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Sample records for glass polyalkenoate cements

  1. Glass Polyalkenoate Cements Designed for Cranioplasty Applications: An Evaluation of Their Physical and Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Basel A. Khader

    2016-03-01

    Full Text Available Glass polyalkenoate cements (GPCs have potential for skeletal cementation. Unfortunately, commercial GPCs all contain, and subsequently release, aluminum ions, which have been implicated in degenerative brain disease. The purpose of this research was to create a series of aluminum-free GPCs constructed from silicate (SiO2, calcium (CaO, zinc (ZnO and sodium (Na2O-containing glasses mixed with poly-acrylic acid (PAA and to evaluate the potential of these cements for cranioplasty applications. Three glasses were formulated based on the SiO2-CaO-ZnO-Na2O parent glass (KBT01 with 0.03 mol % (KBT02 and 0.06 mol % (KBT03 germanium (GeO2 substituted for ZnO. Each glass was then mixed with 50 wt % of a patented SiO2-CaO-ZnO-strontium (SrO glass composition and the resultant mixtures were subsequently reacted with aqueous PAA (50 wt % addition to produce three GPCs. The incorporation of Ge in the glass phase was found to result in decreased working (142 s to 112 s and setting (807 s to 448 s times for the cements manufactured from them, likely due to the increase in crosslink formation between the Ge-containing glasses and the PAA. Compressive (σc and biaxial flexural (σf strengths of the cements were examined at 1, 7 and 30 days post mixing and were found to increase with both maturation and Ge content. The bonding strength of a titanium cylinder (Ti attached to bone by the cements increased from 0.2 MPa, when placed, to 0.6 MPa, after 14 days maturation. The results of this research indicate that Germano-Silicate based GPCs have suitable handling and mechanical properties for cranioplasty fixation.

  2. Comparison of a SiO(2)-CaO-ZnO-SrO glass polyalkenoate cement to commercial dental materials: glass structure and physical properties.

    Science.gov (United States)

    Wren, A W; Coughlan, A; Laffir, F R; Towler, M R

    2013-02-01

    Glass polyalkenoate cements (GPCs) have previously been considered for orthopedic applications. A Zn-GPC (BT 101) was compared to commercial GPCs (Fuji IX and Ketac Molar) which have a setting chemistry analogous to BT 101. Handling properties (working, T (w) and setting, T (s) times) for BT 101 were shorter than the commercial GPCs. BT 101 also had a higher setting exotherm (S (x) -34 °C) than the commercial GPCs (29 °C). The maximum strengths for BT 101, Fuji IX, and Ketac Molar were 75, 238, and 216 MPa (compressive, σ (c)), and 34, 54, and 62 MPa (biaxial flexural strengths, σ (f)), respectively. The strengths of BT 101 are more suitable for spinal applications than commercial GPCs.

  3. Novel adaptations to zinc-silicate glass polyalkenoate cements: the unexpected influences of germanium based glasses on handling characteristics and mechanical properties.

    Science.gov (United States)

    Dickey, B T; Kehoe, S; Boyd, D

    2013-07-01

    Aluminum-free glass polyalkenoate cements (GPC) have been hindered for use as injectable bone cements by their inability to balance handling characteristics with mechanical integrity. Currently, zinc-based, aluminum-free GPCs demonstrate compression strengths in excess of 60MPa, but set in c. 1-2 min. Previous efforts to extend the setting reaction have remained clinically insufficient and are typically accompanied by a significant drop in strength. This work synthesized novel glasses based on a zinc silicate composition with the inclusion of GeO2, ZrO2, and Na2O, and evaluated the setting reaction and mechanical properties of the resultant GPCs. Germanium based GPCs were found to have working times between 5 and 10 min, setting times between 14 and 36 min, and compression strengths in excess of 30 MPa for the first 30 days. The results of this investigation have shown that the inclusion of GeO2, ZrO2, and Na2O into the glass network have produced, for the first time, an aluminum-free GPC that is clinically viable as injectable bone cements with regards to handling characteristics and mechanical properties. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

  4. Benefits and drawbacks of zinc in glass ionomer bone cements

    Energy Technology Data Exchange (ETDEWEB)

    Brauer, Delia S; Hill, Robert G [Unit of Dental Physical Sciences, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Gentleman, Eileen; Stevens, Molly M [Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Farrar, David F, E-mail: d.brauer@qmul.ac.uk [Smith and Nephew Research Centre, York Science Park, Heslington YO10 5DF (United Kingdom)

    2011-08-15

    Glass polyalkenoate (ionomer) cements (GPCs) based on poly(acrylic acid) and fluoro-alumino-silicate glasses are successfully used in a variety of orthopaedic and dental applications; however, they release small amounts of aluminium, which is a neurotoxin and inhibits bone mineralization in vivo. Therefore there has been significant interest in developing aluminium-free glasses containing zinc for forming GPCs because zinc can play a similar structural role in the glass, allowing for glass degradation and subsequent cement setting, and is reported to have beneficial effects on bone formation. We created zinc-containing GPCs and characterized their mechanical properties and biocompatibility. Zinc-containing cements showed adhesion to bone close to 1 MPa, which was significantly greater than that of zinc-free cements (<0.05 MPa) and other currently approved biological adhesives. However, zinc-containing cements produced significantly lower metabolic activity in mouse osteoblasts exposed to cell culture medium conditioned with the cements than controls. Results show that although low levels of zinc may be beneficial to cells, zinc concentrations of 400 {mu}M Zn{sup 2+} or more resulted in cell death. In summary, we demonstrate that while zinc-containing GPCs possess excellent mechanical properties, they fail basic biocompatibility tests, produce an acute cytotoxic response in vitro, which may preclude their use in vivo.

  5. Benefits and drawbacks of zinc in glass ionomer bone cements

    International Nuclear Information System (INIS)

    Brauer, Delia S; Hill, Robert G; Gentleman, Eileen; Stevens, Molly M; Farrar, David F

    2011-01-01

    Glass polyalkenoate (ionomer) cements (GPCs) based on poly(acrylic acid) and fluoro-alumino-silicate glasses are successfully used in a variety of orthopaedic and dental applications; however, they release small amounts of aluminium, which is a neurotoxin and inhibits bone mineralization in vivo. Therefore there has been significant interest in developing aluminium-free glasses containing zinc for forming GPCs because zinc can play a similar structural role in the glass, allowing for glass degradation and subsequent cement setting, and is reported to have beneficial effects on bone formation. We created zinc-containing GPCs and characterized their mechanical properties and biocompatibility. Zinc-containing cements showed adhesion to bone close to 1 MPa, which was significantly greater than that of zinc-free cements ( 2+ or more resulted in cell death. In summary, we demonstrate that while zinc-containing GPCs possess excellent mechanical properties, they fail basic biocompatibility tests, produce an acute cytotoxic response in vitro, which may preclude their use in vivo.

  6. Glass ionomer cement: literature review

    OpenAIRE

    Sérgio Spezzia

    2017-01-01

    Introduction: In the dental area preventive actions occur in an attempt to avoid the installation of caries, a disease that has an increased prevalence in the population and which is a Public Health problem. Some resources are used for such, such as: performing early diagnosis and the option for conservative treatments of minimal intervention. The glass ionomer cement (CIV), coming from its beneficial characteristics that meet current trends, is closely related to the precepts of Preventive a...

  7. Glass ionomer cement: literature review

    Directory of Open Access Journals (Sweden)

    Sérgio Spezzia

    2017-12-01

    Full Text Available Introduction: In the dental area preventive actions occur in an attempt to avoid the installation of caries, a disease that has an increased prevalence in the population and which is a Public Health problem. Some resources are used for such, such as: performing early diagnosis and the option for conservative treatments of minimal intervention. The glass ionomer cement (CIV, coming from its beneficial characteristics that meet current trends, is closely related to the precepts of Preventive and Minimally Invasive Dentistry and the new preservative techniques recommended. Objective: The objective of the present article was to carry out a literature review study, to determine the characteristics of CIV that has a prominent role in the Minimally Invasive Dentistry profile. Results: The dentist surgeon must be aware of the classification, according to its composition and physical-chemical nature: conventional ionomers; ionomers reinforced by metals; high viscosity and various types of resin modified glass ionomers to correctly choose the CIV that will be used in their clinical interventions, which should occur based on the properties of the material and its clinical indication. Conclusion: It was concluded that the implementation of preventive techniques with CIV in public health care, tend to minimize curative treatments, concurrently valuing the low complexity dental procedures performed in Primary Care, avoiding referrals for treatment of cases of greater complexity at the level Secondary and tertiary care, saving resources.

  8. Spheroidization of glass powders for glass ionomer cements.

    Science.gov (United States)

    Gu, Y W; Yap, A U J; Cheang, P; Kumar, R

    2004-08-01

    Commercial angular glass powders were spheroidized using both the flame spraying and inductively coupled radio frequency plasma spraying techniques. Spherical powders with different particle size distributions were obtained after spheroidization. The effects of spherical glass powders on the mechanical properties of glass ionomer cements (GICs) were investigated. Results showed that the particle size distribution of the glass powders had a significant influence on the mechanical properties of GICs. Powders with a bimodal particle size distribution ensured a high packing density of glass ionomer cements, giving relatively high mechanical properties of GICs. GICs prepared by flame-spheroidized powders showed low strength values due to the loss of fine particles during flame spraying, leading to a low packing density and few metal ions reacting with polyacrylic acid to form cross-linking. GICs prepared by the nano-sized powders showed low strength because of the low bulk density of the nano-sized powders and hence low powder/liquid ratio of GICs.

  9. Substitution of strontium for calcium in glass ionomer cements (Part ...

    African Journals Online (AJOL)

    Substitution of strontium for calcium in glass ionomer cements (Part 1): Glass synthesis and characterisation, and the effects on the cement handling variables and ... acid to form glass ionomer cements, whose properties were investigated at different time points: working and setting times were determined by rheometry; and, ...

  10. Evaluation of Marginal Microgaps of Two Glass-ionomer Cements (GIC in Dogs and Sheep in vivo

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    M. Figurová

    2006-01-01

    Full Text Available The aim of the experiment was to evaluate the marginal microgaps of two ionomer cements: Kavitan Plus (Spofa Dental and Vitremer (3M ESPE in dog and sheep dentition in vivo. Dentitions of sheep and dogs were restored in vivo with a conventional, glass polyalkenoic, chemically activated cement Kavitan Plus with hydrophilic properties capable and with a resinmodified glass-ionomer cement Vitremer with light-induced polymerization and autopolymerization reaction of methyl metacrylate group. The parameters of glass-ionomers were evaluated in 6 groups of animals, 2 animals in each, at various time intervals (after 1, 4 and 6 months in dogs and 3, 6 and 9 months in sheep, starting from the beginning of the experiment. The restorative materials were placed to buccal surfaces of permanent teeth. At the intervals specified, under general injection anaesthesia, throughout the experiment we extracted 24 teeth from sheep and 30 from dogs. When processing the samples of dog's teeth two samples were damaged. One month after the placement, Kavitan plus restorations became loose only in one case in dogs (80% successfulness. In sheep two Kavitan Plus restorations became loose after 9 months (50% successfulness. During the experiment we observed neither cracks nor marginal discoloration in both Kavitan Plus and Vitremer restorations. Statistically significant (P = 0.04 differences were observed in the dentin of dogs receiving glass-ionomer Vitremer restorations which exhibited lower marginal microgaps. The remaining results were non- significant (ANOVA test. Fluoride ions released from GIC support the treatment of dental hard tissues. These materials could be used as definitive restorations of class A - D cavities in dogs and dental cervical caries in sheep as well as underlying layers ofcomposite and amalgam materials.

  11. Study of glass alteration mechanisms in cement waters

    International Nuclear Information System (INIS)

    Depierre, S.

    2012-01-01

    In the French deep geological repository concept, intermediate-level vitrified waste packages could be disposed of concrete medium. Chemical composition and pH of the interstitial leaching water are expected to influence the chemical durability of glass. Investigations have thus been carried out to study glass dissolution mechanisms and kinetics in contact with cement waters. Three cement pore waters were studied: the first two correspond to two stages of the Portland cement aging and the third corresponds to equilibrium with a low pH concrete. The S/V ratio (glass-surface-area-to-solution-volume ratio) and the chemistry of cement waters are the two main parameters that control glass alteration mechanisms. If the leaching flow from the glass allows a degree of supersaturation to be reached and maintained which leads to nucleation of secondary phases, then precipitation of these phases drives glass dissolution. At a very low S/V ratio, the calcium uptake into the alteration layer increases its passivating properties. Conversely, at a high S/V ratio, the calcium precipitates as cementitious phases consuming elements which form the alteration layer. The glass dissolution is maintained at a high rate. This study contributes to highlighting the beneficial role of low pH cement in glass alteration, and is a first step towards understanding the mechanisms between the glass and the cement medium. (author) [fr

  12. Magnesium-phosphate-glass cements with ceramic-type properties

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    Sugama, T.; Kukacka, L.E.

    1982-09-23

    Rapid setting magnesium phosphate (Mg glass) cementitious materials consisting of magnesium phosphate cement paste, polyborax and water-saturated aggregate, exhibits rapid setting and high early strength characteristics. The magnesium glass cement is prepared from a cation-leachable powder and a bivalent metallic ion-accepting liquid such as an aqueous solution of diammonium phosphate and ammonium polyphosphate. The cation-leachable powder includes a mixture of two different magnesium oxide powders processed and sized differently which when mixed with the bivalent metallic ion-accepting liquid provides the magnesium glass cement consisting primarily of magnesium ortho phosphate tetrahydrate, with magnesium hydroxide and magnesium ammonium phosphate hexahydrate also present. The polyborax serves as a set-retarder. The resulting magnesium mono- and polyphosphate cements are particularly suitable for use as a cementing matrix in rapid repair systems for deteriorated concrete structures as well as construction materials and surface coatings for fireproof structures.

  13. Magnesium phosphate glass cements with ceramic-type properties

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    Sugama, Toshifumi; Kukacka, Lawrence E.

    1984-03-13

    Rapid setting magnesium phosphate (Mg glass) cementitious materials consisting of magnesium phosphate cement paste, polyborax and water-saturated aggregate exhibiting rapid setting and high early strength characteristics. The magnesium glass cement is prepared from a cation-leachable powder and a bivalent metallic ion-accepting liquid such as an aqueous solution of diammonium phosphate and ammonium polyphosphate. The cation-leachable powder includes a mixture of two different magnesium oxide powders processed and sized differently which when mixed with the bivalent metallic ion-accepting liquid provides the magnesium glass cement consisting primarily of magnesium ortho phosphate tetrahydrate, with magnesium hydroxide and magnesium ammonium phosphate hexahydrate also present. The polyborax serves as a set-retarder. The resulting magnesium mono- and polyphosphate cements are particularly suitable for use as a cementing matrix in rapid repair systems for deteriorated concrete structures as well as construction materials and surface coatings for fireproof structures.

  14. Evaluation of stainless steel crowns cemented with glass-ionomer and resin-modified glass-ionomer luting cements.

    Science.gov (United States)

    Yilmaz, Yucel; Simsek, Sera; Dalmis, Anya; Gurbuz, Taskin; Kocogullari, M Elcin

    2006-04-01

    To evaluate in vitro and in vivo conditions of stainless steel crowns (SSC) cemented using one luting glass-ionomer cement (Aqua Meron) and one luting resin-modified glass-ionomer cement (Vitremer). In the in vitro part of this study, retentive properties of SSCs cemented using Aqua Meron and Vitremer on extracted primary first molars were tested. In addition, two specimens of each group were used to evaluate the tooth hard tissue-cement, within the cement itself, cement-SSC, and tooth hard tissue-cement-SSC under scanning electron microscope (SEM). In the in vivo part of this study, 152 SSCs were placed on the first or second primary molars of 86 children, and cemented using either Aqua Meron or Vitremer. The crowns were examined for retention. In addition, the clinical views of the crowns were recorded with an intraoral camera. No significant difference was found between the mean retentive forces of Aqua Meron and Vitremer (P> 0.05). SSCs cemented with Aqua Meron and Vitremer had an average lifespan of 26.44 and 24.07 months respectively. Only one (0.66%) of 152 SSCs was lost from the Aqua Meron group during post-cementation periods. Nineteen of the 152 SSCs (12.5%) had dents or perforations.

  15. The differences between soil grouting with cement slurry and cement-water glass slurry

    Science.gov (United States)

    Zhu, Mingting; Sui, Haitong; Yang, Honglu

    2018-01-01

    Cement slurry and cement-water glass slurry are the most widely applied for soil grouting reinforcement project. The viscosity change of cement slurry is negligible during grouting period and presumed to be time-independent while the viscosity of cement-water glass slurry increases with time quickly and is presumed to be time-dependent. Due to the significantly rheology differences between them, the grouting quality and the increasing characteristics of grouting parameters may be different, such as grouting pressure, grouting surrounding rock pressure, i.e., the change of surrounding rock pressure deduced by grouting pressure. Those are main factors for grouting design. In this paper, a large-scale 3D grouting simulation device was developed to simulate the surrounding curtain grouting for a tunnel. Two series of surrounding curtain grouting experiments under different geo-stress of 100 kPa, 150 kPa and 200 kPa were performed. The overload test on tunnel was performed to evaluate grouting effect of all surrounding curtain grouting experiments. In the present results, before 240 seconds, the grouting pressure increases slowly for both slurries; after 240 seconds the increase rate of grouting pressure for cement-water glass slurry increases quickly while that for cement slurry remains roughly constant. The increasing trend of grouting pressure for cement-water glass is similar to its viscosity. The setting time of cement-water glass slurry obtained from laboratory test is less than that in practical grouting where grout slurry solidifies in soil. The grouting effect of cement-water glass slurry is better than that of cement slurry and the grouting quality decreases with initial pressure.

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

    Science.gov (United States)

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

    2016-12-15

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

  17. Substitution of strontium for calcium in glass ionomer cements (Part ...

    African Journals Online (AJOL)

    Objectives: To investigate the effects of substituting strontium for calcium in fluoroaluminosilicate glass on the mechanical and ion-releasing properties of high-viscosity glass ionomer cements. Design: An exploratory, laboratory-based study. Setting: Dental biomaterials research laboratory, Dental Physical Sciences Unit, ...

  18. Using of borosilicate glass waste as a cement additive

    International Nuclear Information System (INIS)

    Han, Weiwei; Sun, Tao; Li, Xinping; Sun, Mian; Lu, Yani

    2016-01-01

    Highlights: • Borosilicate glass waste used as cement additive can improves its radiation shielding. • When content is 14.8%, the linear attenuation coefficient is 0.2457 cm"−"1 after 28 d. • From 0 to 22.2%, linear attenuation coefficient firstly increase and then decrease. - Abstract: Borosilicate glass waste is investigated as a cement additive in this paper to improve the properties of cement and concrete, such as setting time, compressive strength and radiation shielding. The results demonstrate that borosilicate glass is an effective additive, which not only improves the radiation shielding properties of cement paste, but also shows the irradiation effect on the mechanical and optical properties: borosilicate glass can increase the compressive strength and at the same time it makes a minor impact on the setting time and main mineralogical compositions of hydrated cement mixtures; and when the natural river sand in the mortar is replaced by borosilicate glass sand (in amounts from 0% to 22.2%), the compressive strength and the linear attenuation coefficient firstly increase and then decrease. When the glass waste content is 14.8%, the compressive strength is 43.2 MPa after 28 d and the linear attenuation coefficient is 0.2457 cm"−"1 after 28 d, which is beneficial for the preparation of radiation shielding concrete with high performances.

  19. Using of borosilicate glass waste as a cement additive

    Energy Technology Data Exchange (ETDEWEB)

    Han, Weiwei [State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan, Hubei 430070 (China); School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan, Hubei 430070 (China); Sun, Tao, E-mail: sunt@whut.edu.cn [State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan, Hubei 430070 (China); Key Laboratory of Roadway Bridge & Structure Engineering, Wuhan University of Technology, Wuhan, Hubei 430070 (China); Li, Xinping [Key Laboratory of Roadway Bridge & Structure Engineering, Wuhan University of Technology, Wuhan, Hubei 430070 (China); Sun, Mian [School of Materials Science and Engineering, Wuhan University of Technology, Wuhan, Hubei 430070 (China); Lu, Yani [Urban Construction Institute, Hubei Engineering University, Xiaogan, Hubei 432000 (China)

    2016-08-15

    Highlights: • Borosilicate glass waste used as cement additive can improves its radiation shielding. • When content is 14.8%, the linear attenuation coefficient is 0.2457 cm{sup −1} after 28 d. • From 0 to 22.2%, linear attenuation coefficient firstly increase and then decrease. - Abstract: Borosilicate glass waste is investigated as a cement additive in this paper to improve the properties of cement and concrete, such as setting time, compressive strength and radiation shielding. The results demonstrate that borosilicate glass is an effective additive, which not only improves the radiation shielding properties of cement paste, but also shows the irradiation effect on the mechanical and optical properties: borosilicate glass can increase the compressive strength and at the same time it makes a minor impact on the setting time and main mineralogical compositions of hydrated cement mixtures; and when the natural river sand in the mortar is replaced by borosilicate glass sand (in amounts from 0% to 22.2%), the compressive strength and the linear attenuation coefficient firstly increase and then decrease. When the glass waste content is 14.8%, the compressive strength is 43.2 MPa after 28 d and the linear attenuation coefficient is 0.2457 cm{sup −1} after 28 d, which is beneficial for the preparation of radiation shielding concrete with high performances.

  20. Studies on the Potential of Waste Soda Lime Silica Glass in Glass Ionomer Cement Production

    Directory of Open Access Journals (Sweden)

    V. W. Francis Thoo

    2013-01-01

    Full Text Available Glass ionomer cements (GIC are produced through acid base reaction between calcium-fluoroaluminosilicate glass powder and polyacrylic acid (PAA. Soda lime silica glasses (SLS, mainly composed of silica (SiO2, have been utilized in this study as the source of SiO2 for synthesis of Ca-fluoroaluminosilicate glass. Therefore, the main objective of this study was to investigate the potential of SLS waste glass in producing GIC. Two glasses, GWX 1 (analytical grade SiO2 and GWX 2 (replacing SiO2 with waste SLS, were synthesized and then characterized using X-ray diffraction (XRD and energy dispersive X-ray (EDX. Synthesized glasses were then used to produce GIC, in which the properties were characterized using Fourier transform infrared spectroscopy (FT-IR and compressive test (from 1 to 28 days. XRD results showed that amorphous glass was produced by using SLS waste glass (GWX 2, which is similar to glass produced using analytical grade SiO2 (GWX 1. Results from FT-IR showed that the setting reaction of GWX 2 cements is slower compared to cement GWX 1. Compressive strengths for GWX 1 cements reached up to 76 MPa at 28 days, whereas GWX 2 cements showed a slightly higher value, which is 80 MPa.

  1. Utilization of waste glass in ECO-cement: Strength properties and microstructural observations

    International Nuclear Information System (INIS)

    Sobolev, Konstantin; Tuerker, Pelin; Soboleva, Svetlana; Iscioglu, Gunsel

    2007-01-01

    Waste glass creates a serious environmental problem, mainly because of the inconsistency of the waste glass streams. The use of waste glass as a finely ground mineral additive (FGMA) in cement is a promising direction for recycling. Based on the method of mechano-chemical activation, a new group of ECO-cements was developed. In ECO-cement, relatively large amounts (up to 70%) of portland cement clinker can be replaced with waste glass. This report examines the effect of waste glass on the microstructure and strength of ECO-cement based materials. Scanning electron microscopy (SEM) investigations were used to observe the changes in the cement hydrates and interface between the cement matrix and waste glass particles. According to the research results, the developed ECO-cement with 50% of waste glass possessed compressive strength properties at a level similar to normal portland cement

  2. Push-out bond strengths of different dental cements used to cement glass fiber posts.

    Science.gov (United States)

    Pereira, Jefferson Ricardo; Lins do Valle, Accácio; Ghizoni, Janaina Salomon; Lorenzoni, Fábio César; Ramos, Marcelo Barbosa; Barbosa, Marcelo Ramos; Dos Reis Só, Marcus Vinícius

    2013-08-01

    Since the introduction of glass fiber posts, irreversible vertical root fractures have become a rare occurrence; however, adhesive failure has become the primary failure mode. The purpose of this study was to evaluate the push-out bond strength of glass fiber posts cemented with different luting agents on 3 segments of the root. Eighty human maxillary canines with similar root lengths were randomly divided into 8 groups (n=10) according to the cement assessed (Rely X luting, Luting and Lining, Ketac Cem, Rely X ARC, Biscem, Duo-link, Rely X U100, and Variolink II). After standardized post space preparation, the root dentin was pretreated for dual-polymerizing resin cements and untreated for the other cements. The mixed luting cement paste was inserted into post spaces with a spiral file and applied to the post surface that was seated into the canal. After 7 days, the teeth were sectioned perpendicular to their long axis into 1-mm-thick sections. The push-out test was performed at a speed of 0.5 mm/min until extrusion of the post occurred. The results were evaluated by 2-way ANOVA and the all pairwise multiple comparison procedures (Tukey test) (α=.05). ANOVA showed that the type of interaction between cement and root location significantly influenced the push-out strength (Pcements and glass ionomer cements showed significantly higher values compared to dual-polymerizing resin cements. In all root segments, dual-polymerizing resin cements provided significantly lower bond strength. Significant differences among root segments were found only for Duo-link cement. Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  3. Cementation of Glass-Ceramic Posterior Restorations: A Systematic Review

    Science.gov (United States)

    van den Breemer, Carline R. G.; Gresnigt, Marco M. M.; Cune, Marco S.

    2015-01-01

    Aim. The aim of this comprehensive review is to systematically organize the current knowledge regarding the cementation of glass-ceramic materials and restorations, with an additional focus on the benefits of Immediate Dentin Sealing (IDS). Materials and Methods. An extensive literature search concerning the cementation of single-unit glass-ceramic posterior restorations was conducted in the databases of MEDLINE (Pubmed), CENTRAL (Cochrane Central Register of Controlled Trials), and EMBASE. To be considered for inclusion, in vitro and in vivo studies should compare different cementation regimes involving a “glass-ceramic/cement/human tooth” complex. Results and Conclusions. 88 studies were included in total. The in vitro data were organized according to the following topics: (micro)shear and (micro)tensile bond strength, fracture strength, and marginal gap and integrity. For in vivo studies survival and quality of survival were considered. In vitro studies showed that adhesive systems (3-step, etch-and-rinse) result in the best (micro)shear bond strength values compared to self-adhesive and self-etch systems when luting glass-ceramic substrates to human dentin. The highest fracture strength is obtained with adhesive cements in particular. No marked clinical preference for one specific procedure could be demonstrated on the basis of the reviewed literature. The possible merits of IDS are most convincingly illustrated by the favorable microtensile bond strengths. No clinical studies regarding IDS were found. PMID:26557651

  4. Utilization of recycled glass derived from cathode ray tube glass as fine aggregate in cement mortar

    International Nuclear Information System (INIS)

    Ling, Tung-Chai; Poon, Chi-Sun

    2011-01-01

    Graphical abstract: Display Omitted Highlights: → A recycling/treatment process to remove lead on funnel glass surface is described. → Utilizing recycled funnel glass in mortar can reduce hazardous CRT glass wastes. → Effects of CRT glass content on the properties of cement mortar are studied. → Fly ash can effectively mitigate ASR expansion of mortar even at 100% glass content. → Alkaline medium in cement matrix successfully prevented the leaching of lead. - Abstract: Rapid advances in the electronic industry led to an excessive amount of early disposal of older electronic devices such as computer monitors and old televisions (TV) before the end of their useful life. The management of cathode ray tubes (CRT), which have been a key component in computer monitors and TV sets, has become a major environmental problem worldwide. Therefore, there is a pressing need to develop sustainable alternative methods to manage hazardous CRT glass waste. This study assesses the feasibility of utilizing CRT glass as a substitute for natural aggregates in cement mortar. The CRT glass investigated was an acid-washed funnel glass of dismantled CRT from computer monitors and old TV sets. The mechanical properties of mortar mixes containing 0%, 25%, 50%, 75% and 100% of CRT glass were investigated. The potential of the alkali-silica reaction (ASR) and leachability of lead were also evaluated. The results confirmed that the properties of the mortar mixes prepared with CRT glass was similar to that of the control mortar using sand as fine aggregate, and displayed innocuous behaviour in the ASR expansion test. Incorporating CRT glass in cement mortar successfully prevented the leaching of lead. We conclude that it is feasible to utilize CRT glass in cement mortar production.

  5. Coating glass-ionomer cements with a nanofilled resin

    NARCIS (Netherlands)

    Bonifacio, C.C.; Werner, A.; Kleverlaan, C.J.

    2012-01-01

    Objectives. The objective of this study was to investigate the effect of a nanofilled resin coat on the flexural strength (FS) and the early wear (after 50 000 and 200 000 cycles) of the glass-ionomer cements Fuji IX GP Extra (FIXE) and Ketac Molar Aplicap (KM). Materials and methods. Specimens were

  6. Cementation of Glass-Ceramic Posterior Restorations : A Systematic Review

    NARCIS (Netherlands)

    van den Breemer, Carline R. G.; Gresnigt, Marco M. M.; Cune, Marco S.

    2015-01-01

    Aim. The aim of this comprehensive review is to systematically organize the current knowledge regarding the cementation of glass-ceramic materials and restorations, with an additional focus on the benefits of Immediate Dentin Sealing (IDS). Materials and Methods. An extensive literature search

  7. Comparison between three glass fiber post cementation techniques.

    Science.gov (United States)

    Migliau, Guido; Piccoli, Luca; Di Carlo, Stefano; Pompa, Giorgio; Besharat, Laith Konstantinos; Dolci, Marco

    2017-01-01

    The aim of this experimental study was to compare the traditional cement systems with those of the latest generation, to assess if indeed these could represent of viable substitutes in the cementation of indirect restorations, and in the specific case of endodontic posts. The assessment of the validity of the cementing methods was performed according to the test of the push-out, conducted on sections obtained from the roots of treated teeth. The samples were divided into three groups. Group A (10 samples): etching for 30 seconds with 37% orthophosphoric acid (Superlux-Thixo-etch-DMG) combined with a dual-curing adhesive system (LuxaBond-Total Etch-DMG), dual-cured resin-composite cement (LuxaCore-DMG) and glass fiber posts (LuxaPost-DMG). Group B (10 samples): self-adhesive resin cement (Breeze-Pentron Clinical) and glass fiber posts (LuxaPost-DMG). Group C (10 samples): 3 steps light-curing, self-etching, self-conditioning bonding agent (Contax-Total-etch-DMG), dual-cured resin-composite cement (LuxaCore-DMG) and glass fiber posts (LuxaPost-DMG). The survey was conducted by examining the breaking resistance of the post-cement-tooth complex, subjected to a mechanical force. Statistical analysis was performed using SPSS Inc. ver. 13.0, Chicago, IL, USA. Group A values of bond strenth ranged from a minimum of 10.14 Mpa to a maximum value of 14.73 Mpa with a mean value of 12.58 Mpa. In Group B the highest value of bond strength was 6.54 Mpa and the minimum 5.55 Mpa. The mean value of the bond strength for the entire group was 6.58 Mpa. In Group C the highest bond strength was 6.59 Mpa whereas the lowest bond strength was 4.84 Mpa. Mean value of the bond strength of Group C was calculated at 5.7 Mpa. Etching with orthophosphoric acid combined with a dual-curing adhesive system and a dual-cured resin-composite cement was the technique that guaranteed the highest bond strength. Lowest bond strength values were obtained when dual self-adhesive cement was used.

  8. A Review of Glass-Ionomer Cements for Clinical Dentistry

    Directory of Open Access Journals (Sweden)

    Sharanbir K. Sidhu

    2016-06-01

    Full Text Available This article is an updated review of the published literature on glass-ionomer cements and covers their structure, properties and clinical uses within dentistry, with an emphasis on findings from the last five years or so. Glass-ionomers are shown to set by an acid-base reaction within 2–3 min and to form hard, reasonably strong materials with acceptable appearance. They release fluoride and are bioactive, so that they gradually develop a strong, durable interfacial ion-exchange layer at the interface with the tooth, which is responsible for their adhesion. Modified forms of glass-ionomers, namely resin-modified glass-ionomers and glass carbomer, are also described and their properties and applications covered. Physical properties of the resin-modified glass-ionomers are shown to be good, and comparable with those of conventional glass-ionomers, but biocompatibility is somewhat compromised by the presence of the resin component, 2 hydroxyethyl methacrylate. Properties of glass carbomer appear to be slightly inferior to those of the best modern conventional glass-ionomers, and there is not yet sufficient information to determine how their bioactivity compares, although they have been formulated to enhance this particular feature.

  9. R7T7 glass alteration in the presence of mortar: effect of the cement grade

    International Nuclear Information System (INIS)

    Andriambololona, Z.; Godon, N.; Vernaz, E.

    1991-01-01

    R7T7 glass alteration was investigated in the presence of four mortars prepared from four different cement grades: 'CPA' Portland cement (mortar M1), CPA with pozzolana additive (M2), CPA with amorphous silica additive (M3) and 'CLK' blast furnace slag cement (M4). Glass specimens were also altered in Volvic mineral water and in a cement effluent. Glass corrosion in the cement media was greater than in Volvic water, but well below what could be expected from the high pH (approx 12.5). The relatively low alteration was probably related to the protective action of the calcium-enriched gel layer that formed at the glass surface. The glass corrosion rate was 2 to 3 times lower with cement containing pozzolana or silica gel additives or with CLK cement than with CPA cement alone. 8 refs., 8 figs

  10. How mobile are protons in the structure of dental glass ionomer cements?

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Jacobsen, Johan; Lehnhoff, Benedict

    2015-01-01

    The development of dental materials with improved properties and increased longevity can save costs and minimize discomfort for patients. Due to their good biocompatibility, glass ionomer cements are an interesting restorative option. However, these cements have limited mechanical strength...... the hydrogen mobility within these cements. Our findings suggest that the lower mechanical strength in glass ionomer cements results not only from the presence of pores, but also from the increased hydrogen mobility within the material. The relationship between microstructure, hydrogen mobility and strength...

  11. Thermo-cured glass ionomer cements in restorative dentistry.

    Science.gov (United States)

    Gorseta, Kristina; Glavina, Domagoj

    2017-01-01

    Numerous positive properties of glass ionomer cements including biocompatibility, bioactivity, releasing of fluoride and good adhesion to hard dental tissue even under wet conditions and easy of handling are reasons for their wide use in paediatric and restorative dentistry. Their biggest drawbacks are the weaker mechanical properties. An important step forward in improving GIC's features is thermo-curing with the dental polymerization unit during setting of the material. Due to their slow setting characteristics the GIC is vulnerable to early exposure to moisture. After thermo curing, cements retain all the benefits of GIC with developed better mechanical properties, improved marginal adaptation, increased microhardness and shear bond strength. Adding external energy through thermocuring or ultrasound during the setting of conventional GIC is crucial to achieve faster and better initial mechanical properties. Further clinical studies are needed to confirm these findings.

  12. DEHYDRATION AND REHYDRATION OF AN ION-LEACHABLE GLASS USED IN GLASS-IONOMER CEMENTS

    Directory of Open Access Journals (Sweden)

    Jacek Klos

    2017-03-01

    Full Text Available Samples of the ionomer glass known as G338 have been heated at 240°C for 24 hours, after which they lost 1.19 % (Standard deviation 0.16% of their original mass. This loss was attributed to removal of water, as both molecular water and the product of reaction of silanol groups to form siloxane bridges. Exposing samples of glass either to air at ambient humidity or to air at 95% relative humidity showed a degree of rehydration, but mass uptake did not approach the original mass loss in either case. It is suggested that this is because of the relatively difficulty in forming new silanol groups from the siloxane bridges. Glass-ionomer cements prepared from these glass samples with aqueous poly(acrylic acid solution had different properties, depending on the glass used. Dehydrated glass gave cements which set faster but were weaker than those formed by as-received glass. The role of silanol groups in influencing reaction rate and promoting strength development is discussed.

  13. Glass-making furnaces, cement kilns and baking ovens

    Energy Technology Data Exchange (ETDEWEB)

    1989-01-01

    Possible areas for future strategic R and D within the European Community in the cement, glass and bake industries are identified based upon the current scenario of R and D in process industries and following views of main industries and research experts. Priority topics for R and D should include advanced flow modelling, the implementation of control strategies and expert systems and the development of on-line sensors. Fundamental research in some areas, such as advanced diagnostic techniques and sensor systems and modelling of two-phase and pollutant formation, is considered of primary importance.

  14. Glass-ionomer cements as restorative and preventive materials.

    Science.gov (United States)

    Ngo, Hien

    2010-07-01

    This article focuses on glass-ionomer cement (GIC) and its role in the clinical management of caries. It begins with a brief description of GIC, the mechanism of fluoride release and ion exchange, the interaction between GIC and the external environment, and finally the ion exchange between GIC and the tooth at the internal interface. The importance of GIC, as a tool, in caries management, in minimal intervention dentistry (MI), and Caries Management by Risk Assessment (CAMBRA) also will be highlighted. Copyright 2010. Published by Elsevier Inc.

  15. Formulation of portland composite cement using waste glass as a supplementary cementitious material

    Science.gov (United States)

    Manullang, Ria Julyana; Samadhi, Tjokorde Walmiki; Purbasari, Aprilina

    2017-09-01

    Utilization of waste glass in cement is an attractive options because of its pozzolanic behaviour and the market of glass-composite cement is potentially available. The objective of this research is to evaluate the formulation of waste glass as supplementary cementitious material (SCM) by an extreme vertices mixture experiment, in which clinker, waste glass and gypsum proportions are chosen as experimental variables. The composite cements were synthesized by mixing all of powder materials in jar mill. The compressive strength of the composite cement mortars after being cured for 28 days ranges between 229 to 268 kg/cm2. Composite cement mortars exhibit lower compressive strength than ordinary Portland cement (OPC) mortars but is still capable of meeting the SNI 15-7064-2004 standards. The highest compressive strength is obtained by shifting the cement blend composition to the direction of increasing clinker and gypsum proportions as well as reducing glass proportion. The lower compressive strength of composite cement is caused by expansion due to ettringite and ASR gel. Based on the experimental result, the composite cement containing 80% clinker, 15% glass and 5% gypsum has the highest compressive strength. As such, the preliminary technical feasibility of reuse of waste glass as SCM has been confirmed.

  16. Comparison of the Amount of Fluoride Release from Nanofilled Resin Modified Glass Ionomer Conventional and Resin Modified Glass Ionomer Cements

    Directory of Open Access Journals (Sweden)

    Sumitha Upadhyay

    2013-01-01

    Full Text Available Objective: To investigate and compare the amount of fluoride release of conventional, resin modified and nanofilled resin modified glass ionomer cements.Materials and Methods: Tablets of glass-ionomer cements were immersed in deionized water and incubated at 37◦C. After 1, 2, 7, 15 and 30 days, fluoride ion was measured under normal atmospheric conditions by fluoride ion selective electrode. Buffer (TISAB II was used to decomplex the fluoride ion and to provide a constant background ionic strength and to maintain the pH of water between 5.0 and 5.5 as the fluoride electrode is sensitive to changes in pH. Statistical evaluation was carried out by one way ANOVA (Analysis of Variance using SPSS 11.0. The significance level was set at p< 0.05.Results: The release of fluoride was highest on day 1 and there was a sudden fall on day 2 in all three groups. Initially fluoride release from conven-tional glass-ionomer cement was highest compared to the other two glass-ionomer cements, but the amount drastically reduced over the period. Although the amount of fluoride release was less than both the resin modified and nanofilled resin modified glass-ionomer cement, the release was sustained consistently for 30 daysConclusion: The cumulative fluoride release of nanofilled resin modified glass ionomer cement was very less compared to the conventional and resin modified glass ionomer cements and Nanofilled resin modified glass ionomer cement released less but steady fluoride as compared to other resin modified glass ionomer cements.

  17. Long-term modeling of glass waste in portland cement- and clay-based matrices

    International Nuclear Information System (INIS)

    Stockman, H.W.; Nagy, K.L.; Morris, C.E.

    1995-12-01

    A set of ''templates'' was developed for modeling waste glass interactions with cement-based and clay-based matrices. The templates consist of a modified thermodynamic database, and input files for the EQ3/6 reaction path code, containing embedded rate models and compositions for waste glass, cement, and several pozzolanic materials. Significant modifications were made in the thermodynamic data for Th, Pb, Ra, Ba, cement phases, and aqueous silica species. It was found that the cement-containing matrices could increase glass corrosion rates by several orders of magnitude (over matrixless or clay matrix systems), but they also offered the lowest overall solubility for Pb, Ra, Th and U. Addition of pozzolans to cement decreased calculated glass corrosion rates by up to a factor of 30. It is shown that with current modeling capabilities, the ''affinity effect'' cannot be trusted to passivate glass if nuclei are available for precipitation of secondary phases that reduce silica activity

  18. Comparative Evaluation of the Antimicrobial Properties of Glass Ionomer Cements with and without Chlorhexidine Gluconate.

    Science.gov (United States)

    Yadiki, Josna Vinutha; Jampanapalli, Sharada Reddy; Konda, Suhasini; Inguva, Hema Chandrika; Chimata, Vamsi Krishna

    2016-01-01

    Chlorhexidine gluconate is a widely used antimicrobial agent. Adding chlorhexidine and quaternary ammonium compounds to filling materials, such as composite resins, acrylic resins, and glass ionomer cements increases the antibacterial property of restorative materials. This study includes antibacterial property of glass ionomer restorative cements with chlorhexidine gluconate. The primary objective of our study was to compare the antimicrobial properties of two commercially available glass ionomer cements with and without chlorhexidine gluconate on strains of mutans streptococci. Two glass ionomers (Fuji II Conventional and Fuji IX) were used. Chlorhexidine gluconate was mixed with glass ionomer cements, and antimicrobial properties against mutans streptococci were assessed by agar diffusion. The tested bacterial strain was inhibited and the antimicrobial properties decreased with time. The highest amount of antimicrobial activity with mean inhibitory zone was found in Fuji II with chlorhexidine gluconate followed by Fuji IX with chlorhexidine gluconate, Fuji II without chlorhexidine gluconate, and Fuji IX without chlorhexidine gluconate. The results of the study confirmed that the addition of 5% chlorhexidine gluconate to Fuji II and Fuji IX glass ionomer cements resulted in a restorative material that had increased antimicrobial properties over the conventional glass ionomer cements alone for Streptococcus mutans. How to cite this article: Yadiki JV, Jampanapalli SR , Konda S, Inguva HC, Chimata VK. Comparative Evaluation of the Antimicrobial Properties of Glass Ionomer Cements with and without Chlorhexidine Gluconate. Int J Clin Pediatr Dent 2016;9(2):99-103.

  19. Indirect pulp capping in primary molar using glass ionomer cements

    Directory of Open Access Journals (Sweden)

    Murtia Metalita

    2014-12-01

    Full Text Available Background: Indirect pulp capping in primary teeth, however, is more rarely conducted than permanent teeth, since it thought to have low impact and most suggestion is for taking caries lesion aggressively on primary teeth. Purpose: The study was aimed to evaluate the subjective complaint, clinical symptom, and radiographic appearance of indirect pulp capping treatment using glass ionomers cements in primary molar. Methods: Sixteen children in range of age 6 to 8 years old, who visited Clinic of Pediatric Dentistry Universitas Airlangga Dental Hospital, Surabaya Indonesia, were the subject of study. They had one occlusal dental caries on one side of maxillary or mandibular primary molar with the diagnose of pulpitis reversible. The experimental group, had indirect pulp capping treatment with glass ionomer cements (GC Fuji VII®, while the control group, had indirect pulp capping treatment with calcium hydroxide (Metapaste. Each group was filled with GC Fuji IX® as permanent restoration. After one week, one month, and three months later, the observations were made on subjective complaint, clinical symptom, and radiographic appearance. Results: The results showed no subjective complaint such as pain or problem on mastication; no negative clinical symptoms such as pain on palpation, gingivitis or periodontitis, and abnormal tooth mobility; no negative radiographic appearance such as pathological apical radioluscency, internal or external resorbtion, and change of ligament periodontal widthafter the treatment. Conclusion: The study suggested that indirect pulp capping treatment using glass ionomer cement materials on primary teeth might be considered to be the treatment choice.Latar belakang: Indirect pulp capping pada gigi sulung lebih jarang dilakukan dibandingkan gigi permanen, karena dianggap memiliki dampak yang rendah dan sebagian besar menyarankan untuk mengambil lesi karies secara agresif pada gigi sulung. Tujuan: Penelitian ini bertujuan

  20. The effect of replaced recycled glass on thermal conductivity and compression properties of cement

    Science.gov (United States)

    khalil, A. S.; Mahmoud, M. A.; AL-Hathal, A.; Jawad, M. K.; Mozahim, B. M.

    2018-05-01

    This study deal with recycling of waste colorless glass bottles which are prepared as a powder and use them as an alternative for cement to save the environment from west and reduce some of cement(ceramic) damage and interactions with conserving physical properties of block concrete. Different weight percentage (0%, 2%, 4%, 5%, 6%, 8%, 10%, 15%, 20% and 25%) of recycled glass bottle were use in this research to be replaced by a certain percentages of cement. Thermal conductivity was studied for prepared samples. Results show that the thermal conductivity decrease with the increase of weight percentage of glass powder comparing with the stander sample.

  1. The influence of particle size and fluorine content of aluminosilicate glass on the glass ionomer cement properties.

    Science.gov (United States)

    De Caluwé, T; Vercruysse, C W J; Fraeyman, S; Verbeeck, R M H

    2014-09-01

    Glass ionomer cements (GIC) are clinically accepted dental restorative materials mainly due to their direct chemical adhesion to both enamel and dentin and their ability to release fluoride. However, their mechanical properties are inferior compared to those of amalgam and composite. The aim of this study is to investigate if combinations of nano- and macrogranular glass with different compositions in a glass ionomer cement can improve the mechanical and physical properties. Glasses with the composition 4.5 SiO2-3 Al2O3-1.5 P2O5-(5-x) CaO-x CaF2 (x=0 and x=2) were prepared. Of each type of glass, particles with a median size of about 0.73 μm and 6.02 μm were made. The results show that the setting time of GIC decreases when macrogranular glass particles are replaced by nanogranular glass particles, whereas the compressive strength and Young's modulus, measured after 24 h setting, increase. The effects are more pronounced when the nanogranular glass particles contain fluoride. After thermocycling, compressive strength decreases for nearly all formulations, the effect being most pronounced for cements containing nanogranular glass particles. Hence, the strength of the GIC seems mainly determined by the macrogranular glass particles. Cumulative F--release decreases when the macrogranular glass particles with fluoride are replaced by nanogranular glass particles with(out) fluoride. The present study thus shows that replacing macro- by nanogranular glass particles with different compositions can lead to cements with approximately the same physical properties (e.g. setting time, consistency), but with different physicochemical (e.g. F--release, water-uptake) and initial mechanical properties. On the long term, the mechanical properties are mainly determined by the macrogranular glass particles. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  2. Push-out bond strength of fiber posts to root dentin using glass ionomer and resin modified glass ionomer cements

    Directory of Open Access Journals (Sweden)

    Jefferson Ricardo PEREIRA

    2014-10-01

    Full Text Available OBJECTIVE: The purpose of this study was to assess the push-out bond strength of glass fiber posts to root dentin after cementation with glass ionomer (GICs and resinmodified glass ionomer cements (RMGICs. MATERIAL AND METHODS: Fifty human maxillary canines were transversally sectioned at 15 mm from the apex. Canals were prepared with a step back technique until the application of a #55 K-file and filled. Post spaces were prepared and specimens were divided into five groups according to the cement used for post cementation: Luting & Lining Cement; Fuji II LC Improved; RelyX Luting; Ketac Cem; and Ionoseal. After cementation of the glass fiber posts, all roots were stored at 100% humidity until testing. For push-out test, 1-mm thick slices were produced. The push-out test was performed in a universal testing machine at a crosshead speed of 0.5 mm/minute and the values (MPa were analyzed by Kolmogorov-Smirnov and Levene's tests and by two-way ANOVA and Tukey's post hoc test at a significance level of 5%. RESULTS: Fiber posts cemented using Luting & Lining Cement, Fuji II LC Improved, and Ketac Cem presented the highest bond strength to root dentin, followed by RelyX Luting. Ionoseal presented the lowest bond strength values (P>0.05. The post level did not influence the bond strength of fiber posts to root dentin (P=0.148. The major cause of failure was cohesive at the cement for all GICs and RMGICs. CONCLUSIONS: Except for Ionoseal, all cements provided satisfactory bond strength values.

  3. Characterization of Mechanical and Bactericidal Properties of Cement Mortars Containing Waste Glass Aggregate and Nanomaterials

    Directory of Open Access Journals (Sweden)

    Pawel Sikora

    2016-08-01

    Full Text Available The recycling of waste glass is a major problem for municipalities worldwide. The problem concerns especially colored waste glass which, due to its low recycling rate as result of high level of impurity, has mostly been dumped into landfills. In recent years, a new use was found for it: instead of creating waste, it can be recycled as an additive in building materials. The aim of the study was to evaluate the possibility of manufacturing sustainable and self-cleaning cement mortars with use of commercially available nanomaterials and brown soda-lime waste glass. Mechanical and bactericidal properties of cement mortars containing brown soda-lime waste glass and commercially available nanomaterials (amorphous nanosilica and cement containing nanocrystalline titanium dioxide were analyzed in terms of waste glass content and the effectiveness of nanomaterials. Quartz sand is replaced with brown waste glass at ratios of 25%, 50%, 75% and 100% by weight. Study has shown that waste glass can act as a successful replacement for sand (up to 100% to produce cement mortars while nanosilica is incorporated. Additionally, a positive effect of waste glass aggregate for bactericidal properties of cement mortars was observed.

  4. Characterization of Mechanical and Bactericidal Properties of Cement Mortars Containing Waste Glass Aggregate and Nanomaterials

    Science.gov (United States)

    Sikora, Pawel; Augustyniak, Adrian; Cendrowski, Krzysztof; Horszczaruk, Elzbieta; Rucinska, Teresa; Nawrotek, Pawel; Mijowska, Ewa

    2016-01-01

    The recycling of waste glass is a major problem for municipalities worldwide. The problem concerns especially colored waste glass which, due to its low recycling rate as result of high level of impurity, has mostly been dumped into landfills. In recent years, a new use was found for it: instead of creating waste, it can be recycled as an additive in building materials. The aim of the study was to evaluate the possibility of manufacturing sustainable and self-cleaning cement mortars with use of commercially available nanomaterials and brown soda-lime waste glass. Mechanical and bactericidal properties of cement mortars containing brown soda-lime waste glass and commercially available nanomaterials (amorphous nanosilica and cement containing nanocrystalline titanium dioxide) were analyzed in terms of waste glass content and the effectiveness of nanomaterials. Quartz sand is replaced with brown waste glass at ratios of 25%, 50%, 75% and 100% by weight. Study has shown that waste glass can act as a successful replacement for sand (up to 100%) to produce cement mortars while nanosilica is incorporated. Additionally, a positive effect of waste glass aggregate for bactericidal properties of cement mortars was observed. PMID:28773823

  5. Performance Characteristics of Waste Glass Powder Substituting Portland Cement in Mortar Mixtures

    Science.gov (United States)

    Kara, P.; Csetényi, L. J.; Borosnyói, A.

    2016-04-01

    In the present work, soda-lime glass cullet (flint, amber, green) and special glass cullet (soda-alkaline earth-silicate glass coming from low pressure mercury-discharge lamp cullet and incandescent light bulb borosilicate glass waste cullet) were ground into fine powders in a laboratory planetary ball mill for 30 minutes. CEM I 42.5N Portland cement was applied in mortar mixtures, substituted with waste glass powder at levels of 20% and 30%. Characterisation and testing of waste glass powders included fineness by laser diffraction particle size analysis, specific surface area by nitrogen adsorption technique, particle density by pycnometry and chemical analysis by X-ray fluorescence spectrophotometry. Compressive strength, early age shrinkage cracking and drying shrinkage tests, heat of hydration of mortars, temperature of hydration, X-ray diffraction analysis and volume stability tests were performed to observe the influence of waste glass powder substitution for Portland cement on physical and engineering properties of mortar mixtures.

  6. Coating glass-ionomer cements with a nanofilled resin.

    Science.gov (United States)

    Bonifácio, Clarissa Calil; Werner, Arie; Kleverlaan, Cornelis Johanes

    2012-12-01

    The objective of this study was to investigate the effect of a nanofilled resin coat on the flexural strength (FS) and the early wear (after 50,000 and 200,000 cycles) of the glass-ionomer cements Fuji IX GP Extra (FIXE) and Ketac Molar Aplicap (KM). Specimens were prepared and half of them were coated with G-Coat plus. The uncoated specimens were used as controls. Flexural strength (n = 10) was evaluated after 24 h using a 3-point bending test on a universal testing machine (ISO 9917-2). Wear (n = 20) was evaluated after 50,000 and 200,000 cycles using the ACTA wear machine. One-way, two-way ANOVA and Tukey post-hoc tests were used to analyze differences in FS and wear. For FIXE the coat significantly increased the FS and the wear along the two time spans. KM did not show a significant difference in FS with the coat. Improvements in wear were observed only after 50,000 cycles. Based on these laboratory results, it is concluded that G-coat Plus is indicated in association with GP IX Extra with the aim to improve the mechanical properties of the former. However, this study is limited to a short-term observation.

  7. [Effect of nano-hydroxyapatite to glass ionomer cement].

    Science.gov (United States)

    Mu, Ya-Bing; Zang, Guang-Xiang; Sun, Hong-Chen; Wang, Cheng-Kun

    2007-12-01

    To investigate the mechanical character, microleakage and mineralizing potential of nano-hydroxyapatite (nano-HAP)-added glass ionomer cement(GIC). 8% nano-HAP were incorporated into GIC as composite, and pure GIC as control. Both types of material were used to make 20 cylinders respectively in order to detect three-point flexural strength and compressive strength. Class V cavities were prepared in 120 molars extracted for orthodontic treatment, then were filled by two kinds of material. The microleakage at the composite-dentine interface was observed with confocal laser scanning microscope (CLSM) after stained with 1% rhodamin-B-isothiocyanate for 24 hours. Class V cavities were prepared in the molars of 4 healthy dogs, filled with composite, and the same molars in the other side were filled with GIC as control. The teeth were extracted to observe the mineralizing property with polarimetric microscope in 8 weeks after filling. Three-point flexural strength and compressive of nano-HAP-added GIC were increased compared with pure GIC (P nano-HAP-added GIC, while there was no hydroxyapatite crystals formed at the interface of tooth and pure GIC. 8% nano-HAP-added GIC can tightly fill tooth and have mineralizing potential, and can be used as liner or filling material for prevention.

  8. Physicochemical properties of newly developed bioactive glass cement and its effects on various cells.

    Science.gov (United States)

    Washio, Ayako; Nakagawa, Aika; Nishihara, Tatsuji; Maeda, Hidefumi; Kitamura, Chiaki

    2015-02-01

    Biomaterials used in dental treatments are expected to have favorable properties such as biocompatibility and an ability to induce tissue formation in dental pulp and periapical tissue, as well as sealing to block external stimuli. Bioactive glasses have been applied in bone engineering, but rarely applied in the field of dentistry. In the present study, bioactive glass cement for dental treatment was developed, and then its physicochemical properties and effects on cell responses were analyzed. To clarify the physicochemical attributes of the cement, field emission scanning electron microscopy, X-ray diffraction, and pH measurement were carried out. Cell attachment, morphology, and viability to the cement were also examined to clarify the effects of the cement on odontoblast-like cells (KN-3 cells), osteoblastic cells (MC3T3-E1 cells), human periodontal ligament stem/progenitor cells and neuro-differentiative cells (PC-12 cells). Hydroxyapatite-like precipitation was formed on the surface of the hardened cement and the pH level changed from pH10 to pH9, then stabilized in simulate body fluid. The cement had no cytotxic effects on these cells, and particulary induced process elongation of PC-12 cells. Our results suggest that the newly developed bioactive glass cement have capability of the application in dental procedures as bioactive cement. © 2014 Wiley Periodicals, Inc.

  9. Effect of insertion method on knoop hardness of high viscous glass ionomer cements

    NARCIS (Netherlands)

    Raggio, D.P.; Bonifácio, C.C.; Bönecker, M.; Imparato, J.C.P.; de Gee, A.J.; van Amerongen, W.E.

    2010-01-01

    The aim of this study was to assess the Knoop hardness of three high viscous glass ionomer cements: G1 - Ketac Molar; G2 - Ketac Molar Easymix (3M ESPE) and G3 - Magic Glass ART (Vigodent). As a parallel goal, three different methods for insertion of Ketac Molar Easymix were tested: G4 -

  10. Marginal gap, cement thickness, and microleakage of 2 zirconia crown systems luted with glass ionomer and MDP-based cements.

    Science.gov (United States)

    Sener, Isil; Turker, Begum; Valandro, Luiz Felipe; Ozcan, Mutlu

    2014-01-01

    This in vitro study evaluated the marginal gap, cement thickness, and microleakage of glass-ionomer cement (GIC) and phosphate monomer-containing resin cement (MDP-RC) under 2 zirconia crown systems (Cercon and DC-Zirkon). Forty human premolars were prepared for all-ceramic zirconia crowns with a 1 mm circumferential finish line and a 1.5 mm occlusal reduction. The crowns (n = 10 per group) from each zirconia system were randomly divided into 2 groups and cemented either with GIC (Vivaglass CEM) or MDP-RC (Panavia F 2.0) cement. The cemented crowns were thermocycled 5000 times (5°-55°C). The crowns were immersed in 0.5% basic fuchsine dye solution for 24 hours and sectioned buccolingually and mesiodistally. Specimens were examined under optical microscope (100X). Data were analyzed using Student t-test and chi-square tests (α = 0.05). Mean marginal gap values for Cercon (85 ± 11.4 μm) were significantly higher than for DC-Zircon (75.3 ± 13.2 μm) (P = 0.018). The mean cement thickness values of GIC (81.7 ± 13.9 μm) and MDP-RC (78.5 ± 12.5 μm) were not significantly different (P = 0.447). Microleakage scores did not demonstrate significant difference between GIC (P = 0.385) and MDP-RC (P = 0.631) under Cercon or DC-Zircon. Considering the cement thickness values and microleakage scores obtained, both zirconia crown systems could be cemented in combination with either GIC or MDP-RC.

  11. Enhancement of thermal neutron shielding of cement mortar by using borosilicate glass powder.

    Science.gov (United States)

    Jang, Bo-Kil; Lee, Jun-Cheol; Kim, Ji-Hyun; Chung, Chul-Woo

    2017-05-01

    Concrete has been used as a traditional biological shielding material. High hydrogen content in concrete also effectively attenuates high-energy fast neutrons. However, concrete does not have strong protection against thermal neutrons because of the lack of boron compound. In this research, boron was added in the form of borosilicate glass powder to increase the neutron shielding property of cement mortar. Borosilicate glass powder was chosen in order to have beneficial pozzolanic activity and to avoid deleterious expansion caused by an alkali-silica reaction. According to the experimental results, borosilicate glass powder with an average particle size of 13µm showed pozzolanic activity. The replacement of borosilicate glass powder with cement caused a slight increase in the 28-day compressive strength. However, the incorporation of borosilicate glass powder resulted in higher thermal neutron shielding capability. Thus, borosilicate glass powder can be used as a good mineral additive for various radiation shielding purposes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Fluoride release and surface roughness of a new glass ionomer cement: glass carbomer

    Directory of Open Access Journals (Sweden)

    Célia Maria Condeixa de França LOPES

    2018-02-01

    Full Text Available Abstract Objective This study analyzed the fluoride release/recharge and surface roughness of glass carbomer compared to other encapsulated glass ionomer cements (GICs. Material and method The GICs tested were Glass Fill® (GC-GCP Dental, Riva Self Cure® (RS-SDI, Riva Light Cure® (RL-SDI, Equia Fil® (EF-GC Europe. The composite resin Luna® (LU-SDI was used as control. Five samples of each material were prepared and kept in a humidifier for 24 hours (37 °C, 100% relative humidity. Fluoride release was measured in two times: before (T1: days 1, 2, 7, 14 and after topical application of fluoride (T2: days 15, 16, 21 and 28. The surface roughness was also measured in both times (T1: days 1 and 14; T2: days 15 and 28. All samples were submitted to a single topical application of acidulated fluoride phosphate (Fluor Care - FGM. Two-way ANOVA with repeated measures and Tukey's post-test (p <0.05 were used in the statistical analysis. Result Equia Fil presented the highest fluoride release in both evaluation periods, with a higher release in T1 (p <0.05. The other materials tested, including glass carbomer presented similar release in both periods (T1 and T2. Regarding surface roughness, no significant differences were observed in the interaction between the material × time factors (T1 and T2 (p=0.966. Conclusion The GICs tested presented fluoride release and recharge ability and showed no surface roughness increase by topical application of fluoride.

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

    Science.gov (United States)

    Kakaboura, A; Vougiouklakis, G

    1990-04-01

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

  14. Bond strength of a composite resin to glass ionomer cements using different adhesive systems

    Directory of Open Access Journals (Sweden)

    Ana Carolina de Oliveira BECCI

    2017-08-01

    Full Text Available Abstract Introduction Glass ionomer cements are often used as a base or cavity lining prior to restorative material. Objective To evaluate the bond strength of a composite resin to different glass ionomer cements, when using a two-step conventional and self-etching adhesive systems. Material and method Three glass ionomer cements (Ketac Molar Easymix, Vitremer and Vitrebond, the composite resin Filtek Z350 XT and the adhesive systems Adper Single Bond 2, Clearfil SE Bond and Adper Easy One were used. As negative control, resin was bonded to cement without using an adhesive system. Holes (4 mm diameter, 2 mm deep prepared in acrilic bloks were filled with the glass ionomer cements (n=12/group. On the surface, an area of 1mm in diameter was delimited, the adhesive system was applied, and a specimen of composite resin with 1 mm height was made. After 24 hours storage (37 °C and 100% humidity, the microshear test was performed. Data were analyzed using two-way ANOVA and Tukey test for comparison between groups (α=0.05. Result The adhesive systems significantly improved the bond strenght of composite resin to glass ionomer cements (p≤0.001. There was no significant difference in bond strength when self-etching adhesive systems were compared with the simplified etch-and-rinse adhesive, except for Vitrebond where Clearfil SE Bond determined higher bond strength when compared to Adper Single Bond 2 (p=0.003. Conclusion Self-etching adhesive systems are a good option for establishing the bond between the composite resin and the glass ionomer cement.

  15. Microleakage of Glass Ionomer-based Provisional Cement in CAD/CAM-Fabricated Interim Crowns: An in vitro Study.

    Science.gov (United States)

    Farah, Ra'fat I; Al-Harethi, Naji

    2016-10-01

    The aim of this study was to compare in vitro the marginal microleakage of glass ionomer-based provisional cement with resin-based provisional cement and zinc oxide non-eugenol (ZONE) provisional cement in computer-aided design and computer-aided manufacturing (CAD/CAM)-fabricated interim restorations. Fifteen intact human premolars were prepared in a standardized manner for complete coverage of crown restorations. Interim crowns for the prepared teeth were then fabricated using CAD/CAM, and the specimens were randomized into three groups of provisional cementing agents (n = 5 each): Glass ionomer-based provisional cement (GC Fuji TEMP LT™), bisphenol-A-glycidyldimethacrylate (Bis-GMA)/ triethylene glycol dimethacrylate (TEGDMA) resin-based cement (UltraTemp® REZ), and ZONE cement (TempBond NE). After 24 hours of storage in distilled water at 37°C, the specimens were thermocycled and then stored again for 24 hours in distilled water at room temperature. Next, the specimens were placed in freshly prepared 2% aqueous methylene blue dye for 24 hours and then embedded in autopolymerizing acrylic resin blocks and sectioned in buccolingual and mesiodistal directions to assess dye penetration using a stereomicroscope. The results were statistically analyzed using a nonparametric Kruskal-Wallis test. Dunn's post hoc test with a Bonferroni correction test was used to compute multiple pairwise comparisons that identified differences among groups; the level of significance was set at p provisional cement demonstrated the lowest microleakage scores, which were statistically different from those of the glass ionomer-based provisional cement and the ZONE cement. The provisional cementing agents exhibited different sealing abilities. The Bis-GMA/TEGDMA resin-based provisional cement exhibited the most effective favorable sealing properties against dye penetration compared with the glass ionomer-based provisional cement and conventional ZONE cement. Newly introduced glass

  16. Genotoxicity and cytotoxicity induced by eluates from orthodontic glass ionomer cements in vitro

    Directory of Open Access Journals (Sweden)

    Fernanda Angelieri

    2018-01-01

    Full Text Available The aim of this study was to investigate genotoxicity and cytotoxicity of some orthodontic glass ionomer cements commercially available by means of the single cell gel (comet assay. For this purpose, five commercial orthodontic glass ionomer cements (Vidrion C®, Meron®, Optiband®, Multicure® and Ultra Band Lok® were tested in murine fibroblasts in vitro. For this purpose, eluates from each cement were prepared according manufactures instructions at 0, 2, 4, 8, 18, 32 and 64 days of immersion in artificial saliva at 37 °C. All orthodontic glass ionomer cements failed to induce cytotoxicity to murine fibroblasts for all periods evaluated in this study. However, Vidrion C® was able to induce genotoxicity after 64 days of exposure to eluates. Meron® also demonstrated genotoxicity as depicted by increasing DNA damage on 2nd day. Multicure® demonstrated genotoxicity on 32nd day and Ultra band Lok on 18th, 32nd days of exposure. Taken together, our results demonstrated that orthodontic cements derived from resin-modified glass ionomer composite (Multicure® and compomer (Ultra Band Lok® cause genetic damage in mammalian cells in vitro.

  17. Effects of Particle Size and Cement Replacement of LCD Glass Powder in Concrete

    Directory of Open Access Journals (Sweden)

    Seong Kyum Kim

    2017-01-01

    Full Text Available The high quality liquid crystal display (LCD processing waste glass (LPWG generated from the manufacturing process of Korea’s LCD industries, having the world’s highest technological level and production, was finely ground into particles smaller than cement particles (higher fineness than OPC to verify their applicability and performance as a replacement for cement. For a concrete mix having a W/B ratio of 0.44, cement was replaced with LPWG glass powder (LGP at ratios of 5, 10, 15, and 20% (LGP12 and 5 and 10% (LGP5 according to the particle size to prepare test cylinder specimens, which were tested with respect to air contents, slump in fresh concrete, and compressive strength and splitting tensile strength of hardened concrete. The microstructure of the concrete specimens was analyzed through Scanning Electron Microscopy (SEM, Energy Dispersive X-ray (EDX, and a Mercury Intrusion Porosimetry (MIP. Replacement of cement with LGP for cement could effectively decrease the quantity of cement used due to the excellent performance of LGP. It may positively contribute to the sustainable development of the cement industry as well as waste recycling and environment conservation on a national scale.

  18. Microleakage under orthodontic bands cemented with nano-hydroxyapatite-modified glass ionomer.

    Science.gov (United States)

    Enan, Enas T; Hammad, Shaza M

    2013-11-01

    To estimate the in vivo effect of nano-hydroxyapatite (HA) modification of banding glass-ionomer cement on microleakage under orthodontic bands. Eighty noncarious premolars scheduled for extraction in 20 orthodontic patients were randomly divided into four groups. Grouping was based on the ratio of nano-HA (0%, 5%, 10%, 15% by weight) added to the luting glass-ionomer cement (GIC) Ketac-Cem, which was used for cementation of prefabricated micro-etched orthodontic bands. Dye penetration method was used for microleakage evaluation at the cement-band and cement-enamel interfaces. Statistical evaluation was performed with a Kruskal-Wallis test and a Mann-Whitney U-test, and a Bonferroni-adjusted significance level was calculated. Bands cemented with conventional GIC showed the highest microleakage scores in comparison to those cemented with nano-HA-modified GIC. No significant difference was found between teeth banded with 10% and 15% modified GIC. Modification of the banding GIC with 15% nano-HA revealed a positive effect on reducing microleakage around orthodontic bands.

  19. Bactericidal strontium-releasing injectable bone cements based on bioactive glasses

    OpenAIRE

    Brauer, Delia S.; Karpukhina, Natalia; Kedia, Gopal; Bhat, Aditya; Law, Robert V.; Radecka, Izabela; Hill, Robert G.

    2013-01-01

    Strontium-releasing injectable bone cements may have the potential to prevent implant-related infections through the bactericidal action of strontium, while enhancing bone formation in patients suffering from osteoporosis. A melt-derived bioactive glass (BG) series (SiO2–CaO–CaF2–MgO) with 0–50% of calcium substituted with strontium on a molar base were produced. By mixing glass powder, poly(acrylic acid) and water, cements were obtained which can be delivered by injection and set in situ, gi...

  20. Aluminum-free glass-ionomer bone cements with enhanced bioactivity and biodegradability

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Filipa O.; Pires, Ricardo A., E-mail: rpires@dep.uminho.pt; Reis, Rui L.

    2013-04-01

    Al-free glasses of general composition 0.340SiO{sub 2}:0.300ZnO:(0.250-a-b)CaO:aSrO:bMgO:0.050Na{sub 2}O:0.060P{sub 2}O{sub 5} (a, b = 0.000 or 0.125) were synthesized by melt quenching and their ability to form glass-ionomer cements was evaluated using poly(acrylic acid) and water. We evaluated the influence of the poly(acrylic acid) molecular weight and glass particle size in the cement mechanical performance. Higher compressive strength (25 ± 5 MPa) and higher compressive elastic modulus (492 ± 17 MPa) were achieved with a poly(acrylic acid) of 50 kDa and glass particle sizes between 63 and 125 μm. Cements prepared with glass formulation a = 0.125 and b = 0.000 were analyzed after immersion in simulated body fluid; they presented a surface morphology consistent with a calcium phosphate coating and a Ca/P ratio of 1.55 (similar to calcium-deficient hydroxyapatite). Addition of starch to the cement formulation induced partial degradability after 8 weeks of immersion in phosphate buffer saline containing α-amylase. Micro-computed tomography analysis revealed that the inclusion of starch increased the cement porosity from 35% to 42%. We were able to produce partially degradable Al-free glass-ionomer bone cements with mechanical performance, bioactivity and biodegradability suitable to be applied on non-load bearing sites and with the appropriate physical characteristics for osteointegration upon partial degradation. Zn release studies (concentrations between 413 μM and 887 μM) evidenced the necessity to tune the cement formulations to reduce the Zn concentration in the surrounding environment. Highlights: ► We developed partially degradable, bioactive, Al-free glass-ionomer cements (GICs). ► Enhanced mechanical behavior was achieved using 63–125 μm glass particle size range. ► The highest mechanical resistance was obtained using poly(acrylic acid) of 50 kDa. ► Biodegradation was successfully tuned to start 8 weeks after GIC preparation. ► Zn

  1. The role of ceramics, cement and glass in the immobilization of radioactive wastes

    International Nuclear Information System (INIS)

    Glasser, F.P.

    1985-01-01

    A brief account is given of the constitution and origin of nuclear waste. The immobilization of wastes is discussed: borosilicate glasses are considered as possible matrices; ceramic forms are dealt with in more detail. The principles of the use of ceramics are explained, with examples of different ceramic structures; cements are mentioned as being suitable for wet, medium- to low-active wastes. The effects of radiation on cement, ceramic and glass waste forms are indicated. The account concludes with 'summary and future progress'. (U.K.)

  2. Hydration of Blended Portland Cements Containing Calcium-Aluminosilicate Glass Powder and Limestone

    DEFF Research Database (Denmark)

    Moesgaard, M; Poulsen, Søren Lundsted; Herfort, D

    2012-01-01

    M. MOESGAARD, S.L. POULSEN, D. HERFORT, M. STEENBERG, L.F. KIRKEGAARD, J. SKIBSTED, Y. YUE, Hydration of Blended Portland Cements Containing Calcium-Aluminosilicate Glass Powder and Limestone, Journal of the American Ceramic Society 95, 403 – 409 (2012).......M. MOESGAARD, S.L. POULSEN, D. HERFORT, M. STEENBERG, L.F. KIRKEGAARD, J. SKIBSTED, Y. YUE, Hydration of Blended Portland Cements Containing Calcium-Aluminosilicate Glass Powder and Limestone, Journal of the American Ceramic Society 95, 403 – 409 (2012)....

  3. Aluminum-free glass-ionomer bone cements with enhanced bioactivity and biodegradability

    International Nuclear Information System (INIS)

    Gomes, Filipa O.; Pires, Ricardo A.; Reis, Rui L.

    2013-01-01

    Al-free glasses of general composition 0.340SiO 2 :0.300ZnO:(0.250-a-b)CaO:aSrO:bMgO:0.050Na 2 O:0.060P 2 O 5 (a, b = 0.000 or 0.125) were synthesized by melt quenching and their ability to form glass-ionomer cements was evaluated using poly(acrylic acid) and water. We evaluated the influence of the poly(acrylic acid) molecular weight and glass particle size in the cement mechanical performance. Higher compressive strength (25 ± 5 MPa) and higher compressive elastic modulus (492 ± 17 MPa) were achieved with a poly(acrylic acid) of 50 kDa and glass particle sizes between 63 and 125 μm. Cements prepared with glass formulation a = 0.125 and b = 0.000 were analyzed after immersion in simulated body fluid; they presented a surface morphology consistent with a calcium phosphate coating and a Ca/P ratio of 1.55 (similar to calcium-deficient hydroxyapatite). Addition of starch to the cement formulation induced partial degradability after 8 weeks of immersion in phosphate buffer saline containing α-amylase. Micro-computed tomography analysis revealed that the inclusion of starch increased the cement porosity from 35% to 42%. We were able to produce partially degradable Al-free glass-ionomer bone cements with mechanical performance, bioactivity and biodegradability suitable to be applied on non-load bearing sites and with the appropriate physical characteristics for osteointegration upon partial degradation. Zn release studies (concentrations between 413 μM and 887 μM) evidenced the necessity to tune the cement formulations to reduce the Zn concentration in the surrounding environment. Highlights: ► We developed partially degradable, bioactive, Al-free glass-ionomer cements (GICs). ► Enhanced mechanical behavior was achieved using 63–125 μm glass particle size range. ► The highest mechanical resistance was obtained using poly(acrylic acid) of 50 kDa. ► Biodegradation was successfully tuned to start 8 weeks after GIC preparation. ► Zn release should be

  4. Evaluation of an injectable bioactive borate glass cement to heal bone defects in a rabbit femoral condyle model

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Xu [Institute of Bioengineering and Information Technology Materials, Tongji University, Shanghai 200092 (China); Center for Human Tissues and Organs Degeneration, Shenzhen Institute of Advanced Technology, Chinese Academy of Science, Shenzhen 518055 (China); Huang, Wenhai [Institute of Bioengineering and Information Technology Materials, Tongji University, Shanghai 200092 (China); Zhang, Yadong, E-mail: zhangyadong6@126.com [Department of Spine Surgery, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai 200120 (China); Huang, Chengcheng; Yu, Zunxiong; Wang, Lei; Liu, Wenlong; Wang, Ting [Center for Human Tissues and Organs Degeneration, Shenzhen Institute of Advanced Technology, Chinese Academy of Science, Shenzhen 518055 (China); Zhou, Jie; Wang, Hui; Zhou, Nai; Wang, Deping [Institute of Bioengineering and Information Technology Materials, Tongji University, Shanghai 200092 (China); Pan, Haobo, E-mail: hb.pan@siat.ac.cn [Center for Human Tissues and Organs Degeneration, Shenzhen Institute of Advanced Technology, Chinese Academy of Science, Shenzhen 518055 (China); Rahaman, Mohamed N., E-mail: rahaman@mst.edu [Department of Spine Surgery, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai 200120 (China); Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409-0340 (United States)

    2017-04-01

    There is a need for synthetic biomaterials to heal bone defects using minimal invasive surgery. In the present study, an injectable cement composed of bioactive borate glass particles and a chitosan bonding solution was developed and evaluated for its capacity to heal bone defects in a rabbit femoral condyle model. The injectability and setting time of the cement in vitro decreased but the compressive strength increased (8 ± 2 MPa to 31 ± 2 MPa) as the ratio of glass particles to chitosan solution increased (from 1.0 g ml{sup −1} to 2.5 g ml{sup −1}). Upon immersing the cement in phosphate-buffered saline, the glass particles reacted and converted to hydroxyapatite, imparting bioactivity to the cement. Osteoblastic MC3T3-E1 cells showed enhanced proliferation and alkaline phosphatase activity when incubated in media containing the soluble ionic product of the cement. The bioactive glass cement showed a better capacity to stimulate bone formation in rabbit femoral condyle defects at 12 weeks postimplantation when compared to a commercial calcium sulfate cement. The injectable bioactive borate glass cement developed in this study could provide a promising biomaterial to heal bone defects by minimal invasive surgery. - Highlights: • New class of injectable bone cement composed of bioactive borate glass particles and chitosan bonding phase was created. • The cement is biocompatible and bioactive, and has a much lower temperature increase during setting than PMMA cement. • The cement has a more controllable degradation rate and higher strength over a longer time than calcium sulfate cement. • The cement showed a better ability to heal bone defects than calcium sulfate over a twelve-week implantation period.

  5. Increasing the compressive strength of portland cement concrete using flat glass powder

    Energy Technology Data Exchange (ETDEWEB)

    Miranda Junior, Edson Jansen Pedrosa de; Bezerra, Helton de Jesus Costa Leite; Politi, Flavio Salgado; Paiva, Antonio Ernandes Macedo, E-mail: edson.jansen@ifma.edu.br [Instituto Federal de Educacao, Ciencia e Tecnologia do Maranha (IFMA), Sao Luis, MA (Brazil). Dept. de Mecanica e Materiais

    2014-08-15

    This paper analyzes the compressive strength of Portland cement concrete in response to the incorporation of 5%, 10% and 20% of flat glass powder in place of sand, at w/c (water/cement) ratios of 0.50, 0.55 and 0.58. A statistical analysis of variance (ANOVA) was performed after 7, 14 and 28 days of curing. The compressive strength test results indicate that the concrete containing a w/c ratio of 0.50 can be used for structural applications, regardless of the waste glass content, as can that with a w/c ratio of 0.55 containing 20% of waste glass. We suggest that the use of flat glass powder in place of sand in the above mentioned percentages is feasible for the production of an environmentally appropriate and structurally applicable concrete. However, the concrete's fluidity and void content must be taken into account. (author)

  6. Can a soda-lime glass be used to demonstrate how patterns of strength dependence are influenced by pre-cementation and resin-cementation variables?

    LENUS (Irish Health Repository)

    Hooi, Paul

    2013-01-01

    To determine how the variability in biaxial flexure strength of a soda-lime glass analogue for a PLV and DBC material was influenced by precementation operative variables and following resin-cement coating.

  7. Alkali activated slag cements using waste glass as alternative activators. Rheological behaviour

    Directory of Open Access Journals (Sweden)

    Manuel Torres-Carrasco

    2015-03-01

    The findings show that AAS paste behaviour of rheology when the activator was a commercial waterglass solution or NaOH/Na2CO3 with waste glass was similar, fit the Herschel-Bulkley model. The formation of primary C-S-H gel in both cases were confirmed. However, the rheological behaviour in standard cements fit the Bingham model. The use of the waste glass may be feasible from a rheological point of view in pastes can be used.

  8. Properties and osteoblast cytocompatibility of self-curing acrylic cements modified by glass fillers.

    Science.gov (United States)

    Lopes, P; Garcia, M P; Fernandes, M H; Fernandes, M H V

    2013-11-01

    Materials filled with a silicate glass (MSi) and a borate glass (MB) were developed and compared in terms of their in vitro behavior. The effect of filler composition and concentration (0, 30, 40 and 50 wt%) on the curing parameters, residual monomer, water uptake, weight loss, bioactivity, mechanical properties (bending and compression) and osteoblast cytocompatibility was evaluated. The addition of bioactive glass filler significantly improved the cements curing parameters and the mechanical properties. The most relevant results were obtained for the lower filler concentration (30 t%) a maximum flexural strength of 40.4 Pa for MB3 and a maximum compressive strength of 95.7 MPa for MSi3. In vitro bioactivity in acellular media was enhanced by the higher glass contents in the cements. Regarding the biological assessment, the incorporation of the silicate glass significantly improved osteoblast cytocompatibility, whereas the presence of the borate glass resulted in a poor cell response. Nevertheless it was shown that the surviving cells on the MB surface were in a more differentiated stage compared to those growing over non-filled poly(methyl methacrylate). Results suggest that the developed formulations offer a high range of properties that might be interesting for their use as self-curing cements.

  9. Initial sliding wear kinetics of two types of glass ionomer cement: a tribological study.

    Science.gov (United States)

    Villat, Cyril; Ponthiaux, Pierre; Pradelle-Plasse, Nelly; Grosgogeat, Brigitte; Colon, Pierre

    2014-01-01

    The aim of this work was to characterize the initial wear kinetics of two different types of glass ionomer cement used in dentistry (the conventional glass ionomer cement and the resin-modified glass ionomer cement) under sliding friction after 28-day storing in distilled water or Ringer's solution. Sliding friction was applied through a pin-on-disk tribometer, in sphere-on-plane contact conditions, under 5 N normal load and 120 rotations per minute. The test lasted 7500 cycles and replicas were performed at 2500, 5000 and 7500 cycles. A profilometer was used to evaluate the wear volume. Data were analysed using Student's t-test at a significant level of 5%. There is no statistical significant difference between the results obtained for a given material with the maturation media (P > 0.05). However, for a given maturation medium, there are significant statistical differences between the data obtained for the two materials at each measurement (P glass ionomer cement weakens the tribological behaviour of this material.

  10. Initial Sliding Wear Kinetics of Two Types of Glass Ionomer Cement: A Tribological Study

    Directory of Open Access Journals (Sweden)

    Cyril Villat

    2014-01-01

    Full Text Available The aim of this work was to characterize the initial wear kinetics of two different types of glass ionomer cement used in dentistry (the conventional glass ionomer cement and the resin-modified glass ionomer cement under sliding friction after 28-day storing in distilled water or Ringer’s solution. Sliding friction was applied through a pin-on-disk tribometer, in sphere-on-plane contact conditions, under 5 N normal load and 120 rotations per minute. The test lasted 7500 cycles and replicas were performed at 2500, 5000 and 7500 cycles. A profilometer was used to evaluate the wear volume. Data were analysed using Student’s t-test at a significant level of 5%. There is no statistical significant difference between the results obtained for a given material with the maturation media (P>0.05. However, for a given maturation medium, there are significant statistical differences between the data obtained for the two materials at each measurement (P<0.0001. The wear rates of both materials decrease continuously during the running-in period between 0 and 2500 cycles. After 2500 cycles, the wear rate becomes constant and equal for both materials. The resin matrix contained in the resin-modified glass ionomer cement weakens the tribological behaviour of this material.

  11. Shear bond strengths of three glass ionomer cements to enamel and dentine

    NARCIS (Netherlands)

    Carvalho, T.S.; van Amerongen, W.E.; de Gee, A.; Bönecker, M.; Sampaio, F.C.

    2011-01-01

    Objectives: The shear bond strength of three glass ionomer cements (GIC) to enamel and dentine was evaluated. Study Design: Sound permanent human molars (n=12) were grinded perpendicular to their axial axes, exposing smooth, flat enamel and dentine surfaces. The teeth were embedded in resin and

  12. Low-cost glass ionomer cement as ART sealant in permanent molars: a randomized clinical trial

    NARCIS (Netherlands)

    Hesse, D.; Bonifácio, C.C.; Guglielmi, C. de Almeida Brandao; da Franca, C.; Mendes, F.M.; Raggio, D.P.

    2015-01-01

    Clinical trials are normally performed with well-known brands of glass ionomer cement (GIC), but the cost of these materials is high for public healthcare in less-affluent communities. Given the need to research cheaper materials, it seems pertinent to investigate the retention rate of a low-cost

  13. Influence of Salvadora persica (miswak) extract on physical and antimicrobial properties of glass ionomer cement

    NARCIS (Netherlands)

    El-Tatari, A.; de Soet, J.J.; de Gee, A.J.; Abou Shelib, M.; van Amerongen, W.E.

    2011-01-01

    AIM: To investigate physical and antimicrobial properties of Glass Ionomer Cement (GIC) combined with Salvadora Persica Extract (SPE). METHODS: SPE was added to GIC (Fuji IX) in concentrations of 1%, 2% and 4% w/w. The compressive strength and diametral tensile strength were measured at 1 h, 24 h

  14. Physical-mechanical properties of glass ionomer cements indicated for atraumatic restorative treatment

    NARCIS (Netherlands)

    Bonifacio, C.C.; Kleverlaan, C.J.; Raggio, D.P.; Werner, A.; de Carvalho, R.C.R.; van Amerongen, W.E.

    2009-01-01

    Background:  This study evaluated mechanical properties of glass ionomer cements (GICs) used for atraumatic restorative treatment. Wear resistance, Knoop hardness (Kh), flexural (Fs) and compressive strength (Cs) were evaluated. The GICs used were Riva Self Cure (RVA), Fuji IX (FIX), Hi Dense (HD),

  15. Aspects of bonding between resin luting cements and glass ceramic materials.

    Science.gov (United States)

    Tian, Tian; Tsoi, James Kit-Hon; Matinlinna, Jukka P; Burrow, Michael F

    2014-07-01

    The bonding interface of glass ceramics and resin luting cements plays an important role in the long-term durability of ceramic restorations. The purpose of this systematic review is to discuss the various factors involved with the bond between glass ceramics and resin luting cements. An electronic Pubmed, Medline and Embase search was conducted to obtain laboratory studies on resin-ceramic bonding published in English and Chinese between 1972 and 2012. Eighty-three articles were included in this review. Various factors that have a possible impact on the bond between glass ceramics and resin cements were discussed, including ceramic type, ceramic crystal structure, resin luting cements, light curing, surface treatments, and laboratory test methodology. Resin-ceramic bonding has been improved substantially in the past few years. Hydrofluoric acid (HF) etching followed by silanizaiton has become the most widely accepted surface treatment for glass ceramics. However, further studies need to be undertaken to improve surface preparations without HF because of its toxicity. Laboratory test methods are also required to better simulate the actual oral environment for more clinically compatible testing. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  16. Dental Glass Ionomer Cements as Permanent Filling Materials? – Properties, Limitations and Future Trends

    Directory of Open Access Journals (Sweden)

    Ulrich Lohbauer

    2009-12-01

    Full Text Available Glass ionomer cements (GICs are clinically attractive dental materials that have certain unique properties that make them useful as restorative and luting materials. This includes adhesion to moist tooth structures and base metals, anticariogenic properties due to release of fluoride, thermal compatibility with tooth enamel, biocompatibility and low toxicity. The use of GICs in a mechanically loaded situation, however, has been hampered by their low mechanical performance. Poor mechanical properties, such as low fracture strength, toughness and wear, limit their extensive use in dentistry as a filling material in stress-bearing applications. In the posterior dental region, glass ionomer cements are mostly used as a temporary filling material. The requirement to strengthen those cements has lead to an ever increasing research effort into reinforcement or strengthening concepts.

  17. Fracture strengths of chair-side-generated veneers cemented with glass fibers.

    Science.gov (United States)

    Turkaslan, S; Bagis, B; Akan, E; Mutluay, M M; Vallittu, P K

    2015-01-01

    CAD/CAM (computer-aided design and computer-aided manufacturing) systems have refreshed the idea of chair-side production of restorations, but the fracture of ceramic veneers remains a problem. Cementation with glass fibers may improve the fracture strengths and affect the failure modes of CAD/CAM-generated ceramic veneers. Therefore, this study compared the fracture strengths of ceramic veneers produced at chair side and cemented with or without glass fibers with those of composite veneers. Thirty intact mandibular incisors were randomly divided into three groups ( n = 10) and treated with CAD/CAM-fabricated veneers cemented with dual-cure composite resin luting cement (CRLC; Group 1), CAD/CAM-fabricated veneers cemented with a glass fiber network (GFN) and dual-cure CRLC (Group 2), and a direct particulate filler composite veneer constructed utilizing fiber and a restorative composite resin (Group 3). The specimens were tested with a universal testing machine after thermal cycling treatment. The loads at the start of fracture were the lowest for traditionally fabricated composite veneers and higher for CAD/CAM-generated. Veneers cemented either without or with the GFN. The failure initiation loads (N) for the veneers were 798.92 for Group 1, 836.27 for Group 2, and 585.93 for Group 3. The predominant failure mode is adhesive failure between the laminates and teeth for Group 1, cohesive failure in the luting layer for Group 2, and cohesive laminate failure for Group 3, which showed chipping and small fractures. Ceramic material is a reliable alternative for veneer construction at chair side. Fibers at the cementation interface may improve the clinical longevity and provide higher fracture strength values.

  18. SEALING ABILITY OF MINERAL TRIOXIDE AGGREGATE, CALCIUM PHOSPHATE CEMENT, AND GLASS IONOMER CEMENT IN THE REPAIR OF FURCATION PERFORATIONS

    Directory of Open Access Journals (Sweden)

    Prabath Singh

    2013-01-01

    Full Text Available Objectives: The purpose of this study was to evaluate the in vitro sealing ability of three repair materials. Mineral trioxide aggregate (MTA; Group A, calcium phosphate cement (CPC; Group B, and light cured glass ionomer cement (GIC; Group C when used to repair the perforation created in the pulpal floor of fifty extracted human permanent molars. Materials and methods: Preparation of access openings and furcation perforations were done, and the teeth divided into five experimental groups (A, B, C including two controls (D, E with ten samples in each group randomly. Following the repair procedure, the pulp chambers and access openings were filled with composite resin and immersed in 2% methylene blue solution for 48 hours. The teeth were sectioned longitudinally and the linear dye penetration measured under a stereo­microscope. Results: The comparison of the linear length of micro-leakage (mm among the experimental groups revealed no significant difference (p = 0.332. On calculating the percentage of depth of leakage to the total length of the perforation, it was observed that the mean leakage was 35.5% in Group A, 53.6% in Group B and the highest, 87.5% in Group C. The mean of leakage percentage was statistically significant by Kruskal-Wallis test (p = 0.003. The results indicated that the dye penetration used as furcation perforation repair material was least with mineral trioxide aggregate. Comparing the depth of penetration of dye, 50% of the Group A samples showed less than 25% of depth penetration. While 40% of Group B cases had more than 50% dye penetration. In our study, all Group C teeth had ≥ 50% dye penetration. Conclusions: The present study indicated that GIC had the greatest dye penetration followed by CPC and MTA. Mineral trioxide aggregate and calcium phosphate cement had comparatively better sealing ability than glass ionomer cement.

  19. Post-irradiation hardness of resin-modified glass ionomer cements and a polyacid-modified composite resin

    International Nuclear Information System (INIS)

    Yap, A.U.J.

    1997-01-01

    This study examined the post-irradiation hardness of resin-modified glass ionomer cements and a polyacid-modified composite resin using a digital microhardness tester. Change in hardness of these materials over a period of 6 months was compared to that of conventional glass ionomer cements and a composite resin. With the exception of the composite resin, all materials showed a significant increase in hardness over 24 h after their initial set. Dual-cure resin-modified glass ionomer cements showed decreased hardness with increased storage time in saline at 37 o C. Results suggest that the addition of resins to glass ionomer cements does not improve initial hardness and does not negate the acid-base reaction of conventional cements. Resin addition may, however, lead to increased water sorption and decreased hardness. (author)

  20. Confocal microscopic observation of structural changes in glass-ionomer cements and tooth interfaces.

    Science.gov (United States)

    Watson, T F; Pagliari, D; Sidhu, S K; Naasan, M A

    1998-03-01

    This study aimed to develop techniques to allow dynamic imaging of a cavity before, during and after placement of glass-ionomer restorative materials. Cavities were cut in recently extracted third molars and the teeth longitudinally sectioned. Each hemisected tooth surface was placed in green modelling compound at 90 to the optical axis of the microscope. The cavity surface was imaged using a video rate confocal microscope in conjunction with an internally focusable microscope objective. The sample on the stage was pushed up to the objective lens which 'clamped' the cover glass onto it. Water, glycerine or oil was placed below the coverglass, with oil above. Internal tooth structures were imaged by changing the internal focus of the objective. The restorative material was then placed into the cavity. Video images were stored either onto video tape or digitally, using a frame grabber, computer and mass memory storage. Software controls produced time-lapse recordings of the interface over time. Preliminary experiments have examined the placement and early maturation of conventional glass-ionomer cements and a syringeable resin-modified glass-ionomer cement. Initial contact of the cement matrix and glass particles was visible as the plastic material rolled past the enamel and dentine, before making a bond. Evidence for water movement from the dentine into the cement has also been seen. After curing, the early dimensional changes in the cements due to water flux were apparent using the time-lapse facility. This new technique enables examination of developing tooth/restoration interfaces and the tracking of movement in materials.

  1. Manufacturing of wollastonite-based glass from cement dust: Physical and mechanical properties

    Directory of Open Access Journals (Sweden)

    A.A. Francis

    2016-12-01

    Full Text Available By-pass cement dust is considered as a source of environmental pollution. Wollastonite-based glass foams are made by adding glass waste and SiC to the cement dust. XRD on samples indicated that the main crystalline phase after heat treatment at 850–1,000°C is wollastonite. Empirical models were developed to derive conclusion on the impact of SiC and temperature on the physical and mechanical properties of the products. The optimum sintering temperature was found to be at 900°C for 60 min, at which crushing strength was about 15 MPa and was the best uniform. Such wollastonite-based glass foam could be very attractive for thermal and acoustic applications.

  2. Kekuatan perlekatan geser semen ionomer kaca terhadap dentin dan NiCr alloy (Shear bond strenght of glass ionomer cement in dentin and NiCr alloy

    Directory of Open Access Journals (Sweden)

    Mira Leonita

    2006-03-01

    Full Text Available Glass ionomer cements were used broadly in restorative dentistry. That’s why researchers always try to invent new form of glass ionomer cement. The newest invention was the paste-paste formulation. Shear bond strenght of powder-liquid glass ionomer cement and paste-paste glass ionomer cement in dentin and NiCr alloy was tested to 4 groups of samples. Each group consisted contain 6 samples that were shaped into cylinder with 4 mm of diameter and 5 mm of height. Group A was dentin with powder-liquid glass ionomer cement, group B was dentin with paste-paste glass ionomer cement, group C was alloy with powder-liquid glass ionomer cement, and group D was alloy with paste-paste glass ionomer cement. Each sample in each group was tested with Autograph. The datas were analyzed statistically using T-test with level of signficance 0.05. The result showed that powder-liquid glass ionomer cement shear bond strenght was 211 N and paste-paste glass ionomer cement was 166.92 N. That showed that powder-liquid glass ionomer cement had a better shear bond strenght.

  3. Development of novel strontium containing bioactive glass based calcium phosphate cement.

    Science.gov (United States)

    D'Onofrio, A; Kent, N W; Shahdad, S A; Hill, R G

    2016-06-01

    The aim of this study was to investigate the effect on properties of increasing strontium substitution for calcium in bioactive glasses used as precursors for novel calcium phosphate cements. Glasses were produced by progressively substituting strontium for calcium. Cements were prepared by mixing the glass powder with Ca(H2PO4)2 powder with a 2.5% solution of Na2HPO4. Setting times and compressive strength were measured after 1h, 1 day, 7 days and 28 days immersion in Tris buffer solution. X-ray diffraction (XRD), Fourier transform infrared spectroscopy and radiopacity were measured and crystal morphology was assessed using scanning electron microscopy. A correlation between the phases formed, morphology of the crystallites, setting time and compressive strength were analyzed. Setting time increased proportionally with strontium substitution in the glass up to 25%, whereas for higher substitutions it decreased. Compressive strength showed a maximum value of 12.5MPa and was strongly influenced by the interlocking of the crystals and their morphology. XRD showed that the presence of strontium influenced the crystal phases formed. Octacalcium phosphate (Ca8H2(PO4)6·5H2O, OCP) was the main phase present after 1h and 1 day whereas after 28 days OCP was completely transformed to strontium-containing hydroxyapatite (SrxCa(10-x)(PO4)6(OH)2, SrHA). Radiopacity increased proportionally to strontium substitution in the glass. A novel method to develop a bone substitute forming in vitro SrHA as a final product by using a bioactive glass as a precursor was shown. These novel injectable bioactive glass cements are promising materials for dental and orthopedic applications. Further in vivo characterizations are being conducted. Copyright © 2016 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  4. Effect of porosity on physical properties of lightweight cement composite with foamed glass aggregate

    Directory of Open Access Journals (Sweden)

    Kurpińska Marzena

    2017-01-01

    Full Text Available This paper reports on a study of physical properties of lightweight cement composite. We investigate the possibility of replacing traditional aggregate with Granulated Ash Aggregate (GAA and above all with Granulated Expanded Glass Aggregate (GEGA. For this purpose, 15 specimens of different percentage share of each aggregate in total aggregate volume were tested: 0%, 25%, 50%, 75% or 100% of foam glass aggregate (GEGA partially replaced by ash aggregate (GAA content in the cement composite. The water-cement ratio was constant and equal to w/c=0.5. Three grain sizes were analyzed: 2mm, 4mm (both GEGA and 8mm (GAA. Numerical simulations of concrete specimen behavior under static loading were conducted with the implementation of elastic plastic model of each component. The study shows a significant impact of grain type and size on physical properties of lightweight concrete. Due to lower density of foamed glass aggregate, specimens shows various apparent density and porosity, which affect concrete properties. Compressive strength of concrete decreases with the increase in foam glass aggregate content; however specimens show different workability and in consequence porosity of lightweight concrete.

  5. Alteration of a borosilicate glass in cemented water: antagonist effects of calcium

    International Nuclear Information System (INIS)

    Frizon, F.; Depierre, S.; Angeli, F.; Gin, S.

    2013-01-01

    In the framework of the storage of radioactive wastes in deep geological layers, vitrified waste may be in contact with an environment saturated with solutions stemming from various stages of cement degradation. A series of experiments has been performed to assess how a basic aqueous calcium-rich solution can impact the mechanisms and kinetics of glass alteration. This study shows that 2 main parameters have an impact on the kinetics of the dissolution of glass: the S/V ratio (the glass surface divided by the volume of solution) and the calcium concentration. The calcium concentration is a key parameter whatever the kinetics of glass degradation. In a diluted medium with a pH over 11, the kinetics of glass alteration slows down along with an increase in calcium concentration. What happens is that the silicon flux being too weak to allow the nucleation of C-S-H phases, calcium can penetrate the alteration layer which leads to a better retention of glass components through specific silicon-calcium reactivity and a slowing down of the glass alteration kinetics. On the contrary in a confined environment, a high concentration in calcium leads to the precipitation of C-S-H and to less C-S-H available to cover glass grains diminishing its passivating effect and consequently the dissolving of glass can keep on at more or less the same pace. (A.C.)

  6. Cermet cements.

    Science.gov (United States)

    McLean, J W

    1990-01-01

    Cermet ionomer cements are sintered metal/glass powders, which can be made to react with poly(acids). These new cements are significantly more resistant to abrasion than regular glass ionomer cements and are widely accepted as core build-up materials and lining cements. They can strengthen teeth and provide the clinician with an opportunity to treat early dental caries.

  7. Transient and residual stresses in a pressable glass-ceramic before and after resin-cement coating determined using profilometry.

    LENUS (Irish Health Repository)

    2011-05-01

    The effect of heat-pressing and subsequent pre-cementation (acid-etching) and resin-cementation operative techniques on the development of transient and residual stresses in different thicknesses of a lithium disilicate glass-ceramic were characterised using profilometry prior to biaxial flexure strength (BFS) determination.

  8. Effect of gloss and heat on the mechanical behaviour of a glass carbomer cement.

    Science.gov (United States)

    Menne-Happ, Ulrike; Ilie, Nicoleta

    2013-03-01

    The effect of gloss and heat on the mechanical behaviour of a recently launched glass carbomer cement (GCP, GCP dental) was evaluated and compared with resin-modified glass ionomer cements (Fuji II LC, GC and Photac Fil Quick Aplicap, 3M ESPE). 120bar-shaped specimens (n=20) were produced, maintained in distilled water at 37°C and tested after one week. The GCP specimens were cured with and without heat application and with and without gloss. The flexural strength and modulus of elasticity in flexural test as well as the micro-mechanical properties (Vickers Hardness, indentation modulus, creep) of the top and bottom surface were evaluated. The amount and size of the fillers, voids and cracks were compared using a light and a scanning electron microscope. In the flexural test, the resin-modified glass ionomer cements performed significantly better than GCP. Fuji II LC and Photac Fil (Weibull parameter: 17.7 and 14.3) proved superior reliability in the flexural test compared to GCP (1.4-2.6). The highest Vickers Hardness and lowest creep were achieved by GCP, whereas Fuji II LC reached the highest indentation modulus. The results of this study proved that relationships exist between the compositions, microstructures and mechanical properties of the cements. Heat treatment and gloss application did not influence the mechanical properties of GCP. The mechanical properties were basically influenced by the type of cement and its microstructure. Considering the measured mechanical properties, there is no need of using gloss or heat when restoring teeth with GCP. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. A study of the interactions between glass-ionomer cement and S. sanguis biofilms

    Science.gov (United States)

    Hengtrakool, Chanotai

    Glass-ionomer cements (GIC) have been used for dental procedures for many years and more recently in other medical applications such as bone cements, for bone reconstruction and also as drug release agents. The postulated caries-preventive activities of GIC are thought to result from their sealing ability, remineralization potential and antibacterial effects. Extensive 'in vitro' investigations have attempted to quantify these effects. In this study, an artificial mouth model, simulating 'in vivo' conditions at the tooth surface, was used to achieve a better understanding of the interaction of oral bacteria with the cements. This study investigated the interaction of Streptococcus sanguis, a common mouth commensal, with two glass-ionomer formulations (one containing fluoride and the other without fluoride ion) with particular reference to bacterial growth, changes in surface roughness and hardness of the glass-ionomer cement with respect to time. Restorative materials with rough surfaces will promote bacterial accumulation 'in vivo' and plaque formation is one factor in surface degradation. The constant depth film fermenter (CDFF) permits the examination of these phenomena and was used to investigate glass-ionomer/S. sanguis biofilm interaction over periods up to 14 days. In conjunction with these studies, surface roughness was measured using a 3-dimension laser profilometer and the surface hardness evaluated using a micro-indenter. Fluoride release from the cement was measured over 84 days. The results showed that autoclaving the CDFF prior to bacterial innoculate did not appear to affect the long-term fluoride release of the GIC. Laser profilometry revealed that the initial roughness and surface area of the GICs was significantly greater than the hydroxyapatite control. S. sanguis viable counts were significantly reduced for both glass-ionomer formulations in the shortterm, the greater reduction being with fluoride-GIC. S. sanguis biofilms produced similar

  10. [Comparative investigation of compressive resistance of glass-cermet cements used as a core material in post-core systems].

    Science.gov (United States)

    Ersoy, E; Cetiner, S; Koçak, F

    1989-09-01

    In post-core applications, addition to the cast designs restorations that are performed on fabrication posts with restorative materials are being used. To improve the physical properties of glass-ionomer cements that are popular today, glass-cermet cements have been introduced and those materials have been proposed to be an alternative restorative material in post-core applications. In this study, the compressive resistance of Ketac-Silver as a core material was investigated comparatively with amalgam and composite resins.

  11. "Effect of nano-filled surface coating agent on fluoride release from conventional glass ionomer cement: An in vitro trial"

    OpenAIRE

    S Tiwari; B Nandlal

    2013-01-01

    Context: To overcome the drawbacks of glass ionomer cement of sensitivity to initial desiccation and moisture contamination the use of surface coating agent is recommended. The search in this area led to invent of use of nanofillers in surface coating agent, but its effect on fluoride release is not clear. Aim: The aim of this study is to evaluate and compare the fluoride release from conventional glass ionomer cement with and without surface coating agent. Settings and Design: This in vitro ...

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

    Science.gov (United States)

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

    2010-04-01

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

  13. Influence of the waste glass in the axial compressive strength of Portland cement concrete

    International Nuclear Information System (INIS)

    Miranda Junior, E.J.P.; Paiva, A.E.M.

    2012-01-01

    In this work, was studied the influence of the incorporation of waste glass, coming from the stage of thinning and polishing of a company of thermal glass treatments, in the axial compressive strength of Portland cement concrete. The coarse and ground aggregates used was crushed stone and sand, respectively. For production of the concrete, percentages of glass residues of 5%, 10% and 20% had been used in substitution to the sand, and relations water/cement (a/c) 0,50, 0,55 and 0,58. The cure of the test bodies was carried through in 7, 14 and 28 days. The statistics analysis of the results was carried out through of the analysis of variance for each one of the cure times. From the results of the compressive strength of the concrete, it could be observed that the concrete has structural application for the relation a/c 0,5, independently of waste glass percentage used, and for the relation a/c 0,55 with 20% of waste glass. (author)

  14. Heat transfer properties and thermal cure of glass-ionomer dental cements.

    Science.gov (United States)

    Gavic, Lidia; Gorseta, Kristina; Glavina, Domagoj; Czarnecka, Beata; Nicholson, John W

    2015-10-01

    Under clinical conditions, conventional glass-ionomer dental cements can be cured by application of heat from dental cure lamps, which causes acceleration in the setting. In order for this to be successful, such heat must be able to spread sufficiently through the cement to enhance cure, but not transmit heat so effectively that the underlying dental pulp of the tooth is damaged. The current study was aimed at measuring heat transfer properties of modern restorative glass-ionomers to determine the extent to which they meet these twin requirements. Three commercial glass ionomer cements (Ionofil Molar, Ketac Molar and Equia™ Fill) were used in association with three different light emitting diode cure lamps designed for clinical use. In addition, for each cement, one set of specimens was allowed to cure without application of a lamp. Temperature changes were measured at three different depths (2, 3 and 4 mm) after cure times of 20, 40 and 60 s. The difference among the tested groups was evaluated by ANOVA (P heat irradiation, but much greater temperature increases when exposed to the cure lamp. However, temperature rises did not exceed 12.9 °C. Application of the cure lamp led to the establishment of a temperature gradient throughout each specimen. Differences were typically significant (P heating effect. Because the thermal conductivity of glass-ionomers is low, temperature rises at 4 mm depths were much lower than at 2 mm. At no time did the temperature rise sufficiently to cause concern about potential damage to the pulp.

  15. COMPARATIVE ASSESSMENT OF RICE HUSK ASH, POWDERED GLASS AND CEMENT AS LATERITIC SOIL STABILIZERS

    Directory of Open Access Journals (Sweden)

    Adebisi Ridwan

    2016-10-01

    Full Text Available This paper compares the stabilizing effects of three different materials, namely: rice husk ash, powdered glass, and cement on the properties of lateritic soil. The basic properties of the lateritic soil were first obtained through colour, moisture content determination, specific gravity, particle size distribution and Atterberg limits tests. Each of the stabilizing materials was then mixed with the lateritic soil in varying percentages of 2.5%, 5%, 7.5%, 10%, 12.5% and 15% by weight of the soil. Thereafter, compaction and California bearing ratio (CBR tests were carried out on the sample mixes to determine the effects of the materials on the lateritic soil. Chemical tests were also carried out on the samples to determine their percentage oxides composition. The compaction test showed that the highest maximum dry densities (MDD obtained for the mixed samples were 2.32 g/cm3 (at 2.5% cement addition, 2.28g/cm3 (at 5% powdered glass (PG addition and 2.18 g/cm3 (at 5% rice husk ash (RHA addition with corresponding optimum moisture contents (OMC of 10.06%, 14.3% and 12.31% respectively. The CBR tests showed that the CBR values increased in all cases as the materials were added with those of the cement and powdered glass giving the highest values and showing close semblance under unsoaked conditions. The chemical test showed that the significant oxides present in the cement, powdered glass and rice husk ash were CaO (53.60%, SiO2 (68.45% and SiO2 (89.84% respectively.

  16. Effect of G-Coat Plus on the mechanical properties of glass-ionomer cements.

    Science.gov (United States)

    Bagheri, R; Taha, N A; Azar, M R; Burrow, M F

    2013-12-01

    Although various mechanical properties of tooth-coloured materials have been described, little data have been published on the effect of ageing and G-Coat Plus on the hardness and strength of the glass-ionomer cements (GICs). Specimens were prepared from one polyacid-modified resin composite (PAMRC; Freedom, SDI), one resin-modified glass-ionomer cement; (RM-GIC; Fuji II LC, GC), and one conventional glass-ionomer cement; (GIC; Fuji IX, GC). GIC and RM-GIC were tested both with and without applying G-Coat Plus (GC). Specimens were conditioned in 37 °C distilled water for either 24 hours, four and eight weeks. Half the specimens were subjected to a shear punch test using a universal testing machine; the remaining half was subjected to Vickers Hardness test. Data analysis showed that the hardness and shear punch values were material dependent. The hardness and shear punch of the PAMRC was the highest and GIC the lowest. Applying the G-Coat Plus was associated with a significant decrease in the hardness of the materials but increase in the shear punch strength after four and eight weeks. The mechanical properties of the restorative materials were affected by applying G-Coat Plus and distilled water immersion over time. The PAMRC was significantly stronger and harder than the RM-GIC or GIC. © 2013 Australian Dental Association.

  17. Therapeutic ion-releasing bioactive glass ionomer cements with improved mechanical strength and radiopacity

    Directory of Open Access Journals (Sweden)

    Maximilian eFuchs

    2015-10-01

    Full Text Available Bioactive glasses (BG are used to regenerate bone, as they degrade and release therapeutic ions. Glass ionomer cements (GIC are used in dentistry, can be delivered by injection and set in situ by a reaction between an acid-degradable glass and a polymeric acid. Our aim was to combine the advantages of BG and GIC, and we investigated the use of alkali-free BG (SiO2-CaO-CaF2-MgO with 0 to 50% of calcium replaced by strontium, as the beneficial effects of strontium on bone formation are well documented. When mixing BG and poly(vinyl phosphonic-co-acrylic acid, ions were released fast (up to 90% within 15 minutes at pH 1, which resulted in GIC setting, as followed by infrared spectroscopy. GIC mixed well and set to hard cements (compressive strength up to 35 MPa, staying hard when in contact with aqueous solution. This is in contrast to GIC prepared with poly(acrylic acid, which were shown previously to become soft in contact with water. Strontium release from GIC increased linearly with strontium for calcium substitution, allowing for tailoring of strontium release depending on clinical requirements. Furthermore, strontium substitution increased GIC radiopacity. GIC passed ISO10993 cytotoxicity test, making them promising candidates for use as injectable bone cements.

  18. Influence of glass particle size of resin cements on bonding to glass ceramic: SEM and bond strength evaluation.

    Science.gov (United States)

    Valentini, Fernanda; Moraes, Rafael R; Pereira-Cenci, Tatiana; Boscato, Noéli

    2014-05-01

    This study investigated the effect of the filler particle size (micron or submicron) of experimental resin cements on the microtensile bond strength to a glass-ceramic pretreated with hydrofluoric acid (HFA) etching or alumina airborne-particle abrasion (AA). Cements were obtained from a Bis-GMA/TEGDMA mixture filled with 60 mass% micron-sized (1 ± 0.2 µm) or submicron-sized (180 ± 30 µm) Ba-Si-Al glass particles. Ceramic blocks (PM9; VITA) were treated with 10% HFA for 60 s or AA for 15 s. Silane and adhesive were applied. Ceramic blocks were bonded to resin composite blocks (Z250; 3M ESPE) using one of the cements. Bonded specimens were sectioned into beams (n = 20/group) and subjected to microtensile bond strength tests. Data were analyzed using ANOVA and Student-Newman-Keuls' tests (5%). Failure modes were classified under magnification. Morphologies of the treated ceramic surfaces and bonded interfaces were evaluated by scanning electron microscopy. The HFA-submicron group had lower bond strengths than the other groups. All AA-submicron specimens debonded prematurely. Mixed failures were predominant for HFA groups, whereas interfacial failures predominated for AA groups. SEM revealed a honeycomb-like aspect in the HFA-treated ceramic, whereas the AA-treated groups showed an irregular retentive pattern. Continuity of cement infiltration along the bonded interface was more uniform for HFA-treated compared to AA-treated specimens. Cracks toward the bulk of the ceramic were observed in AA-treated specimens. Particle size significantly influenced the ceramic bond strength, whereas surface treatment had a minor effect. Copyright © 2014 Wiley Periodicals, Inc.

  19. Effect of nano clay particles on mechanical, thermal and physical behaviours of waste-glass cement mortars

    International Nuclear Information System (INIS)

    Aly, M.; Hashmi, M.S.J.; Olabi, A.G.; Messeiry, M.; Hussain, A.I.

    2011-01-01

    Highlights: → Glass powder (GP) and nano clay (NC) were used as a partial cement replacement in cement mortar (CM). → No damaging effect can be detected due to the reaction between GP and CM with particle size up to 75 μm. → Hybrid combination of GP/NC greatly improved mechanical properties and microstructure of CM. - Abstract: Worldwide, around 2.6 billion tons of cement is produced annually. This huge size of production consumes large amounts of energy and is one of the largest contributors to carbon dioxide (CO 2 ) release. Accordingly, there is a pressing demand to minimise the quantity of cement used in the concrete industry. The main challenge to this is to get durable concrete with less cement and within reasonable cost. The economic, environmental and engineering benefits of reusing ground waste-glass powder (WGP) as a partial cement replacement has been established, but low glass reactivity and the possible alkali-silica reaction (ASR) are a drawback. Recent advances in nano-technology have revealed that nano-sized particles such as nano clay (NC) have a high surface area to volume ratio that provides the potential for tremendous chemical reactivity, accelerating pozzolanic activity and hindering ASR. This paper presents a laboratory study of the properties of NC/WGP cement composites. The microstructure, ASR, fracture energy, compressive and flexural properties of cement mortars containing WGP as a cement replacement with and without NC are investigated and compared with plain matrix. In addition, the hydration of cement compounds was followed by differential thermal analysis (DTA), thermogravimetric analysis (TGA), and also X-ray diffraction (XRD). The results showed that incorporation of glass powder has a positive effect on the mechanical properties of cement mortars after 28 days of hydration. Also, the results revealed that the mechanical properties of the cement mortars with a hybrid combination of glass powder and NC were all higher than

  20. The applicability of alkaline-resistant glass fiber in cement mortar of road pavement: Corrosion mechanism and performance analysis

    Directory of Open Access Journals (Sweden)

    Qin Xiaochun

    2017-11-01

    Full Text Available The main technical requirements of road pavement concrete are high flexural strength and fatigue durability. Adding glass fiber into concrete could greatly increase flexural strength and wearing resistance of concrete. However, glass fiber has the great potential of corrosion during the cement hydration, which will directly affect the long-term performance and strength stability. In this paper, accelerated corrosion experiments have been done to find out the corrosion mechanism and property of alkali-resistant glass fiber in cement mortar. The applicability and practicability of alkaline-resistant glass fiber in road concrete have been illustrated in the analysis of flexural strength changing trend of cement mortar mixed with different proportions of activated additives to protect the corrosion of glass fiber by cement mortar. The results have shown that a 30% addition of fly ash or 10% addition of silica fume to cement matrix could effectively improve the corrosion resistance of alkali-resistant glass fiber. The optimal mixing amount of alkali-resistant glass fiber should be about 1.0 kg/m3 in consideration of ensuring the compressive strength of reinforced concrete in road pavement. The closest-packing method has been adopted in the mixture ratio design of alkali-resistant glass fiber reinforced concrete, not only to reduce the alkalinity of the cement matrix through large amount addition of activated additives but also to greatly enhance the flexural performance of concrete with the split pressure ratio improvement of 12.5–16.7%. The results suggested a prosperous application prospect for alkaline-resistant glass fiber reinforced concrete in road pavement.

  1. Potential of Hollow Glass Microsphere as Cement Replacement for Lightweight Foam Concrete on Thermal Insulation Performance

    Directory of Open Access Journals (Sweden)

    Shahidan Shahiron

    2017-01-01

    Full Text Available Global warming can be defined as a gradual increase in the overall temperature of the earth’s atmosphere. A lot of research work has been carried out to reduce that heat inside the residence such as the used of low density products which can reduce the self-weight, foundation size and construction costs. Foamed concrete it possesses high flow ability, low self-weight, minimal consumption of aggregate, controlled low strength and excellent thermal insulation properties. This study investigate the characteristics of lightweight foamed concrete where Portland cement (OPC was replaced by hollow glass microsphere (HGMs at 0%, 3%, 6%, 9% by weight. The density of wet concrete is 1000 kg/m3 were tested with a ratio of 0.55 for all water binder mixture. Lightweight foamed concrete hollow glass microsphere (HGMs produced were cured by air curing and water curing in tank for 7, 14 and 28 days. A total of 52 concrete cubes of size 100mm × 100mm × 100mm and 215mm × 102.5mm × 65mm were produced. Furthermore, Scanning Electron Microscope (SEM and X-ray fluorescence (XRF were carried out to study the chemical composition and physical properties of crystalline materials in hollow glass microspheres. The experiments involved in this study are compression strength, water absorption test, density and thermal insulation test. The results show that the compressive strength of foamed concrete has reached the highest in 3% of hollow glass microsphere with less water absorption and less of thermal insulation. As a conclusion, the quantity of hollow glass microsphere plays an important role in determining the strength and water absorption and also thermal insulation in foamed concrete and 3% hollow glass microspheres as a replacement for Portland cement (OPC showed an optimum value in this study as it presents a significant effect than other percentage.

  2. Effect of incorporation of zinc oxide nanoparticles on mechanical properties of conventional glass ionomer cements.

    Science.gov (United States)

    Panahandeh, Narges; Torabzadeh, Hassan; Aghaee, Mohammadamin; Hasani, Elham; Safa, Saeed

    2018-01-01

    The aim of this study is to investigate the physical properties of conventional and resin-modified glass ionomer cements (GICs) compared to GICs supplemented with zinc oxide (ZnO) nanofiller particles at 5% (w/w). In this in vitro study, ZnO nanoparticles of different morphologies (nanospherical, nanorod, and nanoflower) were incorporated to glass ionomer powder. The samples were subjected to the flexural strength ( n = 20) and surface hardness test ( n = 12) using a universal testing machine and a Vickers hardness machine, respectively. Surface analysis and crystal structure of samples were performed with scanning electron microscope and X-radiation diffraction, respectively. The data were analyzed using one-way ANOVA, Shapiro-Wilk, and Tukey's tests ( P glass ionomer containing nanoparticles was not significantly different from the control group ( P > 0.05). The surface hardness of the glass ionomer containing nanospherical or nanoflower ZnO was significantly lower than the control group ( P glass ionomer containing nanorod ZnO was not significantly different from the control group ( P = 0.868). Incorporation of nanospherical and nanoflower ZnO to glass ionomer decreased their surface hardness, without any changes on their flexural strength. Incorporation of nanorod ZnO particles caused no effect on the mechanical properties.

  3. Lateral-access Class II restoration using resin-modified glass-ionomer or silver-cermet cement.

    Science.gov (United States)

    Croll, T P

    1995-02-01

    Direct-access preparation of a carious proximal surface is perhaps the most conservative approach to restoration. Physical properties and handling characteristics of silver amalgam and of resin composite and lack of fluoride ion release make these materials unsuitable for direct buccal- or lingual-access proximal restoration. Insufficient strengths and radiolucency of self-hardening glass-ionomer cements preclude their use for Class II restorations. However, glass-ionomer silver-cermet cement and some resin-modified glass-ionomer materials are proving useful for non-stress-bearing Class II restorations and may have applications in preventive dentistry. This article describes lateral-access Class II restoration with modified glass-ionomer cements. Emphasis is placed on careful handling of materials, maintenance of an ideal operative field, and conservation of tooth structure.

  4. Bactericidal strontium-releasing injectable bone cements based on bioactive glasses.

    Science.gov (United States)

    Brauer, Delia S; Karpukhina, Natalia; Kedia, Gopal; Bhat, Aditya; Law, Robert V; Radecka, Izabela; Hill, Robert G

    2013-01-06

    Strontium-releasing injectable bone cements may have the potential to prevent implant-related infections through the bactericidal action of strontium, while enhancing bone formation in patients suffering from osteoporosis. A melt-derived bioactive glass (BG) series (SiO2–CaO–CaF2–MgO) with 0–50% of calcium substituted with strontium on a molar base were produced. By mixing glass powder, poly(acrylic acid) and water, cements were obtained which can be delivered by injection and set in situ, giving compressive strength of up to 35 MPa. Strontium release was dependent on BG composition with increasing strontium substitution resulting in higher concentrations in the medium. Bactericidal effects were tested on Staphylococcus aureus and Streptococcus faecalis; cell counts were reduced by up to three orders of magnitude over 6 days. Results show that bactericidal action can be increased through BG strontium substitution, allowing for the design of novel antimicrobial and bone enhancing cements for use in vertebroplasty or kyphoplasty for treating osteoporosis-related vertebral compression fractures.

  5. Effect of colloidal nano-silica on the mechanical and physical behaviour of waste-glass cement mortar

    International Nuclear Information System (INIS)

    Aly, M.; Hashmi, M.S.J.; Olabi, A.G.; Messeiry, M.; Abadir, E.F.; Hussain, A.I.

    2012-01-01

    Highlights: → Glass powder (GP) and nano-silica (CS) were used as a partial cement replacement in cement mortar (CM). → No damaging effect can be detected due to the reaction between GP and CM with particle size up to 75 μm. → Hybrid combination of GP/CS greatly improved mechanical properties and microstructure of CM. -- Abstract: This paper presents a laboratory study of the properties of colloidal nano-silica (CS)/waste glass cement composites. The microstructure, alkali-silica reaction (ASR), and the mechanical properties of cement mortars containing waste glass powder (WG) as a cement replacement with and without CS are investigated and compared with plain mortar. In addition, the hydration of cement compounds was followed by differential thermal analysis (DTA), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The results show that incorporation of WG has a positive effect on the mechanical properties of cement mortars especially when CS is presented. In addition, the DTA/TGA results and XRD analysis show a reduction in the calcium hydroxide (CH) content in mortars with both WG and a hybrid combination of WG and CS. This confirms the improvement of mechanical properties and the occurrence of the pozzolanic reaction after 28 days of hydration.

  6. Influence of Waste Glass Powder Addition on the Pore Structure and Service Properties of Cement Mortars

    Directory of Open Access Journals (Sweden)

    José Marcos Ortega

    2018-03-01

    Full Text Available At present, reusing waste constitutes an important challenge in order to reach a more sustainable environment. The cement industry is an important pollutant industrial sector. Therefore, the reduction of its CO2 emissions is now a popular topic of study. One way to lessen those emissions is partially replacing clinker with other materials. In this regard, the reuse of waste glass powder as a clinker replacement could be possible. This is a non-biodegradable residue that permanently occupies a large amount of space in dumping sites. The aim of this work is to study the long-term effects (400 days of the addition of waste glass powder on the microstructure and service properties of mortars that incorporate up to 20% of this addition as clinker replacement. The microstructure has been characterised using the non-destructive impedance spectroscopy technique and mercury intrusion porosimetry. Furthermore, differential thermal analysis was also performed. Compressive strength and both steady-state and non-steady-state chloride diffusion coefficients have also been determined. Considering the obtained results, mortars with 10% and 20% waste glass powder showed good service properties until 400 days, similar to or even better than those made with ordinary Portland cement without additions, with the added value of contributing to sustainability.

  7. Modifications in Glass Ionomer Cements: Nano-Sized Fillers and Bioactive Nanoceramics

    Directory of Open Access Journals (Sweden)

    Shariq Najeeb

    2016-07-01

    Full Text Available Glass ionomer cements (GICs are being used for a wide range of applications in dentistry. In order to overcome the poor mechanical properties of glass ionomers, several modifications have been introduced to the conventional GICs. Nanotechnology involves the use of systems, modifications or materials the size of which is in the range of 1–100 nm. Nano-modification of conventional GICs and resin modified GICs (RMGICs can be achieved by incorporation of nano-sized fillers to RMGICs, reducing the size of the glass particles, and introducing nano-sized bioceramics to the glass powder. Studies suggest that the commercially available nano-filled RMGIC does not hold any significant advantage over conventional RMGICs as far as the mechanical and bonding properties are concerned. Conversely, incorporation of nano-sized apatite crystals not only increases the mechanical properties of conventional GICs, but also can enhance fluoride release and bioactivity. By increasing the crystallinity of the set matrix, apatites can make the set cement chemically more stable, insoluble, and improve the bond strength with tooth structure. Increased fluoride release can also reduce and arrest secondary caries. However, due to a lack of long-term clinical studies, the use of nano-modified glass ionomers is still limited in daily clinical dentistry. In addition to the in vitro and in vivo studies, more randomized clinical trials are required to justify the use of these promising materials. The aim of this paper is to review the modification performed in GIC-based materials to improve their physicochemical properties.

  8. Composite bone cements loaded with a bioactive and ferrimagnetic glass-ceramic: Leaching, bioactivity and cytocompatibility

    International Nuclear Information System (INIS)

    Verné, Enrica; Bruno, Matteo; Miola, Marta; Maina, Giovanni; Bianco, Carlotta; Cochis, Andrea; Rimondini, Lia

    2015-01-01

    In this work, composite bone cements, based on a commercial polymethylmethacrylate matrix (Palamed®) loaded with ferrimagnetic bioactive glass-ceramic particles (SC45), were produced and characterized in vitro. The ferrimagnetic bioactive glass-ceramic belongs to the system SiO 2 –Na 2 O–CaO–P 2 O 5 –FeO–Fe 2 O 3 and contains magnetite (Fe 3 O 4 ) crystals into a residual amorphous bioactive phase. Three different formulations (containing 10, 15 and 20 wt.% of glass-ceramic particles respectively) have been investigated. These materials are intended to be applied as bone fillers for the hyperthermic treatment of bone tumors. The morphological, compositional, calorimetric and mechanical properties of each formulation have been already discussed in a previous paper. The in vitro properties of the composite bone cements described in the present paper are related to iron ion leaching test (by graphite furnace atomic absorption spectrometer), bioactivity (i.e. the ability to stimulate the formation of a hydroxyapatite – HAp – layer on their surface after soaking in simulated body fluid SBF) and cytocompatibility toward human osteosarcoma cells (ATCC CRL-1427, Mg63). Morphological and chemical characterizations by scanning electron microscopy and energy dispersion spectrometry have been performed on the composite samples after each test. The iron release was negligible and all the tested samples showed the growth of HAp on their surface after 28 days of immersion in a simulated body fluid (SBF). Cells showed good viability, morphology, adhesion, density and the ability to develop bridge-like structures on all investigated samples. A synergistic effect between bioactivity and cell mineralization was also evidenced. - Highlights: • An in vitro biological characterization was carried out on ferromagnetic and bioactive composite cements. • No release of iron was revealed in the physiological solution. • Bioactivity tests show hydroxyapatite precipitates

  9. Composite bone cements loaded with a bioactive and ferrimagnetic glass-ceramic: Leaching, bioactivity and cytocompatibility

    Energy Technology Data Exchange (ETDEWEB)

    Verné, Enrica, E-mail: enrica.verne@polito.it [Institute of Materials Physics and Engineering, Applied Science and Technology Department, Politecnico di Torino, C. so Duca degli Abruzzi 24, 10129 Torino (Italy); Bruno, Matteo [Institute of Materials Physics and Engineering, Applied Science and Technology Department, Politecnico di Torino, C. so Duca degli Abruzzi 24, 10129 Torino (Italy); Miola, Marta [Institute of Materials Physics and Engineering, Applied Science and Technology Department, Politecnico di Torino, C. so Duca degli Abruzzi 24, 10129 Torino (Italy); Department of Health Sciences, Università del Piemonte Orientale “Amedeo Avogadro”, Via Solaroli 17, 28100 Novara (Italy); Maina, Giovanni; Bianco, Carlotta [Traumatology Orthopedics and Occupational Medicine Dept., Università di Torino, Via G. Zuretti 29, 10126 Torino (Italy); Cochis, Andrea [Department of Health Sciences, Università del Piemonte Orientale “Amedeo Avogadro”, Via Solaroli 17, 28100 Novara (Italy); Rimondini, Lia [Department of Health Sciences, Università del Piemonte Orientale “Amedeo Avogadro”, Via Solaroli 17, 28100 Novara (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Via G. Giusti, 9, 50121 Firenze (Italy)

    2015-08-01

    In this work, composite bone cements, based on a commercial polymethylmethacrylate matrix (Palamed®) loaded with ferrimagnetic bioactive glass-ceramic particles (SC45), were produced and characterized in vitro. The ferrimagnetic bioactive glass-ceramic belongs to the system SiO{sub 2}–Na{sub 2}O–CaO–P{sub 2}O{sub 5}–FeO–Fe{sub 2}O{sub 3} and contains magnetite (Fe{sub 3}O{sub 4}) crystals into a residual amorphous bioactive phase. Three different formulations (containing 10, 15 and 20 wt.% of glass-ceramic particles respectively) have been investigated. These materials are intended to be applied as bone fillers for the hyperthermic treatment of bone tumors. The morphological, compositional, calorimetric and mechanical properties of each formulation have been already discussed in a previous paper. The in vitro properties of the composite bone cements described in the present paper are related to iron ion leaching test (by graphite furnace atomic absorption spectrometer), bioactivity (i.e. the ability to stimulate the formation of a hydroxyapatite – HAp – layer on their surface after soaking in simulated body fluid SBF) and cytocompatibility toward human osteosarcoma cells (ATCC CRL-1427, Mg63). Morphological and chemical characterizations by scanning electron microscopy and energy dispersion spectrometry have been performed on the composite samples after each test. The iron release was negligible and all the tested samples showed the growth of HAp on their surface after 28 days of immersion in a simulated body fluid (SBF). Cells showed good viability, morphology, adhesion, density and the ability to develop bridge-like structures on all investigated samples. A synergistic effect between bioactivity and cell mineralization was also evidenced. - Highlights: • An in vitro biological characterization was carried out on ferromagnetic and bioactive composite cements. • No release of iron was revealed in the physiological solution. • Bioactivity tests

  10. Marginal Gaps between 2 Calcium Silicate and Glass Ionomer Cements and Apical Root Dentin.

    Science.gov (United States)

    Biočanin, Vladimir; Antonijević, Đorđe; Poštić, Srđan; Ilić, Dragan; Vuković, Zorica; Milić, Marija; Fan, Yifang; Li, Zhiyu; Brković, Božidar; Đurić, Marija

    2018-01-12

    The outcome of periapical surgery has been directly improved with the introduction of novel material formulations. The aim of the study was to compare the retrograde obturation quality of the following materials: calcium silicate (Biodentine; Septodont, Saint-Maur-des-Fosses, France), mineral trioxide aggregate (MTA+; Cerkamed Company, Stalowa Wola, Poland), and glass ionomer cement (Fuji IX; GC Corporation, Tokyo, Japan). Materials' wettability was calculated concerning the contact angles of the cements measured using a glycerol drop. Cements' porosity was determined using mercury intrusion porosimetry and micro-computed tomographic (μCT) imaging. Extracted upper human incisors were retrofilled, and μCT analysis was applied to calculate the volume of the gap between the retrograde filling material and root canal dentin. Experiments were performed before and after soaking the materials in simulated body fluid (SBF). No statistically significant differences were found among the contact angles of the studied materials after being soaked in SBF. The material with the lowest nanoporosity (Fuji IX: 2.99% and 4.17% before and after SBF, respectively) showed the highest values of microporosity (4.2% and 3.1% before and after SBF, respectively). Biodentine had the lowest value of microporosity (1.2% and 0.8% before and after SBF, respectively) and the lowest value of microgap to the root canal wall ([10 ± 30] × 10 -3  mm 3 ). Biodentine and MTA possess certain advantages over Fuji IX for hermetic obturation of retrograde root canals. Biodentine shows a tendency toward the lowest marginal gap at the cement-to-dentin interface. Copyright © 2018 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  11. Utilization of recycled cathode ray tubes glass in cement mortar for X-ray radiation-shielding applications.

    Science.gov (United States)

    Ling, Tung-Chai; Poon, Chi-Sun; Lam, Wai-Shung; Chan, Tai-Po; Fung, Karl Ka-Lok

    2012-01-15

    Recycled glass derived from cathode ray tubes (CRT) glass with a specific gravity of approximately 3.0 g/cm(3) can be potentially suitable to be used as fine aggregate for preparing cement mortars for X-ray radiation-shielding applications. In this work, the effects of using crushed glass derived from crushed CRT funnel glass (both acid washed and unwashed) and crushed ordinary beverage container glass at different replacement levels (0%, 25%, 50%, 75% and 100% by volume) of sand on the mechanical properties (strength and density) and radiation-shielding performance of the cement-sand mortars were studied. The results show that all the prepared mortars had compressive strength values greater than 30 MPa which are suitable for most building applications based on ASTM C 270. The density and shielding performance of the mortar prepared with ordinary crushed (lead-free) glass was similar to the control mortar. However, a significant enhancement of radiation-shielding was achieved when the CRT glasses were used due to the presence of lead in the glass. In addition, the radiation shielding contribution of CRT glasses was more pronounced when the mortar was subject to a higher level of X-ray energy. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. Composite bone cements loaded with a bioactive and ferrimagnetic glass-ceramic: Leaching, bioactivity and cytocompatibility.

    Science.gov (United States)

    Verné, Enrica; Bruno, Matteo; Miola, Marta; Maina, Giovanni; Bianco, Carlotta; Cochis, Andrea; Rimondini, Lia

    2015-08-01

    In this work, composite bone cements, based on a commercial polymethylmethacrylate matrix (Palamed®) loaded with ferrimagnetic bioactive glass-ceramic particles (SC45), were produced and characterized in vitro. The ferrimagnetic bioactive glass-ceramic belongs to the system SiO2-Na2O-CaO-P2O5-FeO-Fe2O3 and contains magnetite (Fe3O4) crystals into a residual amorphous bioactive phase. Three different formulations (containing 10, 15 and 20 wt.% of glass-ceramic particles respectively) have been investigated. These materials are intended to be applied as bone fillers for the hyperthermic treatment of bone tumors. The morphological, compositional, calorimetric and mechanical properties of each formulation have been already discussed in a previous paper. The in vitro properties of the composite bone cements described in the present paper are related to iron ion leaching test (by graphite furnace atomic absorption spectrometer), bioactivity (i.e. the ability to stimulate the formation of a hydroxyapatite - HAp - layer on their surface after soaking in simulated body fluid SBF) and cytocompatibility toward human osteosarcoma cells (ATCC CRL-1427, Mg63). Morphological and chemical characterizations by scanning electron microscopy and energy dispersion spectrometry have been performed on the composite samples after each test. The iron release was negligible and all the tested samples showed the growth of HAp on their surface after 28 days of immersion in a simulated body fluid (SBF). Cells showed good viability, morphology, adhesion, density and the ability to develop bridge-like structures on all investigated samples. A synergistic effect between bioactivity and cell mineralization was also evidenced. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Characterization of antibacterial and adhesion properties of chitosan-modified glass ionomer cement.

    Science.gov (United States)

    Ibrahim, Marrwa A; Neo, Jennifer; Esguerra, Roxanna J; Fawzy, Amr S

    2015-10-01

    The aim is to investigate the effect of modifying the liquid phase of a conventional glass ionomer restorative material with different chitosan volume contents on the antibacterial properties and adhesion to dentin. The liquids of commercially available restorative glass ionomer cements (GIC) were modified with chitosan (CH) solutions at different volume contents (5%, 10%, 25%, and 50%). The GIC powders were mixed with the unmodified and the CH-modified liquids at the desired powder/liquid (P/L) ratio. For the characterization of the antibacterial properties, Streptococcus mutans biofilms were formed on GIC discs and characterized by scanning electron microscope (SEM), confocal microscopy, colony forming unit (CFU) count, and cell viability assay (MTS). The unmodified and CH-modified GICs were bonded to dentin surfaces and the micro-tensile bond strength (µTBs) was evaluated and the interface was investigated by SEM. Modification with CH solutions enhanced the antibacterial properties against S. mutans in terms of resistance to biofilm formation, CFU count, and MTS assay. Generally, significant improvement in the antibacterial properties was found with the increase in the CH volume content. Modification with 25% and 50% CH adversely affected the µTBs with predominant cohesive failure in the GIC. However, no difference was found between the control and the 5% and 10% CH-modified specimens. Incorporation of acidic solutions of chitosan in the polyacrylic acid liquid of GIC at v/v ratios of 5-10% improved the antibacterial properties of conventional glass ionomer cement against S. mutans without adversely affecting its bonding to dentin surface. © The Author(s) 2015.

  14. Addition of bioactive glass to glass ionomer cements: Effect on the physico-chemical properties and biocompatibility.

    Science.gov (United States)

    De Caluwé, T; Vercruysse, C W J; Ladik, I; Convents, R; Declercq, H; Martens, L C; Verbeeck, R M H

    2017-04-01

    Glass ionomer cements (GICs) are a subject of research because of their inferior mechanical properties, despite their advantages such as fluoride release and direct bonding to bone and teeth. Recent research aims to improve the bioactivity of the GICs and thereby improve mechanical properties on the long term. In this study, two types of bioactive glasses (BAG) (45S5F and CF9) are combined with GICs to evaluate the physico-chemical properties and biocompatibility of the BAG-GIC combinations. The effect of the addition of Al 3+ to the BAG composition and the use of smaller BAG particles on the BAG-GIC properties was also investigated. Conventional aluminosilicate glass (ASG) and (modified) BAG were synthesized by the melt method. BAG-GIC were investigated on setting time, compressive strength and bioactivity. Surface changes were evaluated by Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), EDS and PO 4 3- -and Ca 2+ uptake in SBF. Biocompatibility of selected BAG-GICs was determined by a direct toxicity assay. The addition of BAG improves the bioactivity of the GIC, which can be observed by the formation of an apatite (Ap) layer, especially in CF9-containing GICs. More BAG leads to more bioactivity but decreases strength. The addition of Al 3+ to the BAG composition improves strength, but decreases bioactivity. BAGs with smaller particle sizes have no effect on bioactivity and decrease strength. The formation of an Ap layer seems beneficial to the biocompatibility of the BAG-GICs. Bioactive GICs may have several advantages over conventional GICs, such as remineralization of demineralized tissue, adhesion and proliferation of bone- and dental cells, allowing integration in surrounding tissue. CF9 BAG-GIC combinations containing maximum 10mol% Al 3+ are most promising, when added in ≤20wt% to a GIC. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  15. Effect of different thermo-light polymerization on flexural strength of two glass ionomer cements and a glass carbomer cement.

    Science.gov (United States)

    Gorseta, Kristina; Borzabadi-Farahani, Ali; Moshaverinia, Alireza; Glavina, Domagoj; Lynch, Edward

    2017-07-01

    Whether polymerization lights can be used for heating glass ionomer cements (GICs) or glass carbomer (GCP) to improve their mechanical properties is not well established. The purpose of this in vitro study was to assess the effect of thermo-light polymerization on the flexural strength (FS) of 2 GICs (Fuji IX GP Fast, Ketac Molar) and a GCP. Specimens (n=10) were prepared in stainless steel molds (2×2×25 mm), compressed, exposed to 3 polymerization lights (500, 1000, 1200 mW/cm 2 ) for 2 cycles of 40 seconds on each side, and stored in petroleum jelly (37°C, 24 hours). Significant FS differences were detected among groups after different thermo-light polymerization regimens (F=50.926, df=11, Pthermo-light polymerization with power outputs of 1000 (127.1 ±25.8 MPa) and 1200 mW/cm 2 (117.4 ±18.5 MPa), with no significance difference between them (P=.98), compared with 500 mW/cm 2 (24.1 ±1.7 MPa). For Ketac Molar, compared with autopolymerization setting (15.5 ±3.1 MPa), a significant increase in mean FS (∼2.5 times) was only observed in specimens treated with 1200 mW/cm 2 polymerization light (P=.03). For Fuji IX GP Fast, only the light with 1000 mW/cm 2 output significantly increased the FS (98.9 ±23.4 MPa, PThermo-light polymerization accelerated the development of FS in the tested GICs, potentially protecting against saliva contamination during the first 3 to 4 minutes after mixing GIC. Thermo-light polymerization of the glass carbomer with power outputs of 1000 and 1200 mW/cm 2 also substantially increased FS. The clinical advantages of the findings should be validated by in vivo studies. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  16. Comparison of Film Thickness of Two Commercial Brands of Glass lonomer Cement and One Dual-cured Composite: An in vitro Study.

    Science.gov (United States)

    Khajuria, Rajat R; Singh, Rishav; Barua, Pranamee; Hajira, Nausheen; Gupta, Naveen; Thakkar, Rohit R

    2017-08-01

    The present study is undertaken to examine the film thickness of three most commonly used luting cements and to determine their usage as a luting agent. This study was carried out strictly according to the guidelines of American Dental Association (ADS) specification no. 8. Two glass slabs of 5 cm in length and 2 cm in width were used. One glass slab was kept over the other glass slab and the space between the two glass slabs was measured using metallurgical microscope at the power of 10*. Two brands of glass ionomer cement (GIC) and one dual-cured resin cement were used in this study. The test cement is sandwiched between two glass slabs. A static load of 15 kg was applied using universal testing machine on the glass slabs for 1 hour and the space present between the two glass slabs was measured using metallurgical microscope at the power of 10*. Greatest film thickness was found in group III (Paracore) followed by group II (micron) and lowest in group I (GC luting and lining cement). All the tested samples can be used for luting purposes. Greatest film thickness was observed in Paracore followed by micron and lowest in GC luting and lining cement. This suggests that the 25 to 27°C is ideal for mixing of the cement when used for luting consistency. The cement with film thickness more than 30 urn should never be used for luting purposes. The dentist should choose the luting cement with utmost care noting the film thickness and bond strength of the cement. The cement with low exothermic heat production and good bond strength should be encouraged.

  17. Microleakage of conventional, resin-modified, and nano-ionomer glass ionomer cement as primary teeth filling material

    Directory of Open Access Journals (Sweden)

    Dita Madyarani

    2014-12-01

    Full Text Available Background: Glass ionomer cements are one of many dental materials that widely used in pediatric dentistry due to their advantage of fluoride release and chemical bond to tooth structure. Adherence of the filling material to the cavity walls is one of the most important characteristic that need to be examined its effect on microleakage. Purpose: This study was conducted to examine the microleakage of nano-ionomer glass ionomer cement compared with the conventional and resin-modified glass ionomer cements. Methods: Standard class V cavities sized 3 mm x 2 mm x 2 mm were made on a total of 21 extracted maxillary primary canine teeth and restored with the conventional, resin-modified, dan nano-ionomer glass ionomer cements. All the teeth were immersed in a 2% methylene blue dye for 4 hours. The depth of dye penetration was assessed using digital microscope after sectioning the teeth labio-palatally. The results were statistically analyzed using Kruskal-Wallis test. Results: All type of glass ionomer material showed microleakage. Conventional glass ionomer cement demonstrated the least microleakage with mean score 1.29. the resin-modified glass ionomer cements (mean score 1.57 and nano-ionomer glass ionomer cement (mean score 2.57. Conclusion: The conventional glassionomer, resin modified glassionomer, and nano-ionomer glassionomer showed micro leakage as filling material in primary teeth cavity. The micro leakage among three types was not significant difference. All three material were comparable in performance and can be used for filling material but still needs a coating material to fill the microleakage.Latar belakang: Semen ionomer kaca adalah salah satu dari banyak bahan gigi yang banyak digunakan dalam praktek kedokteran gigi anak karena bahan tersebut merilis fluoride dan berikatan kimia dengan struktur gigi. Perlekatan bahan tumpatan pada dinding kavitas adalah salah satu karakteristik paling penting yang perlu diteliti efeknya terhadap

  18. Microtensile bond strength of a resin cement to glass infiltrated zirconia-reinforced ceramic: The effect of surface conditioning

    NARCIS (Netherlands)

    Amaral, R.; Ozcan, M.; Bottino, M.A.; Valandro, L.F.

    2006-01-01

    Objectives. This study evaluated the effect of three surface conditioning methods on the microtensile bond strength of resin cement to a glass-infiltrated zirconia-reinforced alumina-based core ceramic. Methods. Thirty blocks (5 x 5 x 4 mm) of In-Ceram Zirconia ceramics (In-Ceram Zirconia-INC-ZR,

  19. Microtensile bond strength of a resin cement to glass infiltrated zirconia-reinforced ceramic : The effect of surface conditioning

    NARCIS (Netherlands)

    Amaral, R; Ozcan, M; Bottino, MA; Valandro, LF

    Objectives. This study evaluated the effect of three surface conditioning methods on the microtensile bond strength of resin cement to a glass-infiltrated zirconia-reinforced alumina-based core ceramic. Methods. Thirty blocks (5 x 5 x 4 mm) of In-Ceram Zirconia ceramics (In-Ceram Zirconia-INC-ZR,

  20. Morphology of root canal surface: A reflection on the process of cementation of the composite relined glass fiber post

    Directory of Open Access Journals (Sweden)

    Yasmine Mendes Pupo

    2017-01-01

    Full Text Available Background: The present study was conducted to evaluate the bond strength in the different root thirds (premolars and maxillary central incisors of composite relined glass fiber posts compared to untreated glass fiber posts cemented with dual- or chemical-cure cements. Materials and Methods: Sixty human single-rooted premolars (flat canal (n = 15 and 12 maxillary central incisors were used (round canal (n = 3. The teeth were sectioned, and the roots received endodontic treatment. The standardized preparation of the canals was carried out, and the roots were randomly divided into four groups according to the cementation systems: G1: cemented posts (dual: Ambar/Allcem; G2: relined posts (dual: Ambar/Allcem; G3: cemented posts (chemical: Fusion Duralink/Cement Post; and G4: relined posts (chemical: Fusion Duralink/Cement Post. The roots were cut to give two slices of each third of the root canal per specimen. Push-out test was conducted at a speed of 0.5 mm/min. Data were analyzed by analysis of variance and Tukey's post hoc test (α = 0.05. Results: There was no statistically significant difference between groups for the premolars (flat canal (P = 0.959. There was a significant difference in the central incisors between the middle and apical thirds in the cemented group when using the dual system (P = 0.04 and between the middle and apical thirds (P = 0.003 and cervical and apical thirds (P = 0.033 when using the chemical system. Conclusion: Due to the anatomy of the root canal, flat canal of the premolars does not require relining, but round canal of the maxillary central incisors demands it for more secure in the bond strength.

  1. Improvement of energy efficiency in glass-melting furnaces, cement kilns and baking ovens

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, M.D.G. [Technical University of Lisbon (Portugal). Instituto Superior Tecnico; Nogueira, M. [IrRADIARE, R and D in Engineering andrsholm Environment, Oeiras (Portugal)

    1997-08-01

    This paper is aimed at presenting the utilisation of dedicated modelling tools for the optimisation of a variety of thermal equipment for high-, medium-, and low-temperature heat transfer process. A combination of modelling with advanced extensive on-line measurements is proposed as an approach for the development of optimisation procedures able to be used in equipment design and operation. The industrially oriented utilisation of modelling is discussed considering the state-of-the-art and the application of existing codes capable of computing the three-dimensional characteristics of the aerodynamics, mixing, combustion (single- or multi-phase), pollutants formation and heat transfer of industrial combustion equipment. The present paper describes modelling tools for the optimisation of a glass-melting furnace, a ceramic kiln, a cement kiln and a baking oven. Significant reduction of energy consumption and low-cost abatement were achieved for these four industrial situations. (author)

  2. The effects of shelf life on the compressive strength of resin-modified glass ionomer cement

    Science.gov (United States)

    Wajong, K. H.; Damiyanti, M.; Irawan, B.

    2017-08-01

    Resin-modified glass ionomer cement (RMGIC) is a restoration material composed of powder and liquid whose stability is affected by its shelf life. This is an issue that has not been taken into consideration by customers or sellers. To observe the effects of shelf life on the compressive strength of RMGIC, 30 cylindrical (d = 4mm and t = 6mm) specimens of RMGIC (Fuji II LC, GC, Tokyo, Japan) were divided into three groups with different storage times and their compressive strength was tested with a universal testing machine. Results were statistically analyzed with the one-way ANOVA test. There were significant differences (p<0.05) between the three groups of RMGIC. There is a decrease in the compressive strength value along with the duration of storage time.

  3. Cement plate slab production with the incorporation of glass wool waste ground

    Directory of Open Access Journals (Sweden)

    Nathany Angélica dos Santos

    Full Text Available Abstract One of the characteristics of Civil Construction is its ability to absorb a wide range of wastes to produce new products. Therefore, the objective of this study was to evaluate the behavior of cement plates produced with the addition of ground glass wool waste and in natura, in shredded form. The tensile strength tests in bending and permeability were performed, according to ABNT NBR 15498: 2007 as well as environmental ones according to ABNT NBR 10004: 2004. The plates produced in this study were characterized as being impermeable, with a satisfactory tensile strength in bending and being classified as plates for indoor and outdoor use, and as products that do not offer immediate risk to health and to the environment; however, it should be discarded in landfill.

  4. Incorporation of casein phosphopeptide-amorphous calcium phosphate into a glass-ionomer cement.

    Science.gov (United States)

    Mazzaoui, S A; Burrow, M F; Tyas, M J; Dashper, S G; Eakins, D; Reynolds, E C

    2003-11-01

    Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) nanocomplexes have been shown to prevent demineralization and promote remineralization of enamel subsurface lesions in animal and in situ caries models. The aim of this study was to determine the effect of incorporating CPP-ACP into a self-cured glass-ionomer cement (GIC). Incorporation of 1.56% w/w CPP-ACP into the GIC significantly increased microtensile bond strength (33%) and compressive strength (23%) and significantly enhanced the release of calcium, phosphate, and fluoride ions at neutral and acidic pH. MALDI mass spectrometry also showed casein phosphopeptides from the CPP-ACP nanocomplexes to be released. The release of CPP-ACP and fluoride from the CPP-ACP-containing GIC was associated with enhanced protection of the adjacent dentin during acid challenge in vitro.

  5. Surface roughness of glass ionomer cements indicated for uncooperative patients according to surface protection treatment.

    Science.gov (United States)

    Pacifici, Edoardo; Bossù, Maurizio; Giovannetti, Agostino; La Torre, Giuseppe; Guerra, Fabrizio; Polimeni, Antonella

    2013-01-01

    Even today, use of Glass Ionomer Cements (GIC) as restorative material is indicated for uncooperative patients. The study aimed at estimating the surface roughness of different GICs using or not their proprietary surface coatings and at observing the interfaces between cement and coating through SEM. Forty specimens have been obtained and divided into 4 groups: Fuji IX (IX), Fuji IX/G-Coat Plus (IXC), Vitremer (V), Vitremer/Finishing Gloss (VFG). Samples were obtained using silicone moulds to simulate class I restorations. All specimens were processed for profilometric evaluation. The statistical differences of surface roughness between groups were assessed using One-Way Analysis of Variance (One-Way ANOVA) (p<0.05). The Two-Way Analysis of Variance (Two-Way ANOVA) was used to evaluate the influence of two factors: restoration material and presence of coating. Coated restoration specimens (IXC and VFG) were sectioned perpendicular to the restoration surface and processed for SEM evaluation. No statistical differences in roughness could be noticed between groups or factors. Following microscopic observation, interfaces between restoration material and coating were better for group IXC than for group VFG. When specimens are obtained simulating normal clinical procedures, the presence of surface protection does not significantly improve the surface roughness of GICs.

  6. Evaluation of the cytotoxicity of selected conventional glass ionomer cements on human gingival fibroblasts.

    Science.gov (United States)

    Marczuk-Kolada, Grażyna; Łuczaj-Cepowicz, Elżbieta; Pawińska, Małgorzata; Hołownia, Adam

    2017-10-01

    Dentistry materials are the most frequently used substitutes of human tissues. Therefore, an assessment of dental filling materials should cover not only their chemical, physical, and mechanical characteristics, but also their cytotoxicity. To compare the cytotoxic effects of 13 conventional glass ionomer cements on human gingival fibroblasts. The assessment was conducted using the MTT test. Six samples were prepared for each material. Culture plates with cells and inserts with the materials were incubated at 37°C, 5% CO2, and 95% humidity for 24 h. Then the inserts were removed, 1 mL of MTT was added in the amount of 0.5 mg/1 mL of the medium, and the samples were incubated in the described conditions without light for 2 h. The optical density was measured with an absorption spectrophotometer at a wavelength of 560 nm. The cytotoxic effects of the Argion Molar was significantly stronger than the Fuji Triage (p = 0.007), Chemfil Molar (p cements from the low cytotoxicity group were significantly more toxic vs materials whose presence resulted in fibroblast growth (p < 0.001). The research conducted indicates that, although the materials studied may belong to the same group, they are characterized by low, yet not uniform, cytotoxicity on human gingival fibroblasts. The toxic effects should not be assigned to a relevant group of materials, but each dentistry product should be evaluated individually.

  7. Evaluation of dentin hypersensitivity treatment with glass ionomer cements: A randomized clinical trial

    Directory of Open Access Journals (Sweden)

    Marina de Matos MADRUGA

    Full Text Available Abstract A randomized, double-blind, split-mouth clinical trial was performed compared the desensitizing efficacy of the resin-modified glass ionomer cement (GIC ClinproTM XT (3M ESPE, Minnesota, USA and the conventional GIC Vidrion R (SS White, Gloucester, UK in a 6-month follow-up. Subjects were required to have at least two teeth with dentin hypersensitivity. Teeth were divided at random into 2 groups, one group received Clinpro XT and the other conventional GIC Vidrion R. Treatments were assessed by tactile and air blast tests using Visual Analogue Scale (VAS at baseline, after 20 minutes, and at 7, 15, 21, 30, 90 and 180 days post-treatment. Twenty subjects (152 teeth were included. Both tests (tactile and air blast showed a significant reduction of dentin hypersensitivity immediately after the application of Vidrion R and Clinpro XT (20 min. VAS scores obtained along the 6-month follow-up were statistically lower when compared to initial rates (p 0.05. Both cements provided satisfactory results in long-term dental sensitivity reduction.

  8. Dental glass ionomer cement reinforced by cellulose microfibers and cellulose nanocrystals

    International Nuclear Information System (INIS)

    Silva, Rafael M.; Pereira, Fabiano V.; Mota, Felipe A.P.; Watanabe, Evandro; Soares, Suelleng M.C.S.; Santos, Maria Helena

    2016-01-01

    The aim of this work was to evaluate if the addition of cellulose microfibers (CmF) or cellulose nanocrystals (CNC) would improve the mechanical properties of a commercial dental glass ionomer cement (GIC). Different amounts of CmF and CNC were previously prepared and then added to reinforce the GIC matrix while it was being manipulated. Test specimens with various concentrations of CmF or CNC in their total masses were fabricated and submitted to mechanical tests (to evaluate their compressive and diametral tensile strength, modulus, surface microhardness and wear resistance) and characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). The incorporation of CmF in the GIC matrix did not greatly improve the mechanical properties of GIC. However, the addition of a small amount of CNC in the GIC led to significant improvements in all of the mechanical properties evaluated: compressive strength (increased up to 110% compared with the control group), elastic modulus increased by 161%, diametral tensile strength increased by 53%, and the mass loss decreased from 10.95 to 3.87%. Because the composites presented a considerable increase in mechanical properties, the modification of the conventional GIC with CNC can represent a new and promising dental restorative material. - Highlights: • Cellulose microfibers (CmF) and cellulose nanocrystals (CNC) were prepared. • The CmF and CNC were incorporated in commercial dental glass ionomer cement (GIC). • Small amount of CNC improved significantly all the mechanical properties evaluated. • Modified GIC with CNC can represent a new and promising dental restorative material.

  9. Translationally controlled tumor protein supplemented chitosan modified glass ionomer cement promotes osteoblast proliferation and function

    International Nuclear Information System (INIS)

    Sangsuwan, Jiraporn; Wanichpakorn, Supreya; Kedjarune-Leggat, Ureporn

    2015-01-01

    The objective of this study was to evaluate the effect of translationally controlled tumor protein (TCTP) supplemented in a novel glass ionomer cement (BIO-GIC) on normal human osteoblasts (NHost cells). BIO-GIC was a glass ionomer cement (GIC) modified by adding chitosan and albumin to promote the release of TCTP. NHost cells were seeded on specimens of GIC, GIC + TCTP, BIO-GIC and BIO-GIC + TCTP. Cell proliferation was determined by BrdU assay. It was found that BIO-GIC + TCTP had significantly higher proliferation of cells than other specimens. Bone morphogenetic protein-2 (BMP-2) and osteopontin (OPN) gene expressions assessed by quantitative real time PCR and alkaline phosphatase (ALP) activity were used to determine cell differentiation. Bone cell function was investigated by calcium deposition using alizarin assay. Both BMP-2 and OPN gene expressions of cells cultured on specimens with added TCTP increased gradually up-regulation after day 1 and reached the highest on day 3 then down-regulation on day 7. The ALP activity of cells cultured on BIO-GIC + TCTP for 7 days and calcium content after 14 days were significantly higher than other groups. BIO-GIC + TCTP can promote osteoblast cells proliferation, differentiation and function. - Highlights: • Developed a new GIC by supplementing TCTP in BIO-GIC (GIC with chitosan and albumin) • BIO-GIC + TCTP released a higher amount of TCTP than GIC + TCTP. • BIO-GIC + TCTP promoted cell proliferation higher than other specimens and control. • BIO-GIC + TCTP promoted osteoblasts differentiation and function

  10. Translationally controlled tumor protein supplemented chitosan modified glass ionomer cement promotes osteoblast proliferation and function

    Energy Technology Data Exchange (ETDEWEB)

    Sangsuwan, Jiraporn [Department of Molecular Biology and Bioinformatics, Center for Genomics and Bioinformatics Research, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Department of Oral Biology and Occlusion, Faculty of Dentistry, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand); Wanichpakorn, Supreya; Kedjarune-Leggat, Ureporn [Department of Oral Biology and Occlusion, Faculty of Dentistry, Prince of Songkla University, Hat Yai, Songkhla 90112 (Thailand)

    2015-09-01

    The objective of this study was to evaluate the effect of translationally controlled tumor protein (TCTP) supplemented in a novel glass ionomer cement (BIO-GIC) on normal human osteoblasts (NHost cells). BIO-GIC was a glass ionomer cement (GIC) modified by adding chitosan and albumin to promote the release of TCTP. NHost cells were seeded on specimens of GIC, GIC + TCTP, BIO-GIC and BIO-GIC + TCTP. Cell proliferation was determined by BrdU assay. It was found that BIO-GIC + TCTP had significantly higher proliferation of cells than other specimens. Bone morphogenetic protein-2 (BMP-2) and osteopontin (OPN) gene expressions assessed by quantitative real time PCR and alkaline phosphatase (ALP) activity were used to determine cell differentiation. Bone cell function was investigated by calcium deposition using alizarin assay. Both BMP-2 and OPN gene expressions of cells cultured on specimens with added TCTP increased gradually up-regulation after day 1 and reached the highest on day 3 then down-regulation on day 7. The ALP activity of cells cultured on BIO-GIC + TCTP for 7 days and calcium content after 14 days were significantly higher than other groups. BIO-GIC + TCTP can promote osteoblast cells proliferation, differentiation and function. - Highlights: • Developed a new GIC by supplementing TCTP in BIO-GIC (GIC with chitosan and albumin) • BIO-GIC + TCTP released a higher amount of TCTP than GIC + TCTP. • BIO-GIC + TCTP promoted cell proliferation higher than other specimens and control. • BIO-GIC + TCTP promoted osteoblasts differentiation and function.

  11. In vitro mechanical stimulation facilitates stress dissipation and sealing ability at the conventional glass ionomer cement-dentin interface.

    Science.gov (United States)

    Toledano, Manuel; Osorio, Raquel; Osorio, Estrella; Cabello, Inmaculada; Toledano-Osorio, Manuel; Aguilera, Fátima S

    2018-06-01

    The aim of this study was to evaluate the induced changes in the chemical and mechanical performance at the glass-ionomer cement-dentin interface after mechanical load application. A conventional glass-ionomer cement (GIC) (Ketac Bond), and a resin-modified glass-ionomer cement (RMGIC) (Vitrebond Plus) were used. Bonded interfaces were stored in simulated body fluid, and then tested or submitted to the mechanical loading challenge. Different loading waveforms were applied: No cycling, 24 h cycled in sine or loaded in sustained hold waveforms. The cement-dentin interface was evaluated using a nano-dynamic mechanical analysis, estimating the complex modulus and tan δ. Atomic Force Microscopy (AFM) imaging, Raman analysis and dye assisted confocal microscopy evaluation (CLSM) were also performed. The complex modulus was lower and tan delta was higher at interfaces promoted with the GIC if compared to the RMGIC unloaded. The conventional GIC attained evident reduction of nanoleakage. Mechanical loading favored remineralization and promoted higher complex modulus and lower tan delta values at interfaces with RMGIC, where porosity, micropermeability and nanoleakage were more abundant. Mechanical stimuli diminished the resistance to deformation and increased the stored energy at the GIC-dentin interface. The conventional GIC induced less porosity and nanoleakage than RMGIC. The RMGIC increased nanoleakage at the porous interface, and dye sorption appeared within the cement. Both cements created amorphous and crystalline apatites at the interface depending on the type of mechanical loading. Remineralization, lower stress concentration and resistance to deformation after mechanical loading improved the sealing of the GIC-dentin interface. In vitro oral function will favor high levels of accumulated energy and permits micropermeability at the RMGIC-dentin interface which will become remineralized. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. INTERACTION OF FLUORIDE COMPLEXES DERIVED FROM GLASS-IONOMER CEMENTS WITH HYDROXYAPATITE

    Directory of Open Access Journals (Sweden)

    Lewis S. M.

    2013-09-01

    Full Text Available A study has been undertaken of the interaction of complexed fluoride extracted from glass-ionomer dental cements with synthetic hydroxyapatite powder. Extracts were prepared from two commercial glass-ionomers (Fuji IX and ChemFlex under both neutral and acidic conditions. They were analysed by ICP-OES and by fluoride-ion selective electrode with and without added TISAB to decomplex the fluoride. The pH of the acid extracts was 4, conditions under which fluoride complexes with protons as HF or HF2-, it also complexes with aluminium, which was found to be present in higher amounts in the acid extracts. Fluoride was found to be almost completely complexed in acid extracts, but not in neutral extracts, which contained free fluoride ions. Exposure of these extracts to synthetic hydroxyapatite powder showed that fluoride was taken up rapidly (within 5 minutes, whether or not it was complexed. SEM (EDAX study of recovered hydroxyapatite showed only minute traces of aluminium taken up under all conditions. This showed that aluminium interacts hardly at all with hydroxyapatite, and hence is probably not involved in the remineralisation process.

  13. Bond strength of resin cement to dentin and to surface-treated posts of titanium alloy, glass fiber, and zirconia

    DEFF Research Database (Denmark)

    Sahafi, Alireza; Peutzfeldt, Anne; Asmussen, Erik

    2003-01-01

    PURPOSE: To determine the effect of surface treatments on bond strength of two resin cements (ParaPost Cement and Panavia F) to posts of titanium alloy (ParaPost XH), glass fiber (ParaPost Fiber White), and zirconia (Cerapost), and to dentin. MATERIALS AND METHODS: After embedding, planar surfaces...... of posts (n = 9 to 14) and human dentin (n = 10) were obtained by grinding. The posts received one of three surface treatments: 1. roughening (sandblasting, hydrofluoric acid etching), 2. application of primer (Alloy Primer, Metalprimer II, silane), or 3. roughening followed by application of primer...

  14. The role of Sr2+ on the structure and reactivity of SrO-CaO-ZnO-SiO2 ionomer glasses.

    Science.gov (United States)

    Boyd, Daniel; Towler, Mark R; Watts, Sally; Hill, Robert G; Wren, Anthony W; Clarkin, Owen M

    2008-02-01

    The suitability of Glass Polyalkenoate Cements (GPCs) for use in orthopaedics is retarded by the presence in the glass phase of aluminium, a neurotoxin. Unfortunately, the aluminium ion plays an integral role in the setting process of GPCs and its absence is likely to hinder cement formation. However, the authors have previously shown that aluminium free GPCs may be formulated based on calcium zinc silicate glasses and these novel materials exhibit significant potential as hard tissue biomaterials. To further improve their potential, and given that Strontium (Sr) based drugs have had success in the treatment of osteoporosis, the authors have substituted Calcium (Ca) with Sr in the glass phase of a series of aluminium free GPCs. However to date little data exists on the effect SrO has on the structure and reactivity of SrO-CaO-ZnO-SiO(2) glasses. The objective of this work was to characterise the effect of the Ca/Sr substitution on the structure of such glasses, and evaluate the subsequent reactivity of these glasses with an aqueous solution of Polyacrylic acid (PAA). To this end (29)Si MAS-NMR, differential scanning calorimetry (DSC), X-ray diffraction, and network connectivity calculations, were used to characterize the structure of four strontium calcium zinc silicate glasses. Following glass characterization, GPCs were produced from each glass using a 40 wt% solution of PAA (powder:liquid = 2:1.5). The working times and setting times of the GPCs were recorded as per International standard ISO9917. The results acquired as part of this research indicate that the substitution of Ca for Sr in the glasses examined did not appear to significantly affect the structure of the glasses investigated. However it was noted that increasing the amount of Ca substituted for Sr did result in a concomitant increase in setting times, a feature that may be attributable to the higher basicity of SrO over CaO.

  15. Effect of Silanization on Microtensile Bond Strength of Different Resin Cements to a Lithium Disilicate Glass Ceramic.

    Science.gov (United States)

    Gré, Cristina Parise; de Ré Silveira, Renan C; Shibata, Shizuma; Lago, Carlo Tr; Vieira, Luiz Cc

    2016-02-01

    This study evaluated the influence of a silane-coupling agent on the bond strength of a self-adhesive cement and a conventional resin cement to a lithium disilicate glass ceramic. A total of eight ceramic blocks were fabricated and divided into four groups (n = 2). In groups 1 and 3, ceramic surfaces were etched with hydrofluoric acid 10% for 20 seconds, rinsed for 30 seconds, and air-dried. One layer of a silane agent was applied onto all ceramic specimens and air-dried for 30 seconds. In groups 2 and 4, ceramic surfaces were etched with hydrofluoric acid, rinsed, and air-dried without application of the silane-coupling agent. The ceramic blocks were bonded to a block of composite with a self-adhesive resin cement or with a conventional resin cement, according to the manufacturer's instructions. After 24 hours in distilled water at 37°C, the specimens were sectioned perpendicular to the bonding interface area to obtain beams with a bonding area of 0.8 mm(2) and submitted to a microtensile bond strength test at a crosshead speed of 0.5 mm/min. Data were statistically analyzed with one-way analysis of variance and the Games-Howell post hoc test (p = 0.05). Fractured specimens were examined under optical microscopy at 40x magnification. Silanization resulted in higher microtensile bond strength compared to groups without silane. No significant differences were found between the conventional resin cement and the self-adhesive resin cement with silane agent (p = 0.983), and without silane agent (p = 0.877). Silanization appears to be crucial for resin bonding to a lithium disilicate-based ceramic, regardless of the resin cement used. The self-adhesive resin cement performed as well as the conventional resin cement. Applying one layer of a silane-coupling agent after etching the ceramic surface with hydrofluoric acid 10% enhanced the bond strength between resin cements and a glass ceramic.

  16. Comparison of Elastic Modulus and Compressive Strength of Ariadent and Harvard Polycarboxylate Cement and Vitremer Resin Modified Glass Ionomer

    Directory of Open Access Journals (Sweden)

    Ahmadian Khoshemehr Leila

    2009-09-01

    Full Text Available Background: Luting agents are used to attach indirect restoration into or on the tooth. Poor mechanical properties of cement may be a cause of fracture of this layer and lead to caries and restoration removal. The purpose of this study was to compare the elastic modulus and compressive strength of Ariadent (A Poly and Harvard polycarboxylate (H Poly cements and Vitremer resin modified glass ionomer (RGl.Materials & Methods: In this experimental study 15 specimens were prepared form each experimental cement in Laboratory of Tehran Oil Refining Company. The cylindrical specimens were compressed in Instron machine after 24 hours. Elastic modulus and compressive strength were calculated from stress/strain curve of each specimen. One way ANOVA and Tukey tests were used for statistical analysis and P values<0.05 were considered to be statistically significant.Results: The mean elastic modulus and mean compressive strength were 2.2 GPa and 87.8MPa in H poly, 2.4 GPa and 56.5 MPa in A Poly, and 0.8GPa and 105.6 MPa in RGI, respectively. Statistical analysis showed that compressive strength and elastic modulus of both polycarboxylate cements were significantly different from hybrid ionomer (P<0.05, but the difference between elastic modulus of two types of polycarboxilate cements was not statistically significant. Compressive strength of two polycarboxilate cements were significantly different (P<0.05. Conclusion: An ideal lutting agent must have the best mechanical properties. Between the tested luttins RGl cement had the lowest elastic modulus and the highest compressive strength, but the A poly cement had the highest elastic modulus and the lowest compressive strength. Therefore none of them was the best.

  17. Surface properties and bond strength measurements of N-vinylcaprolactam (NVC)-containing glass-ionomer cements.

    Science.gov (United States)

    Moshaverinia, Alireza; Chee, Winston W; Brantley, William A; Schricker, Scott R

    2011-03-01

    N-vinylcaprolactam (NVC)-containing glass ionomers are promising dental restorative materials with improved mechanical properties; however, little information is available on other physical characteristics of these types of modified glass ionomers, especially their surface properties. Understanding the surface characteristics and behavior of glass ionomers is important for understanding their clinical behavior and predictability as dental restorative materials. The purpose of this study was to investigate the effect of NVC-containing terpolymers on the surface properties and bond strength to dentin of GIC (glass-ionomer cement), and to evaluate the effect of NVC-containing terpolymer as a dentin conditioner. The terpolymer of acrylic acid (AA)-itaconic acid (IA)-N-vinylcaprolactam (NVC) with a molar ratio of 8:1:1 (AA:IA:NVC) was synthesized by free radical polymerization and characterized using nuclear magnetic resonance ((1)H-NMR) and Fourier transform infrared spectroscopy (FTIR). The synthesized terpolymer was used in glass-ionomer cement formulations (Fuji IX GP). Ten disc-shaped specimens (12 × 1 mm) were mixed and fabricated at room temperature. Surface properties (wettability) of modified cements were studied by contact angle measurements as a function of time. Work of adhesion values of different surfaces were also determined. The effect of NVC-modified polyacid on the bond strength of glass-ionomer cement to dentin was investigated. The mean data obtained from contact angle and bonding strength measurements were subjected to t test and 2-way ANOVA (α=.05). NVC-modified glass-ionomer cements showed significantly (Pcement also showed significantly higher values for shear bond strength to dentin (8.7 ±0.15 MPa after 1 month) when compared to the control group (8.4 ±0.13 MPa after 1 month). NVC-containing terpolymers may enhance the surface properties of GICs and increase their bond strength to the dentin. Furthermore, NVC-containing polyelectrolytes are

  18. Mechanical, antibacterial and bond strength properties of nano-titanium-enriched glass ionomer cement

    Directory of Open Access Journals (Sweden)

    Rene GARCIA-CONTRERAS

    2015-06-01

    Full Text Available The use of nanoparticles (NPs has become a significant area of research in Dentistry. Objective The aim of this study was to investigate the physical, antibacterial activity and bond strength properties of conventional base, core build and restorative of glass ionomer cement (GIC compared to GIC supplemented with titanium dioxide (TiO2 nanopowder at 3% and 5% (w/w. Material and Methods Vickers microhardness was estimated with diamond indenter. Compressive and flexural strengths were analyzed in a universal testing machine. Specimens were bonded to enamel and dentine, and tested for shear bond strength in a universal testing machine. Specimens were incubated with S. mutans suspension for evaluating antibacterial activity. Surface analysis of restorative conventional and modified GIC was performed with SEM and EDS. The analyses were carried out with Kolmogorov-Smirnov, ANOVA (post-hoc, Tukey test, Kruskal-Wallis, and Mann Whitney. Results Conventional GIC and GIC modified with TiO2 nanopowder for the base/liner cement and core build showed no differences for mechanical, antibacterial, and shear bond properties (p>0.05. In contrast, the supplementation of TiO2 NPs to restorative GIC significantly improved Vickers microhardness (p<0.05, flexural and compressive strength (p<0.05, and antibacterial activity (p<0.001, without interfering with adhesion to enamel and dentin. Conclusion GIC supplemented with TiO2 NPs (FX-II is a promising material for restoration because of its potential antibacterial activity and durable restoration to withstand the mastication force.

  19. Influence of an alloy addition on the physical and clinical behaviour of glass ionomer cement

    Science.gov (United States)

    Abour, Mohamed Abour Bashir

    These in vitro studies compared the various properties of an experimental high powder liquid content glass ionomer cement (EXPT) with those of a metal addition GIC (Hi-Dense) and disperse phase amalgam (Dispersalloy). Bi-axial, four point flexural and compressive tests were used to evaluate strength. Six groups of ten specimens were constructed for each test for each material and allowed to set in an oven at 37°C for 60 minutes. Specimens were stored in distilled water at 37°C until testing at one day, one week, one, three, six months and year. It was found that the strength of Hi-Dense increased and then maintained over extended time, whereas the strength of EXPT showed a declined at 3 months. The bond strengths of the materials to both enamel and dentine were also evaluated. Ten groups of ten teeth, five for each surface for each glass ionomer materials, were prepared. Teeth were aligned leaving the enamel and dentine surfaces exposed. The mixed material was condensed into a cylinder placed on the appropriate surface. These specimens were also stored in distilled water at 37°C. It was found that Hi-Dense had a higher bond strength to enamel that increased with time. The bond strength to dentine was maintained over the test period. The erosion rate of the materials was evaluated using the lactic acid erosion test. Three groups of six specimens for each material were constructed and tested after one hour, one day and at six months. Each specimen was subjected to an impinging jet of lactic acid solution. The erosion rate was determined by weight loss and dimensional change. It was found that Hi-Dense had a high erosion resistance which was slightly better than the experimental material. The microleakage, around restorations prepared, using the glass ionomer materials, was evaluated after cyclical loading the restoration-tooth complex. It was found that there was less leakage around Hi-Dense than EXPT at both the cervical and occlusal margins. In a clinical

  20. Influence of HEMA content on the mechanical and bonding properties of experimental HEMA-added glass ionomer cements

    Directory of Open Access Journals (Sweden)

    Ho-Nam Lim

    2009-08-01

    Full Text Available The purpose of this study was to determine the influence of incrementally added uncured HEMA in experimental HEMA-added glass ionomer cement (HAGICs on the mechanical and shear bond strength (SBS of these materials. Increasing contents of uncured HEMA (10-50 wt.% were added to a commercial glass ionomer cement liquid (Fuji II, GC, Japan, and the compressive and diametral tensile strengths of the resulting HAGICs were measured. The SBS to non-precious alloy, precious alloy, enamel and dentin was also determined after these surfaces were subjected to either airborne-particle abrasion (Aa or SiC abrasive paper grinding (Sp. Both strength properties of the HAGICs first increased and then decreased as the HEMA content increased, with a maximum value obtained when the HEMA content was 20% for the compressive strength and 40% for the tensile strength. The SBS was influenced by the HEMA content, the surface treatment, and the type of bonding surface (p<0.05. These results suggest that addition of an appropriate amount of HEMA to glass ionomer cement would increase diametral tensile strength as well as bond strength to alloys and teeth. These results also confirm that the optimal HEMA content ranged from 20 to 40% within the limitations of this experimental condition.

  1. Utilization of recycled cathode ray tubes glass in cement mortar for X-ray radiation-shielding applications

    International Nuclear Information System (INIS)

    Ling, Tung-Chai; Poon, Chi-Sun; Lam, Wai-Shung; Chan, Tai-Po; Fung, Karl Ka-Lok

    2012-01-01

    Highlights: ► It is feasible to use recycled CRT glass in mortar as shield against X-ray radiation. ► Shielding properties of CRT mortar is strongly depended on CRT content. ► Linear attenuation coefficient was reduced by 142% upon 100% CRT glass in mortar. ► Effect of mortar thickness and irradiation energies on shielding was investigated. - Abstract: Recycled glass derived from cathode ray tubes (CRT) glass with a specific gravity of approximately 3.0 g/cm 3 can be potentially suitable to be used as fine aggregate for preparing cement mortars for X-ray radiation-shielding applications. In this work, the effects of using crushed glass derived from crushed CRT funnel glass (both acid washed and unwashed) and crushed ordinary beverage container glass at different replacement levels (0%, 25%, 50%, 75% and 100% by volume) of sand on the mechanical properties (strength and density) and radiation-shielding performance of the cement–sand mortars were studied. The results show that all the prepared mortars had compressive strength values greater than 30 MPa which are suitable for most building applications based on ASTM C 270. The density and shielding performance of the mortar prepared with ordinary crushed (lead-free) glass was similar to the control mortar. However, a significant enhancement of radiation-shielding was achieved when the CRT glasses were used due to the presence of lead in the glass. In addition, the radiation shielding contribution of CRT glasses was more pronounced when the mortar was subject to a higher level of X-ray energy.

  2. A pilot study of the marginal adaptation and surface morphology of glass-cermet cements.

    Science.gov (United States)

    Chu, C H; King, N M; Lee, A M; Yiu, C K; Wei, S H

    1996-07-01

    This study investigated changes in the marginal adaptation and surface morphology of Ketac-Silver and Chelon-Silver glass-current cements over time. Dispersalloy amalgam was used as a control. Contralateral pairs of carious primary molars were restored with the test materials and amalgam. Clinical evaluations were scheduled at 12, 18, and 24 months after placement. Gold-plated replicas of the restorations were observed with scanning electron microscopy. Fractures and cracks in the surface of the Dispersalloy and Chelon-Silver increased the surface roughness; however, the damage was superficial and self-limiting in the Dispersalloy restorations, while in Chelon-Silver the fractures caused the material to break down in layers. A substantial quantity of pores, usually smaller than 50 microns in diameter, were observed throughout the surface of the Chelon-Silver restorations. The pores in the surface of Ketac-Silver were fewer and smaller. The incidence of cavomarginal breakdown increased with time. Chelon-Silver restorations had a higher rate of cavomarginal breakdown than did Ketac-Silver and Dispersalloy restorations up to 18 months. However, there was no statistically significant difference in the marginal adaptation of the three groups at 24 months.

  3. Cytotoxic effects of glass ionomer cements on human dental pulp stem cells correlate with fluoride release.

    Science.gov (United States)

    Kanjevac, Tatjana; Milovanovic, Marija; Volarevic, Vladislav; Lukic, Miodrag L; Arsenijevic, Nebojsa; Markovic, Dejan; Zdravkovic, Nebojsa; Tesic, Zivoslav; Lukic, Aleksandra

    2012-01-01

    Glass ionomer cements (GICs) are commonly used as restorative materials. Responses to GICs differ among cell types and it is therefore of importance to thoroughly investigate the influence of these restorative materials on pulp stem cells that are potential source for dental tissue regeneration. Eight biomaterials were tested: Fuji I, Fuji II, Fuji VIII, Fuji IX, Fuji Plus, Fuji Triage, Vitrebond and Composit. We compared their cytotoxic activity on human dental pulp stem cells (DPSC) and correlated this activity with the content of Fluoride, Aluminium and Strontium ions in their eluates. Elution samples of biomaterials were prepared in sterile tissue culture medium and the medium was tested for toxicity by an assay of cell survival/proliferation (MTT test) and apoptosis (Annexin V FITC Detection Kit). Concentrations of Fluoride, Aluminium and Strontium ions were tested by appropriate methods in the same eluates. Cell survival ranged between 79.62% (Fuji Triage) to 1.5% (Fuji Plus) and most dead DPSCs were in the stage of late apoptosis. Fluoride release correlated with cytotoxicity of GICs, while Aluminium and Strontium ions, present in significant amount in eluates of tested GICs did not. Fuji Plus, Vitrebond and Fuji VIII, which released fluoride in higher quantities than other GICs, were highly toxic to human DPSCs. Opposite, low levels of released fluoride correlated to low cytotoxic effect of Composit, Fuji I and Fuji Triage.

  4. Low-cost glass ionomer cement as ART sealant in permanent molars: a randomized clinical trial

    Directory of Open Access Journals (Sweden)

    Daniela HESSE

    2015-01-01

    Full Text Available Clinical trials are normally performed with well-known brands of glass ionomer cement (GIC, but the cost of these materials is high for public healthcare in less-affluent communities. Given the need to research cheaper materials, it seems pertinent to investigate the retention rate of a low-cost GIC applied as atraumatic restorative treatment (ART sealants in two centers in Brazil. Four hundred and thirty-seven 6-to-8-year-old schoolchildren were selected in two cities in Brazil. The children were randomly divided into two groups, according to the tested GIC applied in the first permanent molars. The retention rate was evaluated after 3, 6 and 12 months. Kaplan-Meier survival analysis and the log-rank test were performed. The variables were tested for association with sealant longevity, using logistic regression analyses (α = 5%. The retention rate of sealants after 12 months was 19.1%. The high-cost GIC brand presented a 2-fold-more-likely-to-survive rate than the low-cost brand (p < 0.001. Significant difference was also found between the cities where the treatments were performed, in that Barueri presented a higher sealant survival rate than Recife (p < 0.001. The retention rate of a low-cost GIC sealant brand was markedly lower than that of a well-known GIC sealant brand.

  5. Where and how are Brazilian dental students using Glass lonomer Cement?

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    Marina Sousa Azevedo

    2010-12-01

    Full Text Available Glass Ionomer Cements (GICs have a wide range of uses in Dentistry, and the manipulation technique used can influence the results obtained. This study aimed at assessing the knowledge held by Dental School students from a city in Southern Brazil regarding the use of GIC, and the clinical technique chosen for its use and its applications. A structured questionnaire was applied to 60 advanced dental students. Descriptive statistics was used to analyze the quantitative data. All students had already used the material. Regarding the purpose for which the material was used, all students (100% had used it as a dental cavity liner, 83.3% had used it as a temporary restorative material after endodontic treatment, and 73.3% had used it as a permanent restoration in primary teeth. Regarding the clinical technique used, 86.7% said that they insert the material while it still has a shiny surface, 33% said that they finish and polish the restoration in a following session, and only 28.3% said that they apply a surface protection immediately after the restoration is placed. Although students generally seem to be acquainted with the fundamental knowledge and main techniques involved in GIC use, they occasionally fail to follow all the technical steps required during clinical application, which may affect treatment outcome. Therefore, professors should stress that all the clinical procedures required during GIC application must be followed strictly to improve the performance of this material.

  6. Surface texture of resin-modified glass ionomer cements: effects of finishing/polishing time.

    Science.gov (United States)

    Yap, A U J; Ong, S B; Yap, W Y; Tan, W S; Yeo, J C

    2002-01-01

    This study compared the surface texture of resin-modified glass ionomer cements after immediate and delayed finishing with different finishing/polishing systems. Class V preparations were made on the buccal and lingual/palatal surfaces of 64 freshly extracted teeth. The cavities on each tooth were restored with Fuji II LC (GC) and Photac-Fil Quick (3M-ESPE) according to manufacturers' instructions. Immediately after light-polymerization, gross finishing was done with 8-fluted tungsten carbide burs. The teeth were then randomly divided into four groups of 16 teeth. Half of the teeth in each group were finished immediately, while the remaining half were finished after one-week storage in distilled water at 37 degrees C. The following finishing/polishing systems were employed: (a) Robot Carbides; (b) Super-Snap system; (c) OneGloss and (d) CompoSite Polishers. The mean surface roughness (microm; n=8) in vertical (RaV) and horizontal (RaH) axis was measured using a profilometer. Data was subjected to ANOVA/Scheffe's tests and Independent Samples t-test at significance level 0.05. Ra values were generally lower in both vertical and horizontal axis with delayed finishing/polishing. Although significant differences in RaV and RaH values were observed among several systems with immediate finishing/polishing, only one (Fuji II LC: RaH - Super-Snap < Robot Carbides) was observed with delayed finishing.

  7. Characterization of the calcium-fluoroaluminosilicate glass prepared by a non-hydrolytic sol-gel route for future dental application as glass ionomer cement

    Directory of Open Access Journals (Sweden)

    Alexandre Cestari

    2009-06-01

    Full Text Available Glass ionomer cements are widely employed in dentistry due to their physical, biological and mainly anti-caries properties. Glass ionomers consist of an aluminosilicate glass matrix modified with other elements, and they contain large quantities of fluorine. In this study, we report on the preparation of calcium-fluoroaluminosilicate glasses by a nonhydrolytic sol-gel route as an alternative approach to obtaining alumina-silica matrices. The glass powders were prepared via the non-hydrolytic sol-gel method, by mixing AlCl3, SiCl4, CaF2, AlF3, NaF, and AlPO4. The powders were studied by thermal analysis (TG/DTA/DSC, photoluminescence (PL, nuclear magnetic resonance (NMR27Al-29Si, and X ray diffraction (XRD. TG/DTA/DSC analyses revealed a constant mass loss due to structural changes during the heating process, which was confirmed by NMR and PL. A stable aluminosilicate matrix with potential future application as a glass ionomer base was obtained.

  8. Influence of power density on the setting behaviour of light-cured glass-ionomer cements monitored by ultrasound measurements.

    Science.gov (United States)

    Tonegawa, Motoka; Yasuda, Genta; Chikako, Takubo; Tamura, Yukie; Yoshida, Takeshi; Kurokawa, Hiroyasu; Miyazaki, Masashi

    2009-07-01

    To monitor the influence of the power density of the curing unit on the setting behaviour of light-cured glass-ionomer cements (LCGICs) using ultrasound measurements. The ultrasound equipment comprised a pulser-receiver, transducers and an oscilloscope. The LCGICs used were Fuji II LC, Fuji II LC EM and Fuji Filling LC. The cements were mixed according to the manufacturer's instructions and then inserted into a transparent mould. The specimens were placed on the sample stage and cured with power densities of 0 (no irradiation), 200 or 600 mW/cm(2). The transit time through the cement disk was divided by the specimen thickness and then the longitudinal ultrasound velocity (V) within the material was obtained. Analysis of variance and Tukey's Honestly Significantly Different test were used to compare the V values between the set cements. When the LCGICs were light-irradiated, each curve displayed an initial plateau at approximately 1500 m/s and then rapidly increased to a second plateau at approximately 2600 m/s. The rate of increase of V was retarded when the cements were light-irradiated with a power density of 200 mW/cm(2) than with a power density of 600 mW/cm(2). Although sonic echoes were detected from the beginning of the measurements, the rates of increase of the sonic velocity were relatively slow when the cement was not light-irradiated. The ultrasound device monitored the setting processes of LCGICs accurately based on the longitudinal V. The polymerization behaviour of LCGICs was shown to be affected by the power density of the curing unit.

  9. 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

  10. Comparison of invitro cytotoxic and genotoxic potential of glass ionomer cement type IX on human lymphocytes before and after electron beam irradiation

    International Nuclear Information System (INIS)

    Hegde, Mithra N.; Brijesh; Shetty, Shilpa S.; Hegde, Nidarsh D.; Suchetha Kumari; Sanjeev, Ganesh

    2013-01-01

    Glass ionomer cements are widely used in dentistry as an adhesive restorative materials. However, the results of cytotoxicity and genotoxicity studies using these materials are inconclusive in literature. The aim of this study was to examine the cytotoxic and genotoxic potential of glass ionomer cement type IX available commercially before and after irradiation. Glass ionomer cement type IX was obtained commercially. Samples were prepared as per the ISO standard size of 25x2x2 mm using polytetrafluoroethylene teflon mould and divided into two groups - non irradiated and irradiated groups. The samples in radiated category were exposed to 10 KGy of electron beam irradiation at Microtron Centre, Mangalore University, Mangalore, India. For hemolysis assay, the samples were immersed in phosphate buffer saline and incubated at 370℃ for 24 hrs, 7 days and 14 days. 200 μL of 24 hr material extract was mixed with human peripheral blood lymphocyte tested for comet assay by single cell DNA comet assay and apoptosis by DNA diffusion assay. Hemolytic activity of non irradiated Glass ionomer cement type IX after 24 hrs, 7 days and 14 days was 78.18±10.13, 32.57±12.28, 38.56±4.68 respectively whereas hemolytic activity of irradiated Glass ionomer cement type IX after 24 hrs, 7 days and 14 days was 58.90±2.28, 35.04±1.09 and 34.26±7.71 respectively. The irradiation of Glass ionomer cement type IX with 10 KGy dose of electron beam irradiation did not show significant increase in the frequency of DNA damage when compared to that of the nonirradiated group. Apoptotic index did not show much difference between non-irradiated and irradiated groups. Taken together, we conclude that some components of glass ionomer cements show both genotoxic and cytotoxic effects. (author)

  11. Micro-shear bond strength of different resin cements to ceramic/glass-polymer CAD-CAM block materials.

    Science.gov (United States)

    Cekic-Nagas, Isil; Ergun, Gulfem; Egilmez, Ferhan; Vallittu, Pekka Kalevi; Lassila, Lippo Veli Juhana

    2016-10-01

    The aim of this study was to evaluate the effects of hydrofluoric acid treatment on bond strength of resin cements to three different types of ceramic/glass containing CAD-CAM block composite materials. CAD-CAM block materials of polymer infiltrated (Vita Enamic), resin nanoceramic (Lava Ultimate) and nanoceramic (Cerasmart) with a thickness of 1.5mm were randomly divided into two groups according to the surface treatment performed. In Group 1, specimens were wet-ground with silicon carbide abrasive papers up to no. 1000. In Group 2, 9.6% hydrofluoric acid gel was applied to ceramics. Three different resin cements (RelyX, Variolink Esthetic and G-CEM LinkAce) were applied to the tubes in 1.2-mm thick increments and light-cured for 40s using LED light curing unit. Half of the specimens (n=10) were submitted to thermal cycling (5000 cycles, 5-55°C). The strength measurements were accomplished with a universal testing machine (Lloyd Instruments) at a cross-head speed of 0.5mm/min until the failure occurs. Failure modes were examined using a stereomicroscope and scanning electron microscope. The data were analyzed with multivariate analysis of variance (MANOVA) and Tukey's post hoc tests (α=0.05). There were significant differences between ceramics and resin cements (pceramics (pceramic/glass-polymer materials might promote the bonding capacity of these systems. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  12. Research gaps identified during systematic reviews of clinical trials: glass-ionomer cements.

    Science.gov (United States)

    Mickenautsch, Steffen

    2012-06-29

    To report the results of an audit concerning research gaps in clinical trials that were accepted for appraisal in authored and published systematic reviews regarding the application of glass-ionomer cements (GIC) in dental practice Information concerning research gaps in trial precision was extracted, following a framework that included classification of the research gap reasons: 'imprecision of information (results)', 'biased information', 'inconsistency or unknown consistency' and 'not the right information', as well as research gap characterization using PICOS elements: population (P), intervention (I), comparison (C), outcomes (O) and setting (S). Internal trial validity assessment was based on the understanding that successful control for systematic error cannot be assured on the basis of inclusion of adequate methods alone, but also requires empirical evidence about whether such attempt was successful. A comprehensive and interconnected coverage of GIC-related clinical topics was established. The most common reasons found for gaps in trial precision were lack of sufficient trials and lack of sufficient large sample size. Only a few research gaps were ascribed to 'Lack of information' caused by focus on mainly surrogate trial outcomes. According to the chosen assessment criteria, a lack of adequate randomisation, allocation concealment and blinding/masking in trials covering all reviewed GIC topics was noted (selection- and detection/performance bias risk). Trial results appear to be less affected by loss-to-follow-up (attrition bias risk). This audit represents an adjunct of the systematic review articles it has covered. Its results do not change the systematic review's conclusions but highlight existing research gaps concerning the precision and internal validity of reviewed trials in detail. These gaps should be addressed in future GIC-related clinical research.

  13. Research gaps identified during systematic reviews of clinical trials: glass-ionomer cements

    Directory of Open Access Journals (Sweden)

    Mickenautsch Steffen

    2012-06-01

    Full Text Available Abstract Background To report the results of an audit concerning research gaps in clinical trials that were accepted for appraisal in authored and published systematic reviews regarding the application of glass-ionomer cements (GIC in dental practice Methods Information concerning research gaps in trial precision was extracted, following a framework that included classification of the research gap reasons: ‘imprecision of information (results’, ‘biased information’, ‘inconsistency or unknown consistency’ and ‘not the right information’, as well as research gap characterization using PICOS elements: population (P, intervention (I, comparison (C, outcomes (O and setting (S. Internal trial validity assessment was based on the understanding that successful control for systematic error cannot be assured on the basis of inclusion of adequate methods alone, but also requires empirical evidence about whether such attempt was successful. Results A comprehensive and interconnected coverage of GIC-related clinical topics was established. The most common reasons found for gaps in trial precision were lack of sufficient trials and lack of sufficient large sample size. Only a few research gaps were ascribed to ‘Lack of information’ caused by focus on mainly surrogate trial outcomes. According to the chosen assessment criteria, a lack of adequate randomisation, allocation concealment and blinding/masking in trials covering all reviewed GIC topics was noted (selection- and detection/performance bias risk. Trial results appear to be less affected by loss-to-follow-up (attrition bias risk. Conclusion This audit represents an adjunct of the systematic review articles it has covered. Its results do not change the systematic review’s conclusions but highlight existing research gaps concerning the precision and internal validity of reviewed trials in detail. These gaps should be addressed in future GIC-related clinical research.

  14. The hardness and chemical changes in demineralized primary dentin treated by fluoride and glass ionomer cement

    Directory of Open Access Journals (Sweden)

    Gisele Fernandes DIAS

    Full Text Available Abstract Background Fluoride plays an important role in the control of dental caries. Aim To evaluate the chemical exchange between restoration of glass ionomer cement of high viscosity (GIC and primary dentin with application of sodium fluoride (NaF 2% through changes in hardness from uptake of calcium, phosphate and fluoride. Material and method Class I cavities were prepared in 40 sound primary molars, and the sample was divided into two groups (n=20 according to dentin condition: sound (1 and demineralized (2. Sub-groups (n=10 were formed to investigate the isolated action of the GIC or the association with NaF (F. This in vitro study examined the chemical exchange under two conditions, sound and demineralized dentin (pH cycling, to simulate the occurrence of mineral loss for the caries lesion. G1 and G2 received GIC restoration only; groups G1F and G2F received NaF before GIC restoration. The specimens were prepared for Knoop hardness test and micro-Raman spectroscopy. A two-way ANOVA test (α = 0.05 was used for statistical analysis. Micro-Raman data were qualitatively described. Result Increased hardness was observed in all the sites of direct contact with GIC in sound and demineralized dentin for all groups (p0.05. In the evaluation of micro-Raman, direct contact between GIC and dentin for sound and demineralized dentin resulted in increased peaks of phosphate. Conclusion The exchange between GIC and demineralized dentin may induce changes of mechanical properties of the substrate, and uptake of mineral ions (phosphate occurs without the influence of NaF.

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

    Science.gov (United States)

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

    2011-04-01

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

  16. Improvement of the mechanical, tribological and antibacterial properties of glass ionomer cements by fluorinated graphene.

    Science.gov (United States)

    Sun, Li; Yan, Zhuanjun; Duan, Youxin; Zhang, Junyan; Liu, Bin

    2018-06-01

    The aim of this study was to improve the mechanical properties, wear resistance and antibacterial properties of conventional glass ionomer cements (GICs) by fluorinated graphene (FG), under the premise of not influencing their solubility and fluoride ion releasing property. FG with bright white color was prepared using graphene oxide by a hydrothermal reaction. Experimental modified GICs was prepared by adding FG to the traditional GICs powder with four different weight ratios (0.5wt%, 1wt%, 2wt% and 4wt%) using mechanical blending. Compressive and flexural strength of each experimental and control group materials were investigated using a universal testing machine. The Vickers microhardness of all the specimens was measured by a Vicker microhardness tester. For tribological properties of the composites, specimens of each group were investigated by high-speed reciprocating friction tester. Fluoride ion releasing was measured by fluoride ion selective electrode methods. The antibacterial effect of GICs/FG composites on selected bacteria (Staphylococci aureus and Streptococcus mutans) was tested with pellicle sticking method. The prepared GICs/FG composites with white color were successfully fabricated. Increase of Vickers microhardness and compressive strength and decrease of friction coefficient of the GICs/FG composites were achieved compared to unreinforced materials. The colony count against S. aureus and S. mutans decreased with the increase of the content of FG. And the antibacterial rate of S. mutans can be up to 85.27% when the FG content was 4wt%. Additionally, fluoride ion releasing property and solubility did not show significant differences between unreinforced and FG reinforced GICs. Adding FG to traditional GICs could not only improve mechanical and tribological properties of the composites, but also improve their antibacterial properties. In addition, the GICs/FG composites had no negative effect on the color, solubility and fluoride ion releasing

  17. Release profile of synthesized coumarin derivatives as a novel antibacterial agent from glass ionomer cement (GIC)

    Science.gov (United States)

    Rahman, Fatimah Suhaily Abdul; Osman, Hasnah; Mohamad, Dasmawati

    2017-12-01

    Glass ionomer cements (GIC) are widely used as dental restorative materials due to their aesthetics features and fluoride content. However, a capability of fluoride content in GIC to inhibit bacteria growth in an oral environment was insufficient for a long term which may lead to secondary caries. Therefore, two types of synthesized coumarin derivatives were incorporated with GIC to act as new antibacterial agent. However prior to the antibacterial evaluation, this study investigated the release profile of GIC incorporated with 3-Acetylcoumarin (GIC-1) and hydrazinyl thiosemicarbazide of coumarin derivatives (GIC-2) at three different concentrations of 0.5, 1.0 and 1.5 wt% up to 30 days. At early incubation period, GIC-1 revealed a higher release profile at 0.5 % fabrication that reached almost 45 % of cumulative release for 8 hours observational. Meanwhile, a slightly different output was obtained for GIC-2 in which 1.0 % fabrication of coumarin gave a better release in the initial hour. However, the pattern was replaced by 0.5 % substitution after 4 hours incubation time. A substitution of 1.5 % coumarin seems to be low in releasing activity for all materials. Conversely, in a longer period 1.0 % fabrication was discovered to be the highest coumarin release among others fabrications for both materials. Filler particle size and porosity of the materials were considered to be the main factor that may affect the coumarin release. Nonetheless, both synthesized coumarin derivatives can be incorporated with GIC as their release profile look very promising. Ultimately, the coumarin derivatives could improve the properties of GIC.

  18. Effects of instrumentation time on microleakage of resin-modified glass ionomer cements.

    Science.gov (United States)

    Yap, Adrian U J; Yeo, Egwin J C; Yap, W Y; Ong, Debbie S B; Tan, Jane W S

    2003-01-01

    This study investigated the effect of instrumentation time on the microleakage of resin-modified glass ionomer cements (RMGICs). Class V cavities were prepared on buccal and lingual/ palatal surfaces of 64 freshly extracted non-carious premolars. The cavities on each tooth were restored with Fuji II LC (FT [GC]) and Photac-Fil Quick (PF [3M-ESPE]). The restored teeth were randomly divided into two groups of 32 teeth. Finishing/polishing was done immediately after light-polymerization in one group and was delayed for one week in the other group. The following finishing/polishing systems were evaluated: (a) Robot Carbides (RC); (b) SuperSnap (SS); (c) OneGloss (OG) and (d) CompoSite Polishers (CS). The sample size for each instrumentation time, material and finishing/polishing system combination was 8. Storage medium for both immediate and delayed instrumentation groups was distilled water at 37 degrees C during the hiatus period. The teeth were subsequently subjected to dye penetration testing (0.5% basic fushcin), sectioned and scored. Data were analyzed using Kruskal-Wallis and Mann-Whitney U tests at significance level 0.05. For PF, significant difference in enamel leakage was observed between immediate and delayed instrumentation with SS and CS. Significant differences in dentin leakage were also observed between the two instrumentation times for SS. For FT, significant differences in leakage between instrumentation times were observed only in dentin and with RC. Where significant differences in dye penetration scores existed, delayed finishing/polishing resulted in less microleakage.

  19. Surface texture of resin-modified glass ionomer cements: effects of finishing/polishing systems.

    Science.gov (United States)

    Yap, Adrian U J; Tan, W S; Yeo, J C; Yap, W Y; Ong, S B

    2002-01-01

    This study investigated the surface texture of two resin-modified glass ionomer cements (RMGICs) in the vertical and horizontal axis after treatment with different finishing/polishing systems. Class V preparations were made on the buccal and lingual/palatal surfaces of freshly extracted teeth. The cavities on each tooth were restored with Fuji II LC (GC) and Photac-Fil Quick (ESPE) according to manufacturers' instructions. Immediately after light-polymerization, gross finishing was done with 8-flute tungsten carbide burs. The teeth were then randomly divided into four groups and finished/polished with (a) Robot Carbides (RC); (b) Super-Snap system (SS); (c) OneGloss (OG) and (d) CompoSite Points (CS). The sample size for each material-finishing/polishing system combination was eight. The mean surface roughness (microm) in vertical (RaV) and horizontal (RaH) axis was measured using a profilometer. Data was subjected to ANOVA/Scheffe's tests and Independent Samples t-test at significance level 0.05. Mean RaV ranged from 0.59-1.31 and 0.83-1.52, while mean RaH ranged from 0.80-1.43 and 0.85-1.58 for Fuji II LC and Photac-Fil, respectively. Results of statistical analysis were as follows: Fuji II LC: RaV-RC, SS

  20. [A study of different polishing techniques for amalgams and glass-cermet cement by scanning electron microscope (SEM)].

    Science.gov (United States)

    Kakaboura, A; Vougiouklakis, G; Argiri, G

    1989-01-01

    Finishing and polishing an amalgam restoration, is considered as an important and necessary step of the restorative procedure. Various polishing techniques have been recommended to success a smooth amalgam surface. The aim of this study was to investigate the influence of three different polishing treatments on the marginal integrity and surface smoothness of restorations made of three commercially available amalgams and a glass-cermet cement. The materials used were the amalgams, Amalcap (Vivadent), Dispersalloy (Johnson and Johnson), Duralloy (Degussa) and the glass-cermet Katac-Silver (ESPE). The occlusal surfaces of the restorations were polished by the methods: I) round bur, No4-rubber cup-zinc oxide paste in a small brush, II) round bur No 4-bur-brown, green and super green (Shofu) polishing cups and points successively and III) amalgam polishing bur of 12-blades-smooth amalgam polishing bur. Photographs from unpolished and polished surfaces of the restorations, were taken with scanning electron microscope, to evaluate the polishing techniques. An improvement of marginal integrity and surface smoothness of all amalgam restorations was observed after the specimens had been polished with the three techniques. Method II, included Shofu polishers, proved the best results in comparison to the methods I and III. Polishing of glass-cermet cement was impossible with the examined techniques.

  1. Effect of various amounts of nanosilver incorporation on the mechanical properties of resin modified glass-ionomer cement

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    Roza Haghgoo

    2013-08-01

    Full Text Available   Background and Aims: Metallic nano-particles show exclusive biological, chemical and physical characteristic. The purpose of this research was to evaluate the effect of various amounts of nanosilver incorporation (0 (as control, 20, 40, 80, 120, 200 ppm on the mechanical Properties ( compressive and flexural strength of resin modified Glass ionomer Cement.   Materials and Methods: Based on ISO 4049 and ISO 9971 for polyalkenoid cements, 90 cases in each group were prepared for the flexural and compressive strength. Specimens in 6 groups with different amounts of nanosilver (20, 40, 80, 120 and 200 ppm and control (Fuji II LC improved, stored in distilled water at 37 ° C for 1 day and 30 days. Flexural strength, using a three-point bending method, Modulus of elasticity and the compressive strength were measured by universal testing machine (Zwick with crosshead speed of 0.5 mm/min. Data were analyzed using two-way ANOVA and Tukey post HOC test.   Results: The flexural strength and modulus of various amounts of nanosilver incorporation of resin modified glass-ionomer cement were not significantly different (P>0.05. The compressive strength of incorporating of20 ppm compared with control (P=0.01, 40 ppm (P=0.02 and 80 ppm compared with control (P<0.001 were increased. The flexural strength and compressive strength of Fuji II LC, containing nanosilver particles were increased after 1 day and 1 month significantly (P<0.001.   Conclusion: Incorporation of 20 to 80 ppm nanosilver into Fuji II LC had increased mechanical properties compared to the original cement.

  2. Effects of incorporation of nano-fluorapatite or nano-fluorohydroxyapatite on a resin-modified glass ionomer cement.

    Science.gov (United States)

    Lin, Jun; Zhu, Jiajun; Gu, Xiaoxia; Wen, Wenjian; Li, Qingshan; Fischer-Brandies, Helge; Wang, Huiming; Mehl, Christian

    2011-03-01

    This study aimed to investigate the fluoride release properties and the effect on bond strength of two experimental adhesive cements. Synthesized particles of nano-fluorapatite (nano-FA) or nano-fluorohydroxyapatite (nano-FHA) were incorporated into a resin-modified glass ionomer cement (Fuji Ortho LC) and characterized using X-ray diffraction and scanning electron microscopy. Blocks with six different concentrations of nano-FA or nano-FHA were manufactured and their fluoride release properties evaluated by ultraviolet spectrophotometry. The unaltered glass ionomer cement Fuji Ortho LC (GC, control) and the two experimental cements with the highest fluoride release capacities (nano-FA+Fuji Ortho LC (GFA) and nano-FHA+Fuji Ortho LC (GFHA)) were used to bond composite blocks and orthodontic brackets to human enamel. After 24 h water storage all specimens were debonded, measuring the micro-tensile bond strength (μTBS) and the shear bond strength (SBS), respectively. The optimal concentration of added nano-FA and nano-FHA for maximum fluoride release was 25 wt.%, which nearly tripled fluoride release after 70 days compared with the control group. GC exhibited a significantly higher SBS than GFHA/GFA, with GFHA and GFA not differing significantly (P>0.05). The μTBS of GC and GFA were significantly higher than that of GFHA (P≤0.05). The results seem to indicate that the fluoride release properties of Fuji Ortho LC are improved by incorporating nano-FA or nano-FHA, simultaneously maintaining a clinically sufficient bond strength when nano-FA was added. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  3. A comparative study of retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements with stainless steel crowns - an in vitro study.

    Science.gov (United States)

    Raghunath Reddy, M H; Subba Reddy, V V; Basappa, N

    2010-01-01

    An in vitro study was conducted to compare the retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements using Instron universal testing machine. Thirty preformed and pretrimmed stainless steel crowns were used for cementation on 30 extracted human primary molars which were divided into three groups of 10 teeth in each group. Then the teeth were stored in artificial saliva and incubated at 37°C for 24 h. A load was applied on to the crown and was gradually increased till the crown showed dislodgement, and then the readings were recorded using Instron recorder and analyzed for statistical significance. The surface area of crown was measured by graphical method. The retentive strength was expressed in terms of kg/cm 2 , which was calculated by the equation load divided by area. Retentive strengths of zinc phosphate (ranged from a minimum of 16.93 to amaximum of 28.13 kg/cm 2 with mean of 21.28 kg/cm 2 ) and glass ionomer cement (minimum of 13.69 - 28.15 kg/cm 2 with mean of 20.69 kg/cm 2 ) were greater than that of polycarboxylate cement (minimum of 13.26 - 22.69 kg/cm 2 with mean of 16.79 kg/cm 2 ). Negligible difference (0.59 kg/cm 2 ) of retentive strength was observed between zinc phosphate (21.28 kg/cm 2 ) and glass ionomer cements (20.69 kg/cm 2 ). Glass ionomer cements can be recommended for cementation of stainless steel crowns because of its advantages and the retentive strength was almost similar to that of zinc phosphate cement.

  4. A comparative study of retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements with stainless steel crowns - An in vitro study

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    Raghunath Reddy M

    2010-01-01

    Full Text Available An in vitro study was conducted to compare the retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements using Instron universal testing machine. Thirty preformed and pretrimmed stainless steel crowns were used for cementation on 30 extracted human primary molars which were divided into three groups of 10 teeth in each group. Then the teeth were stored in artificial saliva and incubated at 37°C for 24 h. A load was applied on to the crown and was gradually increased till the crown showed dislodgement, and then the readings were recorded using Instron recorder and analyzed for statistical significance. The surface area of crown was measured by graphical method. The retentive strength was expressed in terms of kg/cm 2 , which was calculated by the equation load divided by area. Retentive strengths of zinc phosphate (ranged from a minimum of 16.93 to amaximum of 28.13 kg/cm 2 with mean of 21.28 kg/cm 2 and glass ionomer cement (minimum of 13.69 - 28.15 kg/cm 2 with mean of 20.69 kg/cm 2 were greater than that of polycarboxylate cement (minimum of 13.26 - 22.69 kg/cm 2 with mean of 16.79 kg/cm 2 . Negligible difference (0.59 kg/cm 2 of retentive strength was observed between zinc phosphate (21.28 kg/cm 2 and glass ionomer cements (20.69 kg/cm 2 . Glass ionomer cements can be recommended for cementation of stainless steel crowns because of its advantages and the retentive strength was almost similar to that of zinc phosphate cement.

  5. A comparative study of retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements with stainless steel crowns--an in vitro study.

    Science.gov (United States)

    Reddy, R; Basappa, N; Reddy, V V

    1998-03-01

    This study was conducted on 30 extracted human primary molars to assess the retentive strengths of zinc phosphate, polycarboxylate and glass ionomer cements. The teeth were embedded in resin blocks and were randomly divided into 3 groups of 10 each. The occlusal surfaces of all teeth were reduced uniformly by 1.0 to 1.5 mm. All mesial, distal undercuts were removed and sharp angles rounded. This was followed by cementing pretrimmed and precontoured stainless steel crowns on each tooth with hand pressure and storing in artificial saliva at 37 degrees C for 24 hours. Retentive strength was tested using Instron Universal Testing Machine. The load was applied starting from a zero reading and gradually increased until the cemented stainless steel crowns showed signs of movement and then the readings were recorded. It was found that retentive strengths of zinc phosphate and glass ionomer cements were statistically better (P cement. Negligible difference (0. 59 kg/cm2) was however observed between zinc phosphate and glass ionomer cements.

  6. "Effect of nano-filled surface coating agent on fluoride release from conventional glass ionomer cement: an in vitro trial".

    Science.gov (United States)

    Tiwari, S; Nandlal, B

    2013-01-01

    To overcome the drawbacks of glass ionomer cement of sensitivity to initial desiccation and moisture contamination the use of surface coating agent is recommended. The search in this area led to invent of use of nanofillers in surface coating agent, but its effect on fluoride release is not clear. The aim of this study is to evaluate and compare the fluoride release from conventional glass ionomer cement with and without surface coating agent. This in vitro study comprised of total 80 samples (40 samples of each with and without surface coating). Specimens were prepared, G coat plus was applied and light cured. Fluoride release of the sample was measured every 24 h for 7 days and weekly from 7th to 21 st day using Sension4 pH/ISE/MV Meter. Descriptive Statistics, Repeated Measure ANOVA, Paired Sample t-test, Independent Sample t-test, Scheffe post hoc test. Mean values clearly reveal a significant decrease in the fluoride release from day 1 to day 21 for both groups. Non-coated group released significantly more fluoride than surface coated group (Pagent will reduce the amount of fluoride released into oral environment as compared to non-coated group and at the same time releasing fluoride into surrounding cavity walls to create zones of inhibition into the cavity floor to help internal remineralization.

  7. Microstructural and mechanical development and characterization of glass ionomer cements; Desenvolvimento e caracterizacao microestrutural e mecanica de cimentos de ionomero de vidro

    Energy Technology Data Exchange (ETDEWEB)

    Freire, W.P.; Barbosa, R.C.; Castanha, E.M.M.; Barbosa, E. F.; Fook, M.V.L., E-mail: waldeniafreire@hotmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Departamento de Ciencias e Engenharia de Materiais

    2013-07-01

    Glass Ionomer Cements (GICs) are widely used in dentistry, indicated as a restorative material, cement for orthopedic and dental prostheses. However, there is need for development of new bone cements as alternative or replacement to current polymethylmethacrylate cements. Thus the aim of this research was develop of an experimental GIC and the mechanical and microstructural characterization of this composite; as a control group it was used a commercial GIC called Vidrion R (SS WHITE). These composites were characterized by X-ray diffraction, Infrared Spectroscopy Fourier Transform and Scanning Electron Microscopy. The mechanical properties of the composites were measured by Vickers microhardness testing, flexural strength and compression. These cements were characterized as a semicrystalline; in FTIR spectra observed characteristic bands of these materials and microstructural studies of experimental GIC revealed that there was no proper interaction of the inorganic particles in the polymer matrix, whereas in the control group this interaction was effective resulting in greater homogeneity among its constituent phases. Experimental cement showed a higher value of microhardness in the control group, however, flexural strength of cement experimental cement was lower than the control group, and this behavior can possibly be attributed to inadequate interaction particle / matrix. In tests of compressive strength, experimental GIC showed resistance similar to that shown for control group after variation in the processing conditions of the material. (author)

  8. A preliminary clinical trial using flowable glass-ionomer cement as a liner in proximal-ART restorations: the operator effect

    NARCIS (Netherlands)

    Bonifácio, C.C.; Hesse, D.; Bönecker, M.; van Loveren, C.; van Amerongen, W.E.; Raggio, D.P.

    2013-01-01

    .Objectives: This in vivo study was carried out to assess the influence of the operator experience on the survival rate of proximal-ART restorations using a two-layer technique to insert the glass-ionomer cement (GIC). Study Design: Forty five proximal cavities in primary molars were restored in a

  9. Two-year survival rates of proximal atraumatic restorative treatment restorations in relation to glass ionomer cements and postrestoration meals consumed

    NARCIS (Netherlands)

    Kemoli, A.M.; Opinya, G.N.; van Amerongen, W.E.; Mwalili, S.M.

    2011-01-01

    Purpose: The purpose of this study was to investigate the influence of 3 glass ionomer cement (GIC) brands and the postrestoration meal consumed on the survival rate of proximal atraumatic restorative treatment (ART) restorations. Methods: A total of 804 proximal restorations were placed in primary

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

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    Mostafa Sadeghi

    2015-12-01

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

  11. Effect of salivary pH on diametral tensile strength of glass ionomer cement coated with coating agent

    Science.gov (United States)

    Farahdillah; Triaminingsih, S.; Eriwati, Y. K.

    2017-08-01

    The aim of this study was to analyze the effect of salivary pH to diametral tensile strength of glass ionomer cement (GIC) coated with a coating agent. GIC specimens coated with varnish and nano-filled coating agent were stored in artificial saliva at pH values of 4.5, 5.5, and 7 for 24 h at 37°C, then the diametral tensile strength was tested by universal testing machine. Results showed that there was no significant difference in the diametral tensile strength of the GIC coated with varnish and nano-filled coating agent with decreasing of salivary pH (p salivary pH does not affect the diametral tensile strength of GIC coated by varnish or nano-filled coating agent

  12. Adhesion of Streptococcus Mutans to Glass Ionomer, BisCem Cement and Enamel: An In Vitro Study

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    Ezzatollah Jalalian

    2016-05-01

    Full Text Available Objectives: Considering the adhesion of some microorganisms such as Streptococcus mutans (S. mutans to restorative materials and the unrecognized consequences of this phenomenon, and due to the controversies in this regard, it is important to discover the materials to which the lowest adhesion of S. mutans occurs. The objective of this study was to assess the level of adhesion of S. mutans to glass ionomer (GI, BisCem Cement and enamel.Materials and Methods:In this in vitro experimental study, 12 specimens including five GI blocks (GC America Inc., Alsip, IL, USA, five BisCem blocks (Bisco Inc., Schaumburg, IL, USA and two enamel blocks were exposed to a bacterial suspension (1×106 mg/mL. After incubation for one hour at 37˚C, the swab samples were taken and cultured in blood agar. The S. mutans colonies were counted by unaided vision after 48 hours of incubation. The results were analyzed using ANOVA followed by the Tukey’s test.Results:The number of colonies attributed to enamel, GI, and BisCem blocks was 24±2, 24.2±2.7 and 14.8±1.7 colonies/mm2, respectively. There was no difference between enamel and GI in terms of adhesion of S. mutans (P=0.08 and P>0.001, respectively; however, the difference between these two and BisCem was statistically significant (P= 0.00075 and P<0.001, respectively.Conclusion:Within the limitations of this study, BisCem cement is superior to GI for the cementation of indirect restorations.  Normal 0 false false false EN-US JA AR-SA Influence of Porous Spherical-Shaped Hydroxyapatite on Mechanical Strength and Bioactive Function of Conventional Glass Ionomer Cement

    Directory of Open Access Journals (Sweden)

    Szu-Yu Chiu

    2017-01-01

    Full Text Available Glass-ionomer-cement (GIC is helpful in Minimal Intervention Dentistry because it releases fluoride ions and is highly biocompatible. The aim of this study is to investigate the mechanisms by which hydroxyapatite (HAp improves the mechanical strength and bioactive functioning of GIC when these materials are combined to make apatite ionomer cement (AIC. A conventional GIC powder was mixed with porous, spherical-HAp particles (HApS, crystalline HAp (HAp200 or one of two types of cellulose. The micro-compressive strengths of the additive particles were measured, and various specimens were evaluated with regard to their compressive strengths (CS, fluoride release concentrations (fluoride electrode and multi-element release concentrations. The AIC was found to release higher concentrations of fluoride (1.2 times and strontium ions (1.5 times compared to the control GIC. It was detected the more release of calcium originated from HApS than HAp200 in AIC. The CS of the AIC incorporating an optimum level of HAp was also significantly higher than that of the GIC. These results suggest that adding HAp can increase the release concentration of ions required for remineralization while maintaining the CS of the GIC. This effect does not result from a physical phenomenon, but rather from chemical reactions between the HAp and polyacrylic acid of GIC.

  13. Biological and mechanical properties of an experimental glass-ionomer cement modified by partial replacement of CaO with MgO or ZnO

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    Dong-Ae KIM

    2015-08-01

    Full Text Available AbstractSome weaknesses of conventional glass ionomer cement (GIC as dental materials, for instance the lack of bioactive potential and poor mechanical properties, remain unsolved.Objective The purpose of this study was to investigate the effects of the partial replacement of CaO with MgO or ZnO on the mechanical and biological properties of the experimental glass ionomer cements.Material and Methods Calcium fluoro-alumino-silicate glass was prepared for an experimental glass ionomer cement by melt quenching technique. The glass composition was modified by partial replacement (10 mol% of CaO with MgO or ZnO. Net setting time, compressive and flexural properties, and in vitrorat dental pulp stem cells (rDPSCs viability were examined for the prepared GICs and compared to a commercial GIC.Results The experimental GICs set more slowly than the commercial product, but their extended setting times are still within the maximum limit (8 min specified in ISO 9917-1. Compressive strength of the experimental GIC was not increased by the partial substitution of CaO with either MgO or ZnO, but was comparable to the commercial control. For flexural properties, although there was no significance between the base and the modified glass, all prepared GICs marked a statistically higher flexural strength (p<0.05 and comparable modulus to control. The modified cements showed increased cell viability for rDPSCs.Conclusions The experimental GICs modified with MgO or ZnO can be considered bioactive dental materials.

  14. Biological and mechanical properties of an experimental glass-ionomer cement modified by partial replacement of CaO with MgO or ZnO

    Science.gov (United States)

    Dong-Ae, KIM; Hany, ABO-MOSALLAM; Hye-Young, LEE; Jung-Hwan, LEE; Hae-Won, KIM; Hae-Hyoung, LEE

    2015-01-01

    Some weaknesses of conventional glass ionomer cement (GIC) as dental materials, for instance the lack of bioactive potential and poor mechanical properties, remain unsolved. Objective The purpose of this study was to investigate the effects of the partial replacement of CaO with MgO or ZnO on the mechanical and biological properties of the experimental glass ionomer cements. Material and Methods Calcium fluoro-alumino-silicate glass was prepared for an experimental glass ionomer cement by melt quenching technique. The glass composition was modified by partial replacement (10 mol%) of CaO with MgO or ZnO. Net setting time, compressive and flexural properties, and in vitro rat dental pulp stem cells (rDPSCs) viability were examined for the prepared GICs and compared to a commercial GIC. Results The experimental GICs set more slowly than the commercial product, but their extended setting times are still within the maximum limit (8 min) specified in ISO 9917-1. Compressive strength of the experimental GIC was not increased by the partial substitution of CaO with either MgO or ZnO, but was comparable to the commercial control. For flexural properties, although there was no significance between the base and the modified glass, all prepared GICs marked a statistically higher flexural strength (p<0.05) and comparable modulus to control. The modified cements showed increased cell viability for rDPSCs. Conclusions The experimental GICs modified with MgO or ZnO can be considered bioactive dental materials. PMID:26398508

  15. Mechanical performance of encapsulated restorative glass-ionomer cements for use with Atraumatic Restorative Treatment (ART).

    Science.gov (United States)

    Molina, Gustavo Fabián; Cabral, Ricardo Juan; Mazzola, Ignacio; Lascano, Laura Brain; Frencken, Jo E

    2013-01-01

    The Atraumatic Restorative Treatment (ART) approach was suggested to be a suitable method to treat enamel and dentine carious lesions in patients with disabilities. The use of a restorative glass-ionomer with optimal mechanical properties is, therefore, very important. To test the null-hypotheses that no difference in diametral tensile, compressive and flexural strengths exists between: (1) The EQUIA system and (2) The Chemfil Rock (encapsulated glass-ionomers; test materials) and the Fuji 9 Gold Label and the Ketac Molar Easymix (hand-mixed conventional glass-ionomers; control materials); (3) The EQUIA system and Chemfil Rock. Specimens for testing flexural (n = 240) and diametral tensile (n=80) strengths were prepared according to standardized specifications; the compressive strength (n=80) was measured using a tooth-model of a class II ART restoration. ANOVA and Tukey B tests were used to test for significant differences between dependent and independent variables. The EQUIA system and Chemfil Rock had significantly higher mean scores for all the three strength variables than the Fuji 9 Gold Label and Ketac Molar Easymix (α=0.05). The EQUIA system had significant higher mean scores for diametral tensile and flexural strengths than the Chemfil Rock (α=0.05). The two encapsulated high-viscosity glass-ionomers had significantly higher test values for diametral tensile, flexural and compressive strengths than the commonly used hand-mixed high-viscosity glass-ionomers.

  16. 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.

  17. Mechanical performance of encapsulated restorative glass-ionomer cements for use with Atraumatic Restorative Treatment (ART)

    NARCIS (Netherlands)

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

    2013-01-01

    The Atraumatic Restorative Treatment (ART) approach was suggested to be a suitable method to treat enamel and dentine carious lesions in patients with disabilities. The use of a restorative glass-ionomer with optimal mechanical properties is, therefore, very important. OBJECTIVE: To test the

  18. A Histopathologic Study on Pulp Response to Glass Ionomer Cements in Human Teeth

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    M. Ghavamnasiri

    2005-12-01

    Full Text Available Statement of Problem: Despite the wide range of new dental materials, there is still a need for biomaterials demonstrating high biocompatibility, antimicrobial effects and ideal mechanical properties.Purpose: The aim of this study was to histologically evaluate the pulpal response to a conventional glass ionomer, a resin modified glass ionomer and a calcium hydroxide in human teeth.Materials and Methods: Fifty five deep class V cavities were prepared in premolars of 31 patients and were divided into 3 groups based on application of the following liners:resin modified glass ionomer (Vivaglass Liner, conventional glass ionomer (ChembondSuperior and calcium hydroxide (Dycal. After applying varnish, teeth were filled with amalgam. Each group was further divided into three subgroups according to time intervals of 7, 30 and 60 days. Teeth were then extracted and their crowns were fixed in formalin. Each sample was assessed microscopically for odontoblastic changes,inflammatory cell infiltration, reactionary dentin formation, remaining dentinal thickness and presence of microorganisms. Statistical analysis including Kruskal Wallis and Mann Whitney was carried out for comparison of mean ranks. (P=0.05.Results: In the Vivaglass Liner group, pulpal response was significantly higher on day 7 as compared to days 30 and 60 (P0.05. There was no correlation between pulpal responses with micro-organisms and remaining dentin thickness (P>0.05.Conclusion: According to the results of this study, light-cured glass ionomer as well as the other tested lining materials were determined to be biologically compatible with vital pulps in deep cavities of sound human teeth.

  19. Sol-gel-derived bioactive glass nanoparticle-incorporated glass ionomer cement with or without chitosan for enhanced mechanical and biomineralization properties.

    Science.gov (United States)

    Kim, Dong-Ae; Lee, Jung-Hwan; Jun, Soo-Kyung; Kim, Hae-Won; Eltohamy, Mohamed; Lee, Hae-Hyoung

    2017-07-01

    This study investigated the mechanical and in vitro biological properties (in immortalized human dental pulp stem cells (ihDPSCs)) of bioactive glass nanoparticle (BGN)-incorporated glass ionomer cement (GIC) with or without chitosan as a binder. After the BGNs were synthesized and characterized, three experimental GICs and a control (conventional GIC) that differed in the additive incorporated into a commercial GIC liquid (Hy-bond, Shofu, Japan) were produced: BG5 (5wt% of BGNs), CL0.5 (0.5wt% of chitosan), and BG5+CL0.5 (5wt% of BGNs and 0.5wt% of chitosan). After the net setting time was determined, weight change and bioactivity were analyzed in simulated body fluid (SBF) at 37°C. Mechanical properties (compressive strength, diametral tensile strength, flexural strength and modulus) were measured according to the incubation time (up to 28 days) in SBF. Cytotoxicity (1day) and biomineralization (14 days), assessed by alizarin red staining, were investigated using an extract from GIC and ihDPSCs. Data were analyzed using one-way analysis of variance (ANOVA) followed by Tukey's post hoc test; pproperties were increased in the BGN-incorporated GICs compared to those in the control (pproperties such as compressive, diametral tensile and flexural strength as well as in vitro biomineralization properties in ihDPSCs without cytotoxicity. Therefore, the developed BGN-incorporated GIC is a promising restorative dental material, although further in vivo investigation is needed before clinical application. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  1. Strength and wear resistance of a dental glass-ionomer cement with a novel nanofilled resin coating.

    Science.gov (United States)

    Lohbauer, Ulrich; Krämer, Norbert; Siedschlag, Gustavo; Schubert, Edward W; Lauerer, Brigitte; Müller, Frank A; Petschelt, Anselm; Ebert, Johannes

    2011-04-01

    To evaluate the influence of different resin coating protocols on the fracture strength and wear resistance of a commercial glass-ionomer cement (GIC). A new restorative concept [Equia (GC Europe)] has been introduced as a system application consisting of a condensable GIC (Fuji IX GP Extra) and a novel nanofilled resin coating material (G-Coat Plus). Four-point fracture strength (FS, 2 x 2 x 25 mm, 14-day storage, distilled water, 37 degrees C) were produced and measured from three experimental protocols: no coating GIC (Group 1), GIC coating before water contamination (Group 2), GIC coating after water contamination (Group 3). The strength data were analyzed using Weibull statistics. Three-body wear resistance (Group 1 vs. Group 2) was measured after each 10,000 wear cycles up to a total of 200,000 cycles using the ACTA method. GIC microstructure and interfaces between GIC and coating materials were investigated under SEM and CLSM. The highest FS of 26.1 MPa and the most homogenous behavior (m = 7.7) has been observed in Group 2. The coated and uncoated GIC showed similar wear resistance until 90,000 cycles. After 200,000 wear cycles, the coated version showed significantly higher wear rate (ANOVA, P< 0.05). The coating protocol has been shown to determine the GIC fracture strength. Coating after water contamination and air drying is leading to surface crack formation thus significantly reducing the FS. The resin coating showed a proper sealing of GIC surface porosities and cracks. In terms of wear, the coating did not improve the wear resistance of the underlying cement as similar or higher wear rates have been measured for Group 1 versus Group 2.

  2. Retentive [correction of Preventive] efficacy of glass ionomer, zinc phosphate and zinc polycarboxylate luting cements in preformed stainless steel crowns: a comparative clinical study.

    Science.gov (United States)

    Khinda, V I S; Grewal, N

    2002-06-01

    This study was undertaken to assess the efficacy of three luting cements, namely, glass ionomer, zinc phosphate and zinc polycarboxylate in retainng the preformed stainless steel crowns in-vivo. Twenty subjects, with an indication for restoration of three primary molars with stainless steel crowns, were selected. Sixty teeth were taken up for the study, and twenty crowns were cemented with each of the three luting cements. After an eight month follow up the crowns were assessed for their presence/ absence or "rocking". Statistical analysis was done using Chi-square test. The results have shown no significant difference in retentivity of stainless steel crowns with the use of either of the three luting agents.

  3. Silicate species of water glass and insights for alkali-activated green cement

    Energy Technology Data Exchange (ETDEWEB)

    Jansson, Helén, E-mail: helen.jansson@chalmers.se [Department of Civil and Environmental Engineering, Chalmers University of Technology, SE-41296 Gothenburg (Sweden); Bernin, Diana, E-mail: diana.bernin@nmr.gu.se [Swedish NMR Centre, Gothenburg University, Gothenburg, 41390 Sweden (Sweden); Ramser, Kerstin, E-mail: kerstin.ramser@ltu.se [Department of Engineering Sciences and Mathematics, Luleå University of Technology, 971 87 Luleå (Sweden)

    2015-06-15

    Despite that sodium silicate solutions of high pH are commonly used in industrial applications, most investigations are focused on low to medium values of pH. Therefore we have investigated such solutions in a broad modulus range and up to high pH values (∼14) by use of infrared (IR) spectroscopy and silicon nuclear magnetic resonance ({sup 29}Si-NMR). The results show that the modulus dependent pH value leads to more or less charged species, which affects the configurations of the silicate units. This in turn, influences the alkali-activation process of low CO{sub 2} footprint cements, i.e. materials based on industrial waste or by-products.

  4. Effect of cement kiln dust and gamma irradiation on the ultrasonic parameters of HMO borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Abd elfadeel, G. [Physics Department, Faculty of Science, Al-Azhar University, Assiut 71524 (Egypt); Saddeek, Yasser B., E-mail: ysaddeek@gmail.com [Physics Department, Faculty of Science, Al-Azhar University, Assiut 71524 (Egypt); Mohamed, Gehan Y. [Experimental Nuclear Physics Department, Nuclear Research Center, Atomic Energy Authority, Post Office No. 13759, Cairo (Egypt); Mostafa, A.M.A. [Physics Department, Faculty of Science, Al-Azhar University, Assiut 71524 (Egypt); Shokry Hassan, H. [Advanced Technology and New Materials Research Institute, City of Scientific Research and Technology Applications, New Borg El-Arab City, Alexandria 21934 (Egypt)

    2017-03-01

    Glass samples with the chemical formula x CKD—(100 − x) (5Na{sub 2}O–65 B{sub 2}O{sub 3}–9 Bi{sub 2}O{sub 3}–21PbO), (0 ⩽ x ⩽ 32 mol%) were prepared. The density and the ultrasonic estimations of the investigated glasses were analyzed at room temperature before and after the impact of two dosages of gamma irradiation to study the effect of both CKD and gamma radiation. It was found that the density, and the ultrasonic parameters are sensitive to the variety of the content of CKD and the effect of γ-radiation. Replacement of oxides with higher atomic weights such as Bi{sub 2}O{sub 3} and PbO by CKD decreases the density. Analysis of the behavior of the ultrasonic parameters demonstrates that creation of CaO{sub 6} and SiO{sub 4} on one hand and an alternate transformation between BO{sub 4} and BO{sub 3} structural units, on the other hand, affect the increase of the ultrasonic velocities and the elastic moduli. Moreover, the density and the ultrasonic parameters decrease somewhat with the increase of the doses of γ-irradiation. The variations of the previous physical parameters can be referred to the creation of radiation imperfections, which occupied the voids inside the glass structure.

  5. Effect of cement kiln dust and gamma irradiation on the ultrasonic parameters of HMO borate glasses

    Science.gov (United States)

    Abd elfadeel, G.; Saddeek, Yasser B.; Mohamed, Gehan Y.; Mostafa, A. M. A.; Shokry Hassan, H.

    2017-03-01

    Glass samples with the chemical formula x CKD-(100 - x) (5Na2O-65 B2O3-9 Bi2O3-21PbO), (0 ⩽ x ⩽ 32 mol%) were prepared. The density and the ultrasonic estimations of the investigated glasses were analyzed at room temperature before and after the impact of two dosages of gamma irradiation to study the effect of both CKD and gamma radiation. It was found that the density, and the ultrasonic parameters are sensitive to the variety of the content of CKD and the effect of γ-radiation. Replacement of oxides with higher atomic weights such as Bi2O3 and PbO by CKD decreases the density. Analysis of the behavior of the ultrasonic parameters demonstrates that creation of CaO6 and SiO4 on one hand and an alternate transformation between BO4 and BO3 structural units, on the other hand, affect the increase of the ultrasonic velocities and the elastic moduli. Moreover, the density and the ultrasonic parameters decrease somewhat with the increase of the doses of γ-irradiation. The variations of the previous physical parameters can be referred to the creation of radiation imperfections, which occupied the voids inside the glass structure.

  6. Photocurable bioactive bone cement based on hydroxyethyl methacrylate-poly(acrylic/maleic) acid resin and mesoporous sol gel-derived bioactive glass

    Energy Technology Data Exchange (ETDEWEB)

    Hesaraki, S., E-mail: S-hesaraki@merc.ac.ir

    2016-06-01

    This paper reports on strong and bioactive bone cement based on ternary bioactive SiO{sub 2}-CaO-P{sub 2}O{sub 5} glass particles and a photocurable resin comprising hydroxyethyl methacrylate (HEMA) and poly(acrylic/maleic) acid. The as-cured composite represented a compressive strength of about 95 MPa but it weakened during soaking in simulated body fluid, SBF, qua its compressive strength reached to about 20 MPa after immersing for 30 days. Biodegradability of the composite was confirmed by reducing its initial weight (~ 32%) as well as decreasing the molecular weight of early cured resin during the soaking procedure. The composite exhibited in vitro calcium phosphate precipitation in the form of nanosized carbonated hydroxyapatite, which indicates its bone bonding ability. Proliferation of calvarium-derived newborn rat osteoblasts seeded on top of the composite was observed during incubation at 37 °C, meanwhile, an adequate cell supporting ability was found. Consequently, it seems that the produced composite is an appropriate alternative for bone defect injuries, because of its good cell responses, high compressive strength and ongoing biodegradability, though more in vivo experiments are essential to confirm this assumption. - Highlights: • Light cure cement based on SiO{sub 2}-CaO-P{sub 2}O{sub 5} glass and polymer-like matrix was formed. • The matrix includes poly(acrylic/maleic acid) and poly(hydroxyethyl methacrylate). • The cement is as strong as polymethylmethacrylate bone cement. • The cement exhibits apatite formation ability in simulated body fluid. • The cement is biodegradable and supports proliferation of osteoblastic cells.

  7. Influence of the waste glass in the axial compressive strength of Portland cement concrete; Influencia dos residuos vitreos na resistencia a compressao axial do concreto de cimento Portland

    Energy Technology Data Exchange (ETDEWEB)

    Miranda Junior, E.J.P.; Paiva, A.E.M., E-mail: edson.jansen@hotmail.com [Instituto Federal de Educacao, Ciencia e Tecnologia do Maranhao (PPGEM/IFMA), Sao Luis, MA (Brazil). Programa de Pos-Graduacao em Engenharia de Materiais

    2012-07-01

    In this work, was studied the influence of the incorporation of waste glass, coming from the stage of thinning and polishing of a company of thermal glass treatments, in the axial compressive strength of Portland cement concrete. The coarse and ground aggregates used was crushed stone and sand, respectively. For production of the concrete, percentages of glass residues of 5%, 10% and 20% had been used in substitution to the sand, and relations water/cement (a/c) 0,50, 0,55 and 0,58. The cure of the test bodies was carried through in 7, 14 and 28 days. The statistics analysis of the results was carried out through of the analysis of variance for each one of the cure times. From the results of the compressive strength of the concrete, it could be observed that the concrete has structural application for the relation a/c 0,5, independently of waste glass percentage used, and for the relation a/c 0,55 with 20% of waste glass. (author)

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

    Science.gov (United States)

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

    2016-01-01

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

  9. Novel Nanotechnology of TiO2 Improves Physical-Chemical and Biological Properties of Glass Ionomer Cement

    Directory of Open Access Journals (Sweden)

    Daniela Dellosso Cibim

    2017-01-01

    Full Text Available The aim of this study was to assess the performance of glass ionomer cement (GIC added with TiO2 nanotubes. TiO2 nanotubes [3%, 5%, and 7% (w/w] were incorporated into GIC’s (Ketac Molar EasyMix™ powder component, whereas unblended powder was used as control. Physical-chemical-biological analysis included energy dispersive spectroscopy (EDS, surface roughness (SR, Knoop hardness (SH, fluoride-releasing analysis, cytotoxicity, cell morphology, and extracellular matrix (ECM composition. Parametric or nonparametric ANOVA were used for statistical comparisons (α≤0.05. Data analysis revealed that EDS only detected Ti at the 5% and 7% groups and that GIC’s physical-chemical properties were significantly improved by the addition of 5% TiO2 as compared to 3% and GIC alone. Furthermore, regardless of TiO2 concentration, no significant effect was found on SR, whereas GIC-containing 7% TiO2 presented decreased SH values. Fluoride release lasted longer for the 5% and 7% TiO2 groups, and cell morphology/spreading and ECM composition were found to be positively affected by TiO2 at 5%. In conclusion, in the current study, nanotechnology incorporated in GIC affected ECM composition and was important for the superior microhardness and fluoride release, suggesting its potential for higher stress-bearing site restorations.

  10. Energy Efficient Microwave Hybrid Processing of Lime for Cement, Steel, and Glass Industries

    Energy Technology Data Exchange (ETDEWEB)

    Fall, Morgana L; Yakovlev, Vadim; Sahi, Catherine; Baranova, Inessa; Bowers, Johnney G; Esquenazi\t, Gibran L

    2012-02-10

    MAT in the US lime industry. This estimate showed that 7.3 TBTU/year could be saved, with reduction of 270 MMlbs of CO2 emissions, and $29 MM/year in economic savings. Taking into account estimates for MAT implementation in the US cement industry, an additional 39 TBTU/year, 3 Blbs of CO2 and $155 MM/year could be saved. One of the main remaining barriers to commercialization of MAT for the lime and cement industries is the sheer size of production. Through this project, it was realized that a production size MAT rotary calciner was not feasible, and a different approach was adapted. The concept of a microwave post heat section located in the upper portion of the cooler was devised and appears to be a more realistic approach for MAT implementation. Commercialization of this technology will require (1) continued pilot scale calcining demonstrations, (2) involvement of lime kiln companies, and (3) involvement of an industrial microwave equipment provider. An initial design concept for a MAT post-heat treatment section was conceived as a retrofit into the cooler sections of existing lime rotary calciners with a 1.4 year payback. Retrofitting will help spur implementation of this technology, as the capital investment will be minimal for enhancing the efficiency of current rotary lime kilns. Retrofits would likely be attractive to lime manufacturers, as the purchase of a new lime kiln is on the order of a $30 million dollar investment, where as a MAT retrofit is estimated on the order of $1 million. The path for commercialization lies in partnering with existing lime kiln companies, who will be able to implement the microwave post heat sections in existing and new build kilns. A microwave equipment provider has been identified, who would make up part of the continued development and commercialization team.

  11. Effects of finishing/polishing techniques on microleakage of resin-modified glass ilonomer cement restorations.

    Science.gov (United States)

    Yap, Adrian U J; Yap, W Y; Yeo, Egwin J C; Tan, Jane W S; Ong, Debbie S B

    2003-01-01

    This study investigated the effect of finishing/polishing techniques on the microleakage of resin-modified glass ionomer restorations. Class V preparations were made on the buccal and lingual/palatal surfaces of freshly extracted teeth. The cavities on each tooth were restored with Fuji II LC (FT [GC]) and Photac-Fil Quick (PF [3M-ESPE]) according to manufacturers' instructions. Immediately after light-polymerization, gross finishing was done with eight-fluted tungsten carbide burs. The teeth were then randomly divided into four groups and finishing/polishing was done with one of the following systems: (a) Robot Carbides (RC); (b) Super-Snap system (SS); (c) OneGloss (OG) and (d) CompoSite Polishers (CS). The sample size for each material-finishing/polishing system combination was eight. After finishing/polishing, the teeth were stored in distilled water at 37 degrees C for one week. The root apices were then sealed with acrylic and two coats of varnish was applied 1 mm beyond the restoration margins. The teeth were subsequently subjected to dye penetration testing (0.5% basic fuchsin), sectioned and scored. Data was analyzed using Kruskal-Wallis and Mann-Whitney U tests at a significance level of 0.05. Results of statistical analysis were as follows: Enamel margins: PF-OG

  12. Effect of Partial Replacement of Cement by Mixture of Glass Powder and Silica Fume Upon Concrete Strength

    OpenAIRE

    Khan , Abdul Ghayoor; Khan , Bazid

    2017-01-01

    International audience; All over the world the most common consuming construction material is concrete. It is well know that concrete is the combination of cement, aggregates and water. The production of cement results in the formation of carbon dioxide gas causes the environmental pollution. About 7 percent of carbon dioxide gas is evolved from cement industries to atmosphere. Keeping in view about the environmental pollution which may leads to some serious issues of health, so it is essenti...

  13. EFEKTIFITAS PENCEGAHAN KARIES DENGAN A TRAUMATIC RESTORATIVE TREATMENT DAN TUMPATAN GLASS IONOMER CEMENT DALAM PENGENDALIAN KARIES DI BEBERAPA NEGARA

    Directory of Open Access Journals (Sweden)

    Magdarina Destri Agtini

    2012-12-01

    that implementation of ART-GIC is needed in outreach areas with limited facilities; in all primary schools,all health services, under-5 years children, geriatric groups (Panti Wreda. As an alternative way to conduct ART-GIC development through dental nurses. More over suggested, although it is a simple method, a careful implementation of ART-GIC are need to be concern. Thus sustainability of continuing ART-GIC education and training is needed. Key words: Atraumatic Restorative Treatment (ART, Glass lonomer Cement (GiC, Efektifitas ART dan GIC

  14. Microleakage after Thermocycling of Three Self-Etch Adhesives under Resin-Modified Glass-Ionomer Cement Restorations

    Directory of Open Access Journals (Sweden)

    Sabine O. Geerts

    2010-01-01

    Full Text Available This study was designed to evaluate microleakage that appeared on Resin-Modified Glass-Ionomer Cement (RMGIC restorations. Sixty class V cavities (h×w×l=2mm×2mm×3mm were cut on thirty extracted third molars, which were randomly allocated to three experimental groups. All the buccal cavities were pretreated with polyacrylic acid, whereas the lingual cavities were treated with three one-step Self-Etch adhesives, respectively, Xeno III (Dentsply Detrey GmbH, Konstanz, Germany, iBond exp (Heraeus Kulzer gmbH & Co. KG, Hanau, Germany, and Adper Prompt-L-Pop (3M ESPE AG, Dental products Seefeld, Germany. All cavities were completely filled with RMGIC, teeth were thermocycled for 800 cycles, and leakage was evaluated. Results were expressed as means ± standard deviations (SDs. Microleakage scores were analysed by means of generalized linear mixed models (GLMMs assuming an ordinal logistic link function. All results were considered to be significant at the 5% critical level (<.05. The results showed that bonding RMGIC to dentin with a Self-Etch adhesive rather than using polyacrylic acid did not influence microleakage scores (=.091, except for one tested Self-Etch adhesive, namely, Xeno III (<.0001. Nevertheless, our results did not show any significant difference between the three tested Self-Etch adhesive systems. In conclusion, the pretreatment of dentin with Self-Etch adhesive system, before RMGIC filling, seems to be an alternative to the conventional Dentin Conditioner for the clinicians as suggested by our results (thermocycling and others (microtensile tests.

  15. Doxycycline-containing glass ionomer cement for arresting residual caries: an in vitro study and a pilot trial

    Science.gov (United States)

    Duque, Cristiane; Kreling, Paula Fernanda; Pereira, Jesse Augusto; de Paula, Andreia Bolzan; Sinhoreti, Mario Alexandre Coelho; Puppin-Rontani, Regina Maria

    2018-01-01

    Abstract In a previous study, we demonstrated that the incorporation of doxycycline hyclate (DOX) into resin-modified glass ionomer cement (RMGIC) inhibited important cariogenic microorganisms, without modifying its biological and mechanical characteristics. In this study, we keep focused on the effect of that experimental material as a potential therapy for arresting residual caries by analyzing other in vitro properties and conducting a pilot clinical trial assessing the in vivo effect of DOX-containing RMGIC on residual mutans streptococci after partial carious removal in primary molars. Specimens of the groups RMGIC (control); RMGIC + 1.5% DOX; RMGIC + 3% DOX; and RMGIC + 4.5% DOX were made to evaluate the effect of DOX incorporation on surface microhardness and fluoride release of RMGIC and against biofilm of Streptococcus mutans. Clinical intervention consisted of partial caries removal comparing RMGIC and RMGIC + 4.5% DOX as lining materials. After 3 months, clinical and microbiologic evaluations were performed. Data were submitted to ANOVA/Tukey or Wilcoxon/Mann-Whitney set as α=0.05. Fluoride release and surface microhardness was not influenced by the incorporation of DOX (p>0.05). There was a significant reduction of S. mutans biofilm over the material surface with the increase of DOX concentration. After clinical trial, the remaining dentin was hard and dry. Additionally, mutans streptococci were completely eliminated after 3 months of treatment with RMGIC + 4.5% DOX. The incorporation of DOX provided better antibiofilm effect, without jeopardizing fluoride release and surface microhardness of RMGIC. This combination also improved the in vivo shortterm microbiological effect of RMGIC after partial caries removal. PMID:29742263

  16. Doxycycline-containing glass ionomer cement for arresting residual caries: an in vitro study and a pilot trial.

    Science.gov (United States)

    Castilho, Aline Rogéria Freire de; Duque, Cristiane; Kreling, Paula Fernanda; Pereira, Jesse Augusto; Paula, Andreia Bolzan de; Sinhoreti, Mario Alexandre Coelho; Puppin-Rontani, Regina Maria

    2018-01-01

    In a previous study, we demonstrated that the incorporation of doxycycline hyclate (DOX) into resin-modified glass ionomer cement (RMGIC) inhibited important cariogenic microorganisms, without modifying its biological and mechanical characteristics. In this study, we keep focused on the effect of that experimental material as a potential therapy for arresting residual caries by analyzing other in vitro properties and conducting a pilot clinical trial assessing the in vivo effect of DOX-containing RMGIC on residual mutans streptococci after partial carious removal in primary molars. Specimens of the groups RMGIC (control); RMGIC + 1.5% DOX; RMGIC + 3% DOX; and RMGIC + 4.5% DOX were made to evaluate the effect of DOX incorporation on surface microhardness and fluoride release of RMGIC and against biofilm of Streptococcus mutans. Clinical intervention consisted of partial caries removal comparing RMGIC and RMGIC + 4.5% DOX as lining materials. After 3 months, clinical and microbiologic evaluations were performed. Data were submitted to ANOVA/Tukey or Wilcoxon/Mann-Whitney set as α=0.05. Fluoride release and surface microhardness was not influenced by the incorporation of DOX (p>0.05). There was a significant reduction of S. mutans biofilm over the material surface with the increase of DOX concentration. After clinical trial, the remaining dentin was hard and dry. Additionally, mutans streptococci were completely eliminated after 3 months of treatment with RMGIC + 4.5% DOX. The incorporation of DOX provided better antibiofilm effect, without jeopardizing fluoride release and surface microhardness of RMGIC. This combination also improved the in vivo shortterm microbiological effect of RMGIC after partial caries removal.

  17. Casein Phosphopeptide-Amorphous Calcium Phosphate Reduces Streptococcus mutans Biofilm Development on Glass Ionomer Cement and Disrupts Established Biofilms.

    Science.gov (United States)

    Dashper, Stuart G; Catmull, Deanne V; Liu, Sze-Wei; Myroforidis, Helen; Zalizniak, Ilya; Palamara, Joseph E A; Huq, N Laila; Reynolds, Eric C

    2016-01-01

    Glass ionomer cements (GIC) are dental restorative materials that are suitable for modification to help prevent dental plaque (biofilm) formation. The aim of this study was to determine the effects of incorporating casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) into a GIC on the colonisation and establishment of Streptococcus mutans biofilms and the effects of aqueous CPP-ACP on established S mutans biofilms. S. mutans biofilms were either established in flow cells before a single ten min exposure to 1% w/v CPP-ACP treatment or cultured in static wells or flow cells with either GIC or GIC containing 3% w/w CPP-ACP as the substratum. The biofilms were then visualised using confocal laser scanning microscopy after BacLight LIVE/DEAD staining. A significant decrease in biovolume and average thickness of S. mutans biofilms was observed in both static and flow cell assays when 3% CPP-ACP was incorporated into the GIC substratum. A single ten min treatment with aqueous 1% CPP-ACP resulted in a 58% decrease in biofilm biomass and thickness of established S. mutans biofilms grown in a flow cell. The treatment also significantly altered the structure of these biofilms compared with controls. The incorporation of 3% CPP-ACP into GIC significantly reduced S. mutans biofilm development indicating another potential anticariogenic mechanism of this material. Additionally aqueous CPP-ACP disrupted established S. mutans biofilms. The use of CPP-ACP containing GIC combined with regular CPP-ACP treatment may lower S. mutans challenge.

  18. Casein Phosphopeptide-Amorphous Calcium Phosphate Reduces Streptococcus mutans Biofilm Development on Glass Ionomer Cement and Disrupts Established Biofilms.

    Directory of Open Access Journals (Sweden)

    Stuart G Dashper

    Full Text Available Glass ionomer cements (GIC are dental restorative materials that are suitable for modification to help prevent dental plaque (biofilm formation. The aim of this study was to determine the effects of incorporating casein phosphopeptide-amorphous calcium phosphate (CPP-ACP into a GIC on the colonisation and establishment of Streptococcus mutans biofilms and the effects of aqueous CPP-ACP on established S mutans biofilms. S. mutans biofilms were either established in flow cells before a single ten min exposure to 1% w/v CPP-ACP treatment or cultured in static wells or flow cells with either GIC or GIC containing 3% w/w CPP-ACP as the substratum. The biofilms were then visualised using confocal laser scanning microscopy after BacLight LIVE/DEAD staining. A significant decrease in biovolume and average thickness of S. mutans biofilms was observed in both static and flow cell assays when 3% CPP-ACP was incorporated into the GIC substratum. A single ten min treatment with aqueous 1% CPP-ACP resulted in a 58% decrease in biofilm biomass and thickness of established S. mutans biofilms grown in a flow cell. The treatment also significantly altered the structure of these biofilms compared with controls. The incorporation of 3% CPP-ACP into GIC significantly reduced S. mutans biofilm development indicating another potential anticariogenic mechanism of this material. Additionally aqueous CPP-ACP disrupted established S. mutans biofilms. The use of CPP-ACP containing GIC combined with regular CPP-ACP treatment may lower S. mutans challenge.

  19. Bond strength of resin modified glass ionomer cement to primary dentin after cutting with different bur types and dentin conditioning

    Directory of Open Access Journals (Sweden)

    Rebeca Di Nicoló

    2007-10-01

    Full Text Available The aim of this in vitro study was to evaluate the effect of different bur types and acid etching protocols on the shear bond strength (SBS of a resin modified glass ionomer cement (RM-GIC to primary dentin. Forty-eight clinically sound human primary molars were selected and randomly assigned to four groups (n=12. In G1, the lingual surface of the teeth was cut with a carbide bur until a 2.0-mm-diameter dentin area was exposed, followed by the application of RM-GIC (Vitremer - 3M/ESPE prepared according to the manufacturer's instructions. The specimens of G2, received the same treatment of G1, however the dentin was conditioned with phosphoric acid. In groups G3 and G4 the same procedures of G1 and G2 were conducted respectively, nevertheless dentin cutting was made with a diamond bur. The specimens were stored in distilled water at 37ºC for 24h, and then tested in a universal testing machine. SBS. data were submitted to 2-way ANOVA (= 5% and indicated that SBS values of RM-GIC bonded to primary dentin cut with different burs were not statistically different, but the specimens that were conditioned with phosphoric acid presented SBS values significantly higher that those without conditioning. To observe micromorphologic characteristics of the effects of dentin surface cut by diamond or carbide rotary instruments and conditioners treatment, some specimens were examined by scanning electron microscopy. Smear layer was present in all specimens regardless of the type of rotary instrument used for dentin cutting, and specimens etched with phosphoric acid presented more effective removal of smear layer. It was concluded that SBS of a RM-GIC to primary dentin was affected by the acid conditioning but the bur type had no influence.

  20. Long-term In Vitro Adhesion of Polyalkenoate-based Adhesives to Dentin.

    Science.gov (United States)

    Sezinando, Ana; Perdigão, Jorge; Ceballos, Laura

    2017-01-01

    To study the influence of a polyalkenoate copolymer (VCP) on the immediate (24 h) and 6-month dentin bonding stability of VCP-based adhesives, using microtensile bond strength (μTBS), nanoleakage (NL), and ultramorphological analyses (FE-SEM). Eighty-four caries-free molars were randomly assigned to seven adhesives: Clearfil SE Bond (CSE, Kuraray Noritake); Adper Single Bond Plus (SB, 3M ESPE); SB without VCP (SBnoVCP, 3M ESPE); Scotchbond Universal Adhesive applied as a etch-and-rinse adhesive (SBU_ER); SBU without VCP applied as an etch-and-rinse adhesive (SBUnoVCP_ER); SBU applied as a self-etch adhesive (SBU_SE, 3M ESPE); SBU without VCP applied as a self-etch adhesive (SBUnoVCP_SE, 3M ESPE). Half of the beams were tested after 24 h, and the other half was aged in water for 6 months prior to testing. For each tooth/evaluation time, two beams were randomly selected for NL analysis. Statistical analyses of µTBS results were performed using two-way ANOVA, Tukey's post-hoc tests, and Student's t-test for paired data (α = 0.05). Nanoleakage was statistically analyzed using the Kruskal-Wallis and Mann-Whitney tests, with Wilcoxon's test for paired data. For FE-SEM, four caries-free molars were assigned to each of the seven groups. Dentin disks were restored and cross sectioned into halves. One half was observed at 24 h, and the other at 6 months. The highest 6-month mean μTBS was obtained with SBU_SE/SBUnoVCP_SE and SBUnoVCP_ER. SBUnoVCP_SE resulted in greater silver deposition at 6 months. FE-SEM observations showed that CSE and SBU_SE specimens resulted in a submicron hybrid layer without signs of degradation at 6 months. VCP may contribute to the long-term bonding stability of VCP-based adhesives.

  1. The sealing of second mandibular temporary molar pits and fissure with the laser of Nd: YAG, phosphoric acid and the glass ionomer cement

    International Nuclear Information System (INIS)

    Toda, Maria Aparecida

    2003-01-01

    The main of our study was to check the sealing of second mandibular temporary molar pits and fissure, in vitro, with the laser of Nd: YAG, phosphoric acid at 37% and the glass ionomer cement (CIV, Fuji IX GC).The proposal was to check the structural morphologic changes in the laser irradiation upon the enamel surface to watch the pits and fissure sealing with the glass ionomer cement use after the laser irradiation and to verify the efficiency of the 'double conditioning' (phosphoric acid + Nd: YAG). At the same time we watch the evolution of the temperature in the pulp chamber's inside. Our desire was to achieve a therapeutic alternative technic to prevent the dental caries. The Nd: YAG laser parameters were the same: 79 mJ of energy per pulse; frequency of 5 Hz; mean power of 0,4 W; optical fiber on contact of 320 μm diameter; fluency of 99,52 J/ cm 2 , assuming that the only differential was the time of the laser application on the enamel surface. The samples were prepared with this way: Laser Nd: YAG (53 second) + acid + CIV (Fuji IX); Laser Nd: YAG (53 s); Laser Nd: YAG (20 s + 20 s) + acid + CIV; Laser Nd: YAG (20 s + 20 s); Acid + CIV; Control. Through the scanning electron microscopy (MEV) we noticed fusion and resolidification regions due to the laser irradiation and a better adaptation of the glass ionomer cement when we did the 'double conditioning'. Concerning the temperature increase we can conclude that the echeloned period was the best recommended because the temperature was found in a pattern that would not cause any damage to the dental pulp. For future studies we suggest a longer relaxing time between the laser irradiation, a comparative study of this method with other lasers, the use of other sealing materials and the study with the permanent teeth. (author)

  2. In vitro and in vivo evaluations of glass-ionomer cement containing chlorhexidine for Atraumatic Restorative Treatment

    Science.gov (United States)

    Duque, Cristiane; Aida, Kelly Limi; Pereira, Jesse Augusto; Teixeira, Gláucia Schuindt; Caldo-Teixeira, Angela Scarparo; Perrone, Luciana Rodrigues; Caiaffa, Karina Sampaio; Negrini, Thais de Cássia; de Castilho, Aline Rogéria Freire; Costa, Carlos Alberto de Souza

    2017-01-01

    Abstract Objectives: Addition of chlorhexidine has enhanced the antimicrobial effect of glass ionomer cement (GIC) indicated to Atraumatic Restorative Treatment (ART); however, the impact of this mixture on the properties of these materials and on the longevity of restorations must be investigated. The aim of this study was to evaluate the effects of incorporating chlorhexidine (CHX) in the in vitro biological and chemical-mechanical properties of GIC and in vivo clinical/ microbiological follow-up of the ART with GIC containing or not CHX. Material and Methods: For in vitro studies, groups were divided into GIC, GIC with 1.25% CHX, and GIC with 2.5% CHX. Antimicrobial activity of GIC was analyzed using agar diffusion and anti-biofilm assays. Cytotoxic effects, compressive tensile strength, microhardness and fluoride (F) release were also evaluated. A randomized controlled trial was conducted on 36 children that received ART either with GIC or GIC with CHX. Saliva and biofilm were collected for mutans streptococci (MS) counts and the survival rate of restorations was checked after 7 days, 3 months and one year after ART. ANOVA/Tukey or Kruskal-Wallis/ Mann-Whitney tests were performed for in vitro tests and in vivo microbiological analysis. The Kaplan-Meier method and Log rank tests were applied to estimate survival percentages of restorations (p<0.05). Results: Incorporation of 1.25% and 2.5% CHX improved the antimicrobial/anti-biofilm activity of GIC, without affecting F release and mechanical characteristics, but 2.5% CHX was cytotoxic. Survival rate of restorations using GIC with 1.25% CHX was similar to GIC. A significant reduction of MS levels was observed for KM+CHX group in children saliva and biofilm 7 days after treatment. Conclusions: The incorporation of 1.25% CHX increased the in vitro antimicrobial activity, without changing chemical-mechanical properties of GIC and odontoblast-like cell viability. This combination improved the in vivo short

  3. The effect of a nano-filled resin coating on the 3-year clinical performance of a conventional high-viscosity glass-ionomer cement.

    Science.gov (United States)

    Diem, Vu Thi Kieu; Tyas, Martin J; Ngo, Hien C; Phuong, Lam Hoai; Khanh, Ngo Dong

    2014-04-01

    The main aim of the study was to compare the clinical performance of the conventional high-powder/liquid ratio glass-ionomer cement (GIC) Fuji IX GP Extra (F IX), Fuji IX GP Extra with a low-viscosity nano-filled resin coating, G-Coat Plus (F IX+GCP), and a resin composite, Solare (S), as a comparison material. Moderate-depth occlusal cavities in the first permanent molars of 91 11-12-year-old children (1-4 restorations per child) were restored with either F IX (87 restorations), F IX+GCP (84 restorations) or S (83 restorations). Direct clinical assessment, photographic assessment and assessment of stone casts of the restorations were carried out at 6 months, 1 year, 2 years and 3 years. The colour match with the tooth of the GIC restorations improved over the 3 years of the study. Marginal staining and marginal adaptation were minimal for all restorations; three restorations exhibited secondary caries at 3 years. From the assessment of the casts, at 2 years, there was significantly less wear of the F IX GP Extra+GCP restorations than the F IX GP Extra restorations (P G-Coat Plus showed acceptable clinical performance in occlusal cavities in children, the application of G-Coat Plus gave some protection against wear. The application of G-Coat Plus to Fuji IX GP Extra glass-ionomer cement may be beneficial in reducing wear in occlusal cavities.

  4. Resistance to fracture of endodontically treated premolars restored with glass ionomer cement or acid etch composite resin: An in vitro study

    Directory of Open Access Journals (Sweden)

    B Ranga

    2010-01-01

    Full Text Available Aim: Due to the weakness of endodontically treated posterior teeth requires more strengthened restoration to withstand occlusal forces. The purpose of the present study was to determine and compare the resistance to fracture of endodontically treated maxillary 1 st premolars restored with different materials in mesio-occluso-distal (MOD cavity preparations. Materials and Methods: MOD cavity preparations in 80 endodontically treated maxillary 1 st premolars were restored using four different methods. Fiber rings were filled with stone plaster and the teeth were placed into the plaster up to the level of cemento-enamel junction. The teeth were grouped according to restorative method, mounted in an Instrom T.T. machine, and the buccal walls subjected to a slowly increasing compressive force until fracture occurred. Result: The force of fracture of the walls of each tooth was recorded and the results in the various groups compared. All teeth fractured in a similar manner irrespective of the restorative method used. Conclusion: The resistance to the fracture of the teeth was the same when they were stored with glass ionomer cement as a base over which composite resin was placed. When the entire cavities were filled with glass ionomer cement, the resistance to fracture of the teeth decreased significantly compared with the acid etch resin technique.

  5. Experimental study and modeling of gas diffusion through partially water saturated porous media. Application to Vycor glasses, geo-polymers and CEM V cement pastes

    International Nuclear Information System (INIS)

    Boher, C.

    2012-01-01

    This work documents the relationship that exists between the transfer properties of a material (pore size distribution, total porosity accessible to water, water saturation degree), and its diffusion coefficient. For this sake, materials having a quasi mono modal porosity are used: Vycor glasses and geo-polymers. We also use materials having a complex porosity: CEM V cement pastes. The use of Vycor glasses and geo-polymers allows quantifying the gas diffusion coefficient through materials having known pores size, as a function of their water saturation degree. The use of cement pastes allows checking if it is possible to decompose the diffusion coefficient of a complex porosity material, in an assembling of diffusion coefficients of quasi mono modal porosity materials. For this sake, the impact of pore network arrangement on the diffusion coefficient is studied in great details. This study is divided into three parts:1)Measurement of the geometric characteristics of materials porous network by means of the mercury intrusion porosimetry, water porosimetry, isotherms of nitrogen sorption / desorption, and water desorption tests. 2) Measurement of the materials diffusion coefficient, as a function of their relative humidity storage, and their water saturation degree. 3) Modeling the diffusion coefficient of the materials, and study the impact of the pore network (tortuosity, pores connection). (author) [fr

  6. ULTRA-LIGHTWEIGHT CEMENT

    International Nuclear Information System (INIS)

    Fred Sabins

    2001-01-01

    The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). Work reported herein addresses Task 1: Assess Ultra-Lightweight Cementing Issues, Task 2: Review Russian Ultra-Lightweight Cement Literature, Task 3: Test Ultra-Lightweight Cements, and Task 8: Develop Field ULHS Cement Blending and Mixing Techniques. Results reported this quarter include: preliminary findings from a literature review focusing on problems associated with ultra-lightweight cements; summary of pertinent information from Russian ultra-lightweight cement literature review; laboratory tests comparing ULHS slurries to foamed slurries and sodium silicate slurries for two different applications; and initial laboratory studies with ULHS in preparation for a field job

  7. Glasses

    DEFF Research Database (Denmark)

    Dyre, Jeppe

    2004-01-01

    The temperature dependence of the viscosity of most glassforming liquids is known to depart significantly from the classical Arrhenius behaviour of simple fluids. The discovery of an unexpected correlation between the extent of this departure and the Poisson ratio of the resulting glass could lead...... to new understanding of glass ageing and viscous liquid dynamics....

  8. Fracture frequency and longevity of fractured resin composite, polyacid-modified resin composite, and resin-modified glass ionomer cement class IV restorations: an up to 14 years of follow-up

    DEFF Research Database (Denmark)

    van Dijken, Jan W V; Pallesen, Ulla

    2010-01-01

    The aim of this study was to evaluate the fracture frequency and longevity of fractured class IV resin composite (RC), polyacid-modified resin composite (compomer; PMRC), and resin-modified glass ionomer cement (RMGIC) restorations in a longitudinal long-term follow-up. Eighty-five class IV RC (43...

  9. ULTRA-LIGHTWEIGHT CEMENT

    International Nuclear Information System (INIS)

    Fred Sabins

    2001-01-01

    The objective of this project is to develop an improved ultra-lightweight cement using ultralight hollow glass spheres (ULHS). Work reported herein addresses Task 1: Assess Ultra-Lightweight Cementing Problems and Task 3: Test Ultra-Lightweight Cements. Results reported this quarter include a review and summary of Halliburton Energy Services (HES) and BJ Services historical performance data for lightweight cement applications. These data are analyzed and compared to ULHS cement and foamed cement performances. Similar data is expected from Schlumberger, and an analysis of this data will be completed in the following phases of the project. Quality control testing of materials used to formulate ULHS cements in the laboratory was completed to establish baseline material performance standards. A testing protocol was developed employing standard procedures as well as procedures tailored to evaluate ULHS and foamed cement. This protocol is presented and discussed. Results of further testing of ULHS cements are presented along with an analysis to establish cement performance design criteria to be used during the remainder of the project. Finally, a list of relevant literature on lightweight cement performance is compiled for review during the next quarter

  10. The effect of salivary pH on diametral tensile strength of resin modified glass ionomer cement coated with coating agent

    Science.gov (United States)

    Ismayanti, D.; Triaminingsih, S.; Eriwati, Y. K.

    2017-08-01

    The aim of this study was to evaluate the effect of artificial saliva with different acidities on the diametral tensile strength of Resin Modified Glass Ionomer Cement (RMGIC) coated with varnish and nanofilled coating agent. The specimens coated with coating agents were immersed in artificial saliva with pH of 4.5, 5.5, and 7 for 24 hours in an incubatorat 37°C. The diametral tensile strength of the specimens was tested with Universal Testing Machine. There were no significant differences on the diametral tensile strength of all specimens that were put into groups based on the acidity of the saliva and the type of coating agent (p>0.05). Both varnish and nanofilled coating agent stayed on the RMGIC in the acidic condition that simulated the true condition of oral cavity in people with high caries risk for the 24 hours of maturation.

  11. A Comparative Study of the Addition Effect of Diopside and Silica Sulfuric Acid Nanoparticles on Mechanical Properties of Glass Ionomer Cements

    Directory of Open Access Journals (Sweden)

    M. Rezazadeh

    2016-09-01

    Full Text Available The aim of the present study is to study the effects of adding  diopside (CaMgSi2O6 as well as silica sulfuric acid nanoparticles to ceramic part of glass ionomer cement (GIC in order to improve its mechanical properties. To do this, firstly, diopside (DIO nanoparticles with chemical formula of CaMgSi2O6 were synthesized using sol-gel process and then, the structural and morphological properties of synthesized diopside nanoparticles were investigated. The results of scanning electron microscopy (SEM and particle size analyzing (PSA confirmed that synthesized diopside are nanoparticles and agglomerated. Besides, the result of X-ray diffraction (XRD analyses approved the purity of diopside nanoparticles compounds. Silica sulfuric acid (SSA nanoparticles are also prepared by chemical modification of silica nanoparticles by means of chlorosulfonic acid. Fourier transform infrared spectroscopy (FTIR technique was used to find about the presence of the (SO3H groups on the surface of silica sulfuric acid nanoparticles. Furthermore, various amounts (0.1, 3 and 5 wt.% of diopside and silica sulfuric acid nanoparticles were added to the ceramic part of GIC (Fuji II GIC commercial type to produce glass ionomer cement nanocomposites. The mechanical properties of the produced nanocomposites were measured using the compressive strength, three-point flexural strength and diametral tensile strength methods. Fourier transform infrared spectroscopy technique confirmed the presence of the (SO3H groups on the surface of silica nanoparticles. The compressive strength, three-point flexural strength and diametral tensile strength were 42.5, 15.4 and 6 MPa, respectively, without addition. Although adding 1% silica solfonic acid improved nanocomposite mchanical properties by almost 122%, but maximum increase in nanocomposite mechanical properties was observed in the nanocomposites with 3% diposid, in which 160% increase was seen in the mechanical properties.

  12. The effect of CO2 laser irradiation plus fluoride dentifrice on the inhibition of secondary caries on root surfaces adjacent to glass ionomer cement or composite resin restorations

    International Nuclear Information System (INIS)

    Rodrigues, S R; Moraes, M; Youssef, M N; De Souza-Zaroni, W C; Hanashiro, F S; Brugnera Junior, A; Nobre-dos-Santos, M

    2016-01-01

    Although the cariostatic effects of CO 2 laser on the root surface have been shown, there is scarce information regarding its effects on root secondary caries. The objective of this research was to investigate the effect of the association of CO 2 laser and a fluoride dentifrice on the inhibition of secondary caries on root surfaces adjacent to composite-resin or glass-ionomer-cement restorations. Dental blocks of human roots were divided into two groups: composite resin (CR) or glass ionomer cement (GIC). Subsequently, the blocks were divided into four subgroups (n  =  10): C, non-fluoride dentifrice; FD, fluoride dentifrice; L, CO 2 laser with an energy density of 6.0 J cm −2   +  non-fluoride dentifrice; and L  +  FD, CO 2 laser  +  fluoride dentifrice. The blocks were subjected to pH cycling to simulate a high cariogenic challenge. Dental demineralization around the restorations was quantified by microhardness analysis. The results were subjected to analysis of variance (ANOVA) and the Tukey–Kramer test (p  ⩽  0.05). As for mineral loss, it can be observed that all the groups that were treated with a fluoride dentifrice and laser, used alone or not, were statistically similar and superior to the RC–C group. It was concluded that CO 2 laser irradiation and a fluoride dentifrice used alone or combined with each other are efficient surface treatments for preventing secondary root caries, regardless of the restorative material used. (paper)

  13. Waste Material Based "Terrazzo" Tiles: The Effect Of Curing Time And Extreme Environmental Conditions Over Glass Aggregate/Cement Matrix Boundary

    Science.gov (United States)

    Paris, E.; Radica, F.; Stabile, P.; Ansaloni, F.; Giuli, G.; Carroll, M. R.

    2017-12-01

    Currently, more than half of all materials extracted globally (over three billion tonnes/year in the EU only) are transformed for use in construction. Before year 2020, the EU aims to reduce the environmental impact of the construction sector by recycling or re-using large amounts of these materials, thus reducing the consumption of raw materials and helping promote the sector's economic stability. With this challenge in mind an aesthetically pleasant and fully recycled (up to 78%) pre-cast cement based tile (Terrazzo tiles) was designed by replacing raw materials with Glass Waste (GW) and Construction/Demolition Waste (CDW). Several recent studies explored the effect of the addition of GW in the manufacture of urban pavements, concluding that the use of GW can improve various phases of pavement life and structure by enhancing the structural performance, durability, environmental friendliness, and aesthetic features. In this study we extend this knowledge also to interior cement-based tiles by evaluating the technical performances of this this novel designed tile, in particular by focusing on the interface between the GW aggregates and different Portland cement based matrix at extreme environmental conditions. For this work three representative waste material based "terrazzo" tiles were selected and characterized by means of XRD and SEM imaging in order to study the boundary effect between GW aggregate and different binding materials: limestone powder, quartz powder and fine ground WG powder. A fourth additional mixture of Portland cement and CDW material was characterized. Fragments of a Limestone matrix tile were also thermally threated at -18°C and at 60°C for one week to witness the possible formation of new harmful phases at the grain-matrix boundary. Preliminary results on X-ray diffraction patterns show that 1 year after manufacture and/or thermal treatment there is no new formation of harmful phases other than the starting ones. High magnification SEM

  14. Seating load parameters impact on dental ceramic reinforcement conferred by cementation with resin-cements.

    LENUS (Irish Health Repository)

    Addison, Owen

    2010-09-01

    Cementation of all-ceramic restorations with resin-cements has been demonstrated to reduce the incidence of fracture in service. The aim was to investigate the influence of loading force and loading duration applied during cementation on the reinforcement conferred by a resin-cement on a leucite reinforced glass-ceramic.

  15. Resin-modified and conventional glass ionomer restorations in primary teeth: 8-year results

    DEFF Research Database (Denmark)

    Qvist, V.; Manscher, E.; Teglers, P.T.

    2004-01-01

    clinical trial, cariostatic effects, dental restorations, glass ionomer cement, long-term behaviour, pedodontics, resin-modified glass ionomer......clinical trial, cariostatic effects, dental restorations, glass ionomer cement, long-term behaviour, pedodontics, resin-modified glass ionomer...

  16. Evaluation of rheological properties of cement slurries doped with fiber of glass wool; Avaliacao das propriedades reologicas e mecanicas de pastas de cimento aditivadas com fibra de la de vidro

    Energy Technology Data Exchange (ETDEWEB)

    Paiva, Luanna Carla Matias; Barros, Marcus Vinicius Cavalcanti; Martinelli, Antonio E.; Freitas, Julio Cezar Oliveira [Universidade Federal do Rio Grande do Norte (LABCIM/UFRN), RN (Brazil). Lab. de Cimentos; Lima, Cicero S.; Barroso, Carlos Andre Marques; Oliveira, Theogenes S. [Universidade Federal do Rio Grande do Norte (UFRN), RN (Brazil); Bezerra, Ulisses Targino [Instituto Federal de Educacao, Ciencia e Tecnologia da Paraiba (LABEME/IFPB), Joao Pessoa, PB (Brazil). Lab. de Ensaio de Materiais e Estruturas

    2012-07-01

    This paper describes the results of cement slurry systems using silica-based glass wool fiber as admixture after grinding during 90 s, 180 s, 300 s and 600 s. Scanning electron microscopy images of the fiber depicted the changes in the material as a result of milling. Slurries were formulated with specific mass 15.6 ppg using 2% (BWOC) of the wool fibers. Rheological and mechanical tests were performed. Increasing in milling time improved both the rheological properties and compressive strength of the slurries. Preliminary tests obtained with the fibers revealed the potential application of the material in cement slurries for oil wells. (author)

  17. Effect of protective coating on microhardness of a new glass ionomer cement: Nanofilled coating versus unfilled resin

    OpenAIRE

    Faraji, Foad; Heshmat, Haleh; Banava, Sepideh

    2017-01-01

    Background and Objectives: EQUIATM is a new gastrointestinal (GI) system with high compressive strength, surface microhardness (MH), and fluoride release potential. This in vitro study aimed to assess the effect of aging and type of protective coating on the MH of EQUIATM GI cement. Materials and Methods: A total of 30 disc-shaped specimens measuring 9 mm in diameter and 2 mm in thickness were fabricated of EQUIATM GI and divided into three groups of G-Coat nanofilled coating (a), no coating ...

  18. Clinical evaluation of glass-ionomer cement restorations Avaliação clínica de restaurações de cimento de ionômero de vidro

    Directory of Open Access Journals (Sweden)

    Martin John Tyas

    2006-01-01

    Full Text Available This article mentions the general structure, properties and clinical performance of conventional and resin-modified glass-ionomer cements, focusing on adhesion, caries inhibition effect and recommendations of their use.Este artigo menciona a estrutura geral, propriedades e performance clínica de cimentos de ionômero de vidro convencionais e modificados por resina, enfocando propriedades como adesão, efeito anti-cariogênico e recomendações de uso.

  19. Effects of the addition of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on mechanical properties of luting and lining glass ionomer cement

    Science.gov (United States)

    Heravi, Farzin; Bagheri, Hossein; Rangrazi, Abdolrasoul; Mojtaba Zebarjad, Seyed

    2016-07-01

    Recently, the addition of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) into glass ionomer cements (GICs) has attracted interest due to its remineralization of teeth and its antibacterial effects. However, it should be investigated to ensure that the incorporation of CPP-ACP does not have significant adverse effects on its mechanical properties. The purpose of this study was to evaluate the effects of the addition of CPP-ACP on the mechanical properties of luting and lining GIC. The first step was to synthesize the CPP-ACP. Then the CPP-ACP at concentrations of 1%, 1.56% and 2% of CPP-ACP was added into a luting and lining GIC. GIC without CPP-ACP was used as a control group. The results revealed that the incorporation of CPP-ACP up to 1.56%(w/w) increased the flexural strength (29%), diametral tensile strength (36%) and microhardness (18%), followed by a reduction in these mechanical properties at 2%(w/w) CPP-ACP. The wear rate was significantly decreased (23%) in 1.56%(w/w) concentration of CPP-ACP and it was increased in 2%(w/w). Accordingly, the addition of 1.56%(w/w) CPP-ACP into luting and lining GIC had no adverse effect on the mechanical properties of luting and lining GIC and could be used in clinical practice.

  20. Streptococcus mutans counts in plaque adjacent to orthodontic brackets bonded with resin-modified glass ionomer cement or resin-based composite

    Directory of Open Access Journals (Sweden)

    Solange Machado Mota

    2008-03-01

    Full Text Available This study investigated the number of Streptococcus mutans CFU (colony forming units in the saliva and plaque adjacent to orthodontic brackets bonded with a glass ionomer cement - GIC (Fuji Ortho or a resin-based composite - RC (Concise. Twenty male and female patients, aged 12 to 20 years, participated in the study. Saliva was collected before and after placement of appliances. Plaque was collected from areas adjacent to brackets and saliva was again collected on the 15th, 30th, and 45th day after placement. On the 30th day, 0.4% stannous fluoride gel was applied for 4 minutes. No significant modification in the number of Streptococcus mutans CFU in saliva was observed after placement of the fixed orthodontic appliances. On the 15th day, the percentage of Streptococcus mutans CFU in plaque was statistically lower in sites adjacent to GIC-bonded brackets (mean = 0.365 than in those adjacent to RC-bonded brackets (mean = 0.935. No evidence was found of a contribution of GIC to the reduction of CFU in plaque after the 15th day. Topical application of stannous fluoride gel on the 30th day reduced the number of CFU in saliva, but not in plaque. This study suggests that the antimicrobial activity of GIC occurs only in the initial phase and is not responsible for a long-term anticariogenic property.

  1. In vitro quantitative evaluation of marginal microleakage in class II restorations confected with a glass ionomer cement and two composite resins

    Directory of Open Access Journals (Sweden)

    BIJELLA Maria Fernanda Borro

    2001-01-01

    Full Text Available This study evaluated, in vitro, marginal microleakage in class II restorations confected with the glass ionomer cement Vitremer and with the composite resins Ariston pHc and P-60. The aims of the study were to assess the effect of thermocycling on those materials and to evaluate two methods utilized in the analysis of dye penetration. Sixty premolars divided in three groups were utilized; the teeth had proximal cavities whose cervical walls were located 1 mm below the cementoenamel junction. Half of the test specimens from each group underwent thermocycling; the other half remained in deionized water, at 37ºC. The specimens were immersed, for 24 hours, in a basic 0.5% fuchsin solution at 37ºC. For the analysis of microleakage, the specimens were sectioned in a mesio-distal direction, and the observation was carried out with the software Imagetools. The results were evaluated through the 2-way ANOVA and through the Tukey?s test. All groups presented marginal microleakage. The smallest values were obtained with Vitremer, followed by those obtained with the composite resins P-60 and Ariston pHc. There was no statistically significant difference caused by thermocycling, and the method of maximum infiltration was the best for detecting the extension of microleakage.

  2. Effect of protective coating on microhardness of a new glass ionomer cement: Nanofilled coating versus unfilled resin.

    Science.gov (United States)

    Faraji, Foad; Heshmat, Haleh; Banava, Sepideh

    2017-01-01

    EQUIA TM is a new gastrointestinal (GI) system with high compressive strength, surface microhardness (MH), and fluoride release potential. This in vitro study aimed to assess the effect of aging and type of protective coating on the MH of EQUIA TM GI cement. A total of 30 disc-shaped specimens measuring 9 mm in diameter and 2 mm in thickness were fabricated of EQUIA TM GI and divided into three groups of G-Coat nanofilled coating (a), no coating (b) and margin bond (c). The Vickers MH value of specimens was measured before (baseline) and at 3 and 6 months after water storage. Data were analyzed using repeated measures ANOVA. Group B had significantly higher MH than the other two groups at baseline. Both G-Coat and margin bond increased the surface MH of GI at 3 and 6 months. The MH values of G-Coat and margin bond groups did not significantly increase or decrease between 3 and 6 months. The increase in MH was greater in the G-Coat compared to the margin bond group in the long-term. Clinically, margin bond may be a suitable alternative when G-Coat is not available.

  3. Effect of resin-modified glass-ionomer cement lining and composite layering technique on the adhesive interface of lateral wall

    Directory of Open Access Journals (Sweden)

    Larissa Marinho AZEVEDO

    2015-06-01

    Full Text Available Interface integrity can be maintained by setting the composite in a layering technique and using liners. Objective The aim of this in vitro study was to verify the effect of resin-modified glass-ionomer cement (RMGIC lining and composite layering technique on the bond strength of the dentin/resin adhesive interface of lateral walls of occlusal restorations. Material and Methods Occlusal cavities were prepared in 52 extracted sound human molars, randomly assigned into 4 groups: Group 2H (control – no lining + two horizontal layers; Group 4O: no lining + four oblique layers; Group V-2H: RMGIC lining (Vitrebond + two horizontal layers; and Group V-4O: RMGIC lining (Vitrebond + four oblique layers. Resin composite (Filtek Z250, 3M ESPE was placed after application of an adhesive system (Adper™ Single Bond 2, 3M ESPE dyed with a fluorescent reagent (Rhodamine B to allow confocal microscopy analysis. The teeth were stored in deionized water at 37oC for 24 hours before being sectioned into 0.8 mm slices. One slice of each tooth was randomly selected for Confocal Laser Scanning Microscopy (CLSM analysis. The other slices were sectioned into 0.8 mm x 0.8 mm sticks to microtensile bond strength test (MPa. Data were analyzed by two-way ANOVA and Fisher's test. Results There was no statistical difference on bond strength among groups (p>0.05. CLSM analysis showed no significant statistical difference regarding the presence of gap at the interface dentin/resin among groups. Conclusions RMGIC lining and composite layering techniques showed no effect on the microtensile bond strength and gap formation at the adhesive interface of lateral walls of high C-factor occlusal restorations.

  4. In vitro Evaluation of Effect of Dental Bleaching on the Shear Bond Strength of Sapphire Orthodontics Brackets Bonded with Resin Modified Glass Ionomer Cement

    Directory of Open Access Journals (Sweden)

    Zainab M Kadhom

    2017-11-01

    Full Text Available Aim: This study aimed to assess the effect of various types of bleaching agents on the shear bond strength of sapphire brackets bonded to human maxillary premolar teeth using resin modified glass ionomer cement (RMGIC and to determine the site of bond failure. Materials and Methods: Thirty freshly extracted maxillary human premolars were selected and assigned into three equal groups, ten teeth in each. The first group was the control (unbleached group; the second group comprised teeth bleached with hydrogen peroxide group (HP 37.5% (in-office bleaching while the third group included teeth bleached with carbamide peroxide group (CP 16% (at-home bleaching. The teeth in the experimental groups were bleached and stored in water one day then bonded with sapphire brackets using RMGIC with the control group and left another day. De-bonding was performed using Instron universal testing machine. To determine the site of bond failure, both the enamel surface and bracket base of each tooth were examined under magnifying lens (20X of a stereomicroscope. Results: Results showed statistically highly significant difference in the shear bond strengths between control group and both of bleaching groups being low in the control group. Score III was the predominant site of bond failure in all groups. Conclusions: RMGIC provides adequate bond strength when bonding the sapphire brackets to bleached enamel; this bonding was strong enough to resist both the mechanical and masticatory forces. Most of the adhesive remained on the brackets, so it reduced the time required for removal of the bonding material’s remnants during enamel finishing and polishing.

  5. A comparative evaluation of the retention of metallic brackets bonded with resin-modified glass ionomer cement under different enamel preparations: A pilot study

    Directory of Open Access Journals (Sweden)

    Padmaja Sharma

    2013-01-01

    Full Text Available Introduction: For orthodontists, the ideal bonding material should be less moisture-sensitive and should release fluoride, thereby reducing unfavorable iatrogenic decalcification. Resin-Modified Glass Ionomer Cements (RMGICs, due to their ability to bond in the presence of saliva and blood can be a very good bonding agent for orthodontic attachments especially in the areas of mouth, which are difficult to access. Moreover, their fluoride releasing property makes them an ideal bonding agent for patients with poor oral hygiene. However, their immediate bond strength is said to be too low to immediately ligate the initial wire, which could increase the total number of appointments. The effect of sandblasting and the use of sodium hypochlorite (NaOCL on the immediate bond failure of RMGIC clinically have not been reported in the literature until the date. This investigation intended to assess the effect of sandblasting (of the bracket base and enamel and NaOCL on the rate of bond failure (with immediate ligation at 30 min of Fuji Ortho LC and its comparison with that of conventional light cured composite resin over a period of 1 year. Materials and Methods: 400 sample teeth were further divided into 4 groups of 100 each and bonded as follows: (1 Group 1: Normal metallic brackets bonded with Fuji Ortho LC. (2 Group 2: Sandblasted bracket base and enamel surface, brackets bonded with Fuji Ortho LC. (3 Group 3: Deproteinized enamel surface using sodium hypochlorite and brackets bonded with Fuji Ortho LC. (4 Group 4: Normal metallic bracket bonded with Transbond XT after etching enamel with 37% phosphoric acid. This group served as control group. Results and Conclusion: Results showed that sandblasting the bracket base and enamel, can significantly reduce the bond failure rate of RMGIC.

  6. Comparative Evaluation of Microleakage Between Nano-Ionomer, Giomer and Resin Modified Glass Ionomer Cement in Class V Cavities- CLSM Study.

    Science.gov (United States)

    Bollu, Indira Priyadarshini; Hari, Archana; Thumu, Jayaprakash; Velagula, Lakshmi Deepa; Bolla, Nagesh; Varri, Sujana; Kasaraneni, Srikanth; Nalli, Siva Venkata Malathi

    2016-05-01

    Marginal integrity of adhesive restorative materials provides better sealing ability for enamel and dentin and plays an important role in success of restoration in Class V cavities. Restorative material with good marginal adaptation improves the longevity of restorations. Aim of this study was to evaluate microleakage in Class V cavities which were restored with Resin Modified Glass Ionomer Cement (RMGIC), Giomer and Nano-Ionomer. This in-vitro study was performed on 60 human maxillary and mandibular premolars which were extracted for orthodontic reasons. A standard wedge shaped defect was prepared on the buccal surfaces of teeth with the gingival margin placed near Cemento Enamel Junction (CEJ). Teeth were divided into three groups of 20 each and restored with RMGIC, Giomer and Nano-Ionomer and were subjected to thermocycling. Teeth were then immersed in 0.5% Rhodamine B dye for 48 hours. They were sectioned longitudinally from the middle of cavity into mesial and distal parts. The sections were observed under Confocal Laser Scanning Microscope (CLSM) to evaluate microleakage. Depth of dye penetration was measured in millimeters. The data was analysed using the Kruskal Wallis test. Pair wise comparison was done with Mann Whitney U Test. A p-valueNano-Ionomer showed less microleakage which was statistically significant when compared to Giomer (p=0.0050). Statistically no significant difference was found between Nano Ionomer and RMGIC (p=0.3550). There was statistically significant difference between RMGIC and Giomer (p=0.0450). Nano-Ionomer and RMGIC showed significantly less leakage and better adaptation than Giomer and there was no statistically significant difference between Nano-Ionomer and RMGIC.

  7. Misfit and microleakage of implant-supported crown copings obtained by laser sintering and casting techniques, luted with glass-ionomer, resin cements and acrylic/urethane-based agents.

    Science.gov (United States)

    Castillo-Oyagüe, Raquel; Lynch, Christopher D; Turrión, Andrés S; López-Lozano, José F; Torres-Lagares, Daniel; Suárez-García, María-Jesús

    2013-01-01

    This study evaluated the marginal misfit and microleakage of cement-retained implant-supported crown copings. Single crown structures were constructed with: (1) laser-sintered Co-Cr (LS); (2) vacuum-cast Co-Cr (CC) and (3) vacuum-cast Ni-Cr-Ti (CN). Samples of each alloy group were randomly luted in standard fashion onto machined titanium abutments using: (1) GC Fuji PLUS (FP); (2) Clearfil Esthetic Cement (CEC); (3) RelyX Unicem 2 Automix (RXU) and (4) DentoTemp (DT) (n=15 each). After 60 days of water ageing, vertical discrepancy was SEM-measured and cement microleakage was scored using a digital microscope. Misfit data were subjected to two-way ANOVA and Student-Newman-Keuls multiple comparisons tests. Kruskal-Wallis and Dunn's tests were run for microleakage analysis (α=0.05). Regardless of the cement type, LS samples exhibited the best fit, whilst CC and CN performed equally well. Despite the framework alloy and manufacturing technique, FP and DT provide comparably better fit and greater microleakage scores than did CEC and RXU, which showed no differences. DMLS of Co-Cr may be a reliable alternative to the casting of base metal alloys to obtain well-fitted implant-supported crowns, although all the groups tested were within the clinically acceptable range of vertical discrepancy. No strong correlations were found between misfit and microleakage. Notwithstanding the framework alloy, definitive resin-modified glass-ionomer (FP) and temporary acrylic/urethane-based (DT) cements demonstrated comparably better marginal fit and greater microleakage scores than did 10-methacryloxydecyl-dihydrogen phosphate-based (CEC) and self-adhesive (RXU) dual-cure resin agents. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Tensile bond strength of glass fiber posts luted with different cements Resistência à tração de pinos de fibra de vidro cimentados com diferentes materiais

    Directory of Open Access Journals (Sweden)

    Gerson Bonfante

    2007-06-01

    Full Text Available Proper selection of the luting agent is fundamental to avoid failure due to lack of retention in post-retained crowns. The objective of this study was to investigate the tensile bond strength and failure mode of glass fiber posts luted with different cements. Glass fiber posts were luted in 40 mandibular premolars, divided into 4 groups (n = 10: Group 1 - resin-modified glass ionomer RelyX Luting; Group 2 - resin-modified glass ionomer Fuji Plus; Group 3 - resin cement RelyX ARC; Group 4 - resin cement Enforce. Specimens were assessed by tensile strength testing and light microscopy analysis for observation of failure mode. The tensile bond strength values of each group were compared by ANOVA and Tukey test. The significance level was set at 5%. The failure modes were described as percentages. The following tensile strength values were obtained: Group 1 - 247.6 N; Group 2 - 256.7 N; Group 3 - 502.1 N; Group 4 - 477.3 N. There was no statistically significant difference between Groups 1 and 2 or between Groups 3 and 4, yet the resin cements presented significantly higher tensile bond strength values than those presented by the glass ionomer cements. Group 1 displayed 70% of cohesive failures, whereas Groups 2, 3 and 4 exhibited 70% to 80% of adhesive failures at the dentin-cement interface. We concluded that resin cements and glass ionomer cements are able to provide clinically sufficient retention of glass fiber posts, and that glass ionomer cements may be especially indicated when the application of adhesive techniques is difficult.A seleção adequada do agente cimentante é essencial para evitar falhas por perda de retenção em coroas retidas por núcleos. O objetivo deste estudo foi investigar a resistência à tração e o tipo de falha de pinos de fibra de vidro cimentados com diferentes materiais. Cimentaram-se pinos de fibra de vidro em 40 pré-molares inferiores, divididos em 4 grupos (n = 10: Grupo 1 - ionômero de vidro modificado

  9. The effect of dentine pre-treatment using bioglass and/or polyacrylic acid on the interfacial characteristics of resin-modified glass ionomer cements.

    Science.gov (United States)

    Sauro, Salvatore; Watson, Timothy; Moscardó, Agustin Pascual; Luzi, Arlinda; Feitosa, Victor Pinheiro; Banerjee, Avijit

    2018-06-01

    To evaluate the effect of load-cycle aging and/or 6 months artificial saliva (AS) storage on bond durability and interfacial ultramorphology of resin-modified glass ionomer cement (RMGIC) applied onto dentine air-abraded using Bioglass 45S5 (BAG) with/without polyacrylic acid (PAA) conditioning. RMGIC (Ionolux, VOCO) was applied onto human dentine specimens prepared with silicon-carbide abrasive paper or air-abraded with BAG with or without the use of PAA conditioning. Half of bonded-teeth were submitted to load cycling (150,000 cycles) and half immersed in deionised water for 24 h. They were cut into matchsticks and submitted immediately to microtensile bond strength (μTBS) testing or 6 months in AS immersion and subsequently μTBS tested. Results were analysed statistically by two-way ANOVA and Student-Newman-Keuls test (α = 0.05). Fractographic analysis was performed using FE-SEM, while further RMGIC-bonded specimens were surveyed for interfacial ultramorphology characterisation (dye-assisted nanoleakage) using confocal microscopy. RMGIC applied onto dentine air-abraded with BAG regardless PAA showed no significant μTBS reduction after 6 months of AS storage and/or load cycling (p > 0.05). RMGIC-dentine interface showed no sign of degradation/nanoleakage after both aging regimens. Conversely, interfaces created in PAA-conditioned SiC-abraded specimens showed significant reduction in μTBS (p air-abrasion might be a suitable strategy to enhance the bonding performance and durability of RMGIC applied to dentine. The use of PAA conditioner in smear layer-covered dentine may increase the risk of degradation at the bonding interface. A combined dentine pre-treatment using bioglass followed by PAA may increase the bond strength and maintain it stable over time. Conversely, the use of PAA conditioning alone may offer no significant contribute to the immediate and prolonged bonding performance. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Time reduction in well construction with the addition of glass microspheres and thixotropic agents in cement slurries in zonal isolation at Solimoes Basin; Reducao do tempo de construcao de pocos de petroelo na Bacia do Solimoes atraves da utilizacao de microsferas de vidro e agentes tixotropicos nas fases de cimentacao

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Cledeilson R.L.; Duque, Luis H.; Steffan, Rodolfo H.P.; Guimaraes, Zacarias [Baker Hyghes, Houston, TX (United States); Corregio, Fabio; Augusto, Marcelo; Mendes, Sandro C. [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil)

    2012-07-01

    One of the problems faced by the oil industry during the well construction is the damage effect of the hydrostatic head of cement slurries on unconsolidated reservoirs, trending to a necessity of lightweight cementing slurries with high resistance for zonal isolation. This paper presents experiences with lightweight cementing slurries obtained by the addition of glass microspheres and thixotropic agents in oil and gas wells located at Solimoes Basin - Amazon Basin, Brazil, which led to 100% time reduction on well construction when compared with the standard cementing procedures, besides the benefit of no reservoir damage. It also includes lab tests, cement slurry designs, case histories and results that allow a complete evaluation of the technique that can be applied in other similar environments. (author)

  11. Preparation, Physical-Chemical Characterization, and Cytocompatibility of Polymeric Calcium Phosphate Cements

    Directory of Open Access Journals (Sweden)

    Rania M. Khashaba

    2011-01-01

    Full Text Available Aim. Physicochemical mechanical and in vitro biological properties of novel formulations of polymeric calcium phosphate cements (CPCs were investigated. Methods. Monocalcium phosphate, calcium oxide, and synthetic hydroxyapatite were combined with either modified polyacrylic acid, light activated polyalkenoic acid, or polymethyl vinyl ether maleic acid to obtain Types I, II, and III CPCs. Setting time, compressive and diametral strength of CPCs was compared with zinc polycarboxylate cement (control. Specimens were characterized using X-ray diffraction, scanning electron microscopy, and infrared spectroscopy. In vitro cytotoxicity of CPCs and control was assessed. Results. X-ray diffraction analysis showed hydroxyapatite, monetite, and brushite. Acid-base reaction was confirmed by the appearance of stretching peaks in IR spectra of set cements. SEM revealed rod-like crystals and platy crystals. Setting time of cements was 5–12 min. Type III showed significantly higher strength values compared to control. Type III yielded high biocompatibility. Conclusions. Type III CPCs show promise for dental applications.

  12. Tensile bond strength between different glass ionomer cement and composite resin using three adhesive systems Avaliação da resistência de união interfacial entre diferentes cimentos de ionômero de vidro e resina composta, usando três sistemas adesivos

    Directory of Open Access Journals (Sweden)

    Patrícia Dias

    2005-10-01

    Full Text Available The purpose of this study was to evaluate the tensile bond strength (TBS among a Composite Resin (Filtek Z250 and six conventional Glass Ionomer Cements, three used for lining (Bioglass F, Vidrion F and Glass Ionomer L.C. and three for restorations (Ketac Fil, Vidrion R and Glass Ionomer type II etched and non etched, using three adhesive systems (Single Bond, Bond 1 and Stae. Thirty-six groups were made, ten samples for each group, totalizing 360 specimens. There were significant differences on TBS among groups. Group 31 (Glass Ionomer Cement type II showed the highest TBS (9.65 MPa in comparison to other tested groups. Group 16 (Glass Ionomer L.C presented the lowest TBS (2.72 MPa in comparison to all the other groups. Therefore, it can be concluded that the acid etching of the Glass Ionomer Cement is not necessary. Foi avaliada, ">in vitro, a resistência de união, por tração, entre uma Resina Composta micro-híbrida (Filtek Z-250 e seis Cimentos de Ionômero de Vidro (CIV convencionais: três utilizados para base/forramento (Bioglass F, Vidrion F e Glass Ionomer Lining Cement e três para restauração (Ketac Fil, Vidrion R e Glass Ionomer Cement type II, sem e com condicionamento ácido ortofosfórico a 37%, usando três sistemas adesivos (Single Bond, Bond 1 e Stae. Foram confeccionados 36 grupos de 10 corpos-de-prova cada, totalizando 360 espécimes. Para análise estatística, foi utilizado o teste de Tukey-Kramer. Dentre os três CIV de base/forramento, os grupos 2 e 5 (Bioglass F apresentaram valores mais altos de adesividade à resina (7,24 e 6,03 MPa respectivamente. Quanto aos três CIV de restauração, todos apresentaram maior resistência de união, superior aos de base/forramento, sendo que o Glass Ionomer Cement type II (Grupo 31 e Vidrion R apresentaram maior força de adesão (9,65 e 7,47 MPa à resina composta. O grupo 16 (Glass Ionomer L.C. mostrou menor adesividade à resina (2,72 MPa. Houve diferenças significantes

  13. ULTRA-LIGHTWEIGHT CEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Fred Sabins

    2001-10-23

    The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). Work reported herein addresses tasks performed in the fourth quarter as well as the other three quarters of the past year. The subjects that were covered in previous reports and that are also discussed in this report include: Analysis of field laboratory data of active cement applications from three oil-well service companies; Preliminary findings from a literature review focusing on problems associated with ultra-lightweight cements; Summary of pertinent information from Russian ultra-lightweight cement literature review; and Comparison of compressive strengths of ULHS systems using ultrasonic and crush methods Results reported from the fourth quarter include laboratory testing of ULHS systems along with other lightweight cement systems--foamed and sodium silicate slurries. These comparison studies were completed for two different densities (10.0 and 11.5 lb/gal) and three different field application scenarios. Additional testing included the mechanical properties of ULHS systems and other lightweight systems. Studies were also performed to examine the effect that circulation by centrifugal pump during mixing has on breakage of ULHS.

  14. In vitro tensile strength of luting cements on metallic substrate.

    Science.gov (United States)

    Orsi, Iara A; Varoli, Fernando K; Pieroni, Carlos H P; Ferreira, Marly C C G; Borie, Eduardo

    2014-01-01

    The aim of this study was to determine the tensile strength of crowns cemented on metallic substrate with four different types of luting agents. Twenty human maxillary molars with similar diameters were selected and prepared to receive metallic core castings (Cu-Al). After cementation and preparation the cores were measured and the area of crown's portion was calculated. The teeth were divided into four groups based on the luting agent used to cement the crowns: zinc phosphate cement; glass ionomer cement; resin cement Rely X; and resin cement Panavia F. The teeth with the crowns cemented were subjected to thermocycling and later to the tensile strength test using universal testing machine with a load cell of 200 kgf and a crosshead speed of 0.5 mm/min. The load required to dislodge the crowns was recorded and converted to MPa/mm(2). Data were subjected to Kruskal-Wallis analysis with a significance level of 1%. Panavia F showed significantly higher retention in core casts (3.067 MPa/mm(2)), when compared with the other cements. Rely X showed a mean retention value of 1.877 MPa/mm(2) and the zinc phosphate cement with 1.155 MPa/mm(2). Glass ionomer cement (0.884 MPa/mm(2)) exhibited the lowest tensile strength value. Crowns cemented with Panavia F on cast metallic posts and cores presented higher tensile strength. The glass ionomer cement showed the lowest tensile strength among all the cements studied.

  15. Recycled materials in Portland cement concrete

    Science.gov (United States)

    2000-06-01

    This report pertains to a comprehensive study involving the use of recycled materials in Portland cement concrete. Three different materials were studied including crushed glass (CG), street sweepings (SS), and recycled concrete (RC). Blast furnace s...

  16. Retention of oral microorganisms on conventional and resin-modified glass-ionomer cements Retenção de microrganismos bucais em cimentos de ionômero de vidro convencionais e modificados por resina

    Directory of Open Access Journals (Sweden)

    Denise PEDRINI

    2001-09-01

    Full Text Available Secondary caries are a worldwide public and socioeconomic problem. The placement of restorations can lead to the development of environmental conditions favorable to microbial colonization, especially on the tooth/restoration interface, which is a predisposing factor for secondary caries. The aim of this study was to evaluate microbial retention on conventional (Chelon-Fil and Vidrion R and resin-modified (Vitremer and Fuji II LC glass-ionomer cements, in situ, using a hybrid composite resin (Z100 as a control. Twelve volunteers wore Hawley appliances with specimens made of all tested filling materials for 7 days. The specimens were then removed from the appliances and transferred to tubes containing 2.0 ml of Ringer-PRAS. Microorganisms from the samples were inoculated onto blood agar and Mitis Salivarius Bacitracin agar and incubated under anaerobiosis (90% N2, 10% CO2, at 37°C, for 10 and 2 days, respectively. The resin-modified glass-ionomer cements and the composite resin retained the same levels of microorganisms on their surfaces. The resin-modified glass-ionomers retained less mutans streptococci than the composite resin and conventional glass-ionomer cements. The conventional glass-ionomer cements retained less mutans streptococci than the composite resin, but that difference was not statistically significant.A cárie secundária representa problema de saúde pública e socioeconômico no mundo. A restauração de dentes acometidos por cárie pode criar condições favoráveis à proliferação microbiana na superfície do material restaurador ou na interface dente/restauração, criando ambiente propício para o estabelecimento de cárie secundária. O objetivo deste estudo foi avaliar a capacidade de retenção de placa bacteriana em cimentos de ionômero de vidro convencionais (Chelon-Fil e Vidrion R e modificados por resina (Vitremer e Fuji II LC e de resina composta híbrida (Z100, utilizada como controle. Nos testes de reten

  17. Durability of cermet ionomer cement conditioned in different media.

    Science.gov (United States)

    el-Din, I M

    1992-01-01

    The glass ionomer cement has exhibited significant adhesion to hard tooth structures, and good cariostatic properties. The sintering of the silver alloy powder and glass ionomer cement "cermet cement" has provided additional improvement in the physical properties of the restorative material. These were flexural resistance, wear resistance, increased radio-opacity, hardness and porosity. The improvement in the physical properties of the cermet glass cements has provided an extension in their clinical use as core build up, lining for inlays, amalgam and composite restoratives, fissure filling, restoration of primary teeth, class II tunnel preparation, treatment of root caries and repair of defective metal margins in crown and inlays.

  18. Physical Property Investigation of Contemporary Glass lonomer and Resin Modified Glass lonomer Restorative Materials

    Science.gov (United States)

    2016-05-24

    selected physical properties of nine contemporary and recently-marketed glass-ionomer cement (GIC) and four resin-modified glass-ionomer cement {RMGIC...stainless steel molds. Testing was completed on a universal testing machine unt il failure. Knoop Hardness was obtained using fai led fracture toughness...address caries, function, biocompatibility, and minimal environmental impact. 2·3 Glass-ionomer cements were invented and developed by Wilson and Kent

  19. Penetration of natural gas in industrial processes for direct burning: the case of ceramics, cement and glass industries; Penetracao do gas natural em processos industriais de queima direta: caso das industrias ceramica, cimento e vidro

    Energy Technology Data Exchange (ETDEWEB)

    Berni, Mauro Donizeti; Leite, Alvaro A. Furtado [Universidade Estadual de Campinas (UNICAMP), SP (Brazil); Dorileo, Ivo Leandro [Universidade Federal do Mato Grosso (NIEPE/UFMT), Cuiaba, MT (Brazil). Nucleo Interdisciplinar de Estudos em Planejamento Energetico; Bajay, Sergio Valdir [Universidade estadual de Campinas (FEM/UNICAMP), SP (Brazil). Fac. de Engenharia Mecanica. Dept. de Energia], e-mail: bajay@fem.unicamp.com.br

    2008-07-01

    Industrial sector can use the natural gas (NG) as raw material, as fuel and in co-generation. The NG as fuel is used, predominantly, to produce heat in the Brazilian industries. That rate, both main forms of industrial use of the NG are its direct burning in kilns - when the direct contact is had with the product - and the supply of process heat through boilers, for instance. Direct burning is used in the ceramic, cement and glass industries. This work discuss the penetration opportunity of the NG in the direct burning regarding the fuel oil and other energy that it can substitute, the environmental effects and the co-generation possibilities in each one of the analyzed industrial blanches in this work. (author)

  20. Cement Formation

    DEFF Research Database (Denmark)

    Telschow, Samira; Jappe Frandsen, Flemming; Theisen, Kirsten

    2012-01-01

    Cement production has been subject to several technological changes, each of which requires detailed knowledge about the high multiplicity of processes, especially the high temperature process involved in the rotary kiln. This article gives an introduction to the topic of cement, including...... an overview of cement production, selected cement properties, and clinker phase relations. An extended summary of laboratory-scale investigations on clinkerization reactions, the most important reactions in cement production, is provided. Clinker formations by solid state reactions, solid−liquid and liquid......−liquid reactions are discussed, as are the influences of particles sizes on clinker phase formation. Furthermore, a mechanism for clinker phase formation in an industrial rotary kiln reactor is outlined....

  1. Surface characterization of the cement for retention of implant supported dental prostheses: In vitro evaluation of cement roughness and surface free energy

    International Nuclear Information System (INIS)

    Brajkovic, Denis; Antonijevic, Djordje; Milovanovic, Petar; Kisic, Danilo; Zelic, Ksenija; Djuric, Marija; Rakocevic, Zlatko

    2014-01-01

    Graphical abstract: - Highlights: • Surface free energy and surface roughness influence bacterial adhesion. • Bacterial colonization causes periimplantitis and implant loss. • Zinc-based, glass-ionomers and resin-cements were investigated. • Glass-ionomers-cements present the lowest values of surface free energy and roughness. • Glass-ionomer-cements surface properties result with reduced bacterial adhesion. - Abstract: Background: Material surface free energy and surface roughness strongly influence the bacterial adhesion in oral cavity. The aim of this study was to analyze these two parameters in various commercial luting agents used for cementation of implant restorations. Materials and methods: Zinc-based, glass-ionomers, resin modified glass-ionomer and resin-cements were investigated. Contact angle and surface free energy were measured by contact angle analyzer using Image J software program. Materials’ average roughness and fractal dimension were calculated based on Atomic Force Microscope topography images. Results: Zinc phosphate cements presented significantly higher total surface free energy and significantly lower dispersive component of surface free energy compared to other groups, while resin-cements showed significantly lower polar component than other groups. The surface roughness and fractal dimension values were statistically the highest in the zinc phosphate cements and the lowest for the glass-ionomers cements. Conclusion: Glass-ionomers-cements presented lower values of surface free energy and surface roughness than zinc phosphate and resin cements, indicating that their surfaces are less prone to biofilm adhesion. Practical implications: Within limitations of an in vitro trial, our results indicate that glass-ionomers-cements could be the cements of choice for fixation of cement retained implant restorations due to superior surface properties compared to zinc phosphate and resin cements, which may result in reduced plaque formation

  2. Surface characterization of the cement for retention of implant supported dental prostheses: In vitro evaluation of cement roughness and surface free energy

    Energy Technology Data Exchange (ETDEWEB)

    Brajkovic, Denis [Clinic for Dentistry, Department of Maxillofacial Surgery, Faculty of Medical Sciences, University of Kragujevac, Svetozara Markovica 69, 34000 Kragujevac (Serbia); Antonijevic, Djordje; Milovanovic, Petar [Laboratory for Anthropology, Institute of Anatomy, School of Medicine, University of Belgrade, Dr. Subotica 4/2, 11000 Belgrade (Serbia); Kisic, Danilo [Laboratory for Atomic Physics, Institute of Nuclear Sciences “Vinca”, University of Belgrade, Belgrade (Serbia); Zelic, Ksenija; Djuric, Marija [Laboratory for Anthropology, Institute of Anatomy, School of Medicine, University of Belgrade, Dr. Subotica 4/2, 11000 Belgrade (Serbia); Rakocevic, Zlatko, E-mail: zlatkora@vinca.rs [Laboratory for Atomic Physics, Institute of Nuclear Sciences “Vinca”, University of Belgrade, Belgrade (Serbia)

    2014-08-30

    Graphical abstract: - Highlights: • Surface free energy and surface roughness influence bacterial adhesion. • Bacterial colonization causes periimplantitis and implant loss. • Zinc-based, glass-ionomers and resin-cements were investigated. • Glass-ionomers-cements present the lowest values of surface free energy and roughness. • Glass-ionomer-cements surface properties result with reduced bacterial adhesion. - Abstract: Background: Material surface free energy and surface roughness strongly influence the bacterial adhesion in oral cavity. The aim of this study was to analyze these two parameters in various commercial luting agents used for cementation of implant restorations. Materials and methods: Zinc-based, glass-ionomers, resin modified glass-ionomer and resin-cements were investigated. Contact angle and surface free energy were measured by contact angle analyzer using Image J software program. Materials’ average roughness and fractal dimension were calculated based on Atomic Force Microscope topography images. Results: Zinc phosphate cements presented significantly higher total surface free energy and significantly lower dispersive component of surface free energy compared to other groups, while resin-cements showed significantly lower polar component than other groups. The surface roughness and fractal dimension values were statistically the highest in the zinc phosphate cements and the lowest for the glass-ionomers cements. Conclusion: Glass-ionomers-cements presented lower values of surface free energy and surface roughness than zinc phosphate and resin cements, indicating that their surfaces are less prone to biofilm adhesion. Practical implications: Within limitations of an in vitro trial, our results indicate that glass-ionomers-cements could be the cements of choice for fixation of cement retained implant restorations due to superior surface properties compared to zinc phosphate and resin cements, which may result in reduced plaque formation

  3. A cement based syntactic foam

    International Nuclear Information System (INIS)

    Li Guoqiang; Muthyala, Venkata D.

    2008-01-01

    In this study, a cement based syntactic foam core was proposed and experimentally investigated for composite sandwich structures. This was a multi-phase composite material with microballoon dispersed in a rubber latex toughened cement paste matrix. A trace amount of microfiber was also incorporated to increase the number of mechanisms for energy absorption and a small amount of nanoclay was added to improve the crystal structure of the hydrates. Three groups of cement based syntactic foams with varying cement content were investigated. A fourth group of specimens containing pure cement paste were also prepared as control. Each group contained 24 beam specimens. The total number of beam specimens was 96. The dimension of each beam was 30.5 cm x 5.1 cm x 1.5 cm. Twelve foam specimens from each group were wrapped with plain woven 7715 style glass fabric reinforced epoxy to prepare sandwich beams. Twelve cubic foam specimens, three from each group, with a side length of 5.1 cm, were also prepared. Three types of testing, low velocity impact test and four-point bending test on the beam specimens and compression test on the cubic specimens, were conducted to evaluate the impact energy dissipation, stress-strain behavior, and residual strength. Scanning electron microscope (SEM) was also used to examine the energy dissipation mechanisms in the micro-length scale. It was found that the cement based syntactic foam has a higher capacity for dissipating impact energy with an insignificant reduction in strength as compared to the control cement paste core. When compared to a polymer based foam core having similar compositions, it was found that the cement based foam has a comparable energy dissipation capacity. The developed cement based syntactic foam would be a viable alternative for core materials in impact-tolerant composite sandwich structures

  4. The effect of pressure changes during simulated diving on the pull out strength of glass fiber posts

    Directory of Open Access Journals (Sweden)

    Meenal Nitin Gulve

    2013-01-01

    Conclusion: Dentist should consider using resin reinforced glass ionomer or resin cement, for the cementation of glass fiber post, for the patients such as divers, who are likely to be exposed to pressure cycling.

  5. In vitro activity of zinc oxide-eugenol and glass ionomer cements on Candida albicans Atividade in vitro dos cimentos de óxido de zinco e eugenol e ionômero de vidro sobre Candida albicans

    Directory of Open Access Journals (Sweden)

    Anna Carolina Aguiar Cassanho

    2005-06-01

    Full Text Available The aim of this study was to evaluate in vitro the antimicrobial activity of glass ionomer (GIC and zinc oxide-eugenol (ZOE cements against Candida albicans. Standardized GIC and ZOE specimens were maintained in contact with C. albicans suspension (1 ´ 10(6 cells/ml at 37°C for 24 h, 48 h or 7 days. A control group without any testing cement was included. After the incubation period, aliquots of 0.1 ml were plated on Sabouraud's agar, and then the number of colonies was counted. The results were expressed as values of logarithms of colony-forming units per milliliter (log CFU/mL and were analyzed statistically by Kruskal-Wallis ANOVA. After 48 h of incubation, the ZOE group presented no growth of C. albicans. GIC and control groups presented similar mean values at all tested periods. According to the results obtained, it could be concluded that, under the experimental conditions, ZOE cement was more effective in vitro against C. albicans than GIC.O objetivo deste estudo foi avaliar in vitro a atividade antimicrobiana dos cimentos de ionômero de vidro (CIV e óxido de zinco e eugenol (OZE sobre Candida albicans. Corpos-de-prova padronizados de CIV e OZE foram mantidos em contato com suspensão (1 ´ 10(6 células/ml de C. albicans a 37°C por 24 horas, 48 horas ou 7 dias. Um grupo controle sem nenhum cimento teste foi incluído. Após o período de incubação, alíquotas de 0,1 ml foram semeadas em ágar Sabouraud e o número de colônias foi contado. Os resultados foram expressos em logaritmos de valores de unidades formadoras de colônias por ml (log UFC/mL e analisados estatisticamente pelo teste ANOVA Kruskal-Wallis. Após 48 horas de incubação, o grupo OZE não apresentou crescimento de C. albicans. Os grupos CIV e controle apresentaram médias similares em todos os períodos testados. De acordo com os resultados obtidos, pode ser concluído que, sob as condições experimentais testadas, o cimento OZE apresentou-se mais efetivo in

  6. Wear and superficial roughness of glass ionomer cements used as sealants, after simulated toothbrushing Desgaste e rugosidade superficial de cimentos de ionômero de vidro utilizados como selantes, após escovação simulada

    Directory of Open Access Journals (Sweden)

    Daniela Rios

    2002-12-01

    Full Text Available The purpose of this study was to evaluate, in vitro, the properties (wear and roughness of glass ionomer cements that could influence their indication as pit and fissure sealants. The utilized materials were Fuji Plus, Ketac-Molar and Vitremer (in two different proportions: 1:1 and ¼:1. The resin-based sealant Delton was used as control. By means of an electronic balance (precision of 10-4 g, wear was measured in function of weight loss after simulated toothbrushing. Superficial roughness was determined by means of a surface roughness-measuring apparatus. The results revealed that diluted Vitremer and Fuji Plus were less resistant to toothbrushing abrasion and had the greatest increase in superficial roughness.Although in clinical situations luting or diluted ionomer cements are often utilized as alternatives to resin-based sealants, the resultsof this study revealed that the properties of those cements are worse than those of restorative ionomers, whichpresented results similar to those of the evaluated resin sealant.O presente estudo foi conduzido in vitro com o intuito de constatar as propriedades (desgaste e rugosidade dos CIV, as quais influenciam na sua indicação como material selador de fossas e fissuras. Os materiais empregados foram Fuji Plus, Ketac-Molar e Vitremer (duas proporções: 1:1 e ¼:1. O selante Delton foi controle. A determinação do desgaste foi obtida através da quantidade de massa perdida após a escovação e a rugosidade através da análise quantitativa da superfície. Os resultados mostraram que o Vitremer diluído e o Fuji Plus apresentaram maior grau de desgaste e maior aumento de rugosidade. Apesar de clinicamente se encontrar um maior uso dos ionômeros de vidro cimentantes ou diluídos como forma alternativa para material selador; este trabalho permitiu concluir que estes possuem propriedades bastante inferiores quando comparados aos ionômeros restauradores que, por sua vez, possuem resultados semelhantes

  7. Compressive strength of glass ionomer cements using different specimen dimensions Resistência à compressão de cimentos de ionômero de vidro utilizando-se diferentes tamanhos de corpos-de-prova

    Directory of Open Access Journals (Sweden)

    André Mallmann

    2007-09-01

    Full Text Available The purpose of this study was to evaluate the compressive strength of two glass ionomer cements, a conventional one (Vitro Fil® - DFL and a resin-modified material (Vitro Fil LC® - DFL, using two test specimen dimensions: One with 6 mm in height and 4 mm in diameter and the other with 12 mm in height and 6 mm in diameter, according to the ISO 7489:1986 specification and the ANSI/ADA Specification No. 66 for Dental Glass Ionomer Cement, respectively. Ten specimens were fabricated with each material and for each size, in a total of 40 specimens. They were stored in distilled water for 24 hours and then subjected to a compressive strength test in a universal testing machine (EMIC, at a crosshead speed of 0.5 mm/min. The data were statistically analyzed using the Kruskal-Wallis test (5%. Mean compressive strength values (MPa were: 54.00 ± 6.6 and 105.10 ± 17.3 for the 12 mm x 6 mm sample using Vitro Fil and Vitro Fil LC, respectively, and 46.00 ± 3.8 and 91.10 ± 8.2 for the 6 mm x 4 mm sample using Vitro Fil and Vitro Fil LC, respectively. The resin-modified glass ionomer cement obtained the best results, irrespective of specimen dimensions. For both glass ionomer materials, the 12 mm x 6 mm matrix led to higher compressive strength results than the 6 mm x 4 mm matrix. A higher variability in results was observed when the glass ionomer cements were used in the larger matrices.Este estudo teve como objetivo avaliar a resistência à compressão de dois cimentos de ionômero de vidro, um convencional (Vitro Fil® - DFL e outro modificado por resina (Vitro Fil LC® - DFL, utilizando-se dois tamanhos de amostras: uma com 6 mm de altura e 4 mm de diâmetro e outra com 12 mm de altura e 6 mm de diâmetro, seguindo-se a especificação 7489:1986 da ISO e a especificação n. 66 da ANSI/ADA para Cimento Dental de Ionômero de Vidro, respectivamente. Foram confeccionados 10 corpos-de-prova (CP de cada material para cada tamanho de amostra, totalizando

  8. Facile synthesis and characterization of novel rapid-setting spherical sub-micron bioactive glasses cements and their biocompatibility in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yuli, E-mail: lily19791002@126.com [Plastic Surgery Institute of Weifang Medical University, Weifang Medical University, Weifang 261053 (China); National Engineering Research Center for Tissue Restoration and Reconstruction, Guangzhou 510006 (China); Liang, Qiming; Lin, Cai; Li, Xian [National Engineering Research Center for Tissue Restoration and Reconstruction, Guangzhou 510006 (China); Chen, Xiaofeng, E-mail: chenxf@scut.edu.cn [National Engineering Research Center for Tissue Restoration and Reconstruction, Guangzhou 510006 (China); Hu, Qing, E-mail: stefan_hu@foxmail.com [School of Material Science and Engineering, Jingdezhen Ceramic Institute, Jingdezhen 333001 (China)

    2017-06-01

    Dental pulp vitality is extremely important for the tooth viability, since it provides nutrition and forms the dentin. Bioactive glasses (BGs) may be promising materials for pulp repair due to their excellent abilities of rapidly bonding to bone and stimulating new bone growth. However, the unsatisfied handling property, low plasticity, and poor rapid-setting property of traditional BGs limit its application in vital pulp therapy. Spherical bioactive glasses (SBGs) exhibited higher osteogenesis and odontogenic differentiation than irregular BGs. This study focuses on the application of SBGs with rapid setting property for dental pulp repair. Here, SBGs with various compositions were successfully synthesized by a sol-gel process using dodecylamine (DDA) served as both a catalyst and a template. The maximum content of CaO in SBGs was about 15%. The non-bridge oxygen amounts of the Si−O network and the apatite-forming ability increased with the content proportion of CaO and P{sub 2}O{sub 5}. Bioactive glass pulp capping materials (BGPCMs) were prepared by mixing the SBGs powders and the phosphate buffer solution (PBS). The K{sub 3}CaH(PO{sub 4}){sub 2} and hydroxyapatite (HA) formed between SBGs particles as soon as they were mixed with PBS solution. The compressive strengths of fully set BCPCM-2 molded were measured to be 31.76 ± 1.9577 MPa after setting for 24 h. The K{sub 3}CaH(PO{sub 4}){sub 2} and the low crystallinity HA phases at the initial stage of solidification transformed to crystalline HA for 3 days, and the compressive strength was still higher than 10 MPa. Additionally, SBG-2 with a designed molar composition of 35% SiO{sub 2}, 55% CaO and 10% P{sub 2}O{sub 5} more promoted dental pulp cell proliferation, and could be potential pulp capping applications. - Highlights: • Spherical bioactive glasses (SBGs) with the maximum content of 15 mol% CaO were successfully synthesized. • BG pulp capping materials (BGPCMs) were prepared by mixing the SBGs

  9. Role of pH Changes on Transforming Growth Factor-β1 Release and on the Fibrin Architecture of Platelet-rich Fibrin When Layered with Biodentine, Glass Ionomer Cement, and Intermediate Restorative Material.

    Science.gov (United States)

    Mullaguri, Harish; Suresh, Nandini; Surendran, Smitha; Velmurugan, Natanasabapathy; Chitra, Selvarajan

    2016-05-01

    The purpose of this study was to evaluate the influence of pH that is due to setting reaction of Biodentine, glass ionomer cement (GIC), and intermediate restorative material (IRM) on transforming growth factor-β1 (TGF-β1) release and on the fibrin architecture of platelet-rich fibrin (PRF). PRF was obtained from 8 volunteers and layered over the freshly prepared GIC, IRM, and Biodentine mixtures. TGF-β1 release was estimated by using enzyme-linked immunosorbent assay (ELISA), and fibrin structure of PRF was analyzed by using scanning electron microscope at 1 and 5 hours. Biodentine, GIC, and IRM increased the TGF-β1 release in comparison with that of control group (PRF alone) at both 1 and 5 hours. Biodentine released significantly more TGF-β1 than GIC and IRM at 1 hour. At 5 hours both GIC and Biodentine released significantly more TGF-β1 than IRM. The fibrin architecture of the Biodentine group was similar to that of control group at both 1 and 5 hours. In GIC and IRM groups the fibrillar structure of fibrin was collapsed, ill-defined, and cloudy with very thick fibers and irregularly reduced porosities. Biodentine induces larger amount of TGF-β1 release and also maintains the integrity of fibrin structure when compared with GIC and IRM when layered over PRF. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  10. Effect of Ascorbic Acid on Shear Bond Strength of Orthodontic Brackets Bonded with Resin-modified Glass-ionomer Cement to Bleached Teeth

    Directory of Open Access Journals (Sweden)

    Behnam Khosravanifard

    2012-04-01

    Full Text Available Background and aims. Bleaching can considerably reduce shear bond strength (SBS of orthodontic brackets bonded with composite adhesives. Application of antioxidants is a method to reverse the negative effect of bleaching on compositeto-enamel bond. However, the efficacy of antioxidants in increasing the SBS of brackets bonded using resin-modified glassionomer cement (RMGIC has not been studied, which was the aim of this study. Materials and methods. Fifty freshly extracted human maxillary first premolars were bleached with 35% hydrogen peroxide (Pola Office Bleaching, SDI. Sodium ascorbate 10% was applied to the experimental specimens (n=25. All the specimens were etched with 37% phosphoric acid (Ivoclar/Vivadent and bonded using RMGIC (Fuji Ortho LC, GC. The specimens were subjected to incubation (37°C, 24h and thermocycling (1000 cycles, 5-55°C, dwell time = 1 min. The SBS was measured at 0.5 mm/min debonding crosshead speed. The adhesive remnant index (ARI was scored under ×10 magnification. Data were analyzed using Mann-Whitney U test, one- and independent-samples t-test, and Fisher’s exact test (α=0.05. Results. The mean SBS of experimental and control groups were 11.97 ± 4.49 and 7.7 ± 3.19 MPa, respectively. The difference was statistically significant (P=0.000 by t-test. SBS of both control (P=0.014 and experimental (P=0.000 groups were significantly higher than the minimum acceptable SBS of 6 MPa, according to one-sample t-test. Conclusion. Application of ascorbic acid can guarantee a strong bond when RMGIC is to be used. However, RMGIC might tolerate the negative effect of bleaching with minimum SA treatments (or perhaps without treatments, which deserves further studies.

  11. CEMENT SLURRIES FOR GEOTHERMAL WELLS CEMENTING

    Directory of Open Access Journals (Sweden)

    Nediljka Gaurina-Međimurec

    1994-12-01

    Full Text Available During a well cementing special place belongs to the cement slurry design. To ensure the best quality of cementing, a thorough understanding of well parameters is essential, as well as behaviour of cement slurry (especially at high temperatures and application of proven cementing techniques. Many cement jobs fail because of bad job planning. Well cementing without regarding what should be accomplished, can lead to well problems (channels in the cement, unwanted water, gas or fluid production, pipe corrosion and expensive well repairs. Cementing temperature conditions are important because bot-tomhole circulating temperatures affect slurry thickening time, arheology, set time and compressive strength development. Knowing the actual temperature which cement encounters during placement allows the selection of proper cementing materials for a specific application. Slurry design is affected by well depth, bottom hole circulating temperature and static temperature, type or drilling fluid, slurry density, pumping time, quality of mix water, fluid loss control, flow regime, settling and free water, quality of cement, dry or liquid additives, strength development, and quality of the lab cement testing and equipment. Most Portland cements and Class J cement have shown suitable performances in geot-hermal wells. Cement system designs for geothermal wells differ from those for conventional high temperature oil and gas wells in the exclusive use of silica flour instead of silica sand, and the avoidance of fly ash as an extender. In this paper, Portland cement behaviour at high temperatures is described. Cement slurry and set cement properties are also described. Published in literature, the composition of cement slurries which were tested in geothermal conditions and which obtained required compressive strength and water permeability are listed. As a case of our practice geothermal wells Velika Ciglena-1 and Velika Ciglena-la are described.

  12. Lunar cement

    Science.gov (United States)

    Agosto, William N.

    1992-01-01

    With the exception of water, the major oxide constituents of terrestrial cements are present at all nine lunar sites from which samples have been returned. However, with the exception of relatively rare cristobalite, the lunar oxides are not present as individual phases but are combined in silicates and in mixed oxides. Lime (CaO) is most abundant on the Moon in the plagioclase (CaAl2Si2O8) of highland anorthosites. It may be possible to enrich the lime content of anorthite to levels like those of Portland cement by pyrolyzing it with lunar-derived phosphate. The phosphate consumed in such a reaction can be regenerated by reacting the phosphorus product with lunar augite pyroxenes at elevated temperatures. Other possible sources of lunar phosphate and other oxides are discussed.

  13. Avaliação clínica de um cimento de ionômero de vidro utilizado como selante oclusal: a clinical evaluation Use of a glass ionomer cement as an occlusal sealant

    Directory of Open Access Journals (Sweden)

    Pedro Cheque BERNARDO

    2000-03-01

    Full Text Available Sabendo-se do papel do flúor na Odontologia Preventiva, cada vez mais procuram-se materiais restauradores com propriedades de liberação deste íon. Dentre os selantes oclusais, grande expectativa existe em relação aos cimentos de ionômero de vidro, particularmente os fotopolimerizáveis, por possuírem melhores propriedades. O objetivo deste trabalho foi testar um destes cimentos, Vitremer (3M, aplicado em: combinação ou não com um adesivo. A avaliação foi realizada em 159 dentes, 6 e 12 meses após a aplicação do selante, observando-se sua retenção e a presença ou ausência de lesão de cárie. Concluiu-se que a técnica modificada, com adesivo, propiciou significativamente melhor retenção após 6 e 12 meses que a técnica convencional, não havendo diferença entre molares e pré-molares. Apenas um dente do grupo sem adesivo desenvolveu lesão de cárie após a perda do material.Since fluoride’s properties are widely known in the field of Preventive Dentistry, fluoride-releasing materials have been extensively investigated. Among the occlusal sealants, there is great expectation regarding the results that can be achieved with light-curing glass-ionomer cements due to their excellent properties. The aim of this study was to assess the use of one of these cements, Vitremer (3M as an occlusal sealant. The material was applied using two different techniques; either associated or not with an adhesive system. After 6 and 12 months of observation, an evaluation was performed in 159 teeth to verify its retention as well as the presence of caries lesions. The technique that included the adhesive system showed better retention than the conventional one. Total retention was 84.9% for the experimental technique and 37.2% for the conventional technique after 12 months. There was no difference between bicuspids and molars regarding retention. Caries lesion was observed in a single tooth, for which a total loss of material was observed

  14. Treatment of root fracture with accompanying resorption using cermet cement.

    Science.gov (United States)

    Lui, J L

    1992-02-01

    A method of treating an apical root fracture with accompanying resorption at the junction of the fracture fragments using glass-cermet cement is described. Endodontically, the material had previously been used for repair of lateral resorptive root defects and retrograde root fillings. Complete bone regeneration was observed three years post-operatively following treatment of the root fracture in the conventional manner. The various advantages of glass-cermet cement as a root filling material used in the technique described are discussed.

  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. Thermal behavior of asphalt cements

    International Nuclear Information System (INIS)

    Claudy, P.M.; Letoffe, J.M.; Martin, D.; Planche, J.P.

    1998-01-01

    Asphalt cements are highly complex mixtures of hydrocarbon molecules whose thermal behavior is of prime importance for petroleum and road industry. From DSC, the determination of several thermal properties of asphalts is given, e.g. glass-transition temperature and crystallized fraction content.The dissolution of a pure n-paraffin C n H 2n+2 in an asphalt, as seen by DSC, should be a single peak. For 20 g of these glasses change with time and temperature. The formation of the crystallized phases is superposed to the enthalpic relaxation of the glasses, making a kinetic study very difficult. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  17. Development of alkali activated cements and concrete mixture design with high volumes of red mud

    OpenAIRE

    Krivenko, Pavel; Kovalchuk, Oleksandr; Pasko, Anton; Croymans, Tom; Hutt, Mikael; Lutter, Guillaume; Vandevenne, Niels; Schreurs, Sonja; Schroeyers, Wouter

    2017-01-01

    Dedicated cement compositions were formulated to enable the incorporation of large volume fractions of red mud in alkali activated cements, taking into account the role of the aluminosilicate phase in the processes of hydration and hardening. High volume red mud alkali activated cements were synthesized using a proper combination of red mud, low basic aluminosilicate compounds with a glass phase (blast-furnace slag) and additives selected from high-basic Ca-containing cements with a crystalli...

  18. The sealing of second mandibular temporary molar pits and fissure with the laser of Nd: YAG, phosphoric acid and the glass ionomer cement; Selamento de fossulas e fissura de segundo molar deciduo inferior com laser de Nd: YAG, acido fosforico e cimento de ionomero de vidro

    Energy Technology Data Exchange (ETDEWEB)

    Toda, Maria Aparecida

    2003-07-01

    The main of our study was to check the sealing of second mandibular temporary molar pits and fissure, in vitro, with the laser of Nd: YAG, phosphoric acid at 37% and the glass ionomer cement (CIV, Fuji IX GC).The proposal was to check the structural morphologic changes in the laser irradiation upon the enamel surface to watch the pits and fissure sealing with the glass ionomer cement use after the laser irradiation and to verify the efficiency of the 'double conditioning' (phosphoric acid + Nd: YAG). At the same time we watch the evolution of the temperature in the pulp chamber's inside. Our desire was to achieve a therapeutic alternative technic to prevent the dental caries. The Nd: YAG laser parameters were the same: 79 mJ of energy per pulse; frequency of 5 Hz; mean power of 0,4 W; optical fiber on contact of 320 {mu}m diameter; fluency of 99,52 J/ cm{sup 2}, assuming that the only differential was the time of the laser application on the enamel surface. The samples were prepared with this way: Laser Nd: YAG (53 second) + acid + CIV (Fuji IX); Laser Nd: YAG (53 s); Laser Nd: YAG (20 s + 20 s) + acid + CIV; Laser Nd: YAG (20 s + 20 s); Acid + CIV; Control. Through the scanning electron microscopy (MEV) we noticed fusion and resolidification regions due to the laser irradiation and a better adaptation of the glass ionomer cement when we did the 'double conditioning'. Concerning the temperature increase we can conclude that the echeloned period was the best recommended because the temperature was found in a pattern that would not cause any damage to the dental pulp. For future studies we suggest a longer relaxing time between the laser irradiation, a comparative study of this method with other lasers, the use of other sealing materials and the study with the permanent teeth. (author)

  19. The sealing of second mandibular temporary molar pits and fissure with the laser of Nd: YAG, phosphoric acid and the glass ionomer cement; Selamento de fossulas e fissura de segundo molar deciduo inferior com laser de Nd: YAG, acido fosforico e cimento de ionomero de vidro

    Energy Technology Data Exchange (ETDEWEB)

    Toda, Maria Aparecida

    2003-07-01

    The main of our study was to check the sealing of second mandibular temporary molar pits and fissure, in vitro, with the laser of Nd: YAG, phosphoric acid at 37% and the glass ionomer cement (CIV, Fuji IX GC).The proposal was to check the structural morphologic changes in the laser irradiation upon the enamel surface to watch the pits and fissure sealing with the glass ionomer cement use after the laser irradiation and to verify the efficiency of the 'double conditioning' (phosphoric acid + Nd: YAG). At the same time we watch the evolution of the temperature in the pulp chamber's inside. Our desire was to achieve a therapeutic alternative technic to prevent the dental caries. The Nd: YAG laser parameters were the same: 79 mJ of energy per pulse; frequency of 5 Hz; mean power of 0,4 W; optical fiber on contact of 320 {mu}m diameter; fluency of 99,52 J/ cm{sup 2}, assuming that the only differential was the time of the laser application on the enamel surface. The samples were prepared with this way: Laser Nd: YAG (53 second) + acid + CIV (Fuji IX); Laser Nd: YAG (53 s); Laser Nd: YAG (20 s + 20 s) + acid + CIV; Laser Nd: YAG (20 s + 20 s); Acid + CIV; Control. Through the scanning electron microscopy (MEV) we noticed fusion and resolidification regions due to the laser irradiation and a better adaptation of the glass ionomer cement when we did the 'double conditioning'. Concerning the temperature increase we can conclude that the echeloned period was the best recommended because the temperature was found in a pattern that would not cause any damage to the dental pulp. For future studies we suggest a longer relaxing time between the laser irradiation, a comparative study of this method with other lasers, the use of other sealing materials and the study with the permanent teeth. (author)

  20. Durability of Mortar Made with Fine Glass Powdered Particles

    Directory of Open Access Journals (Sweden)

    Rosemary Bom Conselho Sales

    2017-01-01

    Full Text Available Different studies investigate the use of waste glass in Portland cement compounds, either as aggregates or as supplementary cementitious materials. Nevertheless, it seems that there is no consensus about the influence of particle color and size on the behavior of the compounds. This study addresses the influence of cement replacement by 10 and 20% of the colorless and amber soda-lime glass particles sized around 9.5 μm on the performance of Portland cement mortars. Results revealed that the partial replacement of cement could contribute to the production of durable mortars in relation to the inhibition of the alkali-aggregate reaction. This effect was more marked with 20% replacement using amber glass. Samples containing glass microparticles were more resistant to corrosion, in particular those made of colorless glass. The use of colorless and amber glass microparticles promoted a reduction in wear resistance.

  1. Producing cement

    Energy Technology Data Exchange (ETDEWEB)

    Stone, E G

    1923-09-12

    A process and apparatus are described for producing Portland cement in which pulverized shale is successively heated in a series of inclined rotary retorts having internal stirrers and oil gas outlets, which are connected to condensers. The partially treated shale is removed from the lowermost retort by a conveyor, then fed separately or conjointly into pipes and thence into a number of vertically disposed retorts. Each of these retorts may be fitted interiorly with vertical arranged conveyors which elevate the shale and discharge it over a lip, from whence it falls to the bottom of the retorts. The lower end of each casing is furnished with an adjustable discharge door through which the spent shale is fed to a hopper, thence into separate trucks. The oil gases generated in the retorts are exhausted through pipes to condensers. The spent shale is conveyed to a bin and mixed while hot with ground limestone. The admixed materials are then ground and fed to a rotary kiln which is fired by the incondensible gases derived from the oil gases obtained in the previous retorting of the shale. The calcined materials are then delivered from the rotary kiln to rotary coolers. The waste gases from the kiln are utilized for heating the retorts in which the ground shale is heated for the purpose of extracting therefrom the contained hydrocarbon oils and gases.

  2. Retention of metal-ceramic crowns with contemporary dental cements.

    Science.gov (United States)

    Johnson, Glen H; Lepe, Xavier; Zhang, Hai; Wataha, John C

    2009-09-01

    New types of crown and bridge cement are in use by practitioners, and independent studies are needed to assess their effectiveness. The authors conducted a study in three parts (study A, study B, and study C) and to determine how well these new cements retain metal-ceramic crowns. The authors prepared teeth with a 20-degree taper and a 4-millimeter length. They cast high-noble metal-ceramic copings, then fitted and cemented them with a force of 196 newtons. The types of cements they used were zinc phosphate, resin-modified glass ionomer, conventional resin and self-adhesive modified resin. They thermally cycled the cemented copings, then removed them. They recorded the removal force and calculated the stress of dislodgment by using the surface area of each preparation. They used a single-factor analysis of variance to analyze the data (alpha = .05). The mean stresses necessary to remove crowns, in megapascals, were 8.0 for RelyX Luting (3M ESPE, St. Paul, Minn.), 7.3 for RelyX Unicem (3M ESPE), 5.7 for Panavia F (Kuraray America, New York) and 4.0 for Fuji Plus (GC America, Alsip, Ill.) in study A; 8.1 for RelyX Luting, 2.6 for RelyX Luting Plus (3M ESPE) and 2.8 for Fuji CEM (GC America) in study B; and 4.9 for Maxcem (Kerr, Orange, Calif.), 4.0 for BisCem (Bisco, Schaumburg, Ill.), 3.7 for RelyX Unicem Clicker (3M ESPE), 2.9 for iCEM (Heraeus Kulzer, Armonk, N.Y.) and 2.3 for Fleck's Zinc Cement (Keystone Industries, Cherry Hill, N.J.) in study C. Powder-liquid versions of new cements were significantly more retentive than were paste-paste versions of the same cements. The mean value of crown removal stress for the new self-adhesive modified-resin cements varied appreciably among the four cements tested. All cements retained castings as well as or better than did zinc phosphate cement. Powder-liquid versions of cements, although less convenient to mix, may be a better clinical choice when crown retention is an issue. All cements tested will retain castings

  3. Influence of cement film thickness on the retention of implant-retained crowns.

    Science.gov (United States)

    Mehl, Christian; Harder, Sönke; Steiner, Martin; Vollrath, Oliver; Kern, Matthias

    2013-12-01

    The main goal of this study was to establish a new, high precision procedure to evaluate the influence of cement film thickness on the retention of cemented implant-retained crowns. Ninety-six tapered titanium abutments (6° taper, 4.3 mm diameter, Camlog) were shortened to 4 mm. Computer-aided design was used to design the crowns, and selective laser sintering, using a cobalt-chromium alloy, was used to produce the crowns. This method used a focused high-energy laser beam to fuse a localized region of metal powder to build up the crowns gradually. Before cementing, preset cement film thicknesses of 15, 50, 80, or 110 μm were established. Glass ionomer, polycarboxylate, or resin cements were used for cementation. After 3 days storage in demineralized water, the retention of the crowns was measured in tension using a universal testing machine. The cement film thicknesses could be achieved with a high level of precision. Interactions between the factors cement and cement film thickness could be found (p ≤ 0.001). For all cements, crown retention decreased significantly between a cement film thickness of 15 and 50 μm (p ≤ 0.001). At 15 μm cement film thickness, the resin cement was the most retentive cement, followed by the polycarboxylate and then the glass ionomer cement (p ≤ 0.05). The results suggest that cement film thickness has an influence on the retentive strength of cemented implant-retained crowns. © 2013 by the American College of Prosthodontists.

  4. Asphalt cement poisoning

    Science.gov (United States)

    ... petroleum material that hardens when it cools. Asphalt cement poisoning occurs when someone swallows asphalt. If hot ... found in: Road paving materials Roofing materials Tile cements Asphalt may also be used for other purposes.

  5. Radioactivity of bone cement

    International Nuclear Information System (INIS)

    Scherer, M.A.; Winkler, R.; Ascherl, R.; Lenz, E.

    1993-01-01

    A total of 14 samples of different types of bone cement from five different manufacturers were examined for their radioactivity. Each of the investigated bone cements showed a low radioactivity level, i.e. between [de

  6. Ultrafine portland cement performance

    Directory of Open Access Journals (Sweden)

    C. Argiz

    2018-04-01

    Full Text Available By mixing several binder materials and additions with different degrees of fineness, the packing density of the final product may be improved. In this work, ultrafine cement and silica fume mixes were studied to optimize the properties of cement-based materials. This research was performed in mortars made of two types of cement (ultrafine Portland cement and common Portland cement and two types of silica fume with different particle-size distributions. Two Portland cement replacement ratios of 4% and 10% of silica fume were selected and added by means of a mechanical blending method. The results revealed that the effect of the finer silica fume mixed with the coarse cement enhances the mechanical properties and pore structure refinement at a later age. This improvement is somewhat lower in the case of ultrafine cement with silica fume.

  7. Sulfur polymer cement concrete

    International Nuclear Information System (INIS)

    Weber, H.H.; McBee, W.C.

    1990-01-01

    Sulfur-based composite materials formulated using sulfur polymer cement (SPC) and mineral aggregates are described and compared with conventional portland cement based materials. Materials characteristics presented include mechanical strength, chemical resistance, impact resistance, moisture permeation, and linear shrinkage during placement and curing. Examples of preparation and placement of sulfur polymer cement concrete (SC) are described using commercial scale equipment. SC applications presented are focused into hostile chemical environments where severe portland cement concrete (PCC) failure has occurred

  8. Long-term monitoring of microleakage of dental cements by radiochemical diffusion

    International Nuclear Information System (INIS)

    Powis, D.R.; Prosser, H.J.; Wilson, A.D.

    1988-01-01

    Radioactive 14 C sucrose was found to be an ideal marker for microleakage because it did not penetrate tooth tissue, dental cement, or mounting resin. The main finding is that the adhesive cements--the glass-ionomer and polycarboxylate--are significantly more effective at preventing microleakage than are the traditional phosphate cements--silicate and zinc phosphate. The differences can be as high as two orders of magnitude. The adhesive cements provide almost perfect and reliable seals. By contrast, the nonadhesive cements are erratic sealants with most of the restorations leaking

  9. Compressive and diametral tensile strength of glass ionomer cements Resistência à compressão e à tração diametral de cimentos de ionômero de vidro

    Directory of Open Access Journals (Sweden)

    Eduardo Bresciani

    2004-12-01

    Full Text Available The aim of this study was to compare, in different periods of time, the compressive and diametral tensile strength of a traditional high viscous glass ionomer cement: Fuji IX (GC Corporation, with two new Brazilian GIC's: Vitro-Molar (DFL and Bioglass R (Biodinamica, all indicated for the Atraumatic Restorative Treatment (ART technique. Fifteen disk specimens (6.0mm diameter x 3.0mm height for the diametral tensile strength (DTS test and fifteen cylindrical specimens (6.0mm diameter x 12.0mm height for the compressive strength (CS test were made of each GIC. Specimens were stored in deionized water at 37º C and 100% of humidity in a stove until testing. Five specimens of each GIC were submitted to CS and DTS test in each period, namely 1 hour, 24 hours and 7 days. The specimens were tested in a testing machine (Emic at a crosshead speed of 1.0mm/min for CS and 0.5mm/min for the DTS test until failure occurred. The data were submitted to two-way ANOVA and Tukey tests (alpha=0.05. The mean CS values ranged from 42.03 to 155.47MPa and means DTS from 5.54 to 13.72 MPa, with test periods from 1h to 7 days. The CS and DTS tests showed no statistically significant difference between Fuji IX and Vitro Molar, except for CS test at 1-hour period. Bioglass R had lowest mean value for CS of the cements tested. In DTS test Bioglass R presented no statistically significant differences when compared with all others tested GICs at 1-hour period and Bioglass R presented no difference at 24-hour and 7-day periods when compared to Vitro-Molar. Further studies to investigate other physical properties such as fracture toughness and wear resistance, as well as chemical composition and biocompatibility, are now needed to better understand the properties of these new Brazilian GIC's.Comparou-se a Resistência à Compressão (RC e à Tração Diametral (TD de um cimento de ionômero de vidro de alta viscosidade [Fuji IX (GC Corporation] e de dois novos cimentos

  10. Microleakage of adhesive and nonadhesive luting cements for stainless steel crowns.

    Science.gov (United States)

    Memarpour, Mahtab; Mesbahi, Maryam; Rezvani, Gita; Rahimi, Mehran

    2011-01-01

    This study's purpose was to compare the ability of 5 luting cements to reduce microleakage at stainless steel crown (SSC) margins on primary molar teeth. Standard preparations were performed on 100 extracted primary molar teeth for SSC restoration. After fitting SSCs, samples were randomly divided into 5 groups of 20 teeth each, which were cemented with nonadhesive cement consisting of polycarboxylate (PC) or zinc phosphate (ZP), or with adhesive cement consisting of glass ionomer (GIC), resin-modified glass ionomer cement (RMGIC), or RMGIC with a bonding agent (RMGIC+DBA). After aging and thermocycling, the specimens were placed in 1% methylene blue, sectioned, and evaluated under a digital microscope. The data were compared between groups with the t test, analysis of variance, and the least significant difference test. Microleakage with adhesive cements was significantly lower than with nonadhesive cements (Pcements were statistically significant at Pcement showed the greatest microleakage. Adhesive cements were more effective in reducing microleakage in stainless steel crowns than nonadhesive cements. Use of a bonding agent with a resin-modified glass ionomer cement yielded better results than using the latter alone.

  11. Shear-peel strength comparison of orthodontic band cements including novel calcium silicate

    DEFF Research Database (Denmark)

    Leo, Mariantonietta; Løvschall, Henrik

    calcium silicate with fluoride and fast-setting, Glass ionomer, and Zinc phosphate cement, used for luting of orthodontic bands on molars kept one month in phosphate buffering solution (PBS). Materials and methods: The roots of 35 extracted human molars were embedded in acryl. Three groups were allocated....... An orthodontic band (AO) was fitted on the free crown. Each group of the teeth (n>10) was cemented with novel calcium silicate (Protooth), Glass ionomer (Orthocem), or Zinc phosphate (DeTrey Zinc). The cements were mixed according to the manufacturers instructions. Samples were stored at 37ºC in humid chamber...... Silicate (Protooth) and Zinc phosphate cement (DeTrey Zinc) were significantly higher than Glass ionomer cement (Orthocem) when looking for the force (N, p

  12. Comparison of retention and demineralization inhibition potential of adhesive banding cements in primary teeth.

    Science.gov (United States)

    Prabhakar, A R; Mahantesh, T; Ahuja, Vipin

    2010-01-01

    The purpose of this study was to evaluate the efficacy of banding cements in terms of retentive capability and demineralization inhibition potential. We included 48 non-carious primary mandibular second molar teeth. Preformed stainless steel bands were adapted onto the teeth. All teeth were randomly assigned to four groups: Group I (Adaptation of bands without cementation), Group II (Cementation of bands using conventional Glass Ionomer Cement), Group III (Cementation of bands using Resin-modified Glass Ionomer Cement), Group IV (Cementation of bands using Resin cement), and placed in artificial saliva. Each day, specimens were taken from artificial saliva and suspended in an artificial caries solution for 35 minutes, every 8 hours. At the end of 3 months, retention of bands was estimated using an Instron Universal Testing Machine. The mode of failure was recorded and specimens were sectioned and examined under polarized microscope for demineralized lesions. The mean retention value was highest with resin cement, followed by RMGIC, GIC, and Control group respectively. The RMGIC group showed more favorable modes of failures. All the experimental groups showed significant demineralization inhibition potential. RMGIC is the preferable banding cement and can be used effectively to cement bands in primary dentition.

  13. Alkaline resistant phosphate glasses and method of preparation and use thereof

    Science.gov (United States)

    Brow, Richard K.; Reis, Signo T.; Velez, Mariano; Day, Delbert E.

    2010-01-26

    A substantially alkaline resistant calcium-iron-phosphate (CFP) glass and methods of making and using thereof. In one application, the CFP glass is drawn into a fiber and dispersed in cement to produce glass fiber reinforced concrete (GFRC) articles having the high compressive strength of concrete with the high impact, flexural and tensile strength associated with glass fibers.

  14. In vitro shear bond strength of cementing agents to fixed prosthodontic restorative materials.

    Science.gov (United States)

    Piwowarczyk, Andree; Lauer, Hans-Christoph; Sorensen, John A

    2004-09-01

    Durable bonding to fixed prosthodontic restorations is desirable; however, little information is available on the strength of the bond between different cements and fixed prosthodontic restorative materials. This study determined the shear-bond strength of cementing agents to high-gold-content alloy castings and different dental ceramics: high-strength aluminum oxide (Procera AllCeram), leucite-reinforced (IPS Empress), and lithium disilicate glass-ceramic (IPS Empress 2). Prepolymerized resin composite cylinders (5.5 mm internal diameter, n=20) were bonded to the pretreated surfaces of prosthodontic materials. High-gold-content alloy and high-strength aluminum oxide surfaces were airborne-particle-abraded, and pressable ceramics were hydrofluoric acid-etched and silanized prior to cementing. The cementing agents tested were a zinc-phosphate cement (Fleck's zinc cement), glass ionomer cements (Fuji I, Ketac-Cem), resin-modified glass ionomer cements (Fuji Plus, Fuji Cem, RelyX Luting), resin cements (RelyX ARC, Panavia F, Variolink II, Compolute), and a self-adhesive universal resin cement (RelyX Unicem). Half the specimens (n=10) were tested after 30 minutes; the other half (n=10) were stored in distilled water at 37 degrees C for 14 days and then thermal cycled 1000 times between 5 degrees C and 55 degrees C prior to testing. Shear-bond strength tests were performed using a universal testing machine at a constant crosshead speed of 0.5 mm/min. Statistical analysis was performed by multifactorial analysis of variance taking interactions between effects into account. For multiple paired comparisons, the Tukey method was used (alpha=.05). In a 3-way ANOVA model, the main factors substrate, cement, time, and all corresponding interactions were statistically significant (all P <.0001). In subsequent separate 1-way or 2-way ANOVA models for each substrate type, significant differences between cement types and polymerizing modes were found (all P <.001). None of the

  15. Identifying glass compositions in fly ash

    Directory of Open Access Journals (Sweden)

    Katherine eAughenbaugh

    2016-01-01

    Full Text Available In this study, four Class F fly ashes were studied with a scanning electron microscope; the glassy phases were identified and their compositions quantified using point compositional analysis with k-means clustering and multispectral image analysis. The results showed that while the bulk oxide contents of the fly ashes were different, the four fly ashes had somewhat similar glassy phase compositions. Aluminosilicate glasses (AS, calcium aluminosilicate glasses (CAS, a mixed glass, and, in one case, a high iron glass were identified in the fly ashes. Quartz and iron crystalline phases were identified in each fly ash as well. The compositions of the three main glasses identified, AS, CAS, and mixed glass, were relatively similar in each ash. The amounts of each glass were varied by fly ash, with the highest calcium fly ash containing the most of calcium-containing glass. Some of the glasses were identified as intermixed in individual particles, particularly the calcium-containing glasses. Finally, the smallest particles in the fly ashes, with the most surface area available to react in alkaline solution, such as when mixed with portland cement or in alkali-activated fly ash, were not different in composition than the large particles, with each of the glasses represented. The method used in the study may be applied to a fly ash of interest for use as a cementing material in order to understand its potential for reactivity.

  16. GLASS-FIBRE REINFORCED COMPOSITES: THE EFFECT OF ...

    African Journals Online (AJOL)

    HOD

    mechanical and corrosion wear behaviour of any reinforced composites. In other ..... physical properties of glass fibre reinforced epoxy resin and the following .... waste in concrete and cement composites," Journal of Cleaner Production, vol.

  17. Glass-ionomer-silver-cermet interim Class I restorations for permanent teeth.

    Science.gov (United States)

    Croll, T P; Killian, C M

    1992-11-01

    Glass-ionomer-silver-cermet cement has proved to be a worthy alternative to silver amalgam for restoring certain Class I lesions in primary teeth. Such restorations are now known to last up to 8 years without need for repair or replacement. Cermet cement has also been used for interim restoration of permanent teeth in special cases, with ideal results. The procedure for placing a glass-ionomer-silver-cermet cement Class I restoration is described.

  18. Thermogravimetric analysis of phase transitions in cement compositions mixed by sodium silicate solution

    Directory of Open Access Journals (Sweden)

    Fedosov Sergey Viktorovich

    2014-01-01

    Full Text Available This paper presents a study of the capability to modify cement by mechanical activation of sodium silicate water solution. Admixtures or blends of binding agents were employed for modifying concrete properties. The liquid glass is applied to protect from chemically or physically unfavorable environmental impacts, such as acidic medium and high temperature. The sodium silicate is a high-capacity setting accelerator. The increasing of the liquid glass proportion in the mix leads to the degradation of the cement paste plasticity and for this reason it is necessary to reduce the amount of liquid glass in the cement paste. The activation of dilute water solution of sodium silicate into rotary pulsating apparatus directly before tempering of the cement paste is an effective way to decrease mass fraction of liquid glass in the cement paste. The results of the combined influence of liquid glass and mechanical activation on physicochemical processes taking place in cement stone are represented in this research. Thermogravimetric analysis was used in order to study cement blends. Thermogravimetric analysis of modified cement stone assays was performed by thermo analyzer SETARAM TGA 92-24. The results of the analysis of phase transition taking place under high-temperature heating of cement stone modified by the mechanical activation of the water solution of the sodium silicate were introduced. Thermograms of cement stone assays were obtained at different hardening age. The comparison of these thermograms allows us to come to a conclusion on the formation and the retention during long time of a more dense structure of the composite matrix mixed by the mechanical activation of sodium silicate water solution. The relation between the concrete composition and its strength properties was stated. Perhaps, the capability of modified concrete to keep calcium ions in sparingly soluble hydrosilicates leads to the increase in its durability and corrosion resistance.

  19. Dentin-cement Interfacial Interaction

    Science.gov (United States)

    Atmeh, A.R.; Chong, E.Z.; Richard, G.; Festy, F.; Watson, T.F.

    2012-01-01

    The interfacial properties of a new calcium-silicate-based coronal restorative material (Biodentine™) and a glass-ionomer cement (GIC) with dentin have been studied by confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), micro-Raman spectroscopy, and two-photon auto-fluorescence and second-harmonic-generation (SHG) imaging. Results indicate the formation of tag-like structures alongside an interfacial layer called the “mineral infiltration zone”, where the alkaline caustic effect of the calcium silicate cement’s hydration products degrades the collagenous component of the interfacial dentin. This degradation leads to the formation of a porous structure which facilitates the permeation of high concentrations of Ca2+, OH-, and CO32- ions, leading to increased mineralization in this region. Comparison of the dentin-restorative interfaces shows that there is a dentin-mineral infiltration with the Biodentine, whereas polyacrylic and tartaric acids and their salts characterize the penetration of the GIC. A new type of interfacial interaction, “the mineral infiltration zone”, is suggested for these calcium-silicate-based cements. PMID:22436906

  20. Antibacterial Activity of Dental Cements Containing Quaternary Ammonium Polyethylenimine Nanoparticles

    International Nuclear Information System (INIS)

    Beyth, N.; Weiss, E.I.; Pilo, R.

    2012-01-01

    Glass ionomer cements (GICs) are commonly used for cementing full cast crown restorations. Regrettably, although the dental cements fill the gap between the tooth and the crown, bacterial micro leakage may occur, resulting in secondary caries. As micro leakage cannot be completely prevented, GCS possessing antibacterial properties are in demand. In the present study the antibacterial activity of insoluble, cross-linked quaternary ammonium polyethylenimine (Qp) nanoparticles incorporated at 1% w/w in two clinically available GCS were studied. The antibacterial activity was tested against Streptococcus mutans and Lactobacillus casei using the direct contact test (Dct) and the agar diffusion test (Ad). Using the direct contact test, antibacterial activity (P<0.05) was found in both tested GICs with incorporated QPEI nanoparticles, the effect lasting for at least one month. However, the ADT showed no inhibition halo in the test bacteria, indicating that the antimicrobial nanoparticles do not diffuse into the agar. The results show that the incorporation of QPEI nanoparticles in glass ionomer cements has a long-lasting antibacterial effect against Streptococcus mutans and Lactobacillus casei. Changing the antibacterial properties of glass ionomer cements by incorporating QPEI antibacterial nanoparticles may prolong the clinical performance of dental crowns.

  1. Antibacterial Activity of Dental Cements Containing Quaternary Ammonium Polyethylenimine Nanoparticles

    Directory of Open Access Journals (Sweden)

    Nurit Beyth

    2012-01-01

    Full Text Available Glass ionomer cements (GICs are commonly used for cementing full cast crown restorations. Regrettably, although the dental cements fill the gap between the tooth and the crown, bacterial microleakage may occur, resulting in secondary caries. As microleakage cannot be completely prevented, GICs possessing antibacterial properties are in demand. In the present study the antibacterial activity of insoluble, cross-linked quaternary ammonium polyethylenimine (QPEI nanoparticles incorporated at 1% w/w in two clinically available GICs were studied. The antibacterial activity was tested against Streptococcus mutans and Lactobacillus casei using the direct contact test (DCT and the agar diffusion test (ADT. Using the direct contact test, antibacterial activity (<0.05 was found in both tested GICs with incorporated QPEI nanoparticles, the effect lasting for at least one month. However, the ADT showed no inhibition halo in the test bacteria, indicating that the antimicrobial nanoparticles do not diffuse into the agar. The results show that the incorporation of QPEI nanoparticles in glass ionomer cements has a long-lasting antibacterial effect against Streptococcus mutans and Lactobacillus casei. Changing the antibacterial properties of glass ionomer cements by incorporating QPEI antibacterial nanoparticles may prolong the clinical performance of dental crowns.

  2. Comparative evaluation of microleakage in conventional glass ionomer cements and triclosan incorporated glass ionomer cements

    Directory of Open Access Journals (Sweden)

    Rani Somani

    2014-01-01

    Full Text Available Aim and Objective: The aim of the following study is to comparatively evaluate the microleakage of triclosan incorporated GIC with conventional restorative GIC. Materials and Methods: Triclosan in powder form was added to conventional GIC to formulate a concentration of 2.5%. Class five cavities were prepared in non-carious extracted molars and were respectively restored with conventional restorative GIC and triclosan incorporated GIC. Samples were kept in 10% methylene blue dye. Ground sections were obtained and were observed under a binocular microscope for dye penetration. Result: No significant difference was found in the microleakage of two groups. Conclusion: Triclosan incorporated GIC can be considered as an alternative to GIC with enhanced antibacterial property.

  3. Fabrication of Phosphate Cement with High Integrity

    International Nuclear Information System (INIS)

    Yang, Jae Hwan; Lee, Chang Hwa; Heo, Cheol Min; Jeon, Min Ku; Kang, Kweon Ho

    2011-01-01

    As the development of industrial society has accelerated, hazardous wastes are generated as well. According to the 1986 statistics of U.S.A, each person made 40 tons of waste in America that year. Treatment of radioactive waste is one of the most important and serious problems related to waste treatments, because its radioactivity and decaying heat have harmful effects to human and environment for a long time. Nuclear developed countries have used conventional method of treatment such as vitrification or cementation in order to stabilize and solidify radioactive waste. Although the former guarantees the formation of high leaching resistant and durable waste form, it requires several hundred (or even more than one thousand) temperature to melt glass frit. This process generates secondary waste volatilized, as well as being non-economical. Cement technology played a role of immobilizing low and middle class wastes. It has advantages of low temperature setting, low cost, easy process, etc. The alkalinity of ordinary cement, however, constrains the utility of cement to the solidification of alkaline waste. In addition, leachability and mechanical strength of cements are not quite appropriate for the stabilization of high level waste. In this regard, chemically bonded phosphate cement(CBPC), which sets by an acid-base reaction, is a potentially expectable material for immobilization of radioactive waste. CBPC not only sets at room temperature, but also encapsulates various isotopes chemically. The performance of CBPC can be enhanced by the addition of fly ash, sand, wollastonite, etc. This study aims at fabricating the CBPC containing fly ash with high integrity. Morphology, microstructure, and compressive strength are evaluated using SEM, and digital compressing machine

  4. Advanced cementation concepts

    International Nuclear Information System (INIS)

    Howard, C.G.

    1989-10-01

    The purpose of this programme of work was to investigate whether improvements could be made to existing formulations for cement suitable for the immobilization of intermediate level radioactive waste. Two additives were selected, microsilica and limestone flour. Improvements to the cement were only slight. (author)

  5. Preparation of hydraulic cement

    Energy Technology Data Exchange (ETDEWEB)

    1921-08-28

    A process for the preparation of hydraulic cement by the use of oil-shale residues is characterized in that the oil-shale refuse is mixed with granular basic blast-furnace slag and a small amount of portland cement and ground together.

  6. Low force cementation.

    Science.gov (United States)

    Wilson, P R

    1996-07-01

    The marginal adaptation of full coverage restorations is adversely affected by the introduction of luting agents of various minimum film thicknesses during the cementation process. The increase in the marginal opening may have long-term detrimental effects on the health of both pulpal and periodontal tissues. The purpose of this study was to determine the effects of varying seating forces (2.5, 12.5, 25 N), venting, and cement types on post-cementation marginal elevation in cast crowns. A standardized cement space of 40 microns was provided between a machined gold crown and a stainless steel die. An occlusal vent was placed that could be opened or closed. The post-cementation crown elevation was measured, following the use of two commercially available capsulated dental cements (Phosphacap, and Ketac-cem Applicap). The results indicate that only the combination of Ketac-Cem Applicap and crown venting produced post-cementation crown elevation of less than 20 microns when 12.5 N seating force was used. Higher forces (25 N) and venting were required for comparable seating when using Phosphacap (19 microns). The amount of force required to allow maximum seating of cast crowns appears to be cement specific, and is reduced by effective venting procedures.

  7. Cementation process study

    International Nuclear Information System (INIS)

    Park, H.H.; Han, K.W.; Ahn, S.J.; Choi, K.S.; Lee, M.W.; Ryu, Y.K.

    1985-01-01

    In the cementation process study, in 1984, design of the waste treatment simulator was finished for the first step. We can experience not only the operation of solidification system but the design and construction of comming large scale plant through the design of cementation process. (Author)

  8. Phase separation in an ionomer glass

    DEFF Research Database (Denmark)

    Pedersen, Malene Thostrup; Tian, K.V.; Dobó-Nagy, C.

    2015-01-01

    The G338 ionomer glass is a fluoro-alumino-silicate system, which is used as the powder component of glass ionomer cements (GICs) in dental applications. However, despite progress in understanding the nature of this glass, chemical identity of its separated amorphous phases has not yet been...... amorphous phases in G388 are Ca/Na-Al-Si-O, Ca-Al-F and Ca-P-O-F phases, respectively. However, the exact chemical compositions of the three phases still require further exploration. The results of this work are important for understanding the impact of phase separation within ionomer glasses on the setting...... conclusively determined. In this work, we identify these phases by performing differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses on both the as-received glass and heat-treated samples. We detected three glass transitions in the as-received G338 glass during DSC upscaning, implying...

  9. Fracture strengths of chair‑side‑generated veneers cemented with ...

    African Journals Online (AJOL)

    2014-06-09

    Jun 9, 2014 ... Group 1), CAD/CAM‑fabricated veneers cemented with a glass fiber ... specimens were tested with a universal testing machine after thermal cycling treatment. ... The purpose of the current in vitro study is to determine the ..... fracture resistance of fiber reinforced cups‑replacing composite restorations.

  10. Fracture strengths of chair‑side‑generated veneers cemented with ...

    African Journals Online (AJOL)

    Introduction: CAD/CAM (computer‑aided design and computer‑aided manufacturing) systems have refreshed the idea of chair‑side production of restorations, but the fracture of ceramic veneers remains a problem. Cementation with glass fibers may improve the fracture strengths and affect the failure modes of ...

  11. Comparative study of digital radiopacity of dental cements

    Directory of Open Access Journals (Sweden)

    Abdolhamid Alhavaz

    2014-03-01

    Full Text Available Introduction: Radiopacity is a necessary property for luting cements . The aim of this study was to investigate the radiopacity of some luting dental cements used in prosthetic dentistry. Methods: Five disclike samples of each material (6 x 1 mm were prepared from panavia F2.0(Pa, Chioce2 (Ch.2, Glass ionomer GC (GI GC, zinc phosphate Hoffmann’s (ZP hof, zinc polycarboxylate Hoffmann’s (ZPC hof, Glass ionomer ariadent( GI ari, zinc phosphate ariadent(ZP ari and zinc polycarboxylate ariadent (ZPC ari. The radiopacity of each material along with aluminium step wedge were measured from radiographic images using a digital radiography. The average measured radiopacities from five areas were taken into account, which were measured by Digora for windows (DFW software using a PSP digital sensor. Results: There was a significant difference between radiopacity value of all luting materials (P≤0.001. ZP ari had the highest radiopacity with 7.7±0.55 mm aluminium. The Glass ionomer ariadent ari dent showed the lowest radiopacity value with 0.82±0.31 mm aluminium. Conclusion: All dental cements showed radiopacity values equivalent to or greater than the ISO 4049:2000(Estandard except ariadent Glass ionomer and this could be considered suitable for use in restoration cementation.

  12. Effects of Hybrid Coat on shear bond strength of five cements: an in vitro study.

    Science.gov (United States)

    Guo, Yue; Zhou, Hou-De; Feng, Yun-Zhi

    2017-12-01

    To evaluate the sealing performance of Hybrid Coat and its influence on the shear bond strength of five dentin surface cements. Six premolars were pretreated to expose the dentin surface prior to the application of Hybrid Coat. The microscopic characteristics of the dentinal surfaces were examined with scanning electron microscopy (SEM). Then, 40 premolars were sectioned longitudinally, and 80 semi-sections were divided into a control group (untreated) and a study group (treated by Hybrid Coat). Alloy restoration was bonded to the teeth specimen using five different cements. Shear bond strength was measured by the universal testing machine. The fracture patterns and the adhesive interface were observed using astereomicroscope. SEM revealed that the lumens of dentinal tubules were completely occluded by Hybrid Coat. The Hybrid Coat significantly improved the shear bond strength of resin-modified glass ionomer cement (RMGIC) and resin cement (RC) but weakened the performance of zinc phosphate cement (ZPC), zinc polycarboxylate cement (ZPCC) and glass ionomer cement (GIC). Hybrid Coat is an effective dentinal tubule sealant, and therefore its combined use with resin or resin-modified glass ionomer cements can be applied for the prostheses attachment purpose.

  13. Fracture resistance of aluminium oxide and lithium disilicate-based crowns using different luting cements: an in vitro study.

    Science.gov (United States)

    Al-Wahadni, Ahed M; Hussey, David L; Grey, Nicholas; Hatamleh, Muhanad M

    2009-03-01

    The aim of this study was to investigate the fracture resistance of two types of ceramic crowns cemented with two different cements. Forty premolar crowns were fabricated using lithium-disilicate (IPS Empress-2) and glass-infiltrated aluminium-oxide (In-Ceram) ceramic systems. The crowns were divided into four groups (n=10) with Group 1 (IPS Empress-2) and Group 2 (In-Ceram) cemented with glass ionomer cement. Group 3 (IPS Empress-2) and Group 4 (In-Ceram) were cemented with resin cement. Crowns were tested in a universal testing machine at a compressive-load speed of 10 mm/min. Fracture modes were grouped into five categories. One way analysis of variance (ANOVA) and Bonferroni post-hoc tests were used to detect statistical significances (p0.05) on fracture resistance within each ceramic system tested. In-Ceram crowns cemented with either glass ionomer or resin cements exhibited a statistically significantly higher fracture-resistance than IPS Empress-2 crowns (pEmpress-2 and In-Ceram crowns was not affected by the type of cement used for luting. Both In-Ceram and IPS Empress-2 crowns can be successfully luted with the cements tested with In-Ceram exhibiting higher fracture resistance than IPS Empress-2.

  14. Glass sealing

    Energy Technology Data Exchange (ETDEWEB)

    Brow, R.K.; Kovacic, L.; Chambers, R.S. [Sandia National Labs., Albuquerque, NM (United States)

    1996-04-01

    Hernetic glass sealing technologies developed for weapons component applications can be utilized for the design and manufacture of fuel cells. Design and processing of of a seal are optimized through an integrated approach based on glass composition research, finite element analysis, and sealing process definition. Glass sealing procedures are selected to accommodate the limits imposed by glass composition and predicted calculations.

  15. Electrochromic Glasses.

    Science.gov (United States)

    1980-07-31

    this glass and that dipole-dipole correlations contribute to the "ferroelectric-like" character of this amorphous system. The TeO2 -W03 glasses can only...shows the dielectric constant and Fig. I(b) glass from pure TeO2 ot pure WO. In addition, glass the tan 8 of the WO glass as a function of temperature... glasses containing WO, in various glass forming nitworks of LifO-B1O0, Na:O-BzO,, and TeO2 were prepared from reagent grade oxides at 800 C - 9SO C in

  16. In Vitro Evaluation of Planktonic Growth on Experimental Cement-Retained Titanium Surfaces

    Science.gov (United States)

    Balci, Nur; Cakan, Umut; Aksu, Burak; Akgul, Oncu; Ulger, Nurver

    2016-01-01

    Background The purpose of this study was to compare the effects of selected cements, or their combination with titanium, on the growth of two periodontopathic bacteria: Prevotella intermedia (Pi) and Fusobacterium nucleatum (Fn). Material/Methods This study was comprised of several experimental groups: 1) Dental luting cements (glass ionomer cement, methacrylate-based resin cement, zinc-oxide eugenol cement, eugenol-free zinc oxide cement; 2) titanium discs; and 3) titanium combination cement discs. The disks were submerged in bacterial suspensions of either Fn or Pi. Planktonic bacterial growth within the test media was measured by determining the optical density of the cultures (OD600). Mean and standard deviations were calculated for planktonic growth from three separate experiments. Results Intergroup comparison of all experimental groups revealed increased growth of Pi associated with cement-titanium specimens in comparison with cement specimens. Regarding the comparison of all groups for Fn, there was an increased amount of bacterial growth in cement-titanium specimens although the increase was not statistically significant. Conclusions The combination of cement with titanium may exacerbate the bacterial growth capacity of Pi and Fn in contrast to their sole effect. PMID:27058704

  17. In Vitro Evaluation of Planktonic Growth on Experimental Cement-Retained Titanium Surfaces.

    Science.gov (United States)

    Balci, Nur; Cakan, Umut; Aksu, Burak; Akgul, Oncu; Ulger, Nurver

    2016-04-08

    BACKGROUND The purpose of this study was to compare the effects of selected cements, or their combination with titanium, on the growth of two periodontopathic bacteria: Prevotella intermedia (Pi) and Fusobacterium nucleatum (Fn). MATERIAL AND METHODS This study was comprised of several experimental groups: 1) Dental luting cements (glass ionomer cement, methacrylate-based resin cement, zinc-oxide eugenol cement, eugenol-free zinc oxide cement; 2) titanium discs; and 3) titanium combination cement discs. The disks were submerged in bacterial suspensions of either Fn or Pi. Planktonic bacterial growth within the test media was measured by determining the optical density of the cultures (OD600). Mean and standard deviations were calculated for planktonic growth from three separate experiments. RESULTS Intergroup comparison of all experimental groups revealed increased growth of Pi associated with cement-titanium specimens in comparison with cement specimens. Regarding the comparison of all groups for Fn, there was an increased amount of bacterial growth in cement-titanium specimens although the increase was not statistically significant. CONCLUSIONS The combination of cement with titanium may exacerbate the bacterial growth capacity of Pi and Fn in contrast to their sole effect.

  18. Modified pavement cement concrete

    Science.gov (United States)

    Botsman, L. N.; Ageeva, M. S.; Botsman, A. N.; Shapovalov, S. M.

    2018-03-01

    The paper suggests design principles of pavement cement concrete, which covers optimization of compositions and structures at the stage of mixture components selection due to the use of plasticizing agents and air-retaining substances that increase the viability of a concrete mixture. It also demonstrates advisability of using plasticizing agents together with air-retaining substances when developing pavement concrete compositions, which provides for the improvement of physical and mechanical properties of concrete and the reduction of cement binding agent consumption thus preserving strength indicators. The paper shows dependences of the main physical-mechanical parameters of concrete on cement consumption, a type and amount of additives.

  19. Radioactive waste cementation

    International Nuclear Information System (INIS)

    Soