da ENCARNAÇÃO, Monalisa Olga Lessa; SANTOS, Gildo Coelho; BOTTINO, Marco Antonio

    2010-01-01

    Objective This study evaluated the surface hardness of a resin cement (RelyX ARC) photoactivated through indirect composite resin (Cristobal) disks of different thicknesses using either a light-emitting diode (LED) or quartz tungsten halogen (QTH) light source. Material and Methods Eighteen resin cement specimens were prepared and divided into 6 groups according to the type of curing unit and the thickness of resin disks interposed between the cement surface and light source. Three indentations (50 g for 15 s) were performed on the top and bottom surface of each specimen and a mean Vickers hardness number (VHN) was calculated for each specimen. The data were analyzed using two-way ANOVA and Tukey-Kramer test was used for post-hoc pairwise comparisons. Results Increased indirect resin disk thickness resulted in decreased mean VHN values. Mean VHN values for the top surfaces of the resin cement specimens ranged from 23.2 to 46.1 (QTH) and 32.3 to 41.7 (LED). The LED curing light source produced higher hardness values compared to the QTH light source for 2- and 3-mm-thick indirect resin disks. The differences were clinically, but not statistically significant. Increased indirect resin disk thickness also resulted in decreased mean VHN values for the bottom surfaces of the resin cement: 5.8 to 19.1 (QTH) and 7.5 to 32.0 (LED). For the bottom surfaces, a statistically significant interaction was also found between the type of curing light source and the indirect resin disk thickness. Conclusions Mean surface hardness values of resin cement specimens decreased with the increase of indirect resin disk thickness. The LED curing light source generally produced higher surface hardness values. PMID:20485920

  17. Hardening of a dual-cure resin cement using QTH and LED curing units

    Directory of Open Access Journals (Sweden)

    Maria Jacinta Moraes Coelho Santos

    2010-04-01

    Full Text Available OBJECTIVE: This study evaluated the surface hardness of a resin cement (RelyX ARC photoactivated through indirect composite resin (Cristobal disks of different thicknesses using either a light-emitting diode (LED or quartz tungsten halogen (QTH light source. MATERIAL AND METHODS: Eighteen resin cement specimens were prepared and divided into 6 groups according to the type of curing unit and the thickness of resin disks interposed between the cement surface and light source. Three indentations (50 g for 15 s were performed on the top and bottom surface of each specimen and a mean Vickers hardness number (VHN was calculated for each specimen. The data were analyzed using two-way ANOVA and Tukey-Kramer test was used for post-hoc pairwise comparisons. RESULTS: Increased indirect resin disk thickness resulted in decreased mean VHN values. Mean VHN values for the top surfaces of the resin cement specimens ranged from 23.2 to 46.1 (QTH and 32.3 to 41.7 (LED. The LED curing light source produced higher hardness values compared to the QTH light source for 2- and 3-mm-thick indirect resin disks. The differences were clinically, but not statistically significant. Increased indirect resin disk thickness also resulted in decreased mean VHN values for the bottom surfaces of the resin cement: 5.8 to 19.1 (QTH and 7.5 to 32.0 (LED. For the bottom surfaces, a statistically significant interaction was also found between the type of curing light source and the indirect resin disk thickness. CONCLUSION: Mean surface hardness values of resin cement specimens decreased with the increase of indirect resin disk thickness. The LED curing light source generally produced higher surface hardness values.

  18. GATEWAY Report Brief: Evaluating Tunable LED Lighting in the Swedish Medical Behavioral Health Unit

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2017-08-23

    Summary of a GATEWAY report evaluation of a tunable LED lighting system installed in the new Swedish Medical Behavioral Health Unit in Seattle that incorporates color-tunable luminaires in common areas, and uses advanced controls for dimming and color tuning, with the goal of providing a better environment for staff and patients. The report reviews the design of the tunable lighting system, summarizes two sets of measurements, and discusses the circadian, energy, and commissioning implications as well as lessons learned from the project.

  19. 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.

  20. Initial and fatigue bond strengths of chromatic and light-cured adhesives.

    Science.gov (United States)

    Lee, June M L; Georgiou, George; Jones, Steven P

    2010-11-01

    To compare the initial and fatigue shear bond strengths of a chromatic adhesive with a light-cured adhesive in an ex vivo laboratory study. Hydroxyapatite discs were used as the bonding substrate. They were produced by cold uni-axial compression at 20 tons, sintered at 1300 degrees C and embedded in epoxy resin before grinding and polishing. One hundred and fifty upper left central incisor brackets were bonded to the discs with Transbond PLUS Color Change (3M Unitek, Monrovia, CA, USA) while another 150 similar brackets were bonded with Transbond XT (3M Unitek, Monrovia, CA, USA). Seventy-five brackets from each group were subjected to cyclic loading (5000 cycles at 2 Hz) at 50 per cent of the mean bond strength in a Dartec Series HC 10 Testing Machine. Initial (unfatigued) and fatigued bond strengths were determined by applying a shear force at the bracket-substrate interface using a custom-made metal jig in an Instron Universal Testing Machine. One-way ANOVA with Bonferroni post-hoc correction and two-way ANOVA were used to analyse the differences between the initial and fatigue mean shear bond strengths of the adhesives. The survival and bond reliability of both adhesives were evaluated with the Kaplan-Meier and Cox regression analyses. The initial mean shear bond strength for Transbond PLUS Color Change (16.72 MPa) was higher than Transbond XT (15.11 MPa), but this was not statistically significant (p = 0.109). The fatigue mean shear bond strength for Transbond XT (15.87 MPa) was similar to that of Transbond PLUS Color Change (15.33 MPa), and the difference was not statistically significant (p > 0.999). There were no significant differences when the effects of the material (p = 0.264) or fatiguing (p = 0.512) were considered separately, but in combination, the effect on bond strength was statistically significant (p = 0.026). The survival analysis showed that both adhesives demonstrated similar survival patterns in the unfatigued and fatigued states. Analysis

  1. Evaluating the outcomes of a podiatry-led assessment service in a public hospital orthopaedic unit.

    Science.gov (United States)

    Bonanno, Daniel R; Medica, Virginia G; Tan, Daphne S; Spring, Anita A; Bird, Adam R; Gazarek, Jana

    2014-01-01

    In Australia, the demand for foot and ankle orthopaedic services in public health settings currently outweighs capacity. Introducing experienced allied health professionals into orthopaedic units to initiate the triage, assessment and management of patients has been proposed to help meet demand. The aim of this study was to evaluate the effect of introducing a podiatry-led assessment service in a public hospital orthopaedic unit. The outcomes of interest were determining: the proportion of patients discharged without requiring an orthopaedic appointment, agreement in diagnosis between the patient referral and the assessing podiatrist, the proportion of foot and ankle conditions presenting to the service, and the proportion of each condition to require an orthopaedic appointment. This study audited the first 100 patients to receive an appointment at a new podiatry-led assessment service. The podiatrist triaged 'Category 3' referrals consisting of musculoskeletal foot and ankle conditions and appointments were provided for those considered likely to benefit from non-surgical management. Following assessment, patients were referred to an appropriate healthcare professional or were discharged. At the initial appointment or following a period of care, patients were discharged if non-surgical management was successful, surgery was not indicated, patients did not want surgery, and if patient's failed to attend their appointments. All other patients were referred for an orthopaedic consultation as indicated. Ninety-five of the 100 patients (69 females and 31 males; mean age 51.9, SD 16.4 years) attended their appointment at the podiatry-led assessment service. The 95 referrals contained a total of 107 diagnoses, of which the podiatrist agreed with the diagnosis stated on the referral in 56 cases (Kappa =0.49, SE = 0.05). Overall, 34 of the 100 patients were referred to an orthopaedic surgeon and the remaining 66 patients were discharged from the orthopaedic waiting

  2. Influence of different shades and LED irradiance on the degree of conversion of composite resins

    Directory of Open Access Journals (Sweden)

    Lívia Aguilera Gaglianone

    2012-04-01

    Full Text Available The aim of this study was to evaluate the degree of conversion (DC of two composite resins with different shades that were light cured by light-emitting diodes (LEDs of different irradiances. Specimens (5 mm ' 2 mm were prepared with a nanofilled (Filtek Supreme - A2E, A2D, and WE or microhybrid resin (Opallis - A2E, A2D, and EBleach Low and were randomly divided into 12 groups (n = 5 each according to the composite resin and light-curing unit (Elipar FreeLight 2, 1250 mW/cm²; Ultralume 5, 850 mW/cm². After 24 h, the DC was measured on two surfaces (top and bottom with Fourier Transform infrared spectroscopy (FTIR. Data were statistically analyzed with two-way ANOVA and Tukey test (a = 0.05. Statistical differences among the surfaces were observed in all experimental conditions, with higher values on the top surface. The microhybrid resin presented the highest DCs for shades A2E and A2D on the top surface. The LED with higher irradiance promoted better DCs. Taken together, the data indicate that the shade of a composite resin and the irradiance of the light source affect the monomeric conversion of the restorative material.

  3. 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.

  4. 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

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

    Directory of Open Access Journals (Sweden)

    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.

  6. Outcomes in emergency general surgery following the introduction of a consultant-led unit.

    Science.gov (United States)

    Shakerian, R; Thomson, B N; Gorelik, A; Hayes, I P; Skandarajah, A R

    2015-12-01

    Patients presenting with emergency surgical conditions place significant demands on healthcare services globally. The need to improve emergency surgical care has led to establishment of consultant-led emergency surgery units. The aim of this study was to determine the effect of a changed model of service on outcomes. A retrospective observational study of all consecutive emergency general surgical admissions in 2009-2012 was performed. A 2-year time frame before and after the establishment of the emergency general surgery (EGS) service was used to determine the number of admissions and operations, emergency department and hospital length of stay, as well as complication rates. The study included 7233 acute admissions. The EGS service managed 4468 patients (61·6 per cent increase) and performed 1804 operations (41·0 per cent increase). The most common diagnoses during the EGS period included acute appendicitis (532, 11·9 per cent), biliary disease (361, 8·1 per cent) and abdominal pain (561, 12·6 per cent). Appendicectomy (536, 29·7 per cent), cholecystectomy (239, 13·2 per cent) and laparotomy (226, 12·5 per cent) were the most commonly performed procedures. In the EGS period, time in the emergency department was reduced (from 8·0 to 6·0 h; P emergency surgical service has been associated with improved provision of care, resulting in timely management and improved clinical outcomes. © 2015 BJS Society Ltd Published by John Wiley & Sons Ltd.

  7. An Analysis of the United States-Led Coalition Air Campaign Conducted During the 1991 War with IRAQ: Desert Storm

    National Research Council Canada - National Science Library

    Murphy, John

    2002-01-01

    Evaluation of the 1991 United States led coalition Persian Gulf War (DESERT STORM) Air Campaign is performed to measure its adherence to basic principles of war and to determine the potential implications for the future conduct of war...

  8. Shear bond strength of metallic brackets photo-activated with light-emitting diode (LED at different exposure times

    Directory of Open Access Journals (Sweden)

    Emanuel Braga Rêgo

    2007-10-01

    Full Text Available The purpose of this study was to compare the shear bond strength of orthodontic metallic brackets photo-activated with two different light-curing sources at different exposure times: halogen light (XL 1500, 3M ESPE and LED light (Ortholux, 3M Unitek. Sixty bovine permanent lower incisors were inserted into PVC tubes containing plaster. The buccal surfaces were cleaned with pumice and water, and then etched with 37% phosphoric acid gel. The XT Primer bonding agent (3M Unitek was applied to the enamel surfaces and the metallic pre-coated brackets (Transbond APC II system, 3M Unitek were attached to upper central incisors. The teeth were randomly divided into four groups (n=15. In Group I (Control, halogen light was used for 40 seconds, while in Groups II, III, and IV were light-cured with LED light unit for 40, 10, and 5 seconds, respectively. The teeth were stored in distilled water at 37°C for 24 hours. The brackets were submitted to shear bond strength test in universal testing machine (Instron at a crosshead speed of 0.5 mm/minute. Shear bond strength means (MPa were 4.87 for Group I; 5.89 for Group II; 4.83 for Group III, and 4.39 for Group IV. Tukey's test detected no statistically significant differences among the groups regarding the shear bond strength (p>0.05. Neither of the types of light-curing sources or exposure times influenced the shear bond strength of metallic brackets.

  9. Efficiency of dual-cured resin cement polymerization induced by high-intensity LED curing units through ceramic material.

    Science.gov (United States)

    Watanabe, H; Kazama, Re; Asai, T; Kanaya, F; Ishizaki, H; Fukushima, M; Okiji, T

    2015-01-01

    This study aimed to evaluate the ability of high-intensity light-emitting diode (LED) and other curing units to cure dual-cured resin cement through ceramic material. A halogen curing unit (Jetlite 3000, Morita), a second-generation LED curing unit (Demi, Kerr), and two high-intensity LED curing units (PenCure 2000, Morita; Valo, Ultradent) were tested. Feldspathic ceramic plates (VITABLOCS Mark II, A3; Vita Zahnfabrik) with thicknesses of 1.0, 2.0, and 3.0 mm were prepared. Dual-cured resin cement samples (Clearfil Esthetic Cement, Kuraray Noritake Dental) were irradiated directly or through one of the ceramic plates for different periods (5, 10, 15, or 20 seconds for the high-intensity LED units and 20, 40, 60, or 80 seconds for the others). The Knoop hardness test was used to determine the level of photopolymerization that had been induced in the resin cement. Data were analyzed by one-way analysis of variance and Dunnett's post-hoc test to identify test-control (maximum irradiation without a ceramic plate) differences for each curing unit (presin cement through a ceramic plate resulted in decreased KHN values compared with direct irradiation. When the irradiation period was extended, only the LED units were able to achieve similar KHN values to those observed under direct irradiation in the presence of plates ≥2.0-mm thick. High-intensity LED units require a shorter irradiation period than halogen and second-generation LED curing units to obtain KHN values similar to those observed during direct irradiation.

  10. Clinical and laboratory evaluation of visible light-cured denture base resins and their application to orthodontics.

    Science.gov (United States)

    Lewis, E A; Ogle, R E; Sorensen, S E; Zysik, D A

    1988-09-01

    A series of investigations is being conducted to examine the applicability of visible light-cured resins to orthodontics. The experimental vehicle is the Hawley retainer, which is made from autopolymerized (AP), heat-cured (HC), thermoplastic Biocryl 2 (BC), and Traid visible light-cured (VLC) resins. In all physical property testing, it was found that VLC resins met or exceeded required values as established by ADA Specification No. 12 for denture base polymers. In vitro bacterial adherence studies showed that more organisms adhered to heat-cured specimens than to the other specimens. In vivo studies using split-palate Hawley retainers demonstrated slightly less bacterial adherence to BC than to the other resins. Scanning electron microscopy (SEM) observations have shown the BC surface to be the smoothest, although surface chemistry also seems important. None of the materials being tested appears to cause any significant change in the subjacent subgingival bacterial flora. There was no adverse tissue reaction under any of the materials when observed clinically. Manipulation characteristics and time of fabrication appear to be dependent on the depth of the palate and the skill of the operator.

  11. Effect of light curing modes and ethanol immersion media on the susceptibility of a microhybrid composite resin to staining

    Directory of Open Access Journals (Sweden)

    Flávio Henrique Baggio Aguiar

    2007-04-01

    Full Text Available The aim of this in vitro study was to evaluate the susceptibility of a hybrid composite resin (Filtek Z250 - 3M ESPE to staining, when light cured in four different modes and immersed in two different media. Composite resin specimens were randomly prepared and polymerized according to the experimental groups (conventional - 550 mW/cm² / 30 seconds; soft start - 300mW/cm² / 10 seconds + 550 mW/cm² / 20 seconds; high intensity - 1060 mW/cm² - 10 seconds; pulse delay - 550 mW/cm² - 1 seconds + 60 seconds of waiting time + 550 mW/cm² - 20 seconds and immersed in one of two media (distilled water or absolute ethanol for 24h. Next, the specimens were immersed in a 2% methylene blue solution for 12 hours. Afterwards, the specimens were washed and prepared for the spectrophotometric analysis. For statistical analysis, two-way ANOVA (4X2 and Tukey's test were performed on the data at 0.05 confidence level. Soft start showed the least staining, and was statistically different from the high intensity and pulse delay light curing modes (p0.05. There were no significant differences between the two immersion media (p>0.05. The soft start polymerization mode showed lower susceptibly of the composite resin to staining than high intensity and pulse delay, irrespective of the immersion medium.

  12. Study on Ultraviolet Light Cured Resin Bond Grind/Lap for Aluminum Oxide Ceramics

    Science.gov (United States)

    Huang, Qiuyun

    After the development of ultraviolet (UV) curing technology, a novel method to manufacture abrasive tools using UV light curing technique was proposed. After decades of research activities, the UV-cured resin bond tools have been studied and proven to have substantial advantages. However, very little research has been done to study the mechanism of such abrasive tools. In this study, the mechanism of UV-cured resin bond diamond tools was proposed as a Grind/Lap (G/L) process and an experimental method was used to verify the mechanism. Furthermore, the models of surface roughness (RA) and material removal rate (MRR) in the process of ceramics have been intensively investigated. The traditional way to fabricate abrasive tools is by utilizing the thermosetting method. The mixture of abrasives and bond material is sintered at high temperature under extremely high pressure, and it is a time consuming and costly procedure. However, for the UV-curing technique, after being exposed to UV light with a certain intensity, the abrasive-mixed resin can be solidified in a short time. The process is environmentally friendly and has strong productivity advantages but coupled with low energy consumption. The purpose of this research is to understand fundamental issues in UV-curable resin and face grinding of ceramic materials using UV-cured resin bond wheels, including to study the kinematics of face grinding (grinding with lapping kinematics) and the properties of UV-cured abrasive-mixed resin, verify the mechanism proposed for grind/lap process and investigate the effects of several factors on the performance of UV-cured resin bond wheel for aluminum oxide ceramics. The kinematic relation between the workpiece, workpiece holder and the wheel were investigated. The trajectories generated under different speed combinations were simulated. Based on the trace distribution, a combination of the speed of wheel and holder can be suggested and an explanation of interactional effect of

  13. 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.

  14. Effect of food/oral-simulating liquids on dynamic mechanical thermal properties of dental nanohybrid light-cured resin composites.

    Science.gov (United States)

    Vouvoudi, Evangelia C; Sideridou, Irini D

    2013-08-01

    The purpose of this work was the study of the effect of food/oral simulating liquids on the dynamic mechanical thermal properties (viscoelastic properties) of current commercial dental light-cured resin composites characterized as nanohybrids. These nanohybrids were Grandio, Protofill-nano and Tetric EvoCeram. The properties were determined under dry conditions (1h at 37°C after light-curing) and also after storage in dry air, distilled water, artificial saliva SAGF(®) or ethanol/water solution (75 vol%) at 37°C for up 1, 7, 30 or 90 days. Dynamic mechanical thermal analysis tests were performed on a Diamond Dynamic Mechanical Analyzer in bending mode. A frequency of 1Hz and a temperature range of 25-185°C were applied, while the heating rate of 2°C/min was selected to cover mouth temperature and the materials' likely Tg. Storage modulus, loss modulus and tangent delta were plotted against temperature over this period. The Tg of composites was obtained as the temperature indicated by tanδ peak. Moreover, the maximum height of tanδ peak, the width at the half of tanδ maximum and a parameter known as "ζ" parameter were determined. All composites analyzed 1h after light-curing and 1 day in air or in food/oral simulating liquids showed two Tg. All composites stored for 7, 30 or 90 days in any medium showed unique Tg value. Also among the various properties studied the most sensible in the structural changes of composites seems to be the Tg. Storage of composites in dry air at 37°C which is very close to their Tg (40°C) for 1 or 7 days caused post curing reactions, while storage for 30 or 90 days has no further effect on composites. Storage in water or artificial saliva 37°C for 1 or 7 days caused post curing reactions, while storage for 30 or 90 days seems to cause plasticization effect affecting some parameters analogously. Storage in ethanol/water solution (75vol%) 37°C for 1 or 7 days caused also post curing reactions, while storage for 30 or 90 days

  15. Compact Stokes shift and fluorescence spectroscopic diagnostics LED ratiometer unit with no moving parts for cancer detection

    Science.gov (United States)

    Sordillo, Laura A.; Pu, Yang; Budansky, Yury; Alfano, R. R.

    2012-01-01

    A compact Stokes shift and fluorescence spectroscopy (S3) LED device with no moving parts is presented. This device can be used diagnostically for the identification of the native biomolecules within cancerous tissue samples. This S3-LED ratiometer unit measures both the emission and absorption spectra of key native organic biomolecules within a tissue sample by using multiple wavelength LEDs (light emitting diodes) coupled to an optical fiber. Thus, an optical fingerprint of the sample can be obtained. This technique could be used to distinguish benign and malignant tissues, and to check for residual or recurrent carcinoma after treatment, thus reducing the necessity of second biopsies. The S3-LED ratiometer unit was tested in vitro on human breast malignant and normal paired tissue samples.

  16. Use of a visible light-cured periodontal dressing material as a temporary restoration for inlay/onlay preparations.

    Science.gov (United States)

    Apltauer, James J; Silver, Joel; Friedman, Lawrence J; Resnick, Steven J; Berkowitz, Leonard I; Rochlen, Glenn K; Blye, Jeffrey S; Hershkowitz, David H; Berkowitz, Gary S

    2013-01-01

    There are numerous materials that are used as temporaries for inlay and onlay preparations while the permanent restoration is being made. This article looks at 2 types of temporary materials that were placed into inlay or onlay preparations by student dentists: a methylmethacrylate acrylic material (DuraLay Inlay Pattern Resin) and a visible light-cured (VLC) periodontal surgical dressing (Barricaid). The resilience and effectiveness of both products are compared and evaluated for use as temporary restorations in inlay or onlay preparations. The study found that use of the VLC periodontal dressing material offers a novel technique for a quick and efficient method to provide a temporary restoration for various inlay and onlay preparations.

  17. LED Curing Lights and Temperature Changes in Different Tooth Sites

    Directory of Open Access Journals (Sweden)

    E. Armellin

    2016-01-01

    Full Text Available Objectives. The aim of this in vitro study was to assess thermal changes on tooth tissues during light exposure using two different LED curing units. The hypothesis was that no temperature increase could be detected within the dental pulp during polymerization irrespective of the use of a composite resin or a light-curing unit. Methods. Caries-free human first molars were selected, pulp residues were removed after root resection, and four calibrated type-J thermocouples were positioned. Two LED lamps were tested; temperature measurements were made on intact teeth and on the same tooth during curing of composite restorations. The data was analyzed by one-way analysis of variance (ANOVA, Wilcoxon test, Kruskal-Wallis test, and Pearson’s χ2. After ANOVA, the Bonferroni multiple comparison test was performed. Results. Polymerization data analysis showed that in the pulp chamber temperature increase was higher than that without resin. Starlight PRO, in the same condition of Valo lamp, showed a lower temperature increase in pre- and intrapolymerization. A control group (without composite resin was evaluated. Significance. Temperature increase during resin curing is a function of the rate of polymerization, due to the exothermic polymerization reaction, the energy from the light unit, and time of exposure.

  18. 3D printed UV light cured polydimethylsiloxane devices for drug delivery.

    Science.gov (United States)

    Holländer, Jenny; Hakala, Risto; Suominen, Jaakko; Moritz, Niko; Yliruusi, Jouko; Sandler, Niklas

    2017-11-09

    The goal of this work was to study the printability of PDMS with a semi-solid extrusion printer in combination with the UV-assisted crosslinking technology using UV-LED light to manufacture drug containing structures. Structures with different pore sizes and different drug loadings were prepared containing prednisolone as a model drug. The work showed that it was possible to print drug-free and drug-loaded drug delivery devices of PDMS with the 3D printing technique used in this study. The required UV-curing time to get sufficient crosslinking yield and mechanical strength was minimum three minutes. The microgram drug release from the printed structures was highest for the most drug loaded structures regardless of the porosity of the devices. By altering the surface area/volume ratio it was possible to print structures with differences in the release rate. This study shows that room-temperature semi-solid extrusion printing 3D printing technique in combination with UV-LED crosslinking is an applicable method in the production of prednisolone containing PDMS devices. Both the extrusion 3D printing and the UV-crosslinking was done at room temperature, which make this manufacturing method an interesting alternative for manufacturing controlled release devices containing temperature susceptible drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. [A survey of power density of clinical curing-light units used in Changchun].

    Science.gov (United States)

    Hao, Xin-qing; Luo, Meng; Leng, Xin; Zhu, Song

    2011-09-01

    To investigate the power density and other relevant data of clinical curing-light units used in Changchun, and to provide practice recommendations to clinical dentists about maintaining of cuing-light units. Stomatology hospitals, departments of stomatology in general hospitals, and private dental offices in Changchun were randomly selected to participate in the Survey. The investigation analyzed 270 curing-light units. The following data of curing-light units were gathered: brand, type, operation ages, numbers and types of light guide, resin build-ups on light guides, damages of light guides, use frequency, monitor and maintenance of curing lights, and unit numbers/chair numbers. There were 174 QTH and 96 LED units. The distribution of power density was from 0 to 1702 mW/cm(2). The mean power density was 413.2 mW/cm(2). The power densities of 73 lights were less than 200 mW/cm(2) and could not polymerize resin composites adequately. The mean number of operation age of the light units was 4.74 years. Most of clinical dentists didn't monitor the light-curing units and the situation of build-up from composite resin or damages on light guides was very severe. Most of the light-curing units used in Changchun were QTH. Some QTH units degenerate severely and need to be replaced with the new ones. Most of the clinical doctors lack the knowledge of how to properly monitor and maintain the light-curing units.

  20. Optimizing light-cured composite through variations in camphorquinone and butylhydroxytoluene concentrations.

    Science.gov (United States)

    Nassar, Hani; Chu, Tien-Min; Platt, Jeffrey

    2016-05-20

    The use of a free-radical polymerization inhibitor, butylhydroxytoluene (BHT), and a common photo-initiator, camphorquinone (CQ), to reduce polymerization stress in dental composite was investigated in this study. Samples were prepared by mixing Bis-GMA, UDMA, and TEGDMA at a 1:1:1 ratio (wt%), and silanized borosilicate glass fillers at 70 wt% were added to form the composite. Sixteen groups of resin composite were prepared using combinations of four CQ (0.1%, 0.5%, 1.0%, and 1.5%) and four BHT (0.0%, 0.5%, 1.0%, and 1.5%) concentrations. For each group, six properties were tested, including flexural strength (FS), flexural modulus (FM), degree of conversion (DC), contraction stress (CS), stress rate, and gel point (GP). The effects of CQ and BHT combinations on each of these properties were evaluated using two-way analysis of variance (ANOVA) and Fisher's Protected Least Significant Differences test at the 5% significance level. Groups with low CQ and BHT showed moderate values for FS, FM, and CS with a 70% DC. Increasing the BHT concentration caused a decrease in CS and DC with an increase in GP values. Increasing the CQ content led to a steady increase in values for FS and FM. High CQ and BHT combinations showed the most promising values for mechanical properties with low stress values.

  1. Optimizing light-cured composite through variations in camphorquinone and butylhydroxytoluene concentrations

    Directory of Open Access Journals (Sweden)

    Hani NASSAR

    2016-01-01

    Full Text Available Abstract The use of a free-radical polymerization inhibitor, butylhydroxytoluene (BHT, and a common photo-initiator, camphorquinone (CQ, to reduce polymerization stress in dental composite was investigated in this study. Samples were prepared by mixing Bis-GMA, UDMA, and TEGDMA at a 1:1:1 ratio (wt%, and silanized borosilicate glass fillers at 70 wt% were added to form the composite. Sixteen groups of resin composite were prepared using combinations of four CQ (0.1%, 0.5%, 1.0%, and 1.5% and four BHT (0.0%, 0.5%, 1.0%, and 1.5% concentrations. For each group, six properties were tested, including flexural strength (FS, flexural modulus (FM, degree of conversion (DC, contraction stress (CS, stress rate, and gel point (GP. The effects of CQ and BHT combinations on each of these properties were evaluated using two-way analysis of variance (ANOVA and Fisher’s Protected Least Significant Differences test at the 5% significance level. Groups with low CQ and BHT showed moderate values for FS, FM, and CS with a 70% DC. Increasing the BHT concentration caused a decrease in CS and DC with an increase in GP values. Increasing the CQ content led to a steady increase in values for FS and FM. High CQ and BHT combinations showed the most promising values for mechanical properties with low stress values.

  2. 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.

  3. 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

  4. Water and saliva contamination effect on shear bond strength of brackets bonded with a moisture-tolerant light cure system.

    Science.gov (United States)

    Vicente, Ascensión; Mena, Ana; Ortiz, Antonio José; Bravo, Luis Alberto

    2009-01-01

    To evaluate the effects of water and saliva contamination on shear bond strength of brackets bonded with a moisture-tolerant light cure system. Brackets were bonded to 240 bovine lower incisors divided into 12 groups. Four bonding procedures were evaluated, including (1) TSEP/Transbond XT, (2) TMIP/ Transbond XT, (3) TSEP/Transbond PLUS, and (4) TMIP/Transbond PLUS, each under three different bonding conditions: without contamination, with water contamination, and with saliva contamination. Shear bond strength was measured with a universal testing machine. The adhesive remnant on the teeth was quantified with the use of image analyzing equipment. Without contamination, bond strengths for the four procedures were similar (P > .05). TSEP/Tranbond PLUS and TMIP/Transbond PLUS left significantly less adhesive on the teeth after debonding than TSEP/Transbond XT and TMIP/Transbond XT (P .017), although for TMIP/ Transbond XT, both variables showed significant reductions after contamination (P < .017). TSEP/Transbond PLUS, TMIP/Transbond PLUS, and TSEP/Transbond XT showed greater tolerance to wet conditions than was shown by TMIP/Transbond XT.

  5. Visible Light-Cured Glycol Chitosan Hydrogel Containing a Beta-Cyclodextrin-Curcumin Inclusion Complex Improves Wound Healing In Vivo.

    Science.gov (United States)

    Yoon, Sun-Jung; Hyun, Hoon; Lee, Deok-Won; Yang, Dae Hyeok

    2017-09-10

    Scarless wound healing is ideal for patients suffering from soft tissue defects. In this study, we prepared a novel wet dressing (β-CD-ic-CUR/GC) based on the visible light-cured glycol chitosan (GC) hydrogel and inclusion complex between beta-cyclodextrin (β-CD) and curcumin (CUR). We also evaluated its efficacy in the acceleration of wound healing as compared to that of CUR-loaded GC (CUR/GC). The conjugation of glycidyl methacrylate (GM) to GC for photo-curing was confirmed by ¹H-NMR measurement, and the photo-cured GC hydrogel was characterized by the analyses of rheology, swelling ratio, SEM and degradation rate. After visible light irradiation, the surface/cross-sectional morphologies and storage (G')/loss (G'') moduli revealed the formation of hydrogel with interconnected porosity. The dressing β-CD-ic-CUR/GC exhibited a controlled release of 90% CUR in a sustained manner for 30 days. On the other hand, CUR/GC showed CUR release of 16%. β-CD acted as an excipient in improving the water-solubility of CUR and affected the release behavior of CUR. The in vivo animal tests including measurement of the remaining unhealed wound area and histological analyses showed that β-CD-ic-CUR/GC may have potential as a wet dressing agent to enhance soft tissue recovery in open fractures.

  6. GATEWAY Demonstrations: Tuning Hospital Lighting: Evaluating Tunable LED Lighting at the Swedish Hospital Behavioral Health Unit in Seattle

    Energy Technology Data Exchange (ETDEWEB)

    Wilkerson, Andrea [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Davis, Robert G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Clark, Edward [ZGF Architects LLP, Seattle, WA (United States)

    2017-08-23

    The GATEWAY program evaluated a tunable LED lighting system installed in the new Swedish Medical Behavioral Health Unit in Seattle that incorporates color-tunable luminaires in common areas, and uses advanced controls for dimming and color tuning, with the goal of providing a better environment for staff and patients. The report reviews the design of the tunable lighting system, summarizes two sets of measurements, and discusses the circadian, energy, and commissioning implications as well as lessons learned from the project.

  7. in vitro evaluation of marginal leakage using invasive and noninvasive technique of light cure glass ionomer and flowable polyacid modified composite resin used as pit and fissure sealant

    Directory of Open Access Journals (Sweden)

    Anshu Singla

    2011-01-01

    Full Text Available Aim: This study compared the microleakage of light cure glass ionomer and flowable compomer as pit and fissure sealant, with and without tooth preparation. Materials and Methods: One hundred premolars that were extracted for orthodontic purpose were used. After adequate storage and surface debridement, the teeth were randomly divided into four groups. In Group I and III, the occlusal surfaces were left intact, while in Group II and Group IV, tooth surfaces were prepared. Teeth in Group I and Group II were sealed with Light cure glass ionomer, whereas flowable compomer was used to seal teeth in Group III and IV. The sealed teeth were then immersed in dye. Subsequently, buccolingual sections were made and each section was examined under stereomicroscope for microleakage followed by scoring. Results: In group I, microleakage score ranged from 2 to 4 with mean of 3.64 (±0.757, while in group II the range was observed to be 1-4 with mean of 2.88 (±1.236. Group III recorded a range of 0-4 with the mean of 2.20 (±1.443 while 0-2 and 0.60 (±0.707 being the range and mean observed, respectively, for group IV. Conclusion: Flowable compomer placed after tooth preparation showed better penetration and less marginal leakage than the light cure glass ionomer.

  8. Student perspectives of a Student-Led Groups Program model of professional practice education in a brain injury rehabilitation unit.

    Science.gov (United States)

    Patterson, Freyr; Fleming, Jennifer; Marshall, Kathryn; Ninness, Nadine

    2017-10-01

    Professional practice education is a core and essential component of occupational therapy training. With increasing numbers of education programmes and more students requiring professional practice placements, development of innovative models of professional practice education has emerged, but these require investigation. The aim of this study was to investigate student experiences and perceptions of the Student-Led Groups Program model of professional practice education in an inpatient brain injury rehabilitation unit. A qualitative approach, guided by phenomenological theory was used. Participants were 15 students who had completed a professional practice placement in the Student-Led Groups Program. Data were collected using in-depth semi-structured interviews and analysed thematically. Three over-arching themes emerged from the data; balance of support and freedom, development of clinical skills and missed opportunities. Students described how the structure of the placement facilitated independent learning and autonomy that was balanced with support from clinicians and student peers. Students perceived that they had developed a breadth of clinical skills and also had missed some learning opportunities in this professional practice placement structure. Overall student perceptions of the Student-Led Groups Program were positive, supporting the continued use of this model of professional practice education in this setting. The results highlight the value of structured and consistent approaches for supervision, including the use of formal approaches to peer supervision in the initial stages of learning. © 2017 Occupational Therapy Australia.

  9. Effect of Different Thicknesses of Pressable Ceramic Veneers on Polymerization of Light-cured and Dual-cured Resin Cements

    Science.gov (United States)

    Cho, Seok-Hwan; Lopez, Arnaldo; Berzins, David W.; Prasad, Soni; Ahn, Kwang Woo

    2015-01-01

    Aim This study evaluated the effects of ceramic veneer thicknesses on the polymerization of two different resin cements. Materials and Methods A total of 80 ceramic veneer discs were fabricated by using a pressable ceramic material (e.max Press; Ivoclar Vivadent) from a Low Translucency (LT) ingot (A1 shade). These discs were divided into light-cured (LC; NX3 Nexus LC; Kerr) and dual-cured (DC; NX3 Nexus DC; Kerr) and each group was further divided into 4 subgroups, based on ceramic disc thickness (0.3 mm, 0.6 mm, 0.9 mm, and 1.2 mm). The values of Vickers microhardness (MH) and degree of conversion (DOC) were obtained for each specimen after a 24-hour storage period. Association between ceramic thickness, resin cement type, and light intensity readings (mW/cm2) with respect to microhardness and degree of conversion was statistically evaluated by using ANOVA. Results For the DOC values, there was no significant difference observed among the LC resin cement subgroups, except in the 1.2 mm subgroup; only the DOC value (14.0 ± 7.4%) of 1.2 mm DC resin cement had significantly difference from that value (28.9 ± 7.5%) of 1.2 mm LC resin cement (Presin cement groups, there was statistically significant difference (Presin cement groups demonstrated higher values than DC resin cement groups. On the other hands, among the DC resin cement subgroups, the MH values of 1.2 mm DC subgroup was significantly lower than the 0.3 mm and 0.6 mm subgroups (P.05). Conclusion The degree of conversion and hardness of the resin cement was unaffected with veneering thicknesses between 0.3 and 0.9 mm. However, the DC resin cement group resulted in a significantly lower DOC and MH values for the 1.2 mm subgroup. Clinical Significance While clinically adequate polymerization of LC resin cement can be achieved with a maximum 1.2 mm of porcelain veneer restoration, the increase of curing time or light intensity is clinically needed for DC resin cements at the thickness of more than 0.9 mm

  10. Evaluation of light intensity output of QTH and LED curing devices in various governmental health institutions.

    Science.gov (United States)

    Al Shaafi, Mm; Maawadh, Am; Al Qahtani, Mq

    2011-01-01

    The purpose of this study was to evaluate the light intensity output of quartz-tungsten-halogen (QTH) and light emitting diode (LED) curing devices located at governmental health institutions in Riyadh, Saudi Arabia.Eight governmental institutions were involved in the study. The total number of evaluated curing devices was 210 (120 were QTH and 90 were LED). The reading of the light intensity output for each curing unit was achieved using a digital spectrometer; (Model USB4000 Spectrometer, Ocean Optics Inc, Dunedin, FL, USA). The reading procedure was performed by a single investigator; any recording of light intensity below 300 mW/cm2 was considered unsatisfactory.The result found that the recorded mean values of light intensity output for QTH and LED devices were 260 mW/cm2 and 598 mW/cm2, respectively. The percentage of QTH devices and LED devices considered unsatisfactory was 67.5% and 15.6%, respectively. Overall, the regular assessment of light curing devices using light meters is recommended to assure adequate output for clinical use.

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

    Science.gov (United States)

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

    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 8mm diameter and 2mm thickness were produced and polymerized by 20s 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. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. A psychologist-led educational intervention results in a sustained reduction in neonatal intensive care unit infections.

    Science.gov (United States)

    Van Rostenberghe, Hans; Short, Jacki; Ramli, Noraida; Geok, Tan Beng; Subramaniam, Sivasangari; Che Yaakob, Che Anuar; Othman, Azizah; Ibrahim, Nor Rosidah; Ho, Jacqueline; Mohamed, Zeehaida; Hasan, Habsah

    2014-01-01

    Even though in the corporate world psychological science has been widely used, the formal use of evidence-based psychology in important areas of clinical medicine has been scanty at best. It was the aim of this study to determine the efficacy of a psychologist-led 2-week nurse educator training on the infection rate in the neonatal intensive care unit (NICU). In 2007, six senior neonatal nurses underwent a training course focusing on the retrieval of evidence and knowledge of psychological principles that would allow them to share the evidence in such a way that evidence is effectively brought into practice. The course was led by a psychologist. The nurses created and delivered their own teaching modules, all focused on infection control. The rates of bacteremia, 2 years prior to intervention were analyzed and compared with the rate following the intervention for 3 years. The immediate output of the course included three teaching modules: hand washing, sterile procedures, and general measures to control infection. These modules were subsequently administered to the NICU nurses in regular structured continuous nursing education sessions. The psychological techniques taught in the course were applied. Bacteremia in the NICU significantly decreased in the year of the course and the subsequent years when compared to previous years (from more than 17 in 2005 and 2006 to less than 10 per 100 admissions to the NICU in 2008 and 2009). This study suggests that a psychologist-led course, followed by a structured CNE can lead to a sustainable reduction in infection rates in a NICU.

  13. A comparative evaluation of the marginal adaptation of a thermoplastic resin, a light cured wax and an inlay casting wax on stone dies: Anin vitrostudy.

    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.

  14. A Study of Postwar Japan (1945-1950): What Insights and Lessons Can be Gained From the United States Led Rebirth of Japan

    National Research Council Canada - National Science Library

    Brinson, James D

    2006-01-01

    .... This is a study of the postwar military government and administration of Japan. It will examine the detailed preparation, the initial objectives, and the execution of the occupation by the United States (US)-led forces...

  15. Clinical and radiographic comparison of indirect pulp treatment using light-cured calcium silicate and mineral trioxide aggregate in primary molars: A randomized clinical trial

    OpenAIRE

    Menon, Navya P.; Varma, Balagopal R.; Janardhanan, Sureshkumar; Kumaran, Parvathy; Xavier, Arun Mamachan; Govinda, Bhat Sangeetha

    2016-01-01

    Aim: To clinically and radiographically evaluate the reparative dentin formation in indirect pulp treatment (IPT) using mineral trioxide aggregate (MTA) and light cured calcium silicate (TheraCal) in primary molars over a period of 6 months. Materials and Methods: A clinical trial on IPT on 43 primary molars in 21 patients between the age of 4–7 years, divided into two groups: 22 teeth in MTA group and 21 in TheraCal group. Measurement of the variation in dentin thickness was done on the digi...

  16. Nurse-led implementation of a ventilator-associated pneumonia care bundle in a children's critical care unit.

    Science.gov (United States)

    Hill, Charlotte

    2016-05-09

    Ventilator-associated pneumonia (VAP) is the leading cause of death with hospital-acquired infections, and preventing it is one of the Saving Lives initiatives ( Department of Health 2007 ). This article discusses the implementation of a purpose-designed VAP care bundle in a children's intensive care unit and examines the unique role of nurses in the management of the change process. A nurse-led VAP education, implementation and surveillance programme was set up. Nurse education was paramount, as nursing staff acceptance and involvement was a key feature. A multi-method training strategy was implemented, providing staff with multiple training opportunities and introducing VAP project education as a routine part of staff induction. Bundle compliance was monitored regularly and graphs of the results produced quarterly; feedback proved to be useful in keeping staff informed and engaged in VAP reduction. Comparison of VAP incidence before and after introduction of the care bundle showed a reduction after its implementation. With a co-ordinated, multidisciplinary approach, VAP care bundles can result in significant and sustained reductions in VAP rates in the paediatric intensive care unit. Effective co-ordination and leadership is crucial to successful implementation of the VAP bundle, and nurses are well placed to undertake this role.

  17. 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.

  18. Influence of Curing Units and Indirect Restorative Materials on the Hardness of Two Dual-curing Resin Cements Evaluated by the Nanoindentation Test.

    Science.gov (United States)

    Kuguimiya, Rosiane Noqueira; Rode, Kátia Martins; Carneiro, Paula Mendes Acatauassú; Aranha, Ana Cecilia Corrêa; Turbino, Miriam Lacalle

    2015-06-01

    To evaluate the hardness of a dual-curing self-adhesive resin cement (RelyX U200) and a conventional dual-curing resin cement (RelyX ARC) cured with different light curing units of different wavelengths (Elipar Freelight 2 LED [430 to 480 nm, conventional], Bluephase LED [380 to 515 nm, polywave], AccuCure 3000 Laser [488 nm]) by means of the nanoindentation test. Bovine incisors were cleaned and then sectioned at the cementoenamel junction to remove the crown. After embedding in acrylic, dentin surfaces of the specimens were exposed and ground flat to standardize the surfaces. To simulate clinically placing indirect restorations, ceramic (IPS e.maxPress/Ivoclar Vivadent) or indirect composite resin (SR Adoro/Ivoclar Vivadent) slabs were cemented on dentin surfaces. The specimens were sectioned longitudinally at low speed under constant irrigation and then polished. In the positive control group, the cement was light cured without the interposition of indirect restorative material; in the negative control group, after the indirect restorative material was cemented, no light curing was performed, allowing only chemical polymerization of the cement. All specimens were stored in distilled water at 37°C for 7 days. Nanoindentadion hardness of the cement layer was measured under a 100-mN load. Data were statistically analyzed using ANOVA and Tukey's test (p resin cements evaluated was negatively influenced by the interposition of an indirect restorative material; only the LEDs were able to maintain the same degree of cement polymerization when an indirect restorative material was used. The photoactivation step is required during the cementation of indirect restorations to ensure adequate polymerization of dual-curing resin cements.

  19. LED and Halogen Light Transmission through a CAD/CAM Lithium Disilicate Glass-Ceramic.

    Science.gov (United States)

    Pereira, Carolina Nemesio de Barros; De Magalhães, Cláudia Silami; Daleprane, Bruno; Peixoto, Rogéli Tibúrcio Ribeiro da Cunha; Ferreira, Raquel da Conceição; Cury, Luiz Alberto; Moreira, Allyson Nogueira

    2015-01-01

    The effect of thickness, shade and translucency of CAD/CAM lithium disilicate glass-ceramic on light transmission of light-emitting diode (LED) and quartz-tungsten-halogen units (QTH) were evaluated. Ceramic IPS e.max CAD shades A1, A2, A3, A3.5, high (HT) and low (LT) translucency were cut (1, 2, 3, 4 and 5 mm). Light sources emission spectra were determined. Light intensity incident and transmitted through each ceramic sample was measured to determine light transmission percentage (TP). Statistical analysis used a linear regression model. There was significant interaction between light source and ceramic translucency (p=0.008) and strong negative correlation (R=-0.845, pceramic thickness and TP. Increasing one unit in thickness led to 3.17 reduction in TP. There was no significant difference in TP (p=0.124) between shades A1 (ß1=0) and A2 (ß1=-0.45) but significant reduction occurred for A3 (ß1=-0.83) and A3.5 (ß1=-2.18). The interaction QTH/HT provided higher TP (ß1=0) than LED/HT (ß1=-2.92), QTH/LT (ß1=-3.75) and LED/LT (ß1=-5.58). Light transmission was more effective using halogen source and high-translucency ceramics, decreased as the ceramic thickness increased and was higher for the lighter shades, A1 and A2. From the regression model (R2=0.85), an equation was obtained to estimate TP value using each variable ß1 found. A maximum TP of 25% for QTH and 20% for LED was found, suggesting that ceramic light attenuation could compromise light cured and dual cure resin cements polymerization.

  20. Evaluating Maternity Units: a prospective cohort study of freestanding midwife-led primary maternity units in New Zealand-clinical outcomes.

    Science.gov (United States)

    Grigg, Celia P; Tracy, Sally K; Tracy, Mark; Daellenbach, Rea; Kensington, Mary; Monk, Amy; Schmied, Virginia

    2017-08-29

    To compare maternal and neonatal birth outcomes and morbidities associated with the intention to give birth in a freestanding primary level midwife-led maternity unit (PMU) or tertiary level obstetric-led maternity hospital (TMH) in Canterbury, Aotearoa/New Zealand. Prospective cohort study. 407 women who intended to give birth in a PMU and 285 women who intended to give birth at the TMH in 2010-2011. All of the women planning a TMH birth were 'low risk', and 29 of the PMU cohort had identified risk factors. Mode of birth, Apgar score of less than 7 at 5 min and neonatal unit admission. labour onset, analgesia, blood loss, third stage of labour management, perineal trauma, non-pharmacological pain relief, neonatal resuscitation, breastfeeding, gestational age at birth, birth weight, severe morbidity and mortality. Women who planned a PMU birth were significantly more likely to have a spontaneous vaginal birth (77.9%vs62.3%, adjusted OR (AOR) 1.61, 95% CI 1.08 to 2.39), and significantly less likely to have an instrumental assisted vaginal birth (10.3%vs20.4%, AOR 0.59, 95% CI 0.37 to 0.93). The emergency and elective caesarean section rates were not significantly different (emergency: PMU 11.6% vs TMH 17.5%, AOR 0.88, 95% CI 0.55 to 1.40; elective: PMU 0.7% vs TMH 2.1%, AOR 0.34, 95% CI 0.08 to 1.41). There were no significant differences between the cohorts in rates of 5 min Apgar score of maternity units as physically safe places for well women to plan to give birth, with these women having higher rates of spontaneous vaginal births and lower rates of interventions and their associated morbidities than those who planned a tertiary hospital birth, with no differences in neonatal outcomes. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  1. Patient and Family Member-Led Research in the Intensive Care Unit: A Novel Approach to Patient-Centered Research.

    Science.gov (United States)

    Gill, Marlyn; Bagshaw, Sean M; McKenzie, Emily; Oxland, Peter; Oswell, Donna; Boulton, Debbie; Niven, Daniel J; Potestio, Melissa L; Shklarov, Svetlana; Marlett, Nancy; Stelfox, Henry T

    2016-01-01

    Engaging patients and family members as partners in research increases the relevance of study results and enhances patient-centered care; how to best engage patients and families in research is unknown. We tested a novel research approach that engages and trains patients and family members as researchers to see if we could understand and describe the experiences of patients admitted to the intensive care unit (ICU) and their families. Former patients and family members conducted focus groups and interviews with patients (n = 11) and families of surviving (n = 14) and deceased (n = 7) patients from 13 ICUs in Alberta Canada, and analyzed data using conventional content analysis. Separate blinded qualitative researchers conducted an independent analysis. Participants described three phases in the patient/family "ICU journey"; admission to ICU, daily care in ICU, and post-ICU experience. Admission to ICU was characterized by family shock and disorientation with families needing the presence and support of a provider. Participants described five important elements of daily care: honoring the patient's voice, the need to know, decision-making, medical care, and culture in ICU. The post-ICU experience was characterized by the challenges of the transition from ICU to a hospital ward and long-term effects of critical illness. These "ICU journey" experiences were described as integral to appropriate interactions with the care team and comfort and trust in the ICU, which were perceived as essential for a community of caring. Participants provided suggestions for improvement: 1) provide a dedicated family navigator, 2) increase provider awareness of the fragility of family trust, 3) improve provider communication skills, 4) improve the transition from ICU to hospital ward, and 5) inform patients about the long-term effects of critical illness. Analyses by independent qualitative researchers identified similar themes. Patient and family member-led research is feasible and can

  2. Student-Led Services in a Hospital Aged Care Temporary Stay Unit: Sustaining Student Placement Capacity and Physiotherapy Service Provisions

    Science.gov (United States)

    Nicole, Madelyn; Fairbrother, Michele; Nagarajan, Srivalli Vilapakkam; Blackford, Julia; Sheepway, Lyndal; Penman, Merrolee; McAllister, Lindy

    2015-01-01

    Through a collaborative university-hospital partnership, a student-led service model (SLS-model) was implemented to increase student placement capacity within a physiotherapy department of a 150 bed Sydney hospital. This study investigates the perceived barriers and enablers to increasing student placement capacity through student-led services…

  3. 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.

  4. Comparative evaluation for microleakage between Fuji-VII glass ionomer cement and light-cured unfilled resin: A combined in vivo in vitro study

    Directory of Open Access Journals (Sweden)

    Ashwin R

    2007-06-01

    Full Text Available Glass ionomer cement, besides being used as restorative material, can also be used as pit and fissure sealant. The use of glass ionomer cement as pit and fissure sealant has added benefit by its fluoride-releasing property that results in increased resistance of the fissures to demineralize. The capacity of a sealant to prevent microleakage into the fissure is important, since microleakage may initiate and support a carious lesion beneath the sealant. The study was carried out to compare marginal microleakage between Fuji-VII glass ionomer cement (G C Corporation, Tokyo, Japan and the conventional light-cured unfilled resin as pit and fissure sealants (3M Concise, 3M Dental Products, St. Paul, USA. The dye used was 2% methylene blue (Qualigens Fine Chemicals, Mumbai, India. The teeth were sectioned and studied under the stereomicroscope. The result revealed that there was no difference in microleakage ( P > 0.05 between the two materials.

  5. Assessment of changes in color and color parameters of light-cured composite resin after alternative polymerization methods.

    Science.gov (United States)

    Karaarslan, Emine Sirin; Bulbul, Mehmet; Ertas, Ertan; Cebe, Mehmet Ata; Usumez, Aslihan

    2013-01-01

    To examine the amount of change in color and color parameters of a composite resin (Filtek P60) polymerized by five different polymerization methods. A Teflon mold (6mm in diameter, 2mm in height) was used to prepare the composite resin discs (n=10). G1: Polymerization with inlay oven; G2: Polymerization with HQTH and autoclave; G3: Polymerization with LED and autoclave; G4: Polymerization with HQTH; G5: Polymerization with LED. Colorimetric values of the specimens before and after polymerization were measured using a spectrophotometer. The CIE L*a*b color system was used for the determination of color difference. Analysis of variance (ANOVA) was used to analyze the data for significant differences. Tukey's HSD test and paired two-tailed tests were used to perform multiple comparisons (α=.05). There were no significant differences in total color change (ΔE*ab) among the polymerization groups (P>.05). However, the lowest color change (ΔE*ab) value was 3.3 in LED and autoclave; the highest color change (ΔE*ab) value was 4.6 in HQTH. For all groups, CIE L*, C*ab and a*values decreased after polymerization (PComposite resin material showed color changes above the clinically accepted value in all study groups (ΔE*ab⩾3.3). All specimens became darker during investigation (ΔL*< 0). Specimens polymerized with inlay oven presented the highest Δb* values which means less yellow color in specimens.

  6. Comparison of the Dentin Bond Strength of Two Self-Etch Adhesives After Prolonged Air-Drying and Additional Light-Curing.

    Science.gov (United States)

    Samimi, Pouran; Ghodrati, Masoud; Shirban, Farinaz; Khoroushi, Maryam

    2017-09-01

    It has been reported that the water, solvents, or the primer incorporated into adhesive resins decrease the polymerization, compromise the mechanical properties, reduce the bond strength, and lead to a poor bonding performance of self-etch adhesives. This article evaluated the effect of air-drying and light-curing duration of self-etch adhesives on the micro-shear bond strength between composite resin and dentin. A total of 120 extracted sound human third molars were randomly divided into twelve groups (n=10). The occlusal dentin in each tooth was exposed. Clearfil SE Bond (CSEB) and Clearfil S3 Bond (CS3B) were used according to the manufacturer's instructions, followed by air-drying for 3 and 10 seconds in different groups. The adhesives were light-cured for 10, 20 and 40 seconds in different subgroups. Next, the composite resin (Clearfil AP-X) was placed on the dentin surface and was polymerized for 40 seconds. The micro-shear bond strength values were determined using a universal testing machine, and the results were statistically analyzed by three-way ANOVA and Tukey's post-hoc test (α=0.05). CSEB exhibited a significantly higher dentin bond strength than CS3B. Increasing the curing time of CSEB resulted in an increase in the bond strength, whereas an increase in the air-drying time did not affect the bond strength of the two adhesives. Within the limitations of this study, an increase in the curing time improved the bond strength of CSEB, whereas the air-drying time did not affect the bond strength of the evaluated adhesives.

  7. In-vitro bond strengths and clinical failure rates of metal brackets bonded with different light-emitting diode units and curing times.

    Science.gov (United States)

    Oz, Abdullah Alper; Oz, Aslıhan Zeynep; Arici, Selim

    2016-02-01

    The purpose of this study was to compare the clinical failure rates and the in-vitro bond strengths of metal brackets bonded with different light-emitting diode (LED) devices and curing times. Forty patients were included in the clinical part of this study. A split-mouth design was used, with the adhesive in group 1 cured for 10 seconds with an LED unit (Elipar S10; 3M Unitek, Monrovia, Calif), and the adhesive in group 2 cured for 3 seconds with another LED unit (VALO Ortho; Ultradent Products, South Jordan, Utah). Bond failures during 12 months of orthodontic treatment were recorded. In-vitro performance of the brackets was also compared by bonding brackets to extracted premolars and using the same light units and curing times (n = 20 for each group). The adhesive remnant index was used to determine the bond failure interface. Clinical bond failure rates were 2.90% for the Elipar and 3.16% for the VALO curing units. The difference in bracket failure rates between the 2 LED devices was not statistically significant. No statistically significant difference was found between the in-vitro bond strengths of the groups. Our findings regarding long-term clinical survival rates and in-vitro bond strengths indicate that bracket bonding can be safely accomplished in 10 seconds of light-curing with an Elipar LED and 3 seconds of light-curing with a VALO LED. Copyright © 2016 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

  8. Effects of blue diode laser (445 nm) and LED (430-480 nm) radiant heat treatments on dental glass ionomer restoratives

    Science.gov (United States)

    Dionysopoulos, Dimitrios; Tolidis, Kosmas; Strakas, Dimitrios; Gerasimou, Paris; Sfeikos, Thrasyvoulos; Gutknecht, Norbert

    2018-02-01

    The purpose of this in vitro study was to evaluate the effect of two radiant heat treatments on water sorption, solubility and surface roughness of three conventional glass ionomer cements by using a blue diode laser (445 nm) and a light emitting diode (LED) unit (430-480 nm). Thirty disk-shaped specimens were prepared for each tested GIC (Equia Fil, Ketac Universal Aplicap and Riva Self Cure). The experimental groups (n = 10) of the study were as follows: Group 1 was the control group, in Group 2 the specimens were irradiated for 60 s at the top surface using a LED light-curing unit and in Group 3 the specimens were irradiated for 60 s at the top surface using a blue light diode laser. Statistical analysis was performed using one-way ANOVA and Tukey post hoc tests at a level of significance of a = 0.05. Radiant heat treatments with both laser and LED devices significantly decreased water sorption and solubility (p tested GICs. Blue diode laser treatment was seemed to be more effective compared to LED treatment for some of the tested materials. There were no changes in surface roughness of the GICs after the treatments (p > 0.05). Among the tested materials there were differences in water sorption and solubility (p 0.05). The use of the blue diode laser for this radiant heat treatment was harmless for the surface of the tested GICs and may be advantageous for the longevity of their restorations.

  9. High power light emitting diode (LED) arrays versus halogen light polymerization of oral biomaterials: Barcol hardness, compressive strength and radiometric properties.

    Science.gov (United States)

    Mills, Robin W; Uhl, Alexander; Blackwell, Gordon B; Jandt, Klaus D

    2002-07-01

    The clinical performance of light polymerized dental composites is greatly influenced by the quality of the light curing unit (LCU) used. Commonly used halogen LCUs have some specific drawbacks such as decreasing light output with time. This may result in a low degree of monomer conversion of the composites with negative clinical implications. Previous studies have shown that blue light emitting diode (LED) LCUs have the potential to polymerize dental composites without having the drawbacks of halogen LCUs. Since these studies were carried out LED technology has advanced significantly and commercial LED LCUs are now becoming available. This study investigates the Barcol hardness as a function of depth, and the compressive strength of dental composites that had been polymerized for 40 or 20s with two high power LED LCU prototypes, a commercial LED LCU, and a commercial halogen LCU. In addition the radiometric properties of the LCUs were characterized. The two high power prototype LED LCUs and the halogen LCU showed a satisfactory and similar hardness-depth performance whereas the hardness of the materials polymerized with the commercial LED LCU rapidly decreased with sample depth and reduced polymerization time (20 s). There were statistically significant differences in the overall compressive strengths of composites polymerized with different LCUs at the 95% significance level (p = 0.0016) with the two high power LED LCU prototypes and the halogen LCU forming a statistically homogenous group. In conclusion, LED LCU polymerization technology can reach the performance level of halogen LCUs. One of the first commercial LED LCUs however lacked the power reserves of the high power LED LCU prototypes.

  10. Effects of light intensity and curing time of the newest LED Curing units on the diametral tensile strength of microhybrid composite resins

    Science.gov (United States)

    Ariani, D.; Herda, E.; Eriwati, Y. K.

    2017-08-01

    The aim of this study was to evaluate the influence of light intensity and curing time of the latest LED curing units on the diametral tensile strength of microhybrid composite resins. Sixty-three specimens from three brands (Polofil Supra, Filtek Z250, and Solare X) were divided into two test groups and one control group. The test groups were polymerized with a Flashmax P3 LED curing unit for one or three seconds. The control group was polymerized with a Ledmax 450 curing unit with the curing time based on the resin manufacturer’s instructions. A higher light intensity and shorter curing time did not influence the diametral tensile strength of microhybrid composite resins.

  11. In vitro study of mean loads and modes of failure of all-ceramic crowns cemented with light-cured or dual-cured luting cement, after 1 and 30 d of storage.

    Science.gov (United States)

    Good, Melissa-L; Orr, John F; Mitchell, Christina A

    2008-02-01

    This study compared the mean loads and modes of failure of teeth restored with all-ceramic crowns (ACCs) cemented with dual-cured (RelyX ARC; 3M ESPE) or light-cured (RelyX Veneer; 3M ESPE) luting cements. Clinically, there are advantages of light-cured cements over the recommended dual-cured cements, namely increased working time, improved handling, colour stability, and a homogenous mix. Forty, sound, extracted, human, premolar teeth underwent a standardized preparation for ACCs. IPS Empress (Ivoclar-Vivadent) crowns of standard dimensions were fabricated and 20 were cemented with each cement. The crowns were stored for 1 or 30 d in water and subjected to a compressive load to failure at 0.017 mm s(-1). There were no significant differences in loads at failure, between each cement group, at each storage period, and there were no significant differences in loads at failure, for each cement, at 1 and 30 d of storage. There were also no significant differences in modes of failure between each cement group. Before recommending light-cured cement as an alternative to dual-cured cement for the cementation of all-ceramic crowns, further research is required to establish the depth of ceramic at which light-cured lutes fail to polymerize completely.

  12. 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

  13. Synthesis and study of physical properties of dental light-cured nanocomposites using different amounts of a urethane dimethacrylate trialkoxysilane coupling agent.

    Science.gov (United States)

    Karabela, Maria M; Sideridou, Irini D

    2011-11-01

    The purpose of this work was the study of the effect of the amount of a urethane dimethacrylate silane (UDMS) coupling agent on physical properties of dental light-cured resin nanocomposites based on Bis-GMA/TEGDMA (50/50 wt/wt) matrix and Aerosil OX50 as filler. Silica nanoparticles (Aerosil OX 50) used as filler were silanized with 5 different amounts of UDMS 1.0, 2.5, 5.0, 7.5 and 10 wt% relative to silica. The silanizated silica nanoparticles were identified by FT-IR spectroscopy and thermogravimetric analysis (TGA). Then the silanized nanoparticles (60 wt%) were mixed with a Bis-GMA/TEGDMA (50/50 wt/wt) matrix. Degree of conversion of light cured composites was determined by FT-IR analysis. The static flexural strength and flexural modulus were measured using a three-point bending set up. The dynamic thermomechanical properties were determined by DMA analyzer. Measurements were taken in samples stored, immediately after curing, in water at 37°C for 24 h. Sorption, solubility and volumetric change were determined after storage of composites in water or ethanol/water of 75 vol% for 30 days. Thermogravimetric analysis of composites was performed in nitrogen atmosphere from 50 to 800°C. Almost all of used amount of silane remained chemically bounded on the surface of silica particles, forming a layer around them, which have dense accumulation of methacrylate groups. No significant statistic difference was found to exist between the degree of conversion values of composites with different silane contents. The composite with the lowest amount of UDMS (1.0 wt%) showed the lower flexural strength value, the higher static and dynamic elastic modulus values and the higher sorbed liquid value and solubility. The optimum concentration of UDMS seems to be that of 2.5 wt%. Higher concentrations of UDMS did not improve the properties of composites. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  14. In vitro evaluation of microleakage under ceramic and metal brackets bonded with LED and plasma arc curing.

    Science.gov (United States)

    Davari, Abdolrahim; Yassaei, Soghra; Karandish, Mariam; Zarghami, Fateme

    2012-09-01

    The aim of the present study was to evaluate these two high intensity light curing units regarding microleakage beneath metal and ceramic brackets. A total of 60 freshly extracted human premolar teeth were randomly divided into four groups of 15 samples; group I: Metal bracket + LED cured, group II: Ceramic bracket + LED cured, group III: Metal bracket + plasma arc cured, group IV: Ceramic bracket + plasma arc cured. After photopolymerization, the teeth were immersed in water and thermocycled (500 cycles between 5 and 55). Specimens were further sealed with nail varnish and stained with 5% basic fuchsin for 24 hours. All of the teeth were sectioned with two parallel longitudinal occlusogingival cuts and examined under a stereomicroscope. The microleakage was measured with a digital caliper and scored from 0 to 3 for marginal microleakage at the bracket-adhesive and adhesive-enamel interfaces from both the occlusal and gingival margins. Microleakage was detected in all groups. The plasma arc cured group showed less microleakage than light emitting diode (LED) cured in all samples at the enamel-adhesive interface at the gingival margin (ceramic brackets, p = 0.009 and metal brackets, p = 0.005). The plasma arc cured samples showed less microleakage than LED cured in metal brackets at the adhesive-brackets interface at the occlusal margin (p = 0.033). While curing with an LED unit, ceramic brackets displayed significantly less microleakage than metal ones at the gingival margin of adhesive-enamel interface (p = 0.013). The gingival margin in all groups exhibited higher microleakage compared with those observed in occlusal sides in all sample groups (p white spot lesions beneath the bracket base.

  15. 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.

  16. Clinical and radiographic comparison of indirect pulp treatment using light-cured calcium silicate and mineral trioxide aggregate in primary molars: A randomized clinical trial.

    Science.gov (United States)

    Menon, Navya P; Varma, Balagopal R; Janardhanan, Sureshkumar; Kumaran, Parvathy; Xavier, Arun Mamachan; Govinda, Bhat Sangeetha

    2016-01-01

    To clinically and radiographically evaluate the reparative dentin formation in indirect pulp treatment (IPT) using mineral trioxide aggregate (MTA) and light cured calcium silicate (TheraCal) in primary molars over a period of 6 months. A clinical trial on IPT on 43 primary molars in 21 patients between the age of 4-7 years, divided into two groups: 22 teeth in MTA group and 21 in TheraCal group. Measurement of the variation in dentin thickness was done on the digitalized radiograph at baseline, 3 months and 6 months using CorelDRAW X3 software. Statistical analysis using an independent t -test for intragroup and intergroup comparison showed a significant increase in dentin thickness in both the MTA and TheraCal group (intragroup comparison [ P TheraCal showed no statistical difference in reparative dentin formation ( P > 0.05). Clinically and radiographically, both MTA and TheraCal are good IPT materials. The better handling characteristics and comparable reparative dentin-forming ability of TheraCal make this material an alternative to MTA in pediatric restorative procedures.

  17. Clinical and radiographic comparison of indirect pulp treatment using light-cured calcium silicate and mineral trioxide aggregate in primary molars: A randomized clinical trial

    Directory of Open Access Journals (Sweden)

    Navya P Menon

    2016-01-01

    Full Text Available Aim: To clinically and radiographically evaluate the reparative dentin formation in indirect pulp treatment (IPT using mineral trioxide aggregate (MTA and light cured calcium silicate (TheraCal in primary molars over a period of 6 months. Materials and Methods: A clinical trial on IPT on 43 primary molars in 21 patients between the age of 4–7 years, divided into two groups: 22 teeth in MTA group and 21 in TheraCal group. Measurement of the variation in dentin thickness was done on the digitalized radiograph at baseline, 3 months and 6 months using CorelDRAW X3 software. Results: Statistical analysis using an independent t-test for intragroup and intergroup comparison showed a significant increase in dentin thickness in both the MTA and TheraCal group (intragroup comparison [P 0.05. Conclusion: Clinically and radiographically, both MTA and TheraCal are good IPT materials. The better handling characteristics and comparable reparative dentin-forming ability of TheraCal make this material an alternative to MTA in pediatric restorative procedures.

  18. Clinical and radiographic comparison of indirect pulp treatment using light-cured calcium silicate and mineral trioxide aggregate in primary molars: A randomized clinical trial

    Science.gov (United States)

    Menon, Navya P.; Varma, Balagopal R.; Janardhanan, Sureshkumar; Kumaran, Parvathy; Xavier, Arun Mamachan; Govinda, Bhat Sangeetha

    2016-01-01

    Aim: To clinically and radiographically evaluate the reparative dentin formation in indirect pulp treatment (IPT) using mineral trioxide aggregate (MTA) and light cured calcium silicate (TheraCal) in primary molars over a period of 6 months. Materials and Methods: A clinical trial on IPT on 43 primary molars in 21 patients between the age of 4–7 years, divided into two groups: 22 teeth in MTA group and 21 in TheraCal group. Measurement of the variation in dentin thickness was done on the digitalized radiograph at baseline, 3 months and 6 months using CorelDRAW X3 software. Results: Statistical analysis using an independent t-test for intragroup and intergroup comparison showed a significant increase in dentin thickness in both the MTA and TheraCal group (intragroup comparison [P MTA and TheraCal showed no statistical difference in reparative dentin formation (P > 0.05). Conclusion: Clinically and radiographically, both MTA and TheraCal are good IPT materials. The better handling characteristics and comparable reparative dentin-forming ability of TheraCal make this material an alternative to MTA in pediatric restorative procedures. PMID:27994414

  19. A comparative study to evaluate the effect of fluoride releasing sealant cured by visible light, argon laers, and light emitting diode curing units: An in vitro study

    Directory of Open Access Journals (Sweden)

    Das U

    2009-09-01

    Full Text Available In Pediatric Dentistry, the use of pit and fissure sealant is one of the essential forms of prevention. Pit and fissure caries may be substantially decreased by obliteration of these developmental defects in occlusal, buccal and lingual surfaces with resin based dental sealants. Visible light-curing units, or LCUs, are an integral part of modern adhesive dentistry" They are used to cure resin based composite restoration materials, resin modified glass-ionomer and pit and fissure sealants, as well as to bond orthodontic teeth. Most recently, the argon laser has been approved for initiating the setting reaction with visible light cured-resins. Argon curing of resin materials has been show to enhance the physical properties and degree of polymerization of the resin, while reducing the polymerization time by 75 percent. The study is undertaken considering the inadequate research reports of regarding the comparison of curing ability using argon laser. LEDs and visible light as well as the resistant towards caries activity of the preventive fluoride releasing pit and fissure sealant cured by above mentioned curing units.

  20. Marginal seal of composite resin restorations photo activated by L.E.D. and halogen-based light

    OpenAIRE

    Pineda Mejía, Martha Elena; Dpto. Acad. Estomatología Rehabilitadora. Fac. Odontologia. Universidad Nacional Mayor de San Marcos.; Terán Casafranca, Liliana Ángela; Dpto. Acad. Estomatología Rehabilitadora. Fac. Odontologia. Universidad Nacional Mayor de San Marcos.; Gloria Zevallos, Waldo Ernesto; Dpto. Acad. Estomatología Rehabilitadora. Fac. Odontologia. Universidad Nacional Mayor de San Marcos.; Cuadrao Zavaleta, Luis Alberto; Dpto. Acad. Ciencias Básicas. Fac. Odontologia. Universidad Nacional Mayor de San Marcos.

    2014-01-01

    Objective: to compare in vitro the marginal seal degree of composite resin restorations photopolomerized with L.E.D light and conventional halogen light, was the objective of this research.It was used 20 healthy molars recently extracted, in each of them, standardized dimensions class V cavities were prepared in the buccal and palatal aspects. Both cavities were filled with nanoparticles composite resin, Filteck Z350 and Single Bond adhesive (3M). Vestibular restaurations were light cured usi...

  1. LED lamp

    Science.gov (United States)

    Galvez, Miguel; Grossman, Kenneth; Betts, David

    2013-11-12

    There is herein described a lamp for providing white light comprising a plurality of light sources positioned on a substrate. Each of said light sources comprises a blue light emitting diode (LED) and a dome that substantially covers said LED. A first portion of said blue light from said LEDs is transmitted through said domes and a second portion of said blue light is converted into a red light by a first phosphor contained in said domes. A cover is disposed over all of said light sources that transmits at least a portion of said red and blue light emitted by said light sources. The cover contains a second phosphor that emits a yellow light in response to said blue light. The red, blue and yellow light combining to form the white light and the white light having a color rendering index (CRI) of at least about 80.

  2. Indigenous Youth Peer-Led Health Promotion in Canada, New Zealand, Australia, and the United States: A Systematic Review of the Approaches, Study Designs, and Effectiveness.

    Science.gov (United States)

    Vujcich, Daniel; Thomas, Jessica; Crawford, Katy; Ward, James

    2018-01-01

    Youth peer-led interventions have become a popular way of sharing health information with young people and appear well suited to Indigenous community contexts. However, no systematic reviews focusing on Indigenous youth have been published. We conducted a systematic review to understand the range and characteristics of Indigenous youth-led health promotion projects implemented and their effectiveness. A systematic search of Medline, Embase, and ProQuest Social Sciences databases was conducted, supplemented by gray literature searches. Included studies focused on interventions where young Indigenous people delivered health information to age-matched peers. Twenty-four studies were identified for inclusion, based on 20 interventions (9 Australian, 4 Canadian, and 7 from the United States of America). Only one intervention was evaluated using a randomized controlled study design. The majority of evaluations took the form of pre-post studies. Methodological limitations were identified in a majority of studies. Study outcomes included improved knowledge, attitude, and behaviors. Currently, there is limited high quality evidence for the effectiveness of peer-led health interventions with Indigenous young people, and the literature is dominated by Australian-based sexual health interventions. More systematic research investigating the effectiveness of peer-led inventions is required, specifically with Indigenous populations. To improve health outcomes for Indigenous youth, greater knowledge of the mechanisms and context under which peer-delivered health promotion is effective in comparison to other methods of health promotion is needed.

  3. Clinical long-term success of contemporary nano-filled resin composites in class I and II restorations cured by LED or halogen light.

    Science.gov (United States)

    Pflaum, Torsten; Kranz, Stefan; Montag, Regina; Güntsch, Arndt; Völpel, Andrea; Mills, Robin; Jandt, Klaus; Sigusch, Bernd

    2017-10-28

    The use of LED light-curing units (LED LCUs) for polymerising resin-based composite restorations has become widespread throughout dentistry. Unfortunately, there is a paucity of clinical longitudinal studies that evaluate the comparative efficacy of LED-based polymerisation in direct posterior composite restorations. The aim of the present study was to investigate the performance of class I and II resin composite restorations for two successful composite restorative materials cured with LED versus halogen LCUs. One hundred restorations were placed using the nano-filled composites Grandio® or Filtek™ Supremé. The following test groups were established: LED-Grandio® n = 23 (LG), LED-Filtek™ Supremé n = 21 (LS). As controls were used: Halogen-Grandio® n = 28 (HG), Halogen-Filtek™ Supremé n = 28 (HS). All restorations were evaluated according to the clinical criteria of the CPM index (C-criteria) at baseline and after 6, 12 and 36 months. After 12 and 36 months, there were no significant differences between restorations polymerised with LED or halogen light. At the end of the study, 97% of the restorations showed sufficient results regardless of the employed LCU or composite. Globally, after 36 months, 56% of all restorations were assessed with code 0 (excellent) and 41% with code 1 (acceptable). In detail, excellent results (code 0) among the criteria surface quality; marginal integrity and marginal discoloration were assigned in 72, 70 and 69%. For the current limitations in the clinical trial design, the results showed that LED-polymerisation is appropriate to ensure clinical success of direct posterior resin composite restorations in a range of 3 years. The choice of LCU has no significant influence on the clinical performance of posterior direct resin composite restorations within 3 years of wear.

  4. Fit accuracy of metal partial removable dental prosthesis frameworks fabricated by traditional or light curing modeling material technique: An in vitro study

    Science.gov (United States)

    Anan, Mohammad Tarek M.; Al-Saadi, Mohannad H.

    2015-01-01

    Objective The aim of this study was to compare the fit accuracies of metal partial removable dental prosthesis (PRDP) frameworks fabricated by the traditional technique (TT) or the light-curing modeling material technique (LCMT). Materials and methods A metal model of a Kennedy class III modification 1 mandibular dental arch with two edentulous spaces of different spans, short and long, was used for the study. Thirty identical working casts were used to produce 15 PRDP frameworks each by TT and by LCMT. Every framework was transferred to a metal master cast to measure the gap between the metal base of the framework and the crest of the alveolar ridge of the cast. Gaps were measured at three points on each side by a USB digital intraoral camera at ×16.5 magnification. Images were transferred to a graphics editing program. A single examiner performed all measurements. The two-tailed t-test was performed at the 5% significance level. Results The mean gap value was significantly smaller in the LCMT group compared to the TT group. The mean value of the short edentulous span was significantly smaller than that of the long edentulous span in the LCMT group, whereas the opposite result was obtained in the TT group. Conclusion Within the limitations of this study, it can be concluded that the fit of the LCMT-fabricated frameworks was better than the fit of the TT-fabricated frameworks. The framework fit can differ according to the span of the edentate ridge and the fabrication technique for the metal framework. PMID:26236129

  5. Comparison of Bond Strength of Brackets with Foil Mesh and Laser Structure Base using Light Cure Composite Resin: An in vitro Study.

    Science.gov (United States)

    Rajesh, R N G; Girish, K S; Sanjay, N; Scindhia, Rajath D; Kumar, Sujay G; Rajesh, Suchitra

    2015-12-01

    The purpose of this in vitro study was to evaluate the bond strength of the laser-etched base bracket, site of bond failure, and evaluate for enamel remnants on the bracket base after debonding, when compared to foil mesh base bracket. Sixty noncarious, human premolar extracted for the orthodontic treatment were used for this study. The teeth were randomly divided into two groups containing 30 teeth each, which were bonded with laser-etched base bracket and mesh base bracket using light cure resin. The tensile and mechanical bond strength was tested after 24 hours using TIRA. The forces recorded during debonding were measured in Newton and final readings were tabulated in megapascals (MPa). After debonding, the amount of residual adhesive and enamel detachment on the bracket base were assessed according to adhesive remnant index (ARI) and enamel detachment index (EDI) using stereomicroscope and energy dispersive X-ray spectrometer. The laser-etched base bracket showed statistically significant higher results than mesh base bracket. Mann-Whitney test indicated that laser-etched base bracket had significantly higher tensile bond strength of 8.47 MPa (SD ± 0.84), fatigue strength of 7.75 MPa (SD ± 0.79) compared to mesh base bracket with tensile bond strength of 5.53 Mpa (SD ± 0.89) and fatigue strength of 5.17 MPa (SD ± 1.15). Adhesive remnant index score indicated that laser-etched base bracket had ARI score of 3 for most of the bracket, when compared to mesh base bracket. This was statistically significant. Enamel detachment index scores indicated that less than 10% of enamel detachment occurred in both the types of brackets, which was not statistically significant. Laser-etched base bracket showed superior bond strength, when compared to the foil mesh base bracket. The site of bond failure of these laser-etched base bracket was at the interface of enamel-adhesive and did not induce any significant enamel detachment. Thus, we can conclude that laser-etched base

  6. Biaxial Flexural Strength of High-Viscosity Glass-Ionomer Cements Heat-Cured with an LED Lamp during Setting

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    Gustavo Fabián Molina

    2013-01-01

    Full Text Available Adding heat to glass ionomers during setting might improve mechanical properties. The aim was to compare the biaxial flexural strength (BFS between and within four glass ionomers, by time of exposure to a high-intensity LED light-curing unit. Materials and methods. Samples of Fuji 9 Gold Label, Ketac Molar Easymix, ChemFil Rock, and the EQUIA system were divided into three treatment groups (n=30: without heating (Group 1, heated with LED lamp of 1400 mW/cm2 for 30 s while setting (Group 2, and heated with LED lamp of 1400 mW/cm2 for 60 s while setting (Group 3. Samples were stored for 48 hours in distilled water at 37°C until tested. BFS was tested, using a universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed, using ANOVA test with the Bonferroni correction (α=0.05. Heating the glass-ionomer cements with an LED curing light of 1400 mW/cm2 during setting for 30 s increased the BFS value of all GICs. No statistically significant difference in mean BFS scores was found between the EQUIA system and ChemFil Rock at 30 s and 60 s. The mean BFS value was statistically significantly higher for the EQUIA system and ChemFil Rock than for Fuji 9 Gold Label and Ketac Molar Easymix at all exposure times.

  7. Bond strength of Epiphany™ Sealer combined with different adhesive systems photo-activated with LED and QTH

    Science.gov (United States)

    Minto, A. M. P.; Bandéca, M. C.; Borges, A. H.; Nadalin, M. R.; Thomé, L. H. C.

    2009-08-01

    The Epiphany™ Sealer is a new dual-curing resin-based sealer and has been introduced as an alternative to gutta-percha and traditional root canal sealers. The canal filling is claimed to create a seal with the dentinal tubules within the root canal system producing a ‘monoblock’ effect between the sealer and dentinal tubules. Therefore, considering the possibility to incorporate the others adhesive systems, it is important to study the bond strength of the resulting cement. Forty-eight root mandibular canines were sectioned 8-mm below CEJ. The dentine discs were prepared using a tapered diamond bur and irrigated with 1% NaOCl and 17% EDTA. Previous the application Epiphany™ Sealer, the Epiphany™ Primer, AdheSE, and One Up Bond F were applied to the root canal walls. The LED and QTH (Quartz Tungsten Halogen) were used to photo-activation during 45 s with power density of 400 and 720 mW/cm2, respectively. The specimens were performed on a universal testing machine at a cross-head speed of 1 mm/min until bond failure occurred. The force was recorded and the debonding values were used to calculate Push-out bond strength. The analysis of variance (ANOVA) and Tukey’s post-hoc tests showed significant statistical differences ( P light curing unit used including the power density, the polymerization characteristics of these resin-based filling materials, depending on the primer/adhesive used.

  8. Halogen light versus LED for bracket bonding: shear bond strength

    Directory of Open Access Journals (Sweden)

    Paulo Eduardo Guedes Carvalho

    2013-02-01

    Full Text Available INTRODUCTION: LED light-curing devices seek to provide a cold light activator which allows protocols of material polymerization with shorter duration. OBJECTIVE: The present study aimed to evaluate the shear bond strength of bracket bonding using three types of light-curing devices: One with halogen light (Optilight Plus - Gnatus and two with LEDs (Optilight CL - Gnatus and Elipar Freelight - 3M/ESPE. RESULTS: Comparing the results by analysis of variance, the Gnatus LED device showed an inferior statistical behavior in relation to other light sources, when activated by a short time. But, when it was used for 40 seconds, the polymerization results were consistent with the other evaluated sources. The device with the best average performance was the halogen light, followed by the 3M/ESPE LED. CONCLUSION: It was concluded that the LEDs may be indicated in orthodontic practice, as long as a protocol is used for the application of light with the activation time of 40 seconds.INTRODUÇÃO: os aparelhos de fotopolimerização por LED buscam proporcionar uma luz ativadora fria, que possibilite protocolos de polimerização do material com menor tempo de duração. OBJETIVO: avaliar a resistência à tração da colagem de braquetes, utilizando três tipos de aparelhos fotoativadores: um de luz halógena (Optilight Plus - Gnatus e outros dois de LED (Optilight CL - Gnatus; e Elipar Freelight - 3M/Espe. RESULTADOS: comparando os resultados por meio da análise de variância, o aparelho de LED Gnatus apresentou comportamento estatístico inferior em relação às outras fontes de luz, quando ativado por tempo reduzido. Já quando foi utilizado o tempo de 40 segundos, os resultados de polimerização foram compatíveis com as demais fontes avaliadas. O aparelho que apresentou melhor desempenho médio foi o de luz halógena, seguido pelo LED 3M/Espe. CONCLUSÃO: concluiu-se que os LEDs podem ser indicados na prática ortodôntica, uma vez que seja utilizado

  9. 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.

  10. 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

  11. Polymerization of a dual-cured cement through ceramic: LED curing light vs halogen lamp Polimerização de um cimento resinoso dual através de uma porcelana: LED vs lâmpada halógena

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    Lawrence Gonzaga Lopes

    2004-12-01

    Full Text Available The aim of this study was to investigate the influence of light source, LED unit and halogen lamp (HL, on the effectiveness of Enforce dual-cured cement cured under a ceramic disc. Three exposure times (60, 80 and 120 s were also evaluated. Two experimental groups, in which the polymerization of the dual-cured cement was performed through a ceramic disc, and two control groups, in which the polymerization of the dual-cured cement was performed directly without presence of ceramic disc were subdivided into three subgroups (three different exposure times, with five specimens each: G1A- HL 60s; G1B- HL 80s; G1C- HL 120s; G2A- LED 60s; G2B- LED 80s; G2C- LED 120s; and control groups: G3A- HL 60s; G3B- HL 80s; G3C- HL 120s; G4A- LED 60s; G4B- LED 80s and G4C- LED 120s. Cement was applied in a steel matrix (4mm diameter, 1.2mm thickness. In the experimental groups, a ceramic disc was placed on top. The cement was light-cured through the ceramic by a HL and LED, however, the control groups were cured without the ceramic disc. The specimens were stored in a light-proof container at 37ºC for 24 hours, then Vickers hardness was determined. A four-way ANOVA and Tukey test (p£ 0.05 were performed. All specimens cured by LED for 60s showed inferior values compared with the halogen groups. In general, light-curing by LED for 80s and 120s was comparable to halogen groups (60s and 80s and their control groups. LED technology can be viable for light-curing through conventional ceramic indirect restorations, when curing time is increased in relation to HL curing time.O objetivo deste estudo foi estudar a influência da fonte de luz, LED e lâmpada halógena (LH, na efetividade de polimerização do cimento resinoso dual Enforce fotoativado sob um disco de porcelana. Três tempos de exposição (60, 80 e 120 segundos foram também avaliados. Dois grupos experimentais, na qual a polimerização do cimento resinoso foi feita através de um disco cerâmico, e dois

  12. Audit of a new model of birth care for women with low risk pregnancies in South Africa: the primary care onsite midwife-led birth unit (OMBU).

    Science.gov (United States)

    Hofmeyr, George Justus; Mancotywa, Thozeka; Silwana-Kwadjo, Nomvula; Mgudlwa, Batembu; Lawrie, Theresa A; Gülmezoglu, Ahmet Metin

    2014-12-20

    South Africa's health system is based on the primary care model in which low-risk maternity care is provided at community health centres and clinics, and 'high-risk' care is provided at secondary/tertiary hospitals. This model has the disadvantage of delays in the management of unexpected intrapartum complications in otherwise low-risk pregnancies, therefore, there is a need to re-evaluate the models of birth care in South Africa. To date, two primary care onsite midwife-led birth units (OMBUs) have been established in the Eastern Cape. OMBUs are similar to alongside midwifery units but have been adapted to the South African health system in that they are staffed, administered and funded by the primary care service. They allow women considered to be at 'low risk' to choose between birth in a community health centre and birth in the OMBU. The purpose of this audit was to evaluate the impact of establishing an OMBU at Frere Maternity Hospital in East London, South Africa, on maternity services. We conducted an audit of routinely collected data from Frere Maternity Hospital over two 12 month periods, before and after the OMBU opened. Retrospectively retrieved data included the number of births, maternal and perinatal deaths, and mode of delivery. After the OMBU opened at Frere Maternity Hospital, the total number of births on the hospital premises increased by 16%. The total number of births in the hospital obstetric unit (OU) dropped by 9.3%, with 1611 births out of 7375 (22%) occurring in the new OMBU. The number of maternal and perinatal deaths was lower in the post-OMBU period compared with the pre-OMBU period. These improvements cannot be assumed to be the result of the intervention as observational studies are prone to bias. The mortality data should be interpreted with caution as other factors such as change in risk profile may have contributed to the death reductions. There are many additional advantages for women, hospital staff and primary care staff with

  13. Effect of a broad-spectrum LED curing light on the Knoop microhardness of four posterior resin based composites at 2, 4 and 6-mm depths.

    Science.gov (United States)

    ALShaafi, Maan M; Haenel, Thomas; Sullivan, Braden; Labrie, Daniel; Alqahtani, Mohammed Q; Price, Richard B

    2016-02-01

    To measure the Knoop microhardness at the bottom of four posterior resin-based composites (RBCs): Tetric EvoCeram Bulk Fill (Ivoclar Vivadent), SureFil SDR flow (DENTSPLY), SonicFill (Kerr), and x-tra fil (Voco). The RBCs were expressed into metal rings that were 2, 4, or 6-mm thick with a 4-mm internal diameter at 30°C. The uncured specimens were covered by a Mylar strip and a Bluephase 20i (Ivoclar Vivadent) polywave(®) LED light-curing unit was used in high power setting for 20s. The specimens were then removed and placed immediately on a Knoop microhardness-testing device and the microhardness was measured at 9 points across top and bottom surfaces of each specimen. Five specimens were made for each condition. As expected, for each RBC there was no significant difference in the microhardness values at the top of the 2, 4 and 6-mm thick specimens. SureFil SDR Flow was the softest resin, but was the only resin that had no significant difference between the KHN values at the bottom of the 2 and 4-mm (Mixed Model ANOVA pcure was evaluated when determining the depth of cure. SureFil SDR Flow was the softest material and, in accordance with manufacturer's instructions, this RBC should be overlaid with a conventional resin. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Structured nurse-led follow-up for patients after discharge from the intensive care unit: Prospective quasi-experimental study.

    Science.gov (United States)

    Jónasdóttir, Rannveig J; Jones, Christina; Sigurdsson, Gisli H; Jónsdóttir, Helga

    2018-03-01

    The aim of this study was to describe a structured 3-month nurse-led follow-up of patients after discharge from intensive care and measure its effects on health status. Patients requiring intensive care stay frequently have lengthy and incomplete recovery suggesting need for additional support. The effects of intensive care nurse-led follow-up have not been sufficiently elucidated. A prospective, quasi-experimental study of patients who received structured nurse-led follow-up from intensive care nurses after discharge from intensive care until 3 months afterwards. The control group received usual care. Of 574 patients assessed for eligibility, from November 2012 - May 2015, 168 were assigned to the experimental group (N = 73) and the control group (N = 75). Primary outcome was health status, measured with eight scales of Short Form-36v2, before the intensive care admission and at four time points until 12 months after intensive care. A mixed effect model tested differences between the groups over time. Criteria for Reporting Development and Evaluation of Complex Interventions 2 guideline, guided the reporting of the intervention. The structured nurse-led follow-up did not improve patients' health status compared with usual care (mixed effect model, p = .078-.937). The structured nurse-led follow-up did not reveal an effect on the intensive care patients studied. Further examination of intensive care nurse-led follow-up is needed, taking into account the heterogeneity of the patient population, variations in length of ward stay, patients' health care needs during the first week at home after discharge from general ward and health status before intensive care admission. © 2017 John Wiley & Sons Ltd.

  15. Influence of flowable materials on microleakage of nanofilled and hybrid Class II composite restorations with LED and QTH LCUs

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    Sadeghi Mostafa

    2009-01-01

    Full Text Available Background: Class II composite restorations are more frequently being placed with margins apical to the cementoenamel junction (CEJ and margins within the dentin are prone to microleakage. Aims: This in vitro study was used to evaluate the influence of flowable composite and flowable compomer as gingival liner on microleakage in Class II composite restorations and compare a light-emitting diode (LED unit with a quartz tungsten halogen (QTH unit for light-activating composite resins. Materials and Methods: Mesioocclusal and distoocclusal Class II cavity preparations were made in 72 sound extracted premolars. The buccolingual width was 2.5 mm and the gingival margins of all the cavities were placed 1.0 mm apical to the CEJ. The boxes were prepared 1.5 mm deep axially, making 144 slot cavities. Teeth were randomly divided into the following two groups (n = 72: (I Universal Filtek Supreme XT; Universal Filtek Supreme XT + Flwable Filtek XT and Universal Filtek Supreme XT + Dyract Flow and (II Filtek Z250; Filtek Z250 + Flwable Filtek XT and Filtek Z250 + Dyract Flow. Flowable materials were injected into the gingival floor of the cavity to a thickness of 1.0 mm. Each increment was cured for 20 s. One-half of the subgroups in each group were cured with QTH and the other half with LED light curing units (LCUs. After 1 week of incubation at 37°C, the specimens were thermocycled (5-55°C, x1500, immersed in 0.5% basic fuchsine dye for 24 h and sectioned and microleakage was evaluated at the gingival margin by two examiners using a 0-3 score scale. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests. Results: The groups utilizing flowable liners had significantly less microleakage (P < 0.05. No significant difference was identified between Universal Filtek Supreme XT and Filtek Z250 composites with and without flowable materials. There was no significant between utilizing flowable composite or flowable compomer and between each

  16. A comparative study between the pioneer cohort of waterbirths and conventional vaginal deliveries in an obstetrician-led unit in Singapore

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    Karen M.X. Lim

    2016-06-01

    Conclusion: Waterbirth at our centre does not appear to be associated with an increased incidence of adverse neonatal and maternal outcomes. The results of this study supported waterbirth as a birthing option to groups of low-risk women in an obstetrician-led setting with good midwifery support.

  17. Shear bond strength evaluation of chemically-cured and light-cured orthodontic adhesives after enamel deproteinization with 5.25% sodium hypochlorite

    Science.gov (United States)

    Salim, J. C.; Krisnawati; Purbiati, M.

    2017-08-01

    This study aimed to assess the effect of enamel deproteinization with 5.25% sodium hypochlorite (NaOCl) before etching on the shear bond strength (SBS) of Unite (UN; 3M Unitek) and Xihu-BIOM adhesive (XB). Fifty-two maxillary first premolars were divided into four groups: (1) UN and (2) XB according to manufacturer’s recommendation and (3) UN and (4) XB deproteinized with 5.25% NaOCl. Brackets were bonded, and a mechanical test was performed using a universal testing machine. The mean SBS value for groups A1, A2, B1, and B2 was 13.51 ± 2.552, 14.36 ± 2.902, 16.43 ± 2.615, and 13.05 ± 2.348 MPa, respectively. A statistically significant difference in SBSs was observed between chemically cured groups and between group B (p 0.05). NaOCl enamel deproteinization before acid etching has a significant effect on the SBS of Unite adhesive, but not on that of the Xihu-BIOM adhesive. Furthermore, a significant difference in the SBS of Unite and Xihu-BIOM adhesives within the enamel deproteinization group was observed in this study.

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

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    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.

  19. A Study of Postwar Japan (1945-1950): What Insights and Lessons Can be Gained From the United States Led Rebirth of Japan

    Science.gov (United States)

    2006-06-16

    criminal was Emperor Hirohito . A discussion of the plan for postwar Japan would not be complete without mentioning this monumental decision to leave...Emperor Hirohito on the throne as a symbol of State in postwar Japan. Even though Emperor Hirohito was present and presided over all of the War...Cabinet meetings, he was not tried with seven of the others. This was a strategic decision made by the US-led occupation. There was evidence that Hirohito

  20. Optimizing LED lighting for space plant growth unit: Joint effects of photon flux density, red to white ratios and intermittent light pulses

    Science.gov (United States)

    Avercheva, O. V.; Berkovich, Yu. A.; Konovalova, I. O.; Radchenko, S. G.; Lapach, S. N.; Bassarskaya, E. M.; Kochetova, G. V.; Zhigalova, T. V.; Yakovleva, O. S.; Tarakanov, I. G.

    2016-11-01

    The aim of this work were to choose a quantitative optimality criterion for estimating the quality of plant LED lighting regimes inside space greenhouses and to construct regression models of crop productivity and the optimality criterion depending on the level of photosynthetic photon flux density (PPFD), the proportion of the red component in the light spectrum and the duration of the duty cycle (Chinese cabbage Brassica chinensis L. as an example). The properties of the obtained models were described in the context of predicting crop dry weight and the optimality criterion behavior when varying plant lighting parameters. Results of the fractional 3-factor experiment demonstrated the share of the PPFD level participation in the crop dry weight accumulation was 84.4% at almost any combination of other lighting parameters, but when PPFD value increased up to 500 μmol m-2 s-1 the pulse light and supplemental light from red LEDs could additionally increase crop productivity. Analysis of the optimality criterion response to variation of lighting parameters showed that the maximum coordinates were the following: PPFD = 500 μmol m-2 s-1, about 70%-proportion of the red component of the light spectrum (PPFDLEDred/PPFDLEDwhite = 1.5) and the duty cycle with a period of 501 μs. Thus, LED crop lighting with these parameters was optimal for achieving high crop productivity and for efficient use of energy in the given range of lighting parameter values.

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

    Directory of Open Access Journals (Sweden)

    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

  2. Optimizing LED lighting for space plant growth unit: Joint effects of photon flux density, red to white ratios and intermittent light pulses.

    Science.gov (United States)

    Avercheva, O V; Berkovich, Yu A; Konovalova, I O; Radchenko, S G; Lapach, S N; Bassarskaya, E M; Kochetova, G V; Zhigalova, T V; Yakovleva, O S; Tarakanov, I G

    2016-11-01

    The aim of this work were to choose a quantitative optimality criterion for estimating the quality of plant LED lighting regimes inside space greenhouses and to construct regression models of crop productivity and the optimality criterion depending on the level of photosynthetic photon flux density (PPFD), the proportion of the red component in the light spectrum and the duration of the duty cycle (Chinese cabbage Brassica сhinensis L. as an example). The properties of the obtained models were described in the context of predicting crop dry weight and the optimality criterion behavior when varying plant lighting parameters. Results of the fractional 3-factor experiment demonstrated the share of the PPFD level participation in the crop dry weight accumulation was 84.4% at almost any combination of other lighting parameters, but when PPFD value increased up to 500µmol m -2 s -1 the pulse light and supplemental light from red LEDs could additionally increase crop productivity. Analysis of the optimality criterion response to variation of lighting parameters showed that the maximum coordinates were the following: PPFD = 500µmol m -2 s -1 , about 70%-proportion of the red component of the light spectrum (PPFD LEDred /PPFD LEDwhite = 1.5) and the duty cycle with a period of 501µs. Thus, LED crop lighting with these parameters was optimal for achieving high crop productivity and for efficient use of energy in the given range of lighting parameter values. Copyright © 2016 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

  3. Design of a metal primer containing a dithiooctanoate monomer and a phosphonic acid monomer for bonding of prosthetic light-curing resin composite to gold, dental precious and non-precious metal alloys.

    Science.gov (United States)

    Ikemura, Kunio; Fujii, Toshihide; Negoro, Noriyuki; Endo, Takeshi; Kadoma, Yoshinori

    2011-01-01

    The effect of metal primers on adhesion of a resin composite to dental metal alloys was investigated. Experimental primers containing a dithiooctanoate monomer [10-methacryloyloxydecyl 6,8-dithiooctanoate (10-MDDT) or 6-methacryloyloxyhexyl 6,8-dithiooctanoate (6-MHDT)] and a phosphonic acid monomer [6-methacryloyloxyhexyl phosphonoacetate (6-MHPA) or 6-methacryloyloxyhexyl 3-phosphonopropionate (6-MHPP)] were prepared. After treating Au, Au alloy, Ag alloy, Au-Ag-Pd alloy, and Ni-Cr alloy with the experimental primers, their shear bond strengths (SBSs) with a prosthetic light-curing resin composite (Solidex, Shofu Inc., Japan) were measured after 1-day storage followed by 5,000 thermal cycles. The SBSs between Solidex and the primer-treated metals which were incubated in air at 50°C for 2 months were further measured. Results showed that the SBSs [mean (SD)] of all metal adherends treated with primer DT-PA-1 (5.0 wt% 10-MDDT, 1.0 wt% 6-MHPA) ranged between 31.2 (5.2) and 34.5 (5.8) MPa. The SBSs of the primer-treated metals did not degrade after 2-month incubation at 50°C. Therefore, a combined primer application consisting of a dithiooctanoate monomer and a phosphonic acid monomer provided efficacious bonding to Au as well as precious and non-precious metal alloys.

  4. LED-roulette : LED's vervangen balletje

    NARCIS (Netherlands)

    Goossens, P.

    2007-01-01

    Iedereen waagt wel eens een gokje, in een loterij of misschien ook in een casino. Wie droomt er immers niet van om op een gemakkelijke manier rijk te worden? Met de hier beschreven LED-roulette valt weliswaar weinig te winnen, maar het is wel een uitstekende manier om het roulettespel thuis te

  5. Light-Curing Adhesive Repair Tapes

    Science.gov (United States)

    Allred, Ronald; Haight, Andrea Hoyt

    2009-01-01

    Adhesive tapes, the adhesive resins of which can be cured (and thereby rigidized) by exposure to ultraviolet and/or visible light, are being developed as repair patch materials. The tapes, including their resin components, consist entirely of solid, low-outgassing, nonhazardous or minimally hazardous materials. They can be used in air or in vacuum and can be cured rapidly, even at temperatures as low as -20 C. Although these tapes were originally intended for use in repairing structures in outer space, they can also be used on Earth for quickly repairing a wide variety of structures. They can be expected to be especially useful in situations in which it is necessary to rigidize tapes after wrapping them around or pressing them onto the parts to be repaired.

  6. Pharmacist-led implementation of a vancomycin guideline across medical and surgical units: impact on clinical behavior and therapeutic drug monitoring outcomes

    Directory of Open Access Journals (Sweden)

    Phillips CJ

    2015-10-01

    Full Text Available Cameron J Phillips,1–3 David L Gordon3,4 1Division of Pharmacy, SA Pharmacy, Flinders Medical Centre, Bedford Park, 2School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, 3Department of Microbiology and Infectious Diseases, School of Medicine, Flinders University, Adelaide, 4Department of Microbiology and Infectious Diseases, SA Pathology, Flinders Medical Centre, Bedford Park, SA, Australia Background: Vancomycin is the antibiotic of choice for the treatment of serious infections such as methicillin-resistant Staphylococcus aureus (MRSA. Inappropriate prescribing of vancomycin can lead to therapeutic failure, antibiotic resistance, and drug toxicity. Objective: To examine the effectiveness of pharmacist-led implementation of a clinical practice guideline for vancomycin dosing and monitoring in a teaching hospital. Methods: An observational pre–post study design was undertaken to evaluate the implementation of the vancomycin guideline. The implementation strategy principally involved education, clinical vignettes, and provision of pocket guidelines to accompany release of the guideline to the hospital Intranet. The target cohort for clinical behavioral change was junior medical officers, as they perform the majority of prescribing and monitoring of vancomycin in hospitals. Assessment measures were recorded for vancomycin prescribing, therapeutic drug monitoring, and patient outcomes. Results: Ninety-nine patients, 53 pre- and 46 post-implementation, were included in the study. Prescribing of a loading dose increased from 9% to 28% (P=0.02, and guideline adherence to starting maintenance dosing increased from 53% to 63% (P=0.32. Dose adjustment by doctors when blood concentrations were outside target increased from 53% to 71% (P=0.12, and correct timing of initial concentration measurement increased from 43% to 57% (P=0.23. Appropriately timed trough concentrations improved from 73% to 81% (P=0.08. Pre-dose (trough

  7. Wrapping newborn infants in cloth and newspaper after delivery led to higher temperatures on arrival at the neonatal intensive care unit.

    Science.gov (United States)

    Agrawal, Nitika; Das, Kunal; Patwal, Prachi; Pandita, Neerul; Gupta, Alpa

    2018-01-03

    Neonatal hypothermia is a preventable cause of neonatal mortality and morbidity, and wrapping neonates in newspaper sandwiched between cotton sheets is a simple intervention. This 2017 Indian pilot study tested the heat insulating property of sandwiched sheets. At birth, we randomised 100 neonates who were more than 32 weeks of gestation and needed neonatal intensive care unit (NICU) observation or care without a ventilator or bilevel positive airway pressure support into two groups of 50. The intervention and control groups were wrapped in two prewarmed sheets at birth that did or did not contain a layer of newspaper. Their axillary temperatures on arrival at the NICU and one hour after arrival were measured. Other environmental factors were similar. The neonates wrapped in the sandwiched sheets showed significantly higher temperatures on arrival at the NICU than the control group (35.9°C versus 35.4°C, p newspaper layer resulted in a higher body temperature on arrival at the NICU and after one hour. ©2018 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

  8. Evaluation of curing units used in private dental offices in Tehran in 2005

    Directory of Open Access Journals (Sweden)

    Mirzaei M

    2007-06-01

    Full Text Available Background and Aim: Light cured composites and other restorative materials are quite common in dentistry today. Successful restorations are dependent on efficiency of curing light unit, eg. the intensity of emitted light and its wave length. The aim of this study was to evaluate the efficiency units of curing, in private dental offices in Tehran. Materials and Methods: In this descriptive cross sectional study, light curing devices in 240 private dental offices were evaluated randomly. Light intensity was measured by radiometer, debris on the fan and cracks and scratches on the filter were directly observed and the age of the device, frequency of changing the bulb and satisfaction of the dentist with regard to the light curing unit were recorded in a questionnaire. Data were analyzed using Spearman and t test, with p<0.05 as the level of significance.Results: The results showed that 53.8% of the units had intensities more than 300 mW/cm2. The intensity of 30.4% of curing light units were between 20 and 300 mW/cm2 and 15.8% had intensities lower than "n200 mW/cm2. There was a negative relation between light intensity and the age of the unit, frequency of bulb changing or scratches on the filter and debris on the fan.Conclusion: The results of this study showed that the light intensities of about 46% of light curing units used in private dental practices and clinics were inadequate. Since factors like aging of the curing light unit, frequent bulb changing, increasing the amount of debris on the fan and scratches on the filter reduce the light intensity, regular quality control of these devices is essential.

  9. Broadband Radiometric LED Measurements.

    Science.gov (United States)

    Eppeldauer, G P; Cooksey, C C; Yoon, H W; Hanssen, L M; Podobedov, V B; Vest, R E; Arp, U; Miller, C C

    2016-01-01

    At present, broadband radiometric measurements of LEDs with uniform and low-uncertainty results are not available. Currently, either complicated and expensive spectral radiometric measurements or broadband photometric LED measurements are used. The broadband photometric measurements are based on the CIE standardized V(λ) function, which cannot be used in the UV range and leads to large errors when blue or red LEDs are measured in its wings, where the realization is always poor. Reference irradiance meters with spectrally constant response and high-intensity LED irradiance sources were developed here to implement the previously suggested broadband radiometric LED measurement procedure [1, 2]. Using a detector with spectrally constant response, the broadband radiometric quantities of any LEDs or LED groups can be simply measured with low uncertainty without using any source standard. The spectral flatness of filtered-Si detectors and low-noise pyroelectric radiometers are compared. Examples are given for integrated irradiance measurement of UV and blue LED sources using the here introduced reference (standard) pyroelectric irradiance meters. For validation, the broadband measured integrated irradiance of several LED-365 sources were compared with the spectrally determined integrated irradiance derived from an FEL spectral irradiance lamp-standard. Integrated responsivity transfer from the reference irradiance meter to transfer standard and field UV irradiance meters is discussed.

  10. Dansk LED - Museumsbelysning

    DEFF Research Database (Denmark)

    Poulsen, Peter Behrensdorff; Dam-Hansen, Carsten; Thorseth, Anders

    Projektet har til formål at anvende dansk forskning inden for optik og lys til at realisere innovative energieffektive LED lyssystemer til museumsbranchen.......Projektet har til formål at anvende dansk forskning inden for optik og lys til at realisere innovative energieffektive LED lyssystemer til museumsbranchen....

  11. Large area LED package

    Science.gov (United States)

    Goullon, L.; Jordan, R.; Braun, T.; Bauer, J.; Becker, F.; Hutter, M.; Schneider-Ramelow, M.; Lang, K.-D.

    2015-03-01

    Solid state lighting using LED-dies is a rapidly growing market. LED-dies with the needed increasing luminous flux per chip area produce a lot of heat. Therefore an appropriate thermal management is required for general lighting with LEDdies. One way to avoid overheating and shorter lifetime is the use of many small LED-dies on a large area heat sink (down to 70 μm edge length), so that heat can spread into a large area while at the same time light also appears on a larger area. The handling with such small LED-dies is very difficult because they are too small to be picked with common equipment. Therefore a new concept called collective transfer bonding using a temporary carrier chip was developed. A further benefit of this new technology is the high precision assembly as well as the plane parallel assembly of the LED-dies which is necessary for wire bonding. It has been shown that hundred functional LED-dies were transferred and soldered at the same time. After the assembly a cost effective established PCB-technology was applied to produce a large-area light source consisting of many small LED-dies and electrically connected on a PCB-substrate. The top contacts of the LED-dies were realized by laminating an adhesive copper sheet followed by LDI structuring as known from PCB-via-technology. This assembly can be completed by adding converting and light forming optical elements. In summary two technologies based on standard SMD and PCB technology have been developed for panel level LED packaging up to 610x 457 mm2 area size.

  12. LED roadway luminaires evaluation.

    Science.gov (United States)

    2012-02-01

    This research explores whether LED roadway luminaire technologies are a viable future solution to providing roadway lighting. Roadway lighting : enhances highway safety and traffic flow during limited lighting conditions. The purpose of this evaluati...

  13. Surface plasmon enhanced LED

    OpenAIRE

    Vučković, Jelena; Lončar, Marko; Painter, Oskar; Scherer, Axel

    2000-01-01

    Summary form only given. We designed and fabricated an LED based on a thin semiconductor membrane (λ/2) with silver mirrors. A large spontaneous emission enhancement and a high modulation speed are obtainable due to the strong localization of the electromagnetic field in the microcavity. The coupling to surface plasmon modes which are subsequently scattered out by means of a grating is used to improve the extraction efficiency of the LED. The bottom mirror is thick and unpatterned. The top mi...

  14. Water sorption of resin-modified glass-ionomer cements photoactivated with LED Sorção de água de cimentos de ionômero de vidro modificados por resina fotoativados com LED

    Directory of Open Access Journals (Sweden)

    Daniela Francisca Gigo Cefaly

    2006-12-01

    Full Text Available The Light Emitting Diodes (LED technology has been used to photoactivate composite resins and there is a great number of published studies in this area. However, there are no studies regarding resin-modified glass-ionomer cements (RMGIC, which also need photoactivation. Therefore, the aim of this study was to evaluate water sorption of two RMGIC photoactivated with LED and to compare this property to that obtained with a halogen light curing unit. A resin composite was used as control. Five specimens of 15.0 mm in diameter x 1.0 mm in height were prepared for each combination of material (Fuji II LC Improved, Vitremer, and Filtek Z250 and curing unit (Radii and Optilight Plus and transferred to desiccators until a constant mass was obtained. Then the specimens were immersed into deionized water for 7 days, weighed and reconditioned to a constant mass in desiccators. Water sorption was calculated based on weight and volume of specimens. The data were analyzed by two-way ANOVA and Tukey test (p A tecnologia baseada em Diodos emissores de luz (LED tem sido utilizada para a fotoativação de resinas compostas e existe um grande número de estudos publicados a este respeito. Entretanto, não existem estudos envolvendo cimentos de ionômero de vidro modificados por resina (CIVMR, que também necessitam fotoativação. Assim, o objetivo deste estudo foi o de avaliar a sorção de água de dois CIVMR fotoativados com LED e comparar essa propriedade com aquela obtida com unidade com lâmpada halógena. Uma resina composta foi utilizada como controle. Cinco espécimes com 15,0 mm diâmetro x 1,0 mm de altura foram preparados para cada combinação de material (Fuji II LC Improved, Vitremer e Filtek Z250 e fonte de luz (Radii e Optilight Plus e transferidos a dessecadores até a obtenção de massa constante. Em seguida, os espécimes foram imersos em água deionizada por 7 dias, pesados e recondicionados a uma massa constante em dessecadores. A sor

  15. Light Emitting Diode (LED)

    Science.gov (United States)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique called photodynamic therapy, requires the surgeon to use tiny pinhead-size Light Emitting Diodes (LEDs) (a source releasing long wavelengths of light) to activate light-sensitive, tumor-treating drugs. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can also be used for hours at a time while still remaining cool to the touch. The LED probe consists of 144 tiny pinhead-size diodes, is 9-inches long, and about one-half-inch in diameter. The small balloon aids in even distribution of the light source. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The probe was developed for photodynamic cancer therapy by the Marshall Space Flight Center under a NASA Small Business Innovative Research program grant.

  16. Light Emitting Diodes (LEDs)

    Science.gov (United States)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique, called Photodynamic Therapy, requires the surgeon to use tiny, pinhead-size Light Emitting Diodes (LEDs) (a source that releases long wavelengths of light ) to activate light-sensitive, tumor-treating drugs. 'A young woman operated on in May 1999 has fully recovered with no complications and no evidence of the tumor coming back,' said Dr. Harry Whelan, a pediatric neurologist at the Medical Hospital of Wisconsin in Milwaukee. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can be used for hours at a time while still remaining cool to the touch. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The LEDs, developed and managed by NASA's Marshall Space Flight Center, have been used on seven Space Shuttle flights inside the Microgravity Astroculture Facility. This technology has also been successfully used to further commercial research in crop growth.

  17. Led-sukellusvalaisin

    OpenAIRE

    Saarelainen, Mikko

    2012-01-01

    Opinnäytetyön aiheena on LED ja sen käyttö sukellusvalaisimissa. Työn tarkoitus oli tutkia miten LED toimii ja miten se soveltuu käytettäväksi sukellusvalaisimessa, sekä syventää omaa tietoutta valosta, mitä se on ja miten sitä mitataan. Työssä käydään läpi LEDin ominaisuuksia ja miten se eroaa muista sukellusvalaisimissa käytetyistä lampuista. Työ on toteutettu tutustumalla LEDiin ja valoon käyttämällä erilaisia lähteitä ja päivittämällä nykyinen sukellusvalaisimeni LED-sukellusvalaisime...

  18. [LED lights in dermatology].

    Science.gov (United States)

    Noé, C; Pelletier-Aouizerate, M; Cartier, H

    2017-04-01

    The use in dermatology of light-emitting diodes (LEDs) continues to be surrounded by controversy. This is due mainly to poor knowledge of the physicochemical phases of a wide range of devices that are difficult to compare to one another, and also to divergences between irrefutable published evidence either at the level of in vitro studies or at the cellular level, and discordant clinical results in a variety of different indications: rejuvenation, acne, wound healing, leg ulcers, and cutaneous inflammatory or autoimmune processes. Therapeutic LEDs can emit wavelengths ranging from the ultraviolet, through visible light, to the near infrared (247-1300 nm), but only certain bands have so far demonstrated any real value. We feel certain that if this article remains factual, then readers will have a different, or at least more nuanced, opinion concerning the use of such LED devices in dermatology. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  19. Thermal management for LED applications

    CERN Document Server

    Poppe, András

    2014-01-01

    Thermal Management for LED Applications provides state-of-the-art information on recent developments in thermal management as it relates to LEDs and LED-based systems and their applications. Coverage begins with an overview of the basics of thermal management including thermal design for LEDs, thermal characterization and testing of LEDs, and issues related to failure mechanisms and reliability and performance in harsh environments. Advances and recent developments in thermal management round out the book with discussions on advances in TIMs (thermal interface materials) for LED applications, advances in forced convection cooling of LEDs, and advances in heat sinks for LED assemblies. This book also: Presents a comprehensive overview of the basics of thermal management as it relates to LEDs and LED-based systems Discusses both design and thermal management considerations when manufacturing LEDs and LED-based systems Covers reliability and performance of LEDs in harsh environments Has a hands-on applications a...

  20. Seed-to-seed growth of superdwarf wheat and arabidopsis using red light-emitting diodes (LED's): A report on baseline tests conducted for NASA's proposed Plant Research Unit (PRU)

    Science.gov (United States)

    Goins, G. D.; Yorio, N. C.; Sanwo, M. M.; Brown, C. S.

    1996-01-01

    To determine the influence of narrow-spectrum red light-emitting diodes (LED's) on plant growth and seed production, wheat (Triticum aestivum L.cv Superdwarf) and Arabidopsis (Arabidopsis thaliana (L.) Heynh, race Columbia) plants were grown under red LED's (peak emission 660 nm) and compared to plants grown under daylight fluorescent (white) light and red LED's supplemented with either 1 percent or 10 percent blue fluorescent (BF) light. Wheat growth under red LED's alone appeared normal, whereas Arabidopsis under red LED's alone developed curled leaf margins and a spiraling growth pattern. Both wheat and Arabidopsis under red LED's alone or red LED's + 1 percent BF light had significantly lower seed yield than plants grown under white light. However, the addition of 10 percent BF light to red LED's partially alleviated the adverse effect of red LED's on yield. Irrespective of the light treatment, viable seeds were produced by wheat(75-92 percent germination rate) and Arabidopsis (85-100 percent germination rate). These results indicate that wheat, and to a lesser extent Arabidopsis, can be successfully grown under red LED's alone, but supplemental blue light is required with red LED's to sufficiently match the growth characteristics and seed yield associated with plants grown under white light.

  1. Deslumbramiento en dispositivos led

    OpenAIRE

    Ixtaina, Rubén Pablo; Presso, Matías; Ferreyra, Joaquín

    2012-01-01

    En el presente trabajo se presenta un estudio realizado en el LAL a dispositivos para señalización (semáforos, balizas, barrales lumínicos) con tecnología led. Las mediciones tradicionales de intensidad luminosa se complementaron con el análisis de la luminancia de los dispositivos, evaluada para diversas aperturas angula-res. Los resultados obtenidos marcan un notorio incre-mento en las luminancias puntuales, para valores de emisión globales comparables a los obtenidos en dispo-sitivos conve...

  2. A cost-comparison of midwife-led compared with consultant-led maternity care in Ireland (the MidU study).

    Science.gov (United States)

    Kenny, Christopher; Devane, Declan; Normand, Charles; Clarke, Mike; Howard, Aoife; Begley, Cecily

    2015-11-01

    to compare the cost of maternity care between two midwife-led units, and their linked consultant-led units, following a large randomised trial in Ireland. ethical approval was received for this unblinded, pragmatic randomised trial (MidU) funded by the Health Service Executive (Dublin North-East, Ireland), conducted 2004-2009. A comparison of costs analysis was conducted on the outcomes from the trial. two maternity units in Ireland, with 'alongside' midwife-led units. all women without risk factors for labour and birth who booked at the two maternity units before 24 weeks׳ gestation were assessed for inclusion. Consenting women (n=1653) were centrally randomised on a 2:1 ratio (1101:552) to midwife-led or consultant-led care. women randomised to consultant-led care received standard care. Women randomised to the midwife-led arm received midwife-led care provided by a small group of midwives in two units, situated ׳alongside׳ the consultant-led units, throughout pregnancy, birth and postnatal. mean difference in clinician salaries, cost of care based on managers׳ data, known costs of postnatal bed days and costs of key interventions were measured. the average cost of caring for a woman allocated to the midwife-led units was €2598, compared to €2780 in the consultant-led units (average difference €182 per woman, analysed by 'intention to treat'). care in these two midwife-led units costs less than care provided by the consultant-led units. Given the clinical findings, which showed that care provided in the midwife-led units is as safe as that in the consultant-led units and results in less intervention, more midwife-led units should be incorporated into maternity care in Ireland so that scarce resources can be used more effectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

  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. LED driver for stroboscopic interferometry

    Science.gov (United States)

    Paulin, T.; Heikkinen, V.; Kassamakov, I.; Hæggström, E.

    2012-04-01

    Three different types of white light emitting diodes (LEDs) and three types of single color LEDs were tested as light sources for stroboscopic scanning white light interferometry (SSWLI) for dynamic (MEMS) characterization. Short, intense, light pulses and low duty cycle (DC-10 MHz), and can drive single LEDs at 5A peak current (0.7% duty cycle at 1 MHz). The shortest measured electrical pulses were 6.2 +/- 0.1 ns FDHM. The minimum measured Full Duration at Half Maximum (FDHM) of the optical pulse was 8.4 +/- 0.1 ns using nonphosphor white LED and 32.1 +/- 0.1 ns using white phosphor-converted LED (0.7 % duty cycle at 1 MHz in both cases). The minimum optical pulse FDHM for a single color blue/green LED was 6.4 +/- 0.1 ns. The maximum intensity of these pulses was 630 +/- 40 μW and 540 +/- 30 μW, respectively. All types of white LEDs could be used for stroboscopic SWLI measurements at frequencies up to 2 MHz. For higher frequencies, non-phosphor white LEDs must be used together with a cyan LED to avoid ringing in the SWLI interferogram.

  5. Nobel Prize for blue LEDs

    International Nuclear Information System (INIS)

    Kraftmakher, Yaakov

    2015-01-01

    A brief review of lighting technologies is presented. Unavoidable restrictions for incandescent light bulbs caused by the Planck distribution and properties of the human eye are illustrated. The efficiency and luminous efficacy of thermal radiation are calculated for various temperatures; the results clearly show the limitations for thermal radiators. The only way to overcome these limitations is using non-thermal radiators, such as fluorescent lamps and light-emitting diodes (LEDs). Unique advantages of LEDs undoubtedly made a revolution in this field. A crucial element of this progress is the blue LEDs (Nobel Prize 2014). Some experiments with a blue and a green LED are described: (i) the luminescence triggered in a green-yellow phosphor inside a white LED by the blue LED; (ii) radiant spectra and ‘efficiency droop’ in the LEDs; (iii) modulation of the blue LED up to 4 MHz; and (iv) the h/e ratio from the turn-on voltage of the green LED. The experiments are suitable for undergraduate laboratories and usable as classroom demonstrations. (paper)

  6. Nobel Prize for blue LEDs

    Science.gov (United States)

    Kraftmakher, Yaakov

    2015-05-01

    A brief review of lighting technologies is presented. Unavoidable restrictions for incandescent light bulbs caused by the Planck distribution and properties of the human eye are illustrated. The efficiency and luminous efficacy of thermal radiation are calculated for various temperatures; the results clearly show the limitations for thermal radiators. The only way to overcome these limitations is using non-thermal radiators, such as fluorescent lamps and light-emitting diodes (LEDs). Unique advantages of LEDs undoubtedly made a revolution in this field. A crucial element of this progress is the blue LEDs (Nobel Prize 2014). Some experiments with a blue and a green LED are described: (i) the luminescence triggered in a green-yellow phosphor inside a white LED by the blue LED; (ii) radiant spectra and ‘efficiency droop’ in the LEDs; (iii) modulation of the blue LED up to 4 MHz; and (iv) the h/e ratio from the turn-on voltage of the green LED. The experiments are suitable for undergraduate laboratories and usable as classroom demonstrations.

  7. Influence of the Light Source and Curing Parameters on Microhardness of a Silorane-Based Dental Composite Material

    OpenAIRE

    Malara P.; Czech Z.; Świderski W.

    2016-01-01

    The aim of the study was to determine the influence of the light source and the light-curing parameters (the distance of the material from the light source and time of light-curing) on microhardness of Flitek Silorane dental composite material. Standardized samples of Filtek Silorane material were cured using two types of Light Curing Units (LCUs) – halogen and LED. The distance of the light source and time of curing differed between samples. The Knoop’s microhardness was tested using microha...

  8. New dental applications with LEDs

    DEFF Research Database (Denmark)

    Argyraki, A.; Ou, Yiyu; Petersen, Paul Michael

    Visible and ultraviolet LEDs will in the future give rise to new dental applications. Fluorescence imaging, photodynamic therapy and photoactivated disinfection are important future candidates for diagnostics and treatment in dentistry.......Visible and ultraviolet LEDs will in the future give rise to new dental applications. Fluorescence imaging, photodynamic therapy and photoactivated disinfection are important future candidates for diagnostics and treatment in dentistry....

  9. Silicone materials for LED packaging

    Science.gov (United States)

    Bahadur, Maneesh; Norris, Ann W.; Zarisfi, Afrooz; Alger, James S.; Windiate, Christopher C.

    2006-08-01

    Silicone based materials have attracted considerable attention from light emitting diode (LED) manufacturers for use as encapsulants and lenses for many high brightness LED (HB LED) devices. Currently silicones function in two key roles in HB LED devices, (1) as protective lenses and (2) stress relieving encapsulants for wire bond protection. The key attributes of silicones that make them attractive as light path materials for high brightness HB LEDs include their high transparency in the UV-visible region, controlled refractive index (RI), stable thermo-mechanical properties, and tuneable modulus from soft gels to hard resins. This paper will describe recent developments in moldable silicone hard resin materials. Progress on cavity moldable and liquid injection moldable (LIM) silicone compositions for discreet components is described. Also, an example of liquid injection overmolding is presented.

  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; 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

  11. Development of Wireless Dimming Control System for LED Stage Light

    OpenAIRE

    Wang Hui Qin; Bai Shi Lei

    2016-01-01

    Compared with the existing wire dimming system of LED stage light which uses the heavy light operating console to adjust the brightness of stage light, a portable wireless dimming control system for LED stage lighting is proposed, fabricated and tested in this paper. The scheme with the core of ATmega16L microcontroller is composed of wireless transmission and reception units, constant current driving circuit of LED, and the control circuit between this two modules. Through the system present...

  12. Light pipes for LED measurements

    Science.gov (United States)

    Floyd, S. R.; Thomas, E. F., Jr.

    1976-01-01

    Light pipe directly couples LED optical output to single detector. Small area detector measures total optical output of diode. Technique eliminates thermal measurement problems and channels optical output to remote detector.

  13. Practical lighting design with LEDs

    CERN Document Server

    Lenk, Ron

    2016-01-01

    The second edition of Practical Lighting Design with LEDs has been revised and updated to provide the most current information for developing light-emitting diodes products. The authors, noted authorities in the field, offer a review of the most relevant topics including optical performance, materials, thermal design, and modeling and measurement. Comprehensive in scope, the text covers all the information needed to design LEDs into end products.

  14. Biological Research in Canisters (BRIC) - Light Emitting Diode (LED)

    Science.gov (United States)

    Levine, Howard G.; Caron, Allison

    2016-01-01

    The Biological Research in Canisters - LED (BRIC-LED) is a biological research system that is being designed to complement the capabilities of the existing BRIC-Petri Dish Fixation Unit (PDFU) for the Space Life and Physical Sciences (SLPS) Program. A diverse range of organisms can be supported, including plant seedlings, callus cultures, Caenorhabditis elegans, microbes, and others. In the event of a launch scrub, the entire assembly can be replaced with an identical back-up unit containing freshly loaded specimens.

  15. Are nurse-led chemotherapy clinics really nurse-led? An ethnographic study.

    Science.gov (United States)

    Farrell, Carole; Walshe, Catherine; Molassiotis, Alex

    2017-04-01

    The number of patients requiring ambulatory chemotherapy is increasing year on year, creating problems with capacity in outpatient clinics and chemotherapy units. Although nurse-led chemotherapy clinics have been set up to address this, there is a lack of evaluation of their effectiveness. Despite a rapid expansion in the development of nursing roles and responsibilities in oncology, there is little understanding of the operational aspects of nurses' roles in nurse-led clinics. To explore nurses' roles within nurse-led chemotherapy clinics. A focused ethnographic study of nurses' roles in nurse-led chemotherapy clinics, including semi-structured interviews with nurses. Four chemotherapy units/cancer centres in the UK PARTICIPANTS: Purposive sampling was used to select four cancer centres/units in different geographical areas within the UK operating nurse-led chemotherapy clinics. Participants were 13 nurses working within nurse-led chemotherapy clinics at the chosen locations. Non-participant observation of nurse-led chemotherapy clinics, semi-structured interviews with nurse participants, review of clinic protocols and associated documentation. 61 nurse-patient consultations were observed with 13 nurses; of these 13, interviews were conducted with 11 nurses. Despite similarities in clinical skills training and prescribing, there were great disparities between clinics run by chemotherapy nurses and those run by advanced nurse practitioners. This included the number of patients seen within each clinic, operational aspects, nurses' autonomy, scope of practice and clinical decision-making abilities. The differences highlighted four different levels of nurse-led chemotherapy clinics, based on nurses' autonomy and scope of clinical practice. However, this was heavily influenced by medical consultants. Several nurses perceived they were undertaking holistic assessments, however they were using medical models/consultation styles, indicating medicalization of nurses' roles

  16. Sustainable LED Fluorescent Light Replacement Technology

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2011-09-30

    Ilumisys and the National Center for Manufacturing Sciences (NCMS) partnered on a three-year project awarded by the United States (U.S.) Department of Energy (DOE), to quantify the impacts of LED lamps, incandescent lamps and fluorescent benchmark lamps over a product lifecycle – i.e. to develop a sustainable design and manufacturing strategy that addresses product manufacturing, use, recycling and disposal scenarios for LED-based lighting. Based on the knowledge gained from extensive product tear-down studies of fluorescent and screw-in lighting products, lifecycle assessment tools, and accelerated lifecycle testing protocols, an interactive Sustainable LED Design Guide has been developed to aid architectural and lighting designers and engineers in making design decisions that consider three important environmental impacts (greenhouse gas emissions, energy use and mercury emission) across all phases of the life of an LED lighting product. Critical information developed for the lifecycle analysis and product feature comparisons is the useful life of the lighting product as well as its performance. The Design Guide is available at www.ncms.org, and was developed based on operational and durability testing of a variety of lighting products including power consumption, light output, and useful life of a lamp in order to allow a more realistic comparison of lamp designs. This report describes the main project tasks, results and innovative features of the lifecycle assessment (LCA)-based design tools, and the key considerations driving the sustainable design of LED lighting systems. The Design Guide incorporates the following three novel features for efficiently evaluating LED lighting features in value-chains: Bill-of-Materials (BOM) Builder – Designers may import process data for each component and supply functional data for the product, including power, consumption, lumen output and expected useful life: Environmental Impact Review – Designs are comparable

  17. Semiconductor lasers and herterojunction leds

    CERN Document Server

    Kressel, Henry

    2012-01-01

    Semiconductor Lasers and Heterojunction LEDs presents an introduction to the subject of semiconductor lasers and heterojunction LEDs. The book reviews relevant basic solid-state and electromagnetic principles; the relevant concepts in solid state physics; and the p-n junctions and heterojunctions. The text also describes stimulated emission and gain; the relevant concepts in electromagnetic field theory; and the modes in laser structures. The relation between electrical and optical properties of laser diodes; epitaxial technology; binary III-V compounds; and diode fabrication are also consider

  18. Extracting light out of LEDs

    Science.gov (United States)

    Muschaweck, Julius; Wiesmann, Christopher

    2013-08-01

    `External quantum efficiency', that is, the number of photons generated per electron passing through the p-n junction of an LED is probably the most important number to quantify the performance of an LED chip. Although advances in epitaxy have increased the fraction of radiative recombination to extremely high values, the extraction of the precious photons that are trapped in a high refractive index crystal is still tricky. In this brief tutorial, we look at the physics of light extraction both from a geometrical optics/thermodynamic and a wave optics point of view, discussing both random and deterministic surface structures.

  19. 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

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

    Directory of Open Access Journals (Sweden)

    Siavash Savadi Oskoee

    2017-06-01

    Full Text Available 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 (P<0.05, post hoc Bonferroni test was used for further analyses. Results. The light-curing unit type had no effect on gap formation. However, the results were significant in relation to the composite resin type and margin location (P<0.001. The cumulative effects of light-curing unit*gingival margin and light-curing unit*composite 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.

  1. White LED motorcycle headlamp design

    Science.gov (United States)

    Sun, Wen-Shing

    2015-09-01

    The motorcycle headlamp is composed of a white LED module, an elliptical reflector, a parabolic reflector and a toric lens. We use non-sequential ray to improve the optical efficiency of the compound reflectors. Using the toric lens can meet ECE_113 regulation and obtain a good uniformity.

  2. UV-LED photopolymerised monoliths

    Czech Academy of Sciences Publication Activity Database

    Abele, S.; Nie, F.; Foret, František; Paull, B.; Macka, M.

    2008-01-01

    Roč. 133, č. 7 (2008), s. 864-866 ISSN 0003-2654 R&D Projects: GA AV ČR KAN400310651 Institutional research plan: CEZ:AV0Z40310501 Keywords : photopolymerisation * UV-LED * polymethacrylate monolith Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.761, year: 2008

  3. Architecture-Led Safety Process

    Science.gov (United States)

    2016-12-01

    Contents Acknowledgments iv Abstract v 1 Introduction 1 2 Architecture -Led Processes and ALSA 2 3 ALSA Practices 5 3.1 Example System 8 4 Identify... Architecture Models 13 5 Identify Operational Hazards and Hazard Contributors 15 5.1 System Partitioning 15 5.2 Operational Context as a Control

  4. Light-cured Tricalcium Silicate Toxicity to the Dental Pulp.

    Science.gov (United States)

    Jeanneau, Charlotte; Laurent, Patrick; Rombouts, Charlotte; Giraud, Thomas; About, Imad

    2017-12-01

    Numerous studies reported dentin bridge formation after pulp capping with tricalcium silicates. By contrast, pulp capping with resins leads to pulp toxicity and inflammation. Hybrid materials made up of tricalcium silicates and resins have also been developed to be used in direct pulp capping. This work was designed to study the consequences of adding resins to tricalcium silicates by investigating TheraCal (BISCO, Lançon De Provence, France) and Biodentine (Septodont, Saint Maur des Fosses, France) interactions with the dental pulp. Media conditioned with the biomaterials were used to analyze pulp fibroblast proliferation using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) test and proinflammatory cytokine interleukin 8 (IL-8) secretion using the enzyme-linked immunosorbent assay. The effects of conditioned media on dentin sialoprotein (DSP) and nestin expression by dental pulp stem cells (DPSCs) were investigated by immunofluorescence. The materials' interactions with the vital pulp were investigated using the entire tooth culture model. TheraCal-conditioned media significantly decreased pulp fibroblast proliferation, whereas no effect was observed with Biodentine. When DPSCs were cultured with Biodentine-conditioned media, immunofluorescence showed an increased expression of DSP and nestin. This expression was lower with TheraCal, which significantly induced proinflammatory IL-8 release both in cultured fibroblasts and entire tooth cultures. This IL-8 secretion increase was not observed with Biodentine. Entire tooth culture histology showed a higher mineralization with Biodentine, whereas significant tissue disorganization was observed with TheraCal. Within the limits of these preclinical results, resin-containing TheraCal cannot be recommended for direct pulp capping. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  5. 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.

  6. LED lamp power management system and method

    Science.gov (United States)

    Gaines, James; Clauberg, Bernd; Van Erp, Josephus A. M.

    2013-03-19

    An LED lamp power management system and method including an LED lamp having an LED controller 58; a plurality of LED channels 60 operably connected to the LED controller 58, each of the plurality of LED channels 60 having a channel switch 62 in series with at least one shunted LED circuit 83, the shunted LED circuit 83 having a shunt switch 68 in parallel with an LED source 80. The LED controller 58 reduces power loss in one of the channel switch 62 and the shunt switch 68 when LED lamp electronics power loss (P.sub.loss) exceeds an LED lamp electronics power loss limit (P.sub.lim); and each of the channel switches 62 receives a channel switch control signal 63 from the LED controller 58 and each of the shunt switches 68 receives a shunt switch control signal 69 from the LED controller 58.

  7. LED lamp color control system and method

    Science.gov (United States)

    Gaines, James; Clauberg, Bernd; Van Erp, Josephus A.M.

    2013-02-05

    An LED lamp color control system and method including an LED lamp having an LED controller 58; and a plurality of LED channels 60 operably connected to the LED controller 58, each of the plurality of LED channels 60 having a channel switch 62 in series with at least one shunted LED circuit 83, the shunted LED circuit 83 having a shunt switch 68 in parallel with an LED source 80. The LED controller 58 determines whether the LED source 80 is in a feedback controllable range, stores measured optical flux for the LED source 80 when the LED source 80 is in the feedback controllable range, and bypasses storing the measured optical flux when the LED source 80 is not in the feedback controllable range.

  8. Celebrity-led development organisations

    DEFF Research Database (Denmark)

    Budabin, Alexandra Cosima; Rasmussen, Louise Mubanda; Richey, Lisa Ann

    2017-01-01

    The past decade has seen a frontier open up in international development engagement with the entrance of new actors such as celebrity-led organisations. We explore how such organisations earn legitimacy with a focus on Madonna’s Raising Malawi and Ben Affleck’s Eastern Congo Initiative. The study...... draws from organisational materials, interviews, mainstream news coverage, and the texts of the celebrities themselves to investigate the construction of authenticity, credibility, and accountability. We find these organisations earn legitimacy and flourish rapidly amid supportive elite networks...... for funding, endorsements, and expertise. We argue that the ways in which celebrity-led organisations establish themselves as legitimate development actors illustrate broader dynamics of the machinery of development....

  9. 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

  10. Luminescent ceramics for LED conversion

    Science.gov (United States)

    Raukas, M.; Wei, G.; Bergenek, K.; Kelso, J.; Zink, N.; Zheng, Y.; Hannah, M.; Stough, M.; Wirth, R.; Linkov, A.; Jermann, F.; Eisert, D.

    2011-03-01

    Many LED-based applications would benefit from more efficient and/or high lumen output devices that enable usage in both white and single color illumination schemes. In the present article we briefly review the materials research history leading to optical ceramic converters and discuss their typical characteristics. Recently demonstrated high performance values in terms of efficacy and external quantum efficiency in orange (amber) spectral region are described.

  11. Automotive LED lamp lighted appearance

    Science.gov (United States)

    Conn, Lawrence G.; Bennett, Larry R.

    2001-05-01

    The automotive optical engineer has an entirely new set of rules to follow for a 'smooth lighted appearance' with the introduction of LEDs into the automotive signal lighting market. To move away from the 'polka-dot' appearance long associated with the usage of LEDs as the light source for automotive lighting, and give the consumer a smooth lighted appearance to his lamp, there are several optical parameters that must be observed. The number and type of LEDs used, the size of the optical elements used, the spacing of the optical elements, plus many other factors all play a critical role and must be considered in the solution to the 'smooth lighted appearance' in an automotive signal lamp. The 'smooth lighted appearance' in an automotive signal lamp has long been a difficult problem to which there is more than one solution. The most visually pleasing and effective solution is not always the most easily obtainable solution since photometry requirements and smooth lighted appearance can be diametric goals. Subsequently the most cost effective and the easily 'doable' solution may not give the ultimate in aesthetically pleasing results for the consumer. Therefore, it is the purpose and intent of this paper to outline the parameters that need to be considered to obtain a 'smooth lighted appearance' for an automotive signal lamp, and to clarify the methods and 'tools' that are required to meet this goal.

  12. Evaluating UV-C LED disinfection performance and ...

    Science.gov (United States)

    This study evaluated ultraviolet (UV) light emitting diodes (LEDs) emitting at 260 nm, 280 nm, and the combination of 260|280 nm together for their efficacy at inactivating Escherichia. coli, MS2 coliphage, human adenovirus type 2 (HAdV2), and Bacillus pumilus spores; research included an evaluation of genomic damage. Inactivation by the LEDs was compared with the efficacy of conventional UV sources, the low-pressure (LP) and medium-pressure (MP) mercury vapor lamps. The work also calculated the electrical energy per order of reduction of the microorganisms by the five UV sources.For E. coli, all five UV sources yielded similar inactivation rates. For MS2 coliphage, the 260 nm LED was most effective. For HAdV2 and B. pumilus, the MP UV lamp was significantly more effective than the LP UV and UVC LED sources. When considering electrical energy per order of reduction, the LP UV lamp was the most efficient for E. coli and MS2, and the MPUV and LPUV were equally efficient for HAdV2 and B. pumilus spores. Among the UVC LEDs, the 280 nm LED unit required the least energy per log reduction of E. coli and HAdV2. The 280 nm and 260|280 nm LED units were equally efficient per log reduction of B. pumilus spores, and the 260 nm LED unit required the lowest energy per order of reduction of MS2 coliphage. The combination of the 260 nm and 280 nm UV LED wavelengths was also evaluated for potential synergistic effects. No dual-wavelength synergy was detected for inactivation of

  13. Led enhancement in mitochondrial oxidative phosphorylation for hepatectomized rats

    Directory of Open Access Journals (Sweden)

    Orlando de Castro-e-Silva Jr

    2002-01-01

    Full Text Available Recently, the LED (light emitting diode developed by the Optics Group of IFSC-USP has been used instead of laser for the treatment of skin tumors by the PDT (Photodinamic Therapy because of its low operational cost compared to the use of a laser. In this paper we investigate the effect of LED light on oxidative phosphorylation during liver regeneration after partial hepatectomy. Twenty-four male Wistar rats (250 g were kept in identical housing units on a 12-hour light/12 hour dark cycle. The LED 10 group was exposed to LED at 638 nm (10 J/cm² for 3 minutes. Seventy percent partial hepatectomy was performed in the LED 10 and HPC (Partial Hepatectomy-Control. A sham-operated group (C was used for control. Twenty four hours after the procedure, LED 10, HPC and control animals were sacrificed. Samples of liver tissue were used for the mitochondrial respiration assay. Statistical comparisons of the groups were performed by analysis of variance (ANOVA, followed by the Bonferroni post-test. Probability values less than 0.05 were considered to be statistically significant. the phosphorylation index (FI for the LED 10 group was higher than that for the HPC group and for the sham group (p 0.05. In the present study we noted an effective interaction between LED light and hepatic mitochondria, with an increased phosphorylation rate for the latter.

  14. Practical lighting design with LEDs

    CERN Document Server

    Lenk, Ron

    2011-01-01

    "This book covers all of the information needed to design LEDs into end-products. It is a practical guide, primarily explaning how things are done by practicing engineers. Equations are used only for practical calculations, and are kept to the level of high-school algebra. There are numerous drawings and schematics showing how things such as measurements are actually made, and showing curcuits that actually work. There are practical notes and examples embedded in the text that give pointers and how-to guides on many of the book's topics. After reading each chapter of the book, readers will have the knowledge to implement practical designs. This book will be kept as a reference tool for years to come"--

  15. Water sorption and solubility of bulk-fill composites polymerized with a third generation LED LCU

    Directory of Open Access Journals (Sweden)

    Tuğba MİSİLLİ

    2017-10-01

    Full Text Available Abstract The aim of this study was to compare the degree of water sorption and solubility in bulk-fills after curing with a polywave light source. A total of 120 disc-shaped specimens (8 mm diameter; 4 mm depth were prepared from three regular bulk-fill materials (X-tra Fil, Tetric N-Ceram Bulk Fill, SonicFill, and a control material (Filtek Z250, cured in 3 different modes (standard: 1000 mW/cm2-20 s; high power: 1400 mW/cm2-12 s; xtra power: 3200 mW/cm2-6 s using a third generation light-emitting diode light curing unit. Water sorption and solubility levels of the specimens were measured according to the ISO 4049:2009 specification after storing in distilled water for 30 days. Data were analyzed using two-way ANOVA and Tukey’s post-hoc test (p < 0.05. The Z250 sample exposed to high power presented a higher sorption compared to the X-tra Fil and SonicFill samples. In xtra power mode, the values of Z250 and SonicFill were similar to each other and higher compared to those of X-tra Fil. Only SonicFill exhibited significantly different sorption values depending on the curing mode, the highest of which was achieved when using the xtra power mode. The highest solubility values were obtained for SonicFill. No statistically significant differences were found among other groups. No significant correlation was detected between water sorption and solubility. The traditional composite group exhibited a higher water sorption values than the bulk-fills. The reduction in polymerization time significantly increased the sorption of SonicFill. SonicFill showed the highest water solubility value among the composites tested.

  16. LEDs light up the world

    Energy Technology Data Exchange (ETDEWEB)

    Mather, N.

    2004-06-30

    A lighting system using light-emitting diodes, and privately financed by a Canadian engineering professor at the University of Calgary, has been set up in a village in Nepal in 2000. Since then, through the efforts of the 'Light Up The World' Foundation, established by Dr. Irvine-Halliday, projects have lit up thousands of homes in the Philippines, India, Afghanistan, the Galapagos Islands, Mexico, Sri Lanka, and Angola. Although the goal of the project is primarily to provide lighting for reading and writing for school-children, the project has been the source of many other advantages; creation of enterprise, increased employment, enhanced income, gender equality, and improvements in health and safety among them. Since LED lamps in most cases replace kerosene lamps, the system also has significant environmental benefits. The system as originally envisioned creates electricity by pedal-powered generator, or by solar panels connected to a battery, depending on what is available at each home. Each home is connected to the power supply and supplied with low-energy diode lamps. The lights are extremely efficient and many homes can be equipped with them using less energy than it takes to power a single 100-watt light bulb. 5 photos.

  17. Designing low cost LED display for the billboard

    Science.gov (United States)

    Hong, Yi-Jian; Uang, Chii-Maw; Wang, Ping-Chieh; Ho, Zu-Sheng

    2011-10-01

    With quickly advance of the computer, microelectronics and photonics technologies, LED display panel becomes a new electronic advertising media. It can be used to show any information whatever characters or graphics. Most LED display panels are built of many Light-Emitting Diodes arranged in a matrix form. The display has many advantages such as low power, low cost, long life and high definition. Because the display panel is asked to show rich color, the LED display panel's driving system becomes very complex. The design methodology of LED display panel's driver becomes more and more important to meet the market requirements. Cost is always the most important issue in public market domain. In this paper, we report a design methodology of LED display panel's driver based on the microprocessor control unit (MCU) system and LED display controller IC, HT1632C, to control three colors, RGB, color LED display panel and the modular panel size is 24*16 in matrix form. The HT1632C is a memory mapping LED display controller, it can be used on many applications, such as digital clock, thermometer, counter, voltmeter or other instrumentation readouts. Three pieces of HT1632C are used to drive a 24*16 RGB LED display panel, in our design case. Each HT163C chip is used to control one of the R, G and B color. As the drive mode is driven in DC mode, the RGB display panel can create and totally of seven colors under the control of MCU. The MCU generates the control signal to drive HT1632C. In this study, the software design methodology is adopted with dynamic display principle. When the scan frequency is 60Hz, LED display panel will get the clear picture and be able to display seven colors.

  18. 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.

  19. Fokusgruppeinterview som led i en evalueringsproces

    DEFF Research Database (Denmark)

    Andersen-Mølgaard, Hanna; Harrit, Ole

    2006-01-01

    Teoretiske begrundelser og perspektiver, responsiv-konstruktivistisk evaluering, fokusgruppeinterview som led i BIKVAmodellen, eksempler, vurdering og perspektivering......Teoretiske begrundelser og perspektiver, responsiv-konstruktivistisk evaluering, fokusgruppeinterview som led i BIKVAmodellen, eksempler, vurdering og perspektivering...

  20. Evaluation of LED vehicular and pedestrian modules.

    Science.gov (United States)

    2009-04-01

    This study was conducted to verify the compliance of vehicular and pedestrian LED traffic signal modules with the Institute : of Transportation Engineers specifications; and to assess drivers preferences of the LED modules. Four vehicular modules ...

  1. Goniometric characterization of LED based greenhouse lighting

    DEFF Research Database (Denmark)

    Thorseth, Anders; Lindén, Johannes; Corell, Dennis Dan

    2015-01-01

    This paper describes a demonstration of goniospectroradiometry for characterizations of new light emitting diode (LED) based luminaries for enhanced photosynthesis in greenhouses. It highlights the differences between measurement of the traditional high pressure sodium (HPS) luminaries and the LED...

  2. Goniometric characterization of LED based greenhouse lighting

    DEFF Research Database (Denmark)

    Thorseth, Anders; Lindén, Johannes; Corell, Dennis Dan

    2015-01-01

    This paper describes a demonstration of goniospectroradiometry for characterizations of new light emitting diode (LED) based luminaries for enhanced photosynthesis in greenhouses. It highlights the differences between measurement of the traditional high pressure sodium (HPS) luminaries and the LED...... based luminaries. The LED based luminaries are compared to traditional HPS luminaries; in terms of energy efficiency with regard to the photosynthetic photon flux, and the LED luminaries were found to be more effective than the HPS luminaries...

  3. 76 FR 55416 - In the Matter of Certain Led Photographic Lighting Devices and Components Thereof; Notice of...

    Science.gov (United States)

    2011-09-07

    ... COMMISSION In the Matter of Certain Led Photographic Lighting Devices and Components Thereof; Notice of... sale for importation, and the sale within the United States after importation of certain LED... importation, or the sale within the United States after importation of certain LED photographic lighting...

  4. LED belichting tijdens het voortrekken van lelie

    NARCIS (Netherlands)

    Kok, B.J.; Wildschut, J.

    2010-01-01

    De laatste jaren staat het gebruik van LED-lampen in de tuinbouw in de belangstelling. Uit vele onderzoeken is al gebleken dat LED-lampen op dit moment nog geen alternatief zijn voor de SON-T lampen. Het grote voordeel van LED-lampen is dat ze monochromatisch licht van alle mogelijke golflengtes

  5. ‘No Blue’ White LED

    DEFF Research Database (Denmark)

    Ou, Haiyan; Corell, Dennis Dan; Dam-Hansen, Carsten

    2010-01-01

    This paper explored the feasibility of making a white LED light source by color mixing method without using the blue color. This ‘no blue’ white LED has potential applications in photolithography room illumination, medical treatment and biophotonics research. A no-blue LED was designed, and the p...

  6. Plant growth with Led lighting systems

    International Nuclear Information System (INIS)

    Campiotti, C.A.; Bernardini, A.; Di Carlo, F.; Scoccianti, M.; Alonzo, G.; Carlino, M.; Dondi, F.; Bibbiani, C.

    2009-01-01

    Leds lighting is highly relevant for the horticultural industry. Compared to other light sources used for plant production, leds have several properties which are potentially useful in relation to horticulture. However, although LEDs technology has raised strong interest in research for extraterrestrial agriculture, current LEDs panel costs are still too high for commercial adoption in greenhouse sector, and their electrical efficacies do not compete with those of high-pressure sodium lamps, but several manufactures are working to address these issues. When LEDs become practical, their ability to based light sources specifically suitable for photosynthesis and other horticulturally relevant plant properties (i.e. low radiated heat; lighting from within the canopy) will render the narrow band spectrum of LEDs of particular interest for providing light to greenhouse horticulture. A general description of LEDs application and their technical characteristics is briefly reported. [it

  7. Generation of solar spectrum by using LEDs

    Science.gov (United States)

    Lu, Pengzhi; Yang, Hua; Pei, Yanrong; Li, Jing; Xue, Bin; Wang, Junxi; Li, Jinmin

    2016-09-01

    Light emitting diode (LED) has been recognized as an applicable light source for indoor and outdoor lighting, city beautifying, landscape facilities, and municipal engineering etc. Conventional LED has superior characteristics such as long life time, low power consumption, high contrast, and wide viewing angle. Recently, LED with high color-rendering index and special spectral characteristics has received more and more attention. This paper is intended to report a solar spectrum simulated by multichip LED light source. The typical solar spectrum of 5500k released by CIE was simulated as a reference. Four types of LEDs with different spectral power distributions would be used in the LED light source, which included a 430nm LED, a 480nm LED, a 500nm LED and a white LED. In order to obtain better simulation results, the white LED was achieved by a 450nm LED chip with the mixture of phosphor. The phosphor combination was prepared by mixing green phosphor, yellow phosphor and red phosphor in a certain proportion. The multichip LED light source could provide a high fidelity spectral match with the typical solar spectrum of 5500k by adjusting injection current to each device. The luminous flux, CIE chromaticity coordinate x, y, CCT, and Ra were 104.7 lm, 0.3337, 0.3681, 5460K, and 88.6, respectively. Because of high color-rendering index and highly match to the solar spectrum, the multichip LED light source is a competitive candidate for applications where special spectral is required, such as colorimetric measurements, visual inspection, gemstone identification and agriculture.

  8. Testing Finance-Led, Export-Led and Import-Led Growth Hypotheses on Four Sub-Saharan African Economies

    OpenAIRE

    Evans, Olaniyi

    2013-01-01

    This study carries out an empirical examination of the finance-led, export-led and import-led growth hypothesis for four of the largest Sub-Saharan African economies namely South Africa, Nigeria, Ghana and Kenya. Within a multivariate Vector-Auto Regressive (VAR) framework, the concept of Granger causality is employed to determine the direction of causation between exports and output, duly taking into account the stationarity properties of the time series data. With further substantiation fro...

  9. Influence of the Light Source and Curing Parameters on Microhardness of a Silorane-Based Dental Composite Material

    Directory of Open Access Journals (Sweden)

    Malara P.

    2016-09-01

    Full Text Available The aim of the study was to determine the influence of the light source and the light-curing parameters (the distance of the material from the light source and time of light-curing on microhardness of Flitek Silorane dental composite material. Standardized samples of Filtek Silorane material were cured using two types of Light Curing Units (LCUs – halogen and LED. The distance of the light source and time of curing differed between samples. The Knoop’s microhardness was tested using microhardness tester Micromet 5103. Using LED light curing unit allowed to achieve significantly higher microhardness of silorane-based dental material Filtek Silorane than using halogen light curing unit. Decreasing the distance from the light source to the surface of silorane-based material Filtek Silorane improved its microhardness. A prolonged curing time could compensate the drop in microhardness of Filtek Silorane material resulting from an increased distance from the light source to the surface of the material only in a limited range of intervals.

  10. LEDs for general and horticultural lighting

    OpenAIRE

    Girón González, Emilio

    2012-01-01

    The work begins with an introductory part about Light Emitting Diode (or LEDs) and how these devices work. This report also shows an overview of different artificial light sources such as incandescent lamps, fluorescents tube and high-intensity discharge (HID) lamps. The LED lighting is more energy-efficient than other artificial lighting, since they require less energy to operate. The following part of the work reports LEDs for General Lighting that describes some basic concepts such as spec...

  11. System Reliability for LED-Based Products

    Energy Technology Data Exchange (ETDEWEB)

    Davis, J Lynn; Mills, Karmann; Lamvik, Michael; Yaga, Robert; Shepherd, Sarah D; Bittle, James; Baldasaro, Nick; Solano, Eric; Bobashev, Georgiy; Johnson, Cortina; Evans, Amy

    2014-04-07

    Results from accelerated life tests (ALT) on mass-produced commercially available 6” downlights are reported along with results from commercial LEDs. The luminaires capture many of the design features found in modern luminaires. In general, a systems perspective is required to understand the reliability of these devices since LED failure is rare. In contrast, components such as drivers, lenses, and reflector are more likely to impact luminaire reliability than LEDs.

  12. Solid State Lighting LED Manufacturing Roundtable Summary

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2010-03-31

    Summary of a meeting of LED experts to develop proposed priority tasks for the Manufacturing R&D initiative, including task descriptions, discussion points, recommendations, and presentation highlights.

  13. LEDs: revolution or evolution? Part One

    Energy Technology Data Exchange (ETDEWEB)

    Roush, M.

    2000-11-01

    The historical evolution, the current state of light emitting diodes (LEDs), future implications and the promise of this technology for the lighting industry are explored. Some of the misconceptions relative to that promise are dispelled and some of the less obvious benefits that this technology could deliver in the future are discussed. As far as misconceptions are concerned, it is not true that LEDs will deliver light forever at a fraction of the energy of conventional light sources, or that they come in an infinite variety of colours and cost just pennies. Although LEDs per se may last a long time, the fact is that their true life expectancy is only as long as the wiring and the connection within the system, and they are certainly limited. Energy efficiency is another misconception. The truth is that white LEDs (the best for illumination purposes) are limited to less than 10 lumen per Watt, which is hardly a revolutionary improvement over incandescent light sources. Equally disappointing is the misconception concerning price. In actual fact, LEDs in lighting applications are very new and it would require mass production in the millions before LED lighting packages could become inexpensive. At the same time, LEDs have many advantages that are not commonly known. Compactness, very high level of light utilization, high life expectancy and nearly flat mortality curve are some of these. Operating on direct current lends LED installations to battery and solar applications (as for example solar LED road studs to aid in night driving). The absence of ultraviolet emissions in LEDs is another lesser known, but important feature, especially in applications where material degradation is a major concern (as in stores and museums). In general, all indicators point to a bright future for LEDs as their application progresses from decoration to illumination. This topic will be further explored in Part Two of this article. 4 figs.

  14. On the switching speed of SOI LEDs

    NARCIS (Netherlands)

    Schmitz, Jurriaan; de Vries, R.; Salm, Cora; Hoang, T.; Hueting, Raymond Josephus Engelbart; Holleman, J.

    2008-01-01

    Recently, we presented a novel design for a silicon LED in SmartCUT™ SOI wafers. It exhibits a record quantum efficiency for SOI-based silicon LEDs and opens the way to the integration of light emitters in a VLSI process on SOI. In this paper, we present first experimental and modeling results

  15. Led-licht biedt mogelijkheden in broeierij

    NARCIS (Netherlands)

    Neefjes, H.; PPO Bomen-bollen,

    2010-01-01

    Onderzoekers van PPO Lisse hebben de mogelijkheden van led-licht verkend bij met name lelie en tulp. Bij lelie bieden leds perspectief in de voortrek. Tulp kan er bijna de hele broeifase van profiteren. Veel licht is niet nodig, maar meerlagenteelt is een voorwaarde.

  16. Reduced Component Count RGB LED Driver

    NARCIS (Netherlands)

    De Pedro, I.; Ackermann, B.

    2008-01-01

    The goal of this master thesis is to develop new drive and contrololutions, for creating white light from mixing the light of different-color LEDs, aiming at a reduced component count resulting in less space required by the electronics and lower cost. It evaluates the LED driver concept proposed in

  17. Led Zeppelin reklaamib Narvat / Anti Ronk

    Index Scriptorium Estoniae

    Ronk, Anti

    2007-01-01

    Ilmus Narva-teemaline kahest CD-st koosnev album, kus ühel plaadil on 60 minutit videot linna vaatamisväärsuste ja informatsiooniga, teisel - briti rockansambli Led Zeppelini teosed Narva sümfooniaorkestri ja rockansambli Led R esituses

  18. Advances in LEDs for automotive applications

    Science.gov (United States)

    Bhardwaj, Jy; Peddada, Rao; Spinger, Benno

    2016-03-01

    High power LEDs were introduced in automotive headlights in 2006-2007, for example as full LED headlights in the Audi R8 or low beam in Lexus. Since then, LED headlighting has become established in premium and volume automotive segments and beginning to enable new compact form factors such as distributed low beam and new functions such as adaptive driving beam. New generations of highly versatile high power LEDs are emerging to meet these application needs. In this paper, we will detail ongoing advances in LED technology that enable revolutionary styling, performance and adaptive control in automotive headlights. As the standards which govern the necessary lumens on the road are well established, increasing luminance enables not only more design freedom but also headlight cost reduction with space and weight saving through more compact optics. Adaptive headlighting is based on LED pixelation and requires high contrast, high luminance, smaller LEDs with high-packing density for pixelated Matrix Lighting sources. Matrix applications require an extremely tight tolerance on not only the X, Y placement accuracy, but also on the Z height of the LEDs given the precision optics used to image the LEDs onto the road. A new generation of chip scale packaged (CSP) LEDs based on Wafer Level Packaging (WLP) have been developed to meet these needs, offering a form factor less than 20% increase over the LED emitter surface footprint. These miniature LEDs are surface mount devices compatible with automated tools for L2 board direct attach (without the need for an interposer or L1 substrate), meeting the high position accuracy as well as the optical and thermal performance. To illustrate the versatility of the CSP LEDs, we will show the results of, firstly, a reflector-based distributed low beam using multiple individual cavities each with only 20mm height and secondly 3x4 to 3x28 Matrix arrays for adaptive full beam. Also a few key trends in rear lighting and impact on LED light

  19. High Performance Green LEDs by Homoepitaxial

    Energy Technology Data Exchange (ETDEWEB)

    Wetzel, Christian; Schubert, E Fred

    2009-11-22

    This work's objective was the development of processes to double or triple the light output power from green and deep green (525 - 555 nm) AlGaInN light emitting diode (LED) dies within 3 years in reference to the Lumileds Luxeon II. The project paid particular effort to all aspects of the internal generation efficiency of light. LEDs in this spectral region show the highest potential for significant performance boosts and enable the realization of phosphor-free white LEDs comprised by red-green-blue LED modules. Such modules will perform at and outperform the efficacy target projections for white-light LED systems in the Department of Energy's accelerated roadmap of the SSL initiative.

  20. White LEDs with limit luminous efficacy

    Science.gov (United States)

    Lisitsyn, V. M.; Lukash, V. S.; Stepanov, S. A.; Yangyang, Ju

    2016-01-01

    In most promising widespread gallium nitride based LEDs emission is generated in the blue spectral region with a maximum at about 450 nm which is converted to visible light with the desired spectrum by means of phosphor. The thermal energy in the conversion is determined by the difference in the energies of excitation and emission quanta and the phosphor quantum yield. Heat losses manifest themselves as decrease in the luminous efficacy. LED heating significantly reduces its efficiency and life. In addition, while heating, the emission generation output and the efficiency of the emission conversion decrease. Therefore, the reduction of the energy losses caused by heating is crucial for LED development. In this paper, heat losses in phosphor-converted LEDs (hereinafter chips) during spectrum conversion are estimated. The limit values of the luminous efficacy for white LEDs are evaluated.

  1. White LEDs with limit luminous efficacy

    Energy Technology Data Exchange (ETDEWEB)

    Lisitsyn, V. M.; Stepanov, S. A., E-mail: stepanovsa@tpu.ru; Yangyang, Ju [National Research Tomsk Polytechnic University, 30 Lenin Av., Tomsk, 634050 (Russian Federation); Lukash, V. S. [JSC Research Institute of Semiconductor Devices, 99a Krasnoarmeyskaja St., Tomsk, 634050 (Russian Federation)

    2016-01-15

    In most promising widespread gallium nitride based LEDs emission is generated in the blue spectral region with a maximum at about 450 nm which is converted to visible light with the desired spectrum by means of phosphor. The thermal energy in the conversion is determined by the difference in the energies of excitation and emission quanta and the phosphor quantum yield. Heat losses manifest themselves as decrease in the luminous efficacy. LED heating significantly reduces its efficiency and life. In addition, while heating, the emission generation output and the efficiency of the emission conversion decrease. Therefore, the reduction of the energy losses caused by heating is crucial for LED development. In this paper, heat losses in phosphor-converted LEDs (hereinafter chips) during spectrum conversion are estimated. The limit values of the luminous efficacy for white LEDs are evaluated.

  2. Harmonics Monitoring Survey on LED Lamps

    Directory of Open Access Journals (Sweden)

    Abdelrahman Ahmed Akila

    2017-03-01

    Full Text Available Light Emitting Diode (LED lamps are being increasingly used in many applications. These LED lamps operate using a driver, which is a switching device. Hence, LED lamps will be a source of harmonics in the power system. These harmonics if not well treated, may cause severe performance and operational problems. In this paper, harmonics (amplitude and phase angles generated by both LED lamps and conventional fluorescent lamps will be studied practically. Then they will be analyzed and evaluated. Compared to each other harmonics generated by both LED and conventional florescent lamps, self mitigation may occur based on the phase angle of these harmonics. All data will be measured using power analyzer and will be done on a sample of actual lamps.

  3. Design of an Oximeter Based on LED-LED Configuration and FPGA Technology

    OpenAIRE

    Stojanovic, Radovan; Karadaglic, Dejan

    2013-01-01

    A fully digital photoplethysmographic (PPG) sensor and actuator has been developed. The sensing circuit uses one Light Emitting Diode (LED) for emitting light into human tissue and one LED for detecting the reflectance light from human tissue. A Field Programmable Gate Array (FPGA) is used to control the LEDs and determine the PPG and Blood Oxygen Saturation (SpO2). The configurations with two LEDs and four LEDs are developed for measuring PPG signal and Blood Oxygen Saturation (SpO2). N-LEDs...

  4. White LED with High Package Extraction Efficiency

    International Nuclear Information System (INIS)

    Yi Zheng; Stough, Matthew

    2008-01-01

    The goal of this project is to develop a high efficiency phosphor converting (white) Light Emitting Diode (pcLED) 1-Watt package through an increase in package extraction efficiency. A transparent/translucent monolithic phosphor is proposed to replace the powdered phosphor to reduce the scattering caused by phosphor particles. Additionally, a multi-layer thin film selectively reflecting filter is proposed between blue LED die and phosphor layer to recover inward yellow emission. At the end of the project we expect to recycle approximately 50% of the unrecovered backward light in current package construction, and develop a pcLED device with 80 lm/W e using our technology improvements and commercially available chip/package source. The success of the project will benefit luminous efficacy of white LEDs by increasing package extraction efficiency. In most phosphor-converting white LEDs, the white color is obtained by combining a blue LED die (or chip) with a powdered phosphor layer. The phosphor partially absorbs the blue light from the LED die and converts it into a broad green-yellow emission. The mixture of the transmitted blue light and green-yellow light emerging gives white light. There are two major drawbacks for current pcLEDs in terms of package extraction efficiency. The first is light scattering caused by phosphor particles. When the blue photons from the chip strike the phosphor particles, some blue light will be scattered by phosphor particles. Converted yellow emission photons are also scattered. A portion of scattered light is in the backward direction toward the die. The amount of this backward light varies and depends in part on the particle size of phosphors. The other drawback is that yellow emission from phosphor powders is isotropic. Although some backward light can be recovered by the reflector in current LED packages, there is still a portion of backward light that will be absorbed inside the package and further converted to heat. Heat generated

  5. FREQUENCY CHARACTERISTICS OF MODERN LED PHOSPHOR MATERIALS

    Directory of Open Access Journals (Sweden)

    Maxim S. Fudin

    2014-11-01

    Full Text Available Frequency characteristics of modern LED phosphor materials have been considered for the purpose of assessing the prospects of phosphor-based LEDs in wireless communication data systems which use optical wavelengths. The measurements have been carried out on the dependence of the emission intensity of single LEDs and LED chip-on-board modules with phosphors based on yttrium-aluminum and lutetium-aluminum garnets (with or without addition of nitridebased phosphors as well as silicate-based phosphors, on the frequency of electric pulses exciting the emission. It was shown that from the point of view of data transmission rate, garnet-based phosphors (including systems with added nitride phosphors are more promising than silicate–based ones. Garnet-based materials can be used in optical communication data systems with bandwidth (without extra modulation applied up to 3 MHz with single–chip LEDs and up to 4.5 MHz with 9- chip LED chip-on-board modules. The results of the work indicate that a significant part of white LEDs used in general lighting systems can be even now used for data transfer, for example, in systems assisting positioning in closed spaces to facilitate people searching necessary rooms or objects

  6. High Power UV LED Industrial Curing Systems

    Energy Technology Data Exchange (ETDEWEB)

    Karlicek, Robert, F., Jr; Sargent, Robert

    2012-05-14

    UV curing is a green technology that is largely underutilized because UV radiation sources like Hg Lamps are unreliable and difficult to use. High Power UV LEDs are now efficient enough to replace Hg Lamps, and offer significantly improved performance relative to Hg Lamps. In this study, a modular, scalable high power UV LED curing system was designed and tested, performing well in industrial coating evaluations. In order to achieve mechanical form factors similar to commercial Hg Lamp systems, a new patent pending design was employed enabling high irradiance at long working distances. While high power UV LEDs are currently only available at longer UVA wavelengths, rapid progress on UVC LEDs and the development of new formulations designed specifically for use with UV LED sources will converge to drive more rapid adoption of UV curing technology. An assessment of the environmental impact of replacing Hg Lamp systems with UV LED systems was performed. Since UV curing is used in only a small portion of the industrial printing, painting and coating markets, the ease of use of UV LED systems should increase the use of UV curing technology. Even a small penetration of the significant number of industrial applications still using oven curing and drying will lead to significant reductions in energy consumption and reductions in the emission of green house gases and solvent emissions.

  7. Kansas highway LED illumination manual : a guide for the use of LED lighting systems.

    Science.gov (United States)

    2015-12-01

    The research project was aimed to assist the Kansas Department of Transportation (KDOT) in the development of a Highway LED Illumination Manual for guiding the upcoming implementation of successful LED roadway lighting systems in Kansas to replace th...

  8. Kansas highway LED illumination manual : a guide for the use of LED lighting systems : [technical summary].

    Science.gov (United States)

    2015-12-01

    The research project was aimed to assist the Kansas Department of Transportation (KDOT) in the development of a Highway LED Illumination Manual for guiding the upcoming implementation of successful LED roadway lighting systems in Kansas to replace th...

  9. LED traffic signal management system : final report.

    Science.gov (United States)

    2016-06-01

    This research originated from the opportunity to develop a methodology to assess when LED (Light Emitting Diode) traffic signal modules begin to fail to meet the Institute of Transportation Engineers (ITE) performance specification for luminous inten...

  10. Significant growth in. LED use predicted.

    Science.gov (United States)

    Simpson, Mike

    2012-03-01

    Although LED lighting has its critics, a number of whom (see article 'LED--panacea or marketing hype', HEJ--February 2012) are concerned about what they claim are some manufacturers' 'exaggerated claims' about lighting efficiency and lamp lifetime, Philips Lighting believes that, such are the advances being made in this innovative lighting technology, that LED's overall share of the European lighting market will have risen from around 7% in 2008 to 25% by 2020 and that, a decade later, it will account for a remarkable 75% of lighting sales. In the UK, Philips' technical and design director for Lighting, Mike Simpson, told HEJ editor, Jonathan Baillie, healthcare estates and facilities managers are increasingly recognising the potential to save energy, reduce carbon emissions, and cut maintenance costs, using LED.

  11. LED til væksthuse

    DEFF Research Database (Denmark)

    Dam-Hansen, Carsten; Thorseth, Anders; Rosenqvist, Eva

    2012-01-01

    Den teknologiske udvikling indenfor Lys Emitterende Dioder (LED) går imod stadig større lysmængder og stadig større effektivitet. Kombineret med fordele som lang levetid, dæmpbarhed og ingen varmestråling gør det, at LED baserede lyskilder/lamper i stigende grad benyttes til belysningsformål og kan...

  12. LED Shipboard Lighting: A Comparative Analysis

    Science.gov (United States)

    2009-12-01

    viability of retrofitting the Navy fleet with newer lighting technology . C. RESEARCH QUESTION The research project provided to NPS by Dr. Larry Schuette...LED is a key component in today’s lighting technology . Modern households use LEDs in such components as digital video disc, (DVD) readers...manufactures that the Navy is serious in implementing lighting technology with a multi- year demonstration seeing the benefits provided by the manufactures

  13. The Integration of Virtual Public-Private Partnerships into Local Law Enforcement to Achieve Enhanced Intelligence-Led Policing

    National Research Council Canada - National Science Library

    Simeone, Jr, Matthew J

    2007-01-01

    In light of the recent emergence of fusion centers and centralized intelligence units, and the move to develop intelligence capacity within local law enforcement agencies in the United States, intelligence-led policing (ILP...

  14. Liquid cooling applications on automotive exterior LED lighting

    Science.gov (United States)

    Aktaş, Mehmet; Şenyüz, Tunç; Şenyıldız, Teoman; Kılıç, Muhsin

    2018-02-01

    In this study cooling of a LED unit with heatsink and liquid cooling block which is used in automotive head lamp applications has been investigated numerically and experimentally. Junction temperature of a LED which is cooled with heatsink and liquid cooling block obtained in the experiment. 23°C is used both in the simulation and the experiment phase. Liquid cooling block material is choosed aluminium (Al) and polyamide. All tests and simulation are performed with three different flow rate. Temperature distribution of the designed product is investigated by doing the numerical simulations with a commercially software. In the simulations, fluid flow is assumed to be steady, incompressible and laminar and 3 dimensional (3D) Navier-Stokes equations are used. According to the calculations it is obtained that junction temperature is higher in the heatsink design compared to block cooled one. By changing the block material, it is desired to investigate the variation on the LED junction temperature. It is found that more efficient cooling can be obtained in block cooling by using less volume and weight. With block cooling lifetime of LED can be increased and flux loss can be decreased with the result of decreased junction temperature.

  15. Does size matter? Animal units and animal unit months

    Science.gov (United States)

    Lamar Smith; Joe Hicks; Scott Lusk; Mike Hemmovich; Shane Green; Sarah McCord; Mike Pellant; John Mitchell; Judith Dyess; Jim Sprinkle; Amanda Gearhart; Sherm Karl; Mike Hannemann; Ken Spaeth; Jason Karl; Matt Reeves; Dave Pyke; Jordan Spaak; Andrew Brischke; Del Despain; Matt Phillippi; Dave Weixelmann; Alan Bass; Jessie Page; Lori Metz; David Toledo; Emily Kachergis

    2017-01-01

    The concepts of animal units, animal unit months, and animal unit equivalents have long been used as standards for range management planning, estimating stocking rates, reporting actual use, assessing grazing fees, ranch appraisal, and other purposes. Increasing size of cattle on rangelands has led some to suggest that the definition of animal units and animal unit...

  16. Development of Local-Economic-Development Small and Medium Industries (Led-Sme In East Java

    Directory of Open Access Journals (Sweden)

    Rachmad Hidayat

    2013-04-01

    Full Text Available This paper presents the effects of Indonesian government’s developmental efforts of assistance and training performed  on the growth of LED-SME business units and business performance. Both parameters of the government’s assistance and training were used to analyze the impact to the  growth and performance of business unit. To achieve a comprehensive result, samples acquired in this research were about 190 entrepreneurs and managers of LED-SME from East Java. Based on the parameters above, there are five hypotheses made to prove the relationship of the assistance and training to the growth and performance of business units. The structural equation modeling (SEM was carried out to test the hypotheses. The results have shown that the government’s developmental efforts through both assistance and training for the LED-SME were capable on increasing growth and performance of business units. On the other hand, government’s developmental efforts through only trainings were incapable of directly affecting growth of LED-SME business units and performance. To improve the business unit and performance, the government needs to implement developmental principles of LED-SME with the basis of utilizing local natural resources and also the communities of LED-SME as main suppliers for their local markets. In addition, preservation and development of local cultural and traditional arts also need to be the government’s main concern. 

  17. LEDS GP Success Story: Fostering Coordinated LEDS Support in Kenya (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2014-03-01

    The LEDS Global Partnership (LEDS GP) strives to advance climate-resilient, low-emission development through catalyzing collaboration, information exchange, and action on the ground. The Government of Kenya is a key LEDS GP member and offers an inspiring example of how LEDS GP is having an impact globally. The 2012 LEDS Collaboration in Action workshop in London provided an interactive space for members to share experiences on cross-ministerial LEDS leadership and to learn about concrete development impacts of LEDS around the world. Inspired by these stories, the Kenya's Ministry of State for Planning, National Development and Vision 2030 (MPND) began to collaborate closely with the Ministry of Environment and Mineral Resources to create strong links between climate change action and development in the country, culminating in the integration of Kenya's National Climate Change Action Plan and the country's Medium Term Development Plan.

  18. Affordable underwater wireless optical communication using LEDs

    Science.gov (United States)

    Pilipenko, Vladimir; Arnon, Shlomi

    2013-09-01

    In recent years the need for high data rate underwater wireless communication (WC) has increased. Nowadays, the conventional technology for underwater communication is acoustic. However, the maximum data rate that acoustic technology can provide is a few kilobits per second. On the other hand, emerging applications such as underwater imaging, networks of sensors and swarms of underwater vehicles require much faster data rates. As a result, underwater optical WC, which can provide much higher data rates, has been proposed as an alternative means of communication. In addition to high data rates, affordable communication systems become an important feature in the development requirements. The outcome of these requirements is a new system design based on off-the-shelf components such as blue and green light emitting diodes (LEDs). This is due to the fact that LEDs offer solutions characterized by low cost, high efficiency, reliability and compactness. However, there are some challenges to be met when incorporating LEDs as part of the optical transmitter, such as low modulation rates and non linearity. In this paper, we review the main challenges facing the incorporation of LEDs as an integral part of underwater WC systems and propose some techniques to mitigate the LED limitations in order to achieve high data rate communication

  19. Zernike polynomials for photometric characterization of LEDs

    International Nuclear Information System (INIS)

    Velázquez, J L; Ferrero, A; Pons, A; Campos, J; Hernanz, M L

    2016-01-01

    We propose a method based on Zernike polynomials to characterize photometric quantities and descriptors of light emitting diodes (LEDs) from measurements of the angular distribution of the luminous intensity, such as total luminous flux, BA, inhomogeneity, anisotropy, direction of the optical axis and Lambertianity of the source. The performance of this method was experimentally tested for 18 high-power LEDs from different manufacturers and with different photometric characteristics. A small set of Zernike coefficients can be used to calculate all the mentioned photometric quantities and descriptors. For applications not requiring a great accuracy such as those of lighting design, the angular distribution of the luminous intensity of most of the studied LEDs can be interpolated with only two Zernike polynomials. (paper)

  20. White LED phosphors: the next step

    Science.gov (United States)

    Yamamoto, Hajime

    2010-02-01

    Application of white LEDs is extended toward high-output light sources, e.g. for automotive headlights, and better spectral matching with optical filters for LCD backlighting. To meet such new demands, phosphor materials have been investigated with focus on their luminescence spectra, temperature characteristics and reliability. The conventional yellow phosphor based on Y3Al5O12:Ce3+ has excellent performance as a single phosphor combined with a blue LED. More recently developed nitrido- or oxonitrido-silicates activated with Eu2+ are also promising materials showing green to red luminescence depending on a composition and high thermal and chemical stability. And yet, demands for specific application have been made clear and strong. This paper reviews the present status and challenging goals of phosphors in the next stage further to make progress in white LEDs.

  1. Patient-led versus physician-led titration of insulin glargine in patients with uncontrolled type 2 diabetes: a randomized multinational ATLAS study.

    Science.gov (United States)

    Garg, Satish K; Admane, Karim; Freemantle, Nick; Odawara, Masato; Pan, Chang-Yu; Misra, Anoop; Jarek-Martynowa, Iwona R; Abbas-Raza, Syed; Mirasol, Roberto C; Perfetti, Riccardo

    2015-02-01

    Self-adjustment of insulin dose is commonly practiced in Western patients with type 2 diabetes but is usually not performed in Asian patients. This multinational, 24-week, randomized study compared patient-led with physician-led titration of once-daily insulin glargine in Asian patients with uncontrolled type 2 diabetes who were on 2 oral glucose-lowering agents. Patient-led (n = 275) or physician-led (n = 277) subjects followed the same dose-titration algorithm guided by self-monitored fasting blood glucose (FBG; target, 110 mg/dL [6.1 mmol/L]). The primary endpoint was change in mean glycated hemoglobin (HbA1c) at week 24 in the patient-led versus physician-led titration groups. Patient-led titration resulted in a significantly higher drop in HbA1c value at 24 weeks when compared with physician-led titration (-1.40% vs. -1.25%; mean difference, -0.15; 95% confidence interval, -0.29 to 0.00; P = .043). Mean decrease in FBG was greatest in the patient-led group (-2.85 mmol/L vs. -2.48 mmol/L; P = .001). The improvements in HbA1c and FBG were consistent across countries, with similar improvements in treatment satisfaction in both groups. Mean daily insulin dose was higher in the patient-led group (28.9 units vs. 22.2 units; Ptitration achieved near-target blood glucose levels in Asian patients with uncontrolled type 2 diabetes who were on 2 oral glucose-lowering drugs, demonstrating that Asian patients can self-uptitrate insulin dose effectively when guided.

  2. LED module with high index lens

    Energy Technology Data Exchange (ETDEWEB)

    Bierhuizen, Serge J.; Wang, Nanze Patrick; Eng, Gregory W.; Sun, Decai; Wei, Yajun

    2017-09-05

    An array of housings with housing bodies and lenses is molded, or an array of housing bodies is molded and bonded with lenses to form an array of housings with housing bodies and lenses. Light-emitting diodes (LEDs) are attached to the housings in the array. An array of metal pads may be bonded to the back of the array or insert molded with the housing array to form bond pads on the back of the housings. The array is singulated to form individual LED modules.

  3. Intelligent styring af dynamisk LED belysning

    DEFF Research Database (Denmark)

    Thorseth, Anders; Corell, Dennis Dan; Hansen, Søren Stentoft

    Denne slutrapport giver en kort beskrivelse af arbejdet, der er udført af DTU Fotonik i projektet ”Intelligent styring af dynamisk LED belysning” støttet af EUDP. Arbejdet er udført i perioden 2011‐2012 i samarbejde med Lighten.......Denne slutrapport giver en kort beskrivelse af arbejdet, der er udført af DTU Fotonik i projektet ”Intelligent styring af dynamisk LED belysning” støttet af EUDP. Arbejdet er udført i perioden 2011‐2012 i samarbejde med Lighten....

  4. A user-led approach to information systems investments

    International Nuclear Information System (INIS)

    Pferd, J.W.; Fuller, A.G.

    1993-01-01

    Information-system (IS) expenditures for upstream E ampersand P have come under strong review along with other overhead expenses. Increasing frustration with IS budgets and concern about their business value led Unocal Corp. to change the way it begins, manages, and implements IS projects. Successful IS investments are aligned with the goals and functions of work groups or business units and are balanced against other investments. The twin demands of business needs and sound technical design must be served together to achieve long-term success from IS investments. This paper describes project organizations and methods to achieve these two objectives

  5. Final report LED solutions for public lighting; Eindrapportage LED oplossingen voor openbare verlichting

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2010-04-15

    This report examines if and how LED can be used for public lighting on a large scale. Pilot projects in 29 municipalities were assessed to test the usefulness of LED lighting. This final report provides answers to the questions that relate to the feasibility of the deployment of LED in public lighting and provides some practical pointers. [Dutch] Er is onderzocht of, en zo ja op welke wijze, LED grootschalig toegepast kan worden in de openbare verlichting (OVL). In 29 gemeenten in Nederland zijn proefprojecten geevalueerd om LED verlichting te toetsen op bruikbaarheid. Deze eindrapportage geeft antwoord op vragen die betrekking hebben op de haalbaarheid van de toepassing van LED binnen de OVL en geeft wat praktische aandachtspunten.

  6. Design of an oximeter based on LED-LED configuration and FPGA technology.

    Science.gov (United States)

    Stojanovic, Radovan; Karadaglic, Dejan

    2013-01-04

    A fully digital photoplethysmographic (PPG) sensor and actuator has been developed. The sensing circuit uses one Light Emitting Diode (LED) for emitting light into human tissue and one LED for detecting the reflectance light from human tissue. A Field Programmable Gate Array (FPGA) is used to control the LEDs and determine the PPG and Blood Oxygen Saturation (S(p)O(2)). The configurations with two LEDs and four LEDs are developed for measuring PPG signal and Blood Oxygen Saturation (S(p)O(2)). N-LEDs configuration is proposed for multichannel S(p)O(2) measurements. The approach resulted in better spectral sensitivity, increased and adjustable resolution, reduced noise, small size, low cost and low power consumption.

  7. Design of an Oximeter Based on LED-LED Configuration and FPGA Technology

    Directory of Open Access Journals (Sweden)

    Radovan Stojanovic

    2013-01-01

    Full Text Available A fully digital photoplethysmographic (PPG sensor and actuator has been developed. The sensing circuit uses one Light Emitting Diode (LED for emitting light into human tissue and one LED for detecting the reflectance light from human tissue. A Field Programmable Gate Array (FPGA is used to control the LEDs and determine the PPG and Blood Oxygen Saturation (SpO2. The configurations with two LEDs and four LEDs are developed for measuring PPG signal and Blood Oxygen Saturation (SpO2. N-LEDs configuration is proposed for multichannel SpO2 measurements. The approach resulted in better spectral sensitivity, increased and adjustable resolution, reduced noise, small size, low cost and low power consumption.

  8. LED structure with enhanced mirror reflectivity

    Science.gov (United States)

    Bergmann, Michael; Donofrio, Matthew; Heikman, Sten; Schneider, Kevin S; Haberern, Kevin W; Edmond, John A

    2014-04-01

    Embodiments of the present invention are generally related to LED chips having improved overall emission by reducing the light-absorbing effects of barrier layers adjacent mirror contacts. In one embodiment, a LED chip comprises one or more LEDs, with each LED having an active region, a first contact under the active region having a highly reflective mirror, and a barrier layer adjacent the mirror. The barrier layer is smaller than the mirror such that it does not extend beyond the periphery of the mirror. In another possible embodiment, an insulator is further provided, with the insulator adjacent the barrier layer and adjacent portions of the mirror not contacted by the active region or by the barrier layer. In yet another embodiment, a second contact is provided on the active region. In a further embodiment, the barrier layer is smaller than the mirror such that the periphery of the mirror is at least 40% free of the barrier layer, and the second contact is below the first contact and accessible from the bottom of the chip.

  9. LED Lighting in a Performing Arts Building

    Energy Technology Data Exchange (ETDEWEB)

    Miller, N. J.; Kaye, S. M. [Univ. of Florida, Gainesville, FL (United States); Coleman, P. M. [Univ. of Florida, Gainesville, FL (United States); Wilkerson, A. M.; Perrin, T. E.; Sullivan, G. P. [Efficiency Solutions, Inc., Richland, WA (United States)

    2014-07-31

    At the University of Florida in Gainesville, the DOE Solid-State Lighting GATEWAY program evaluated LED architectural and theatrical lighting in four academic/performance-related spaces within the Nadine McGuire Theatre + Dance Pavilion. Due to a wise choice of products and luminaire light distributions, the change brought significant quality improvements including improved controllability and color.

  10. Preliminary investigations of piezoelectric based LED luminary

    DEFF Research Database (Denmark)

    Nielsen, Dennis; Andersen, Michael A. E.; Meyer, Kaspar Sinding

    2011-01-01

    This paper presents a preliminary study of PT (Piezoelectric Transformer) based SMPS’s (Switch Mode Power Supplies) for LED luminary. The unique properties of PTs (efficiency, power density and EMI) make them highly suitable for this application. Power stage topologies, rectifiers circuits...

  11. Photobiocatalytic alcohol oxidation using LED light sources

    NARCIS (Netherlands)

    Rauch, M.C.R.; Schmidt, S.; Arends, I.W.C.E.; oppelt, K.; Kara, S; Hollmann, F.

    2016-01-01

    The photocatalytic oxidation of NADH using a flavin photocatalyst and a simple blue LED light source is reported. This in situ NAD+ regeneration system can be used to promote biocatalytic, enantioselective oxidation reactions. Compared to the traditional use of white light bulbs this method enables

  12. NASA Ames UV-LED Poster Overview

    Science.gov (United States)

    Jaroux, Belgacem Amar

    2015-01-01

    UV-LED is a small satellite technology demonstration payload being flown on the Saudisat-4 spacecraft that is demonstrating non-contacting charge control of an isolated or floating mass using new solid-state ultra-violet light emitting diodes (UV-LEDs). Integrated to the rest of the spacecraft and launched on a Dnepr in June 19, 2014, the project is a collaboration between the NASA Ames Research Center (ARC), Stanford University, and King Abdulaziz City for Science and Technology (KACST). Beginning with its commissioning in December, 2015, the data collected by UV-LED have validated a novel method of charge control that will improve the performance of drag-free spacecraft allowing for concurrent science collection during charge management operations as well as reduce the mass, power and volume required while increasing lifetime and reliability of a charge management subsystem. UV-LED continues to operate, exploring new concepts in non-contacting charge control and collecting data crucial to understanding the lifetime of ultra-violet light emitting diodes in space. These improvements are crucial to the success of ground breaking missions such as LISA and BBO, and demonstrates the ability of low cost small satellite missions to provide technological advances that far exceed mission costs.

  13. Child-Led Enquiry in Primary Science

    Science.gov (United States)

    Dunlop, Lynda; Compton, Kirsty; Clarke, Linda; McKelvey-Martin, Valerie

    2015-01-01

    This research describes and evaluates the application of a child-led approach to scientific enquiry (the Community of Scientific Enquiry, CoSE) to children aged 8-11 (Key Stage 2) in Northern Ireland. Primary teachers were introduced to CoSE at a workshop and asked to evaluate its implementation with their class. Results from children (n = 364)…

  14. LED light recycling using double prisms

    Science.gov (United States)

    Ouyang, George; Li, Kenneth

    2013-09-01

    A novel LED recycling scheme using double prisms is presented. Two identical triangular prisms with square bases, one cross-stacked on top of the other, are tight-fit into a mirrored light tunnel. The whole prism/light tunnel assembly is then mounted on top of a square LED source, whose emitting area is the same as that of the base plane of the said prism/light tunnel assembly. Each prism acts as a tapered-down light guide in one dimension, which selectively retro-reflects high angle light along that direction. The outer light tunnel serves as a mirrored wall that folds back any light that escapes outside the two prisms. For a given collection cone angle, the height of the two prisms is optimized using ASAP, a commercial ray-tracing software. Simulation and experimental results show promise in significantly increasing the brightness of the LED sources within the collection cone. Specifically for a 4x recycling ratio a 70% recycling gain in center illuminance has been achieved (i.e., illuminance measured in the forward direction). This scheme has advantages over previous recycling configurations due to its compactness and ease of mounting. For example, compared to Wavien's spherical reflector approach that has been previously published, the current recycling configuration is much smaller in size because instead of fitting a much larger mirrored reflector on top of the LED source, this time we're using a structure that has the same lateral dimensions as those of the LED source itself. Further improvement is also possible if optimization of various system parameters is carried out.

  15. Monolayer graphene dispersion and radiative cooling for high power LED

    Science.gov (United States)

    Hsiao, Tun-Jen; Eyassu, Tsehaye; Henderson, Kimberly; Kim, Taesam; Lin, Chhiu-Tsu

    2013-10-01

    Molecular fan, a radiative cooling by thin film, has been developed and its application for compact electronic devices has been evaluated. The enhanced surface emissivity and heat dissipation efficiency of the molecular fan coating are shown to correlate with the quantization of lattice modes in active nanomaterials. The highly quantized G and 2D bands in graphene are achieved by our dispersion technique, and then incorporated in an organic-inorganic acrylate emulsion to form a coating assembly on heat sinks (for LED and CPU). This water-based dielectric layer coating has been formulated and applied on metal core printed circuit boards. The heat dissipation efficiency and breakdown voltage are evaluated by a temperature-monitoring system and a high-voltage breakdown tester. The molecular fan coating on heat dissipation units is able to decrease the equilibrium junction temperature by 29.1 ° C, while functioning as a dielectric layer with a high breakdown voltage (>5 kV). The heat dissipation performance of the molecular fan coating applied on LED devices shows that the coated 50 W LED gives an enhanced cooling of 20% at constant light brightness. The schematics of monolayer graphene dispersion, undispersed graphene platelet, and continuous graphene sheet are illustrated and discussed to explain the mechanisms of radiative cooling, radiative/non-radiative, and non-radiative heat re-accumulation.

  16. CooLED - efficient LED bulbs with custrom optics - final report

    DEFF Research Database (Denmark)

    Wolff, Jesper; Corell, Dennis Dan; Dam-Hansen, Carsten

    Denne rapport indeholder en beskrivelse af arbejdet udført i og resultaterne af forsknings- og udviklingsprojektet EUDP 64012-0226, CooLED – en ny generation LED Lyskilde for det tidsløse high-end marked....

  17. Low-Cost Illumination-Grade LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Epler, John [Philips Lumileds Lighting Company LLC, San Jose, CA (United States)

    2013-08-31

    Solid State Lighting is a cost-effective, energy-conserving technology serving a rapidly expand- ing multi-billion dollar market. This program was designed to accelerate this lighting revolution by reducing the manufacturing cost of Illumination-Grade LEDs. The technical strategy was to investigate growth substrate alternatives to standard planar sapphire, select the most effective and compatible option, and demonstrate a significant increase in Lumen/$ with a marketable LED. The most obvious alternate substrate, silicon, was extensively studied in the first two years of the program. The superior thermal and mechanical properties of Si were expected to improve wavelength uniformity and hence color yield in the manufacture of high-power illumination- grade LEDs. However, improvements in efficiency and epitaxy uniformity on standard c-plane sapphire diminished the advantages of switching to Si. Furthermore, the cost of sapphire decreased significantly and the cost of processing Si devices using our thin film process was higher than expected. We concluded that GaN on Si was a viable technology but not a practical option for Philips Lumileds. Therefore in 2012 and 2013, we sought and received amendments which broadened the scope to include other substrates and extended the time of execution. Proprietary engineered substrates, off-axis (non-c-plane) sapphire, and c-plane patterned sapphire substrates (PSS) were all investigated in the final 18 months of this program. Excellent epitaxy quality was achieved on all three candidates; however we eliminated engineered substrates and non-c-plane sapphire because of their higher combined cost of substrate, device fabrication and packaging. Ultimately, by fabricating a flip-chip (FC) LED based upon c-plane PSS we attained a 42% reduction in LED manufacturing cost relative to our LUXEON Rebel product (Q1-2012). Combined with a flux gain from 85 to 102 Lm, the LUXEON Q delivered a 210% increase in Lm/$ over this time period. The

  18. Lifetime prediction of LED lighting systems considering thermal coupling between LED sources and drivers

    DEFF Research Database (Denmark)

    Alfarog, Azzarn Orner; Qu, Xiaohui; Wang, Huai

    2017-01-01

    The lifetime prediction of LED lighting system is important to guide the designers to fulfill the design specifications and to benchmark the cost-competitiveness of different lighting technologies. Currently, the lifetime of LED system is usually predicted from the source part and the driver part...... separately, and then the thermal design is also optimized independently. In practice, the LED source and driver are usually compacted in a single fixture. The heat dissipated from LED source and driver will be coupled together and affect the heat transfer performance, which may degrade the whole system...... and accelerate the failure. In this paper, a new thermal model concerning the thermal coupling is proposed with Finite Element Method (FEM) simulation for parameter acquirement. The proposed model has a better estimation of the thermal stresses of key components in the LED lamps and therefore an improved...

  19. LED i Københavns Kommunes gadebelysning

    DEFF Research Database (Denmark)

    Bülow, Katja

    2016-01-01

    Artiklen i denne udgivelse formidler resultatet af en undersøgelse, hvor de visuelle forhold i Københavns Kommunes gader undersøges som resultat af gadens belysning. Der lægges vægt på metoden bag undersøgelsen og på hvordan indførelsen af LED forandrer belysningen i gaderne.......Artiklen i denne udgivelse formidler resultatet af en undersøgelse, hvor de visuelle forhold i Københavns Kommunes gader undersøges som resultat af gadens belysning. Der lægges vægt på metoden bag undersøgelsen og på hvordan indførelsen af LED forandrer belysningen i gaderne....

  20. EVALUATING THE CULTURE-LED REGENERATION

    Directory of Open Access Journals (Sweden)

    D'Angelo Francesca

    2010-12-01

    Full Text Available The aim of the paper is to propose a new approach to urban planning, evaluating the culture-led regeneration processes. In the last few years, the cultural turn in urban planning played a central role in the urban studies. In this way we try to elaborate a more robust perspective interpreting the complex phenomenology emerging from the culture-led regeneration processes. Within the concept of complexity we discuss about the metabolic process that are the processes necessary to transform energy, material and information in goods and service functional to the complex urban system life. The approach that will be employed is the MuSIASEM that is based on several novel concept and an innovative methods never applied in this research field.

  1. Uniform LED illuminator for miniature displays

    Science.gov (United States)

    Medvedev, Vladimir; Pelka, David G.; Parkyn, William A.

    1998-10-01

    The Total Internally Reflecting (TIR) lens is a faceted structure composed of prismatic elements that collect a source's light over a much larger angular range than a conventional Fresnel lens. It has been successfully applied to the efficient collimation of light from incandescent and fluorescent lamps, and from light-emitting diodes (LEDs). A novel LED-powered collimating backlight is presented here, for uniformly illuminating 0.25'-diagonal miniature liquid- crystal displays, which are a burgeoning market for pagers, cellular phones, digital cameras, camcorders, and virtual- reality displays. The backlight lens consists of a central dual-asphere refracting section and an outer TIR section, properly curved with a curved exit face.

  2. Notes on LED Installations in Street Illumination

    Directory of Open Access Journals (Sweden)

    Elisabeta Spunei

    2014-09-01

    Full Text Available The paper presents a study made on choosing LED street lighting installations, such that the quality requirements for exterior artificial lighting are fulfilled. We analyze two types of LED street lighting installations from a technical point of view, together with lighting level and brightness values obtained during the measurements. Following on the field measurements, the lighting quality parameters are calculated, and, for the lighting installation with the best performance, optimal mounting suggestions are made. The optimal quality parameters are calculated by simulations using the Dialux software. The same software and the same light sources we also compute an optimal street lighting by determining the size of the installation that provides the best lighting parameter values.

  3. Optical design of a LED searchlight system

    Science.gov (United States)

    Gong, Chen; Xu, Haiping; Liang, Jinhua; Liu, Yunfei; Yuan, Zengquan

    2018-01-01

    A 1200m visible searchlight system is designed based on photometry and application of geometric optics. To generate intensity distribution of this relatively powerful light beam we propose to use a high power LED and several refractive optical elements, which are composed of two plane-convex lenses and a conventional Fresnel lens. Two plane-convex lenses enable refraction of the side rays from the LED to the front direction which incident on the Fresnel lens. Fresnel lens, in its turn, concentrate the light flux and provide a nearly collimated beam to meet the requirement of forming a well-illuminated area across the road in the far field. Simulation data shows that this searchlight allow generating an appropriate illumination distribution for the long range requirements. A proof-of-concept prototype producing acceptable illuminance is developed.

  4. Distributed dimming control for LED lighting.

    Science.gov (United States)

    Lee, Sang Hyun; Kwon, Jae Kyun

    2013-11-04

    This paper presents a distributed energy-saving lighting strategy for the arrangements of a lighting network consisting of a group of light-emitting diode (LED) lamps and users. LED lamps have a dimming support feature to meet the illuminance requirements imposed by individual users. Both groups interact with each other via visible light communication (VLC) or other wireless communication features. This work aims to identify a configuration of lamps leading to the maximal energy saving in adaptive and distributed ways. To this end, a distributed assignment strategy is developed based on a message-passing framework where only local interactions among lamps and users are allowed for calculations and exchanges of the information on their status. The simulation results show that the proposed algorithm outperforms other distributed algorithms in a range of indoor lighting configurations.

  5. Lampu Pintar Berbasis LED Dengan Multi Sensor

    OpenAIRE

    Ramdan, Ade; Prajitno, Dicky Rianto; Herlan, Herlan; Gojali, Elli Ahmad

    2013-01-01

    In this paper, we propose a LED-based smart lamp prototype that integrated with sensor. The smart lamp use information of people and lighting confirmation, to turn on or turn off the lamp automatically. In addition, the sensor calculates and balances flash and ambient light exposure to decrease the light, so that can make energy efficiently in use. PIR (Passive Infrared Receiver) and Ultrasonic sensor is preferred to detect people condition in one place and LDR (Light Dependent Resistant) is ...

  6. Preliminary investigations of piezoelectric based LED luminary

    DEFF Research Database (Denmark)

    Nielsen, Dennis; Andersen, Michael A. E.; Meyer, Kaspar Sinding

    2011-01-01

    This paper presents a preliminary study of PT (Piezoelectric Transformer) based SMPS’s (Switch Mode Power Supplies) for LED luminary. The unique properties of PTs (efficiency, power density and EMI) make them highly suitable for this application. Power stage topologies, rectifiers circuits, modul....... The prototype constitutes a light source equivalent to the 40 W incandescent bulb. Experimental results shows, that the prototype are capable of ZVS and dimming (the later trough use of burst mode control)....

  7. UV LED lighting for automated crystal centring

    International Nuclear Information System (INIS)

    Chavas, Leonard M. G.; Yamada, Yusuke; Hiraki, Masahiko; Igarashi, Noriyuki; Matsugaki, Naohiro; Wakatsuki, Soichi

    2011-01-01

    A low-cost light-emitting diode (LED) UV source has been developed for facilitating macromolecular sample centring in the X-ray beam. A direct outcome of the exponential growth of macromolecular crystallography is the continuously increasing demand for synchrotron beam time, both from academic and industrial users. As more and more projects entail screening a profusion of sample crystals, fully automated procedures at every level of the experiments are being implemented at all synchrotron facilities. One of the major obstacles to achieving such automation lies in the sample recognition and centring in the X-ray beam. The capacity of UV light to specifically react with aromatic residues present in proteins or with DNA base pairs is at the basis of UV-assisted crystal centring. Although very efficient, a well known side effect of illuminating biological samples with strong UV sources is the damage induced on the irradiated samples. In the present study the effectiveness of a softer UV light for crystal centring by taking advantage of low-power light-emitting diode (LED) sources has been investigated. The use of UV LEDs represents a low-cost solution for crystal centring with high specificity

  8. Export-led Growth Hypothesis: Turkey Application

    Directory of Open Access Journals (Sweden)

    İsmail KÜÇÜKAKSOY

    2015-12-01

    Full Text Available This paper aims to investigate validity of “Export-led Growth Hypothesis” for Turkey using quarterly data in period from 2003:Q1 to 2015:Q1. Hypothesis argues that there is causality relationship from real export to real Gross Domestic Product (GDP. Johansen cointegration test, Gregory-Hansen cointegration test, Toda-Yamamoto causality test, Fully Modified Ordinary Least Squares (FMOLS, Canonical cointegrating regression (CCR and Dynamic ordinary least squares (DOLS methods were used in this study. Findings can be summarized as follows: a According to Johansen cointegration test there is no relationship among variables in the long-run whereas Gregory-Hansen cointegration test has determined relationship in the long-run; b According to Toda-Yamamoto causality test there is bidirectional causality between real export and real GDP. This finding proves the validity of “Export-led Growth Hypothesis” for Turkey; c According to FMOLS, CCR, DOLS methods a 1% increase in the real export increases the real GDP by 1.5195%, 1.5552%, 1.3171% respectively in the long-run. These methods prove the validity of “Export-led Growth Hypothesis” for Turkey.

  9. Light out-coupling from LEDs by means of metal nanoparticles; Lichtauskopplung aus LEDs mittels Metallnanoteilchen

    Energy Technology Data Exchange (ETDEWEB)

    Goehler, Tino

    2010-12-17

    The external quantum efficiency of light-emitting diodes (LEDs) based on Al- GaAs/InGaAlP is limited by total internal reflection because of the high refractive index (typically between 3 and 4) of the semiconductor. Metal nanoparticles (MNP) deposited on the surface of the LED can be used as dipole scatterers in order to enhance the emission of the LED. In this thesis, first, single gold nanoparticles of various sizes deposited on such an LED were investigated. A clear enhancement is detected as long as the dipole plasmon resonance of the particle is at a shorter wavelength than the LED emission. If the plasmon resonance coincides with the LED emission or is at a larger wavelength, the enhancement turns into suppression. Numerical simulations indicate that this latter effect is mainly caused by the particle quadrupole resonance producing extra absorption. Arrays of MNPs can be produced by a special mask technique called ''Fischer pattern nanolithography'' and manipulated in shape and size by additional steps. Originally, the MNPs produced by this technique are triangular in shape and turn out to suppress the LED emission. After transformation of the particles to spheres, a clear enhancement was detected. Light that would otherwise remain trapped inside the substrate is coupled out by resonant plasmonic scattering. Investigations on analogous structures on a transparent high-index material (GaP) indicate a stronger coupling between the particles than expected on the basis of literature data. (orig.)

  10. Lamp system with a single second-lens newly designed by using the least square method for 4 LEDs

    Science.gov (United States)

    Jo, Jae Heung; Ryu, Jae Myung; Hong, Chun Gang

    2014-05-01

    It is common for many companies to use multiple LEDs to enhance the brightness of a LED lamp and, in general, four LEDs are used in the LED lamp systems. Moreover, the second-lens must be used to obtain a straight uniform illumination from LED lights. Where four LEDs are used, four second-lenses are also assembled conventionally and those four units of second-lenses are manufactured from a single mold and assembled together with the LEDs. However, this study introduces a new method of using the Least Square Method to get a uniform illumination with the divergence angle of 40 degrees with a new single injection molded lens. Thanks to this optical design with a single lens, the assembling process of LED lamp system was simplified by eliminating the complicated assembly procedure. Also, the uniformity of illumination of this newly designed lamp system was less than 14.1%.

  11. 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

  12. Effect of LED curing on the marginal leakage of a pit and fissure sealant

    OpenAIRE

    Pineda Mejia, Martha Elena; Magister en Estomatología. Profesor Principal. UNMSM. Dpto. Estomatología Rehabilitadora. Facultad Odontología. UNMSM.; Gloria Zevallos, Waldo; Dpto. Estomatología Rehabilitadora. Facultad Odontología. UNMSM.; Abuhadba Hoyos, Tulio; Dpto. Estomatología Rehabilitadora. Facultad Odontología. UNMSM.

    2014-01-01

    The purpose of this study was to evaluate in vitro the curing effect of a light-emitting diode LED unit and conventional halogen light on the marginal leakage of a pit and fissure sealant. We used 40 caries-free permanent premolars recently extracted, which were randomly divided into two groups (n = 20), sealed with a resin based fissure sealant, Helioseal F (Ivoclar Vivadent), according to the manufacturer patterns, then photopolymerized using either L.E.D. light or conventional halogen ligh...

  13. Fabrication of LED full-color display matrix with small pixel

    Science.gov (United States)

    Li, Jing; Xue, Bin; Yang, Hua; Liu, Lili; Xie, Haizhong; Pei, Yanrong; Lu, Pengzhi; Wang, Guohong; Wang, Junxi; Li, Jinmin

    2015-09-01

    With the development in material growth, device fabrication and packaging of LEDs, emission spectral of LED is able to cover the visible spectrum. In addition to the well-known lighting applications of LED, display is also one of the important applications of LED. In contrast with LCD, LEDs display has better contrast ratio, higher response rate, etc., which makes LEDs along with other self-illumination technologies an ideal candidate in making display panel. With the popularization of HD and Ultra HD standard, display panel with better image quality is needed. The number of pixels of the panel needs to be increased and the size of each pixel needs to be minimized. In this paper, we prepared a LED full-color display panel based on a 32×32 LED matrix with typical pixel size of 0.5mm. LED full-color display array with small pixel was obtained by mounting red LEDs, green LEDs and blue LEDs directly onto an isolating substrate such as sapphire . In addition, the substrate has metalized pads and connection before the matrix was connected to control unit. The control line and the column data line are prepared on the substrate, and there is an effective electrical insulation layers between them. The isolation layers consists of a SiO2 layer of 1000nm and polyimide layer of 3000nm. Polyimide as an important electrical insulating layer, we study some properties of it, such as :PI amination rate as a function of the curing temperature, PI resistivity as a function of the curing temperature and the punction electric field intensity of PI as a function of the film thickness of PI.

  14. Buurtzorg: nurse-led community care.

    Science.gov (United States)

    Monsen, Karen A; de Blok, Jos

    2013-01-01

    Buurtzorg is a nurse-led, nurse-run organization of self-managed teams that provide home care to patients in their neighborhoods. Championing humanity over bureaucracy, autonomous teams work with primary care providers, community supports, and family resources to bring patients to optimal functioning as quickly as possible. The award-winning organization grew out of a common sense approach based on principles of trust, autonomy, creativity, simplicity, and collaboration. These organizational principles translate into highly effective and efficient care, satisfied patients, and enthusiastic nurses. The model is being replicated worldwide, with teams starting in Minnesota, Sweden, Japan, and other countries.

  15. Wheat Under LED's (Light Emitting Diodes)

    Science.gov (United States)

    2004-01-01

    Astroculture is a suite of technologies used to produce and maintain a closed controlled environment for plant growth. The two most recent missions supported growth of potato, dwarf wheat, and mustard plants, and provided scientists with the first opportunity to conduct true plant research in space. Light emitting diodes have particular usefulness for plant growth lighting because they emit a much smaller amount of radiant heat than do conventional lighting sources and because they have potential of directing a higher percentage of the emitted light onto plants surfaces. Furthermore, the high output LED's have emissions in the 600-700 nm waveband, which is of highest efficiency for photosynthesis by plants.

  16. Someone Has Led This Child To Believe

    OpenAIRE

    Louise, Regina

    2015-01-01

    ABSTRACTSOMEONE HAS LED THIS CHILD TO BELIEVE is a true story and continuation of the best-selling memoir Somebody’s Someone. After 12 year-old Regina Louise, tired of being beaten, battles and escapes an illegal guardian; she jumps from a two-story window and runs to a local police station where she is taken into custody, locked in a holding cell, and delivered to the Edgar Children’s Shelter, in Martinez California. Regina is closed off about her parents, her past…until she meets Jeanne Ke...

  17. Moral Issues in Intelligence-led Policing

    DEFF Research Database (Denmark)

    The core baseline of Intelligence-led Policing is the aim of increasing efficiency and quality of police work, with a focus on crime analysis and intelligence methods as tools for informed and objective decisions both when conducting targeted, specialized operations and when setting strategic...... priorities. This book critically addresses the proliferation of intelligence logics within policing from a wide array of scholarly perspectives. It considers questions such as: •How are precautionary logics becoming increasingly central in the dominant policing strategies? •What kind of challenges...... and the blurred and confrontational lines that can be observed between prevention, intelligence and investigation in police work....

  18. Design and Manufacture of a Novel LED Table Lamp with Flower Decoration

    Directory of Open Access Journals (Sweden)

    Tzer-Ming Jeng

    2014-08-01

    Full Text Available This work involved the design and manufacture of a novel LED table lamp that provides for flower decoration. It is a combination of a normal LED table lamp and attachments holding flower arrangement frogs. In this application the frogs, as used for traditional flower arrangements, became heat sinks for the LED units. They are made of an aluminum alloy to give good heat transfer and dissipation. In any case since they are fixed to the unit they do not need to be very heavy. The design features of this novel flower-arrangement LED table lamp are: (1 the use of a light aluminum alloy flower decoration frog as a heat sink which gives both high heat dissipation and allows decorative flower arrangement; (2 the installation of LED lamps at three points of the same plate above a cylinder covered with a glass lampshade to achieve a beautiful effect; (3 to provide three different lighting modes for reading, use as a night light and for flower decoration. This novel LED table lamp meets all the energy-saving and environmental protection requirements. It has commercial potential in the market for LED lamps.

  19. An investigation on LED customer’ behavior

    Directory of Open Access Journals (Sweden)

    Samaneh Sadat Khoramgah

    2013-03-01

    Full Text Available The recent advances in technology have created a challenge for customer on purchasing electronic devises since the cycle of media production such as TV, Mobile devices, etc. are getting short and people need to replace them by new products. The recent emerge of Light Emitting Diode (LED television has attracted many people and there is a concern to study the impact of important factors on customer behavior in this business. This paper presents an empirical study to study the effects of six variables including customer perception, motivation, cognitive learning, attitude, information and price on customer behavior for LED televisions produced by an Iranian firm in Tehran, Iran. The study designs a questionnaire consists of 27 questions and distributes it among some people who are potential customers of this product. We use multiple regression analysis to study the behavior of different factors on customer behavior. The results of our survey indicate that cognitive learning had the most influencing impact (0.22 on customer behavior followed by price (0.219, motivation (0.203, attitude (0.193, information (0.183 and perception (0.145.

  20. UV LED lighting for automated crystal centring.

    Science.gov (United States)

    Chavas, Leonard M G; Yamada, Yusuke; Hiraki, Masahiko; Igarashi, Noriyuki; Matsugaki, Naohiro; Wakatsuki, Soichi

    2011-01-01

    A direct outcome of the exponential growth of macromolecular crystallography is the continuously increasing demand for synchrotron beam time, both from academic and industrial users. As more and more projects entail screening a profusion of sample crystals, fully automated procedures at every level of the experiments are being implemented at all synchrotron facilities. One of the major obstacles to achieving such automation lies in the sample recognition and centring in the X-ray beam. The capacity of UV light to specifically react with aromatic residues present in proteins or with DNA base pairs is at the basis of UV-assisted crystal centring. Although very efficient, a well known side effect of illuminating biological samples with strong UV sources is the damage induced on the irradiated samples. In the present study the effectiveness of a softer UV light for crystal centring by taking advantage of low-power light-emitting diode (LED) sources has been investigated. The use of UV LEDs represents a low-cost solution for crystal centring with high specificity.

  1. Studying Light Color using White LED Lighting

    Science.gov (United States)

    Yamagishi, Misako; Yamaba, Kazuo; Nagata, Manori; Kubo, Chiho; Nokura, Kunihiro

    Recently, white Light Emitting Diodes (LEDs) are receiving attention worldwide as new lighting devices. This study examined effects of a lighting application on performance using white LEDs. The light color—the correlated color temperature (CCT) —was assessed. It affected to psychological states and physiological conditions. Three CCT conditions were respectively set for the experiment: 2500 K, 5000 K, and 8200 K. In all, 20 younger subjects (20-30 years old), 15 middle-aged to elderly subjects (45-60 years old) and 12 elderly subjects (over 65 years-old) participated. They were presented a Numerical Verification (NV) task for performance measurement. The psychological states on performance were evaluated using the lighting assessment questionnaire. The physiological conditions were recorded using an electrocardiograph. Results show that the effects of CCT differ among age groups. Especially, the performance of younger subjects might differ from CCT conditions; elderly subjects are affected by CCT condition because of their visual acuity or response to contrast of objects.

  2. [Midwife-led birth centres: an alternative to hospital childbirth?].

    Science.gov (United States)

    Bauer, S; Kötter, C

    2013-02-01

    After midwife-led birth centres had been included into the Social Security Statute Book (§134a SGB V) and thus become covered by German Public Health Insurance since April 1st, 2007 contract negotiations on flat rate costs have followed. Meanwhile the 2nd edition of this -agreement has come into effect. The present contribution describes how this non-hospital obstetric care has developed in the last 3 years. The medical care situation is explained based on legal conditions. Special attention is paid to regulations concerning quality management as well as the certification or auditing required to remain listed in the national register of midwife-led units at the Social Health Insurance. Results are shown from data collected by the Associa-tion for Quality Assurance on Out-of-hospital births (QUAG) and from a pilot project which also contains comparisons with clinical findings. The discussion refers to data taken from German as well as international publications. The conclusion points out some aspects in need of further development. © Georg Thieme Verlag KG Stuttgart · New York.

  3. LED-Absorption-QEPAS Sensor for Biogas Plants

    Directory of Open Access Journals (Sweden)

    Michael Köhring

    2015-05-01

    Full Text Available A new sensor for methane and carbon dioxide concentration measurements in biogas plants is presented. LEDs in the mid infrared spectral region are implemented as low cost light source. The combination of quartz-enhanced photoacoustic spectroscopy with an absorption path leads to a sensor setup suitable for the harsh application environment. The sensor system contains an electronics unit and the two gas sensors; it was designed to work as standalone device and was tested in a biogas plant for several weeks. Gas concentration dependent measurements show a precision better than 1% in a range between 40% and 60% target gas concentration for both sensors. Concentration dependent measurements with different background gases show a considerable decrease in cross sensitivity against the major components of biogas in direct comparison to common absorption based sensors.

  4. LED--panacea or marketing hype?

    Science.gov (United States)

    Baillie, Jonathan

    2012-02-01

    With energy efficiency and carbon reduction, and the importance of a relaxing, therapeutic patient environment, ever more in the spotlight, LED lighting's proponents claim the technology offers healthcare estates personnel many of the answers on both fronts. However some observers believe its benefits are being over-sold, often to the detriment of other high-performing types of more 'conventional lighting', and to a sometimes uninitiated audience too easily swayed by slick sales patter. HEJ editor Jonathan Baillie spoke to one highly experienced lighting professional, Nicholas Bukorović, a former employee of Thorn, Cooper, and Thorlux Lighting, and the principal author of the last CIBSE/Society of Light and Lighting (SLL) Guide LG2 on healthcare lighting, to seek some expert illumination.

  5. Switched-capacitor isolated LED driver

    Science.gov (United States)

    Sanders, Seth R.; Kline, Mitchell

    2016-03-22

    A switched-capacitor voltage converter which is particularly well-suited for receiving a line voltage from which to drive current through a series of light emitting diodes (LEDs). Input voltage is rectified in a multi-level rectifier network having switched capacitors in an ascending-bank configuration for passing voltages in uniform steps between zero volts up to full received voltage V.sub.DC. A regulator section, operating on V.sub.DC, comprises switched-capacitor stages of H-bridge switching and flying capacitors. A current controlled oscillator drives the states of the switched-capacitor stages and changes its frequency to maintain a constant current to the load. Embodiments are described for isolating the load from the mains, utilizing an LC tank circuit or a multi-primary-winding transformer.

  6. Resident-Led Palliative Care Education Project.

    Science.gov (United States)

    Karlen, Naomi; Cruz, Brian; Leigh, A E

    2016-04-01

    Despite the growth of palliative medicine, 39% of hospitals do not have palliative care teams for consultation or to provide resident education. We examined the impact of resident-led education in palliative care principles on attitudes toward and comfort with palliative medicine and end-of-life care among internal medicine residents. An educational module designed by the authors was presented to other internal medicine residents in the program. Pre- and post-intervention survey data measuring residents' agreement with various statements regarding palliative medicine and end-of-life care were analyzed. Residents' agreement with various statements regarding palliative medicine and end-of-life care on a 5-point Likert scale was analyzed. Following the intervention, participants reported improved comfort with general knowledge of palliative medicine (p palliative care and end-of-life care (p curriculum in palliative medicine can improve resident comfort within this still-under-represented area of medicine.

  7. Open LED Illuminator: A Simple and Inexpensive LED Illuminator for Fast Multicolor Particle Tracking in Neurons.

    Science.gov (United States)

    Bosse, Jens B; Tanneti, Nikhila S; Hogue, Ian B; Enquist, Lynn W

    2015-01-01

    Dual-color live cell fluorescence microscopy of fast intracellular trafficking processes, such as axonal transport, requires rapid switching of illumination channels. Typical broad-spectrum sources necessitate the use of mechanical filter switching, which introduces delays between acquisition of different fluorescence channels, impeding the interpretation and quantification of highly dynamic processes. Light Emitting Diodes (LEDs), however, allow modulation of excitation light in microseconds. Here we provide a step-by-step protocol to enable any scientist to build a research-grade LED illuminator for live cell microscopy, even without prior experience with electronics or optics. We quantify and compare components, discuss our design considerations, and demonstrate the performance of our LED illuminator by imaging axonal transport of herpes virus particles with high temporal resolution.

  8. Open LED Illuminator: A Simple and Inexpensive LED Illuminator for Fast Multicolor Particle Tracking in Neurons

    Science.gov (United States)

    Bosse, Jens B.; Tanneti, Nikhila S.; Hogue, Ian B.; Enquist, Lynn W.

    2015-01-01

    Dual-color live cell fluorescence microscopy of fast intracellular trafficking processes, such as axonal transport, requires rapid switching of illumination channels. Typical broad-spectrum sources necessitate the use of mechanical filter switching, which introduces delays between acquisition of different fluorescence channels, impeding the interpretation and quantification of highly dynamic processes. Light Emitting Diodes (LEDs), however, allow modulation of excitation light in microseconds. Here we provide a step-by-step protocol to enable any scientist to build a research-grade LED illuminator for live cell microscopy, even without prior experience with electronics or optics. We quantify and compare components, discuss our design considerations, and demonstrate the performance of our LED illuminator by imaging axonal transport of herpes virus particles with high temporal resolution. PMID:26600461

  9. Open LED Illuminator: A Simple and Inexpensive LED Illuminator for Fast Multicolor Particle Tracking in Neurons.

    Directory of Open Access Journals (Sweden)

    Jens B Bosse

    Full Text Available Dual-color live cell fluorescence microscopy of fast intracellular trafficking processes, such as axonal transport, requires rapid switching of illumination channels. Typical broad-spectrum sources necessitate the use of mechanical filter switching, which introduces delays between acquisition of different fluorescence channels, impeding the interpretation and quantification of highly dynamic processes. Light Emitting Diodes (LEDs, however, allow modulation of excitation light in microseconds. Here we provide a step-by-step protocol to enable any scientist to build a research-grade LED illuminator for live cell microscopy, even without prior experience with electronics or optics. We quantify and compare components, discuss our design considerations, and demonstrate the performance of our LED illuminator by imaging axonal transport of herpes virus particles with high temporal resolution.

  10. LED Virtual Simulation based on Web3D

    OpenAIRE

    Lilan Liu; Liu Han; Zhiqi Lin; Manping Li; Tao Yu

    2014-01-01

    Regarding to the high price and low market popularity of current LED indoor lighting products, a LED indoor lighting platform is proposed based on Web3D technology. The internet virtual reality technology is integrated and applied into the LED collaborative e-commerce website with Virtools. According to the characteristics of the LED indoor lighting products, this paper introduced the method to build encapsulated model and three characteristics of LED lighting: geometrical, optical and behavi...

  11. Experiencing LED: Lighting: New Form and Experiential Qualities Emerging in Lighting Systems using LED

    DEFF Research Database (Denmark)

    Petersen, Kjell Yngve; Kristensen, Ole; Søndergaard, Karin

    2012-01-01

    The project investigates what new forms and qualities of light emerge from technologies such as LED, with a particular focus on basic form qualities and parameters. Existing linear functional understandings of the relation between light source, light flow, reflection and visibility is challenged ...... by relational understandings, where the materiality and visibility of the light emerge through mutual influences between several adaptive and transformative elements....

  12. LED street lighting evaluation -- phase II : LED specification and life-cycle cost analysis.

    Science.gov (United States)

    2015-01-01

    Phase II of this study focused on developing a draft specification for LED luminaires to be used by IDOT : and a life-cycle cost analysis (LCCA) tool for solid state lighting technologies. The team also researched the : latest developments related to...

  13. Baby-led Weaning: A Preliminary Investigation.

    Science.gov (United States)

    D'Andrea, Elisa; Jenkins, Kielyn; Mathews, Maria; Roebothan, Barbara

    2016-06-01

    To date, baby-led weaning (BLW) has not been examined in a Canadian population. This research investigated common BLW practices and compared associated knowledge and perceptions of practicing mothers and health care professionals (HCPs). Sixty-five mothers practicing BLW and 33 HCPs were surveyed using 2 online questionnaires. Mothers were recruited through the Newfoundland and Labrador BLW Facebook page and HCPs via email at 2 regional health authorities. Mothers described BLW in terms of food shape and consistency (whole, solid); however, in practice, some mothers offered puréed foods such as infant cereals. More HCPs than mothers indicated choking, inadequate energy, and iron intake as concerns. Mothers relied on the Facebook page over HCPs for BLW information and support. Although all practicing mothers would recommend BLW to others, less than half (48.5%) of HCPs would support it in their practice. Mothers following BLW vary greatly in their experiences and adherence to BLW. They view the practice and its disadvantages very differently than HCPs. Although most HCPs were aware of BLW, few were familiar with specific practices. HCPs may benefit from a greater understanding of BLW to provide guidance to the growing number of mothers following this practice.

  14. Led Astray by Hemoglobin A1c

    Directory of Open Access Journals (Sweden)

    Jean Chen MD

    2016-01-01

    Full Text Available Hemoglobin A1c (A1c is used frequently to diagnose and treat diabetes mellitus. Therefore, it is important be aware of factors that may interfere with the accuracy of A1c measurements. This is a case of a rare hemoglobin variant that falsely elevated a nondiabetic patient’s A1c level and led to a misdiagnosis of diabetes. A 67-year-old male presented to endocrine clinic for further management after he was diagnosed with diabetes based on an elevated A1c of 10.7%, which is approximately equivalent to an average blood glucose of 260 mg/dL. Multiple repeat A1c levels remained >10%, but his home fasting and random glucose monitoring ranged from 92 to 130 mg/dL. Hemoglobin electrophoresis and subsequent genetic analysis diagnosed the patient with hemoglobin Wayne, a rare hemoglobin variant. This variant falsely elevates A1c levels when A1c is measured using cation-exchange high-performance liquid chromatography. When the boronate affinity method was applied instead, the patient’s A1c level was actually 4.7%. Though hemoglobin Wayne is clinically silent, this patient was erroneously diagnosed with diabetes and started on an antiglycemic medication. Due to this misdiagnosis, the patient was at risk of escalation in his “diabetes management” and hypoglycemia. Therefore, it is important that providers are aware of factors that may result in hemoglobin A1c inaccuracy including hemoglobin variants.

  15. Assessing the colour quality of LED sources

    DEFF Research Database (Denmark)

    Jost-Boissard, S.; Avouac, P.; Fontoynont, Marc

    2015-01-01

    The CIE General Colour Rendering Index is currently the criterion used to describe and measure the colour-rendering properties of light sources. But over the past years, there has been increasing evidence of its limitations particularly its ability to predict the perceived colour quality of light...... but also with a preference index or a memory index calculated without blue and purple hues. A very low correlation was found between appreciation and naturalness indicating that colour quality needs more than one metric to describe subjective aspects.......The CIE General Colour Rendering Index is currently the criterion used to describe and measure the colour-rendering properties of light sources. But over the past years, there has been increasing evidence of its limitations particularly its ability to predict the perceived colour quality of light...... sources and especially some LEDs. In this paper, several aspects of perceived colour quality are investigated using a side-by-side paired comparison method, and the following criteria: naturalness of fruits and vegetables, colourfulness of the Macbeth Color Checker chart, visual appreciation...

  16. Blue LED irradiation to hydration of skin

    Science.gov (United States)

    Menezes, Priscila F. C.; Requena, Michelle B.; Lizarelli, Rosane F., Z.; Bagnato, Vanderlei S.

    2015-06-01

    Blue LED system irradiation shows many important properties on skin as: bacterial decontamination, degradation of endogenous skin chromophores and biostimulation. In this clinical study we prove that the blue light improves the skin hydration. In the literature none authors reports this biological property on skin. Then this study aims to discuss the role of blue light in the skin hydration. Twenty patients were selected to this study with age between 25-35 years old and phototype I, II and III. A defined area from forearm was pre determined (A = 4.0 cm2). The study was randomized in two treatment groups using one blue light device (power of 5.3mW and irradiance of 10.8mW/cm2). The first treatment group was irradiated with 3J/cm2 (277seconds) and the second with 6J/cm2 (555 seconds). The skin hydration evaluations were done using a corneometer. The measurements were collected in 7, 14, 21 and 30 days, during the treatment. Statistical test of ANOVA, Tukey and T-Student were applied considering 5% of significance. In conclusion, both doses were able to improve the skin hydration; however, 6J/cm2 has kept this hydration for 30 days.

  17. Design and radiation tests on a LED based emergency evacuation directional lighting

    CERN Document Server

    Trikoupis, Nikolaos

    2017-01-01

    A LED (Light Emitting Diode) based directional lighting system has been designed to indicate the best evacuation direction for applications like the Large Hadron Collider (LHC) tunnel. The design includes constraints for redundancy required by safety systems and for components selection by radiation effects. Most of the literature for radiation effects on LEDs concern digital communications systems, although some recent reports do exist for visible spectrum power LEDs and the reduction in light output versus dose is coherent with the results presented in this paper. Prototype lighting units were irradiated in CERN’s CHARM facility up to a Total Integrated Dose (TID) of 870 Gy and no failures were observed. This paper describes the basic design, presents field tests and the effects of radiation on the LEDs luminance.

  18. BiliLED low cost neonatal phototherapy, from prototype to industry

    Energy Technology Data Exchange (ETDEWEB)

    Geido, Daniel; Failache, Horacio [Instituto de Fisica de la Facultad de Ingenieria - Universidad de la Republica, Montevideo (Uruguay); Simini, Franco [Nucleo de Ingenieria Biomedica de las Facultades de Medicina e Ingenieria (Uruguay); Hospital de ClInicas. Av Italia S/N. Piso 15 sala 2, 11600 Montevideo (Uruguay)

    2007-11-15

    BiliLED is a phototherapy instrument designed to reduce bilirrubin blood rates in new born babies with jaundice. The light source is centred at 470 nm with a bandwidth of 35 nm and includes a matrix of 196 (14x14) InGaN LEDs. The optical elements are designed to maximize the light intensity useful for treatment, with a small number of LEDs in a compact and low cost unit. The optic array is such that every LED illuminates all the treatment area, which ensures redundancy and, thus, a high reliability not to be found in single-lamp instruments. Thermal dissipation and cost of BiliLED are both an order-of-magnitude smaller than conventional therapy lamps. BiliLED adjusts coetaneous irradiation with a feedback loop to compensate the loss or aging of LEDs achieving a calibrated light source for over a decade of use. A clinical trial in 20 hyperbilirrubinaemia patients shows 16% bilirrubin degradation within 24 hours of treatment, higher than most lamp phototherapy instruments. The steps from prototype to commercial model are described.

  19. BiliLED low cost neonatal phototherapy, from prototype to industry

    Science.gov (United States)

    Geido, Daniel; Failache, Horacio; Simini, Franco

    2007-11-01

    BiliLED is a phototherapy instrument designed to reduce bilirrubin blood rates in new born babies with jaundice. The light source is centred at 470 nm with a bandwidth of 35 nm and includes a matrix of 196 (14×14) InGaN LEDs. The optical elements are designed to maximize the light intensity useful for treatment, with a small number of LEDs in a compact and low cost unit. The optic array is such that every LED illuminates all the treatment area, which ensures redundancy and, thus, a high reliability not to be found in single-lamp instruments. Thermal dissipation and cost of BiliLED are both an order-of-magnitude smaller than conventional therapy lamps. BiliLED adjusts coetaneous irradiation with a feedback loop to compensate the loss or aging of LEDs achieving a calibrated light source for over a decade of use. A clinical trial in 20 hyperbilirrubinaemia patients shows 16% bilirrubin degradation within 24 hours of treatment, higher than most lamp phototherapy instruments. The steps from prototype to commercial model are described.

  20. Energy-Saving Tunnel Illumination System Based on LED's Intelligent Control

    International Nuclear Information System (INIS)

    Guo Shanshan; Wu Lan; Gu Hanting; Jiang Shuixiu

    2011-01-01

    At present there is a lot of electric energy wastage in tunnel illumination, whose design is based on the maximum brightness outside and the maximum vehicle speed all year round. LED's energy consumption is low, and the control of its brightness is simple and effective. It can be quickly adjusted between 0-100% of its maximum brightness, and will not affect the service life. Therefore, using LED as tunnel's illumination source, we can achieve a good energy saving effect. According to real-time data acquisition of vehicle speed, traffic flow and brightness outside the tunnel, the auto real-time control of tunnel illumination can be achieved. And the system regulated the LED luminance by means of combination of LED power module and intelligent control module. The tunnel information was detected by inspection equipments, which included luminometer, vehicle detector, and received by RTU(Remote Terminal Unit), then synchronously transmitted to PC. After data processing, RTU emitted the dimming signal to the LED driver to adjust the brightness of LED. Despite the relatively high cost of high-power LED lights, the enormous energy-saving effect and the well-behaved controllability is beyond compare to other lighting devices.

  1. Application of blue laser diodes and LEDs in phototherapy for neonatal jaundice

    Science.gov (United States)

    Hamza, Mostafa; Sayed El-Ahl, Mohammad H.; Hamza, Ahmad M.; Hamza, Aya M.; Hamza, Yahya M.

    2003-10-01

    The authors introduce the design of a compact phototherapy unit capable of fulfilling the recommendations of the clinical use of lasers and LEDs in phototherapy for the treatment of neonatal jaundice. The system keeps the duration of phototherapy to the minimum required for efficient treatment. Our leading clinical experience as well as the wavelength selection rules will be presented.

  2. Market led: Forsmark looks to 2000

    International Nuclear Information System (INIS)

    Anon.

    1994-01-01

    The Forsmark nuclear power plant in Sweden includes three BWR reactors totalling 3200 MWe. From a design level of 70% the average capability factor has been increased to 90%. This has been achieved by a market-orientated approach with efficient outages and a total production cost identified with each unit in order to show how each stands in relation to the market price level and to outside competition. Forsmark's performance, as indicated by capacity factors, refuelling outage length and electricity production costs is better than most. Strategic planning is important and a refurbishment programme up to 2000 is planned to renew the electricity generators, replace the process computers and upgrade the preheater systems. (UK)

  3. Peer-led prenatal breast-feeding education: a viable alternative to nurse-led education.

    Science.gov (United States)

    Rempel, Lynn A; Moore, Katrina C J

    2012-02-01

    To evaluate a prenatal breast-feeding class developed and facilitated by peer Breast-feeding Buddies. Non-equivalent control group quasi-experimental study comparing participants of the peer-led class (PLC) to those attending an established hospital-based breast-feeding nurse-led class (NLC). A brief questionnaire was completed immediately prior to the class, and telephone interviews were conducted approximately one week following the class, and one and six months post partum. 54 expectant mothers who registered for the community PLC and 55 expectant mothers who registered for the NLC. Breast-feeding intentions were measured at all time-points. Class evaluations, breast-feeding experiences, and breast-feeding support were measured at all post-class interviews. Both classes were considered worthwhile, but the PLC class was rated as more helpful and participants appreciated learning from the peers' personal experiences. Mothers taught by peers were more likely to access peer breast-feeding support. PLC participants initially decreased their prenatal breast-feeding duration intentions but had significantly stronger intentions to continue breast feeding at six months than did NLC mothers. A peer-led prenatal breast-feeding class is as effective as a traditional model of breast-feeding education and is a valuable tool to promote and support successful breast feeding. RECOMMENDATIONS FOR PRACTICE: Peer-led breast-feeding classes should be provided to enhance the accessibility of breast-feeding education and support for expectant mothers. Copyright © 2010 Elsevier Ltd. All rights reserved.

  4. Is Nigerian Growth Trade-Led?

    Directory of Open Access Journals (Sweden)

    Ismail Adigun Olayemi

    2017-09-01

    Full Text Available Purpose: Nigeria is currently in recession, a situation described as induced by decreases in oil output and export, caused by the bombings of oil pipelines in its Niger Delta region, and the unanticipated decline in its value of exports and currency, resulting from the decline in oil prices. With the export value decline, somersaulting to growth, could it then be that Nigerian economic growth is trade constrained? How important is export to growth?. This study investigates these, its invention balances in its methodology. Design/methodology/approach: To achieve the above, this paper employs the Autoregressive Distributed Lag Model (ARDL and the Thirlwall's Law of balance of payment led growth, using a combination of annual (1981–2016 and quarterly (2000Q1–2016Q4 data to ensure robustness. This combination not only allows for comparison but also ensures the reflection of the current government's trade decisions and trade activities; these are missing in other studies. Findings: Using the Wald F-Statistic, Economic growth is found to be equal to export growth rate divided by income elasticity of import, the estimated income elasticity of import which is greater than 100% or elastic reflects over dependence on import both in the short and long run, implying that Nigeria imports more than it earns. Exchange rate and terms of trade are insignificant especially in the long run. The study calls for monitoring of import contents; the government needs to enforce its recent directives to stop importation of some products that are already being produced within with higher quality and adequate export promotion strategies should be formulated and enforced. Research limitations/implications: The data span is restricted by data availability, the study could as well confirm its results with monthly data for robustness and better confidence, but most of the variables are reported annually and quarterly only. Originality/value: Many studies have confirmed the

  5. Effect of irradiation type (LED or QTH) on photo-activated composite shrinkage strain kinetics, temperature rise, and hardness.

    Science.gov (United States)

    Hofmann, Norbert; Hugo, Burkard; Klaiber, Bernd

    2002-12-01

    This study compares commercially available light-emitting diode (LED) lights with a quartz tungsten halogen (QTH) unit for photo-activating resin-based composites (RBC). Shrinkage strain kinetics and temperature within the RBC were measured simultaneously using the 'deflecting disc technique' and a thermocouple. Surface hardness (Knoop) at the bottom of 1.5-mm thick RBC specimens was measured 24 h after irradiation to indicate degree of cure. Irradiation was performed for 40 s using either the continuous or the ramp-curing mode of a QTH and a LED light (800 mW cm(-2) and 320 mW cm(-2), respectively) or the continuous mode of a lower intensity LED light (160 mW cm(-2)). For Herculite XRV and Filtek Z250 (both containing only camphoroquinone as a photo-initiator) the QTH and the stronger LED light produced similar hardness, while in the case of Definite (containing an additional photo-activator absorbing at lower wavelength) lower hardness was observed after LED irradiation. The temperature rise during polymerization and heating from radiation were lower with LED compared to QTH curing. The fastest increase of polymerization contraction was observed after QTH continuous irradiation, followed by the stronger and the weaker LED light in the continuous mode. Ramp curing decreased contraction speed even more. Shrinkage strain after 60 min was greater following QTH irradiation compared with both LED units (Herculite, Definite) or with the weaker LED light (Z250).

  6. Potential environmental impacts of light-emitting diodes (LEDs): metallic resources, toxicity, and hazardous waste classification.

    Science.gov (United States)

    Lim, Seong-Rin; Kang, Daniel; Ogunseitan, Oladele A; Schoenung, Julie M

    2011-01-01

    Light-emitting diodes (LEDs) are advertised as environmentally friendly because they are energy efficient and mercury-free. This study aimed to determine if LEDs engender other forms of environmental and human health impacts, and to characterize variation across different LEDs based on color and intensity. The objectives are as follows: (i) to use standardized leachability tests to examine whether LEDs are to be categorized as hazardous waste under existing United States federal and California state regulations; and (ii) to use material life cycle impact and hazard assessment methods to evaluate resource depletion and toxicity potentials of LEDs based on their metallic constituents. According to federal standards, LEDs are not hazardous except for low-intensity red LEDs, which leached Pb at levels exceeding regulatory limits (186 mg/L; regulatory limit: 5). However, according to California regulations, excessive levels of copper (up to 3892 mg/kg; limit: 2500), Pb (up to 8103 mg/kg; limit: 1000), nickel (up to 4797 mg/kg; limit: 2000), or silver (up to 721 mg/kg; limit: 500) render all except low-intensity yellow LEDs hazardous. The environmental burden associated with resource depletion potentials derives primarily from gold and silver, whereas the burden from toxicity potentials is associated primarily with arsenic, copper, nickel, lead, iron, and silver. Establishing benchmark levels of these substances can help manufacturers implement design for environment through informed materials substitution, can motivate recyclers and waste management teams to recognize resource value and occupational hazards, and can inform policymakers who establish waste management policies for LEDs.

  7. Modelling intelligence-led policing to identify its potential

    NARCIS (Netherlands)

    Hengst-Bruggeling, M. den; Graaf, H.A.L.M. de; Scheepstal, P.G.M. van

    2014-01-01

    lntelligence-led policing is a concept of policing that has been applied throughout the world. Despite some encouraging reports, the effect of intelligence-led policing is largely unknown. This paper presents a method with which it is possible to identify intelligence-led policing's potential to

  8. Design methodologies for reliability of SSL LED boards

    NARCIS (Netherlands)

    Jakovenko, J.; Formánek, J.; Perpiñà, X.; Jorda, X.; Vellvehi, M.; Werkhoven, R.J.; Husák, M.; Kunen, J.M.G.; Bancken, P.; Bolt, P.J.; Gasse, A.

    2013-01-01

    This work presents a comparison of various LED board technologies from thermal, mechanical and reliability point of view provided by an accurate 3-D modelling. LED boards are proposed as a possible technology replacement of FR4 LED boards used in 400 lumen retrofit SSL lamps. Presented design

  9. CALiPER Snapshot Report: Indoor LED Luminaires

    Energy Technology Data Exchange (ETDEWEB)

    None

    2014-04-01

    Snapshot reports use data from DOE's LED Lighting Facts product list to compare the LED performance to standard technologies, and are designed to help lighting retailers, distributors, designers, utilities, energy efficiency program sponsors, and other stakeholders understand the current state of the LED market and its trajectory.

  10. Luminaries-level structure improvement of LEDs for heat dissipation ...

    Indian Academy of Sciences (India)

    Heat dissipation enhancement of LED luminaries is of great significance to the large-scale application of LED. Luminaries-level structure improvement by the method of boring through-hole is adopted to intensify heat dissipation. Furthermore, the natural convection heat transfer process of LED luminaries is simulated by ...

  11. EC-LEDS Supports the Low-Carbon Transition

    Energy Technology Data Exchange (ETDEWEB)

    2016-09-01

    EC-LEDS is a flagship U.S. government-led effort that assists countries to create and implement low emission development strategies, or LEDS -- development frameworks that promote sustainable social and economic development while reducing greenhouse gas emissions over the medium to long term.

  12. Thermal design for the high-power LED lamp

    International Nuclear Information System (INIS)

    Tian Xiaogai; Chen Wei; Zhang Jiyong

    2011-01-01

    This paper summarizes different kinds of heat sinks on the market for high power LED lamps. Analysis is made on the thermal model of LED, PCB and heat sink separately with a simplified mode provided. Two examples of simulation are illustrated as a demonstration for the thermal simulation as guidance for LED lamp design. (semiconductor devices)

  13. Mapping Student-Led Peer Learning in the UK

    Science.gov (United States)

    Keenan, Chris

    2014-01-01

    Peer-led academic learning has increased in importance, but there is little sense of how many institutions support it, how they understand its purposes or what peer-led learning best practice is. This report examines the provision of peer-led learning in the UK. It identifies challenges and opportunities, including international perspectives and…

  14. 'No blue' LED solution for photolithography room illumination

    DEFF Research Database (Denmark)

    Ou, Haiyan; Corell, Dennis Dan; Dam-Hansen, Carsten

    2010-01-01

    This paper explored the feasibility of using a LED-based bulb as the illumination light source for photolithography room. A no-blue LED was designed, and the prototype was fabricated. The spectral power distribution of both the LED bulb and the yellow fluorescent tube was measured. Based on that,...

  15. LED surgical lighting system with multiple free-form surfaces for highly sterile operating theater application.

    Science.gov (United States)

    Liu, Peng; Zhang, Yaqin; Zheng, Zhenrong; Li, Haifeng; Liu, Xu

    2014-06-01

    Although the ventilation system is widely employed in the operating theater, a strictly sterile surgical environment still cannot be ensured because of laminar disturbance, which is mainly caused by the surgical lighting system. Abandoning traditional products, we propose an LED surgical lighting system, which can alleviate the laminar disturbance and provide an appropriate lighting condition for surgery. It contains a certain amount of LED lens units, which are embedded in the ceiling and arranged around the air supply smallpox. The LED lens unit integrated with an LED light source and a free-form lens is required to produce a uniform circular illumination with a large tolerance to the change of lighting distance. To achieve such a dedicated lens, two free-form refractive surfaces, which are converted into two ordinary differential equations by the design method presented in this paper, are used to deflect the rays. The results show that the LED surgical lighting system can provide an excellent illumination environment for surgery, and, apparently, the laminar disturbance also can be relieved.

  16. A Systematic Review of Light Emitting Diode (LED) Phototherapy for Treatment of Psoriasis: An Emerging Therapeutic Modality.

    Science.gov (United States)

    Ho, Derek; Koo, Eugene; Mamalis, Andrew; Jagdeo, Jared

    2017-05-01

    Background: Psoriasis is a chronic, inflammatory skin condition. The economic burden of psoriasis is approximately $35.2 billion in the United States per year, and treatment costs are increasing at a higher rate than general inflation. Light emitting diode (LED) phototherapy may represent a cost-effective, efficacious, safe, and portable treatment modality for psoriasis. Objective: The goal of our manuscript is to review the published literature and provide evidence-based recommendations on LED phototherapy for the treatment of psoriasis. Methods & Materials: A search of the databases Pubmed, EMBASE, Web of Science, and CINAHL was performed on April 5, 2016. Key search terms were related to psoriasis and LED-based therapies. Results: A total of 7,793 articles were generated from the initial search and 5 original articles met inclusion criteria for our review. Grade of recommendation: B for LED-blue light. Grade of recommendation: C for LED-ultraviolet B, LED-red light, and combination LED-near-infrared and LED-red light. Conclusion: We envision further characterizing the effects of LED phototherapy to treat psoriasis in patients may increase adoption of LED-based modalities and provide clinicians and patients with new therapeutic options that balance safety, efficacy, and cost. J Drugs Dermatol. 2017;16(5):482-488..

  17. Photobiomodulation with LED and laser in repair of mandibular socket rabbit: clinical evaluation, histological, and histomorphometric.

    Science.gov (United States)

    Comunian, Cláudio Rômulo; Custódio, Antônio Luis Neto; de Oliveira, Leandro Junqueira; Dutra, Carlos Eduardo Assis; D'almeida Ferreira Neto, Milton; Rezende, Cleuza Maria Faria

    2017-06-01

    The aim of this study was to evaluate the effects of LED and low-intensity laser on the healing of rabbit dental alveoli. A total of 18 rabbits were divided into three groups of six; all rabbits underwent surgical extraction of the first lower right premolar. Following surgery, group 1 received LED irradiation, group 2 received laser irradiation, and group 3 were untreated controls. The initial applications of LED and laser began 48 h after tooth extraction and were given perpendicularly to the dental alveoli. The three groups were clinically evaluated for 18 days in the postoperative period. At 90 days, the rabbits were euthanized and the mandibular fragments containing the healing alveoli were collected. These fragments initially underwent computed tomography scans and bone density was measured in Hounsfield units. Following this, the fragments were processed and stained with hematoxylin and eosin for histological and histomorphometric analysis. The results were compatible between the clinical, histological, and histomorphometric parameters evaluated. There were no statistical differences between the LED and laser groups. However, the difference of the average bone density between laser and control group was not statistically significant. It was found that photobiomodulation with LASER and LED presented effects. However, only the LED demonstrated a beneficial effect on the process of bone repair in the dental alveoli of rabbits.

  18. Sensing Light with LEDs: Performance Evaluation for IoT Applications

    Directory of Open Access Journals (Sweden)

    Lorenzo Incipini

    2017-11-01

    Full Text Available The Internet of Things includes all the technologies allowing the connection of everyday objects to the Internet, in order to gather measurements of physical quantities and interact with the surrounding environments through telecommunication devices with embedded sensing and actuating units. The measurements carried out with different LEDs demonstrate the possibility of using these devices both as transmitters and as optical sensors, in addition to their ability to discriminate incident wavelengths, thus making them bi-directional transceivers for Internet of Things (IoT applications, particularly suitable in the context of Visible Light Communication (VLC. In particular, a methodological tool is provided for selecting the LED sensor for VLC applications.

  19. LED lighting for greenhouses. Final report; LED belysning til vaeksthuse. Slutrapport

    Energy Technology Data Exchange (ETDEWEB)

    OEstergaard, J.E. (Syddansk Univ. (SDU). Erhvervsinnovation og Teknologi, Odense (Denmark))

    2011-01-15

    The project had 3 main objectives: 1) To develop a prototype of a LED-based luminaire that can replace the existing glasshouse horticultural lighting. The project have developed a working prototype and experimentally replaced the traditional HPS luminaires in a controlled growing area. The project succeeded in producing plants of comparable quality. However, the project shows that the prototype can be improved by: x) being further integrated into the existing horticultural production technology (eg climate computers and purchase of electricity) x) adapting configuration of luminaires specifically to each plant variety x) adapting different cooling technologies to match specific customer needs x) In some cases being combined with heat input to optimize the overall economy. 2) To achieve an effective electricity savings of 50-80% - equivalent to a value of approx. DKK 5 million for a medium sized nursery. The verified electricity savings was 40%. In test setups and in well defined and controllable production areas the prototypes achieved electricity savings of > 50%. It is expected that a new generation of LEDs (Q3 2010) will allow for greater power savings. 3) To continue prototype development and initiate commercialization of the project through the company Fionia Lighting A/S. The shareholders of the company have allocated capital to the company to allow us to address the main challenges in commercializing the technology. It is expected that the company will enter a strategic alliance with a major industrial player in the beginning of 2011. (Author)

  20. Novel Carbazole Skeleton-Based Photoinitiators for LED Polymerization and LED Projector 3D Printing

    Directory of Open Access Journals (Sweden)

    Assi Al Mousawi

    2017-12-01

    Full Text Available Radical chemistry is a very convenient way to produce polymer materials. Here, an application of a particular photoinduced radical chemistry is illustrated. Seven new carbazole derivatives Cd1–Cd7 are incorporated and proposed as high performance near-UV photoinitiators for both the free radical polymerization (FRP of (methacrylates and the cationic polymerization (CP of epoxides utilizing Light Emitting Diodes LEDs @405 nm. Excellent polymerization-initiating abilities are found and high final reactive function conversions are obtained. Interestingly, these new derivatives display much better near-UV polymerization-initiating abilities compared to a reference UV absorbing carbazole (CARET 9H-carbazole-9-ethanol demonstrating that the new substituents have good ability to red shift the absorption of the proposed photoinitiators. All the more strikingly, in combination with iodonium salt, Cd1–Cd7 are likewise preferred as cationic photoinitiators over the notable photoinitiator bis(2,4,6-trimethylbenzoylphenylphosphine oxide (BAPO for mild irradiation conditions featuring their remarkable reactivity. In particular their utilization in the preparation of new cationic resins for LED projector 3D printing is envisioned. A full picture of the included photochemical mechanisms is given.

  1. Composition and characterization of in situ usable light cured dental drug delivery hydrogel system.

    Science.gov (United States)

    Bakó, József; Vecsernyés, Miklós; Ujhelyi, Zoltán; Kovácsné, Ildikó Bácskay; Borbíró, István; Bíró, Tamás; Borbély, János; Hegedűs, Csaba

    2013-03-01

    Biodegradable polymers are compatible, permeable and nontoxic, thus they can provide a useful tool for drug delivery or tissue engineering. These polymers can form hydrogels, which are suitable vehicles for different types of materials e.g. drugs, bioactive molecules or cells. In the case of dentistry, photopolymerization is an obvious method to obtain in situ useable devices which can provide a more efficient way of tailoring drug release. A hydrogel system was developed based on poly-gamma-glutamic acid that was modified with methacryloyl groups to achieve this purpose. The resulting new reactive structure was proved by NMR spectroscopy. The swelling ratio of this type of hydrogel has been found remarkable, over 300 % after 24 h, and it can release 5 ng/mm(2) metronidazole. The prepared hydrogels were nontoxic as viability, cytotoxicity tests and cell morphology investigations proved it. These results render this model system an excellent candidate for use as an in situ curing local drug delivery device. The new photoactive system can be utilized in the treatment of periodontal diseases or raising the effectiveness of drugs used only in the minimal effective dose.

  2. Load-Bearing Inflatables Using Light-Curing Rigidization Technology Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA is soliciting new concepts for lightweight stabilized inflatables in regards to low weight, high storage density, and ease of deployment. What most of the...

  3. 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.

  4. Light-Curing Structural Tape for In-Space Repair, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has numerous requirements for in-space repair capabilities to aid future missions beyond earth orbit. A subset of these requirements is adhesive patch materials...

  5. The elution and breakdown behavior of constituents from various light-cured composites.

    Science.gov (United States)

    Sevkusic, Marija; Schuster, Lena; Rothmund, Lena; Dettinger, Katharina; Maier, Moritz; Hickel, Reinhard; Van Landhuyt, Kirsten L; Durner, Jürgen; Högg, Christof; Reichl, Franz-Xaver

    2014-06-01

    Constituents of dental composites can be released from dental fillings after polymerization. The aim of this study was to examine the time-related elution and breakdown of separable constituents of polymerized composites using deuterated solvents. Elution and breakdown of constituents were investigated with deuterated solvents methanol and water by gas chromatography/mass spectrometry of following composites for 180 days: Filtek™ Supreme XT, Filtek™ Supreme XT Flow, Tetric Ceram(®), Tetric Flow(®), Grandio(®), Grandio(®) Flow. Within 180 days no compounds were formed as the products of breakdown. 19 compounds were identified as elution products: Bis-EMA, TEGDMA, DDDMA, EGDMA, MAA, BPA, CQ, HQME, DMABEE, CSA, BL, TEG, BHT, TINP, TPP, TPSB, DEDHTP, DCHP, ß-PHEA. The highest concentration of Bis-EMA was measured for Tetric Flow(®) in deuterated methanol on day 90 at 36.993mmol/l and in deuterated water also on day 90 at 0.031mmol/l. The highest TEGDMA concentrations were measured for Grandio(®) Flow in deuterated methanol on day 60 at 1.322mmol/l and for Filtek™ Supreme XT Flow in deuterated water on day 3 at 0.689mmol/l. The highest BPA concentration was measured for Tetric Flow(®) in deuterated methanol on day 90 at 1.469mmol/l. The highest BPA concentration was measured for Grandio(®) in deuterated water on day 180 at 0.007mmol/l. Significance Examination of time-related elution indicates that various elution products (e.g. Bis-EMA, BPA) were only released in small quantities during the first 90 days, but in high quantities between day 90 and day 180. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  6. Wear behavior of light-cured resin composites with bimodal silica nanostructures as fillers.

    Science.gov (United States)

    Wang, Ruili; Bao, Shuang; Liu, Fengwei; Jiang, Xiaoze; Zhang, Qinghong; Sun, Bin; Zhu, Meifang

    2013-12-01

    To enhance wear behavior of resin composites, bimodal silica nanostructures including silica nanoparticles and silica nanoclusters were prepared and proposed as fillers. The silica nanoclusters, a combination of individually dispersed silica nanoparticles and their agglomerations, with size distribution of 0.07-2.70 μm, were fabricated by the coupling reaction between amino and epoxy functionalized silica nanoparticles, which were obtained by the surface modification of silica nanoparticles (~70 nm) using 3-aminopropyl triethoxysilane (APTES) and 3-glycidoxypropyl trimethoxysilane (GPS) as coupling agents, respectively. Silica nanoparticles and nanoclusters were then silanized with 3-methacryloxypropyl trimethoxysilane (γ-MPS) to prepare composites by mixing with bisphenol A glycerolate dimethacrylate (Bis-GMA) and tri (ethylene glycol) dimethacrylate (TEGDMA). Experimental composites with various filler compositions were prepared and their wear behaviors were assessed in this work. The results suggested that composites with increasing addition of silica nanoparticles in co-fillers possessed lower wear volume and smoother worn surface. Particularly, the composite 53:17 with the optimum weight ratio of silica nanoparticles and silica nanoclusters presented the excellent wear behavior with respect to that of the commercial Esthet-X, although the smallest wear volume was achieved by Z350 XT. The introduction of bimodal silica nanostructures as fillers might provide a new sight for the design of resin composites with significantly improved wear resistance. Crown Copyright © 2013. All rights reserved.

  7. Opacity and Color Changes of Light-Cured Ideal Makoo (IDM

    Directory of Open Access Journals (Sweden)

    M.Ghavam

    2004-03-01

    Full Text Available Statement of Problem: Esthetic materials undergo some physical and mechanical changes,during their service in oral cavity.Purpose: The aim of this study was the evaluation of the color and opacity stability of Ideal Makoo (IDM composites and compare it with Tetric ceram.Material and methods: Fifteen disk shaped samples of each material was divided into three groups of five. Different aging treatments were applied to each group. The contrast ratio of 1mm thickness and rE of the samples were evaluated at base line and after aging,using CIE system and Data Flash spectrophotometer. All the samples were kept at 37°C.Results: Baseline opacity of IDM was relatively high (77.60%±8.6. Both materials showed increased opacity after aging. The highest rE belonged to IDM samples of B group, which was significantly more than Tetric Ceram (P<0.05. Tetric Ceram, also showed some degree of color change (rE=4.60 and 5.79, on black and white background,respectively, which is noticeable clinically.Conclusion: The research showed that IDM can not be a reliable esthetic material, unless some improvements in the chemical composition will be achieved.

  8. Optimizing light-cured composite through variations in camphorquinone and butylhydroxytoluene concentrations

    OpenAIRE

    NASSAR, Hani; CHU, Tien-Min; PLATT, Jeffrey

    2016-01-01

    Abstract The use of a free-radical polymerization inhibitor, butylhydroxytoluene (BHT), and a common photo-initiator, camphorquinone (CQ), to reduce polymerization stress in dental composite was investigated in this study. Samples were prepared by mixing Bis-GMA, UDMA, and TEGDMA at a 1:1:1 ratio (wt%), and silanized borosilicate glass fillers at 70 wt% were added to form the composite. Sixteen groups of resin composite were prepared using combinations of four CQ (0.1%, 0.5%, 1.0%, and 1.5%) ...

  9. Light-cured polymer electrolytes for safe, low-cost and sustainable sodium-ion batteries

    Science.gov (United States)

    Colò, Francesca; Bella, Federico; Nair, Jijeesh R.; Gerbaldi, Claudio

    2017-10-01

    In this work we present a very simple preparation procedure of a poly(ethylene oxide) (PEO)-based crosslinked polymer electrolyte (XPE) for application in sodium-ion batteries (NIBs). The polymer electrolyte, containing NaClO4 as Na+ source, is prepared by rapid, energy saving, solvent-free photopolymerization technique, in a single step. Thermal, mechanical, morphological and electrochemical properties of the resulting XPE are thoroughly investigated. The highly ionic conducting (>1 mS cm-1 at 25 °C) polymer electrolyte is used in a lab-scale sodium cell with nanostructured TiO2 working electrode. The obtained results in terms of ambient temperature cycling behaviour (stable specific capacity of about 250 mAh g-1 at 0.1 mA cm-2 and overall remarkable stability, for a quasi-solid state Na polymer cell, upon very long term cycling exceeding 1000 reversible cycles at 0.5 mA cm-2 corresponding to > 5000 h of continuous operation) demonstrate the promising prospects of this novel XPE to be implemented in the next-generation NIBs conceived for large-scale energy storage systems, such as those connected to photovoltaic and wind factories.

  10. Light-Curing Structural Tape for In-Space Repair, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has numerous requirements for in-space repair capabilities to aid future missions beyond earth orbit. A subset of these requirements is adhesive patch materials...

  11. 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...

  12. [Evaluation of porosity in the restorations of light-cured resin composite].

    Science.gov (United States)

    Zhao, Xin-yi; Zhang, Wu; Lee, Sean; Roggenkamp, Clyde; Lu, Mei; Li, Yi-ming

    2010-01-01

    To investigate the influence of the consistency of resin composite and insertion techniques on the homogeneity of the Class I restorations. Standardized Class I cavitie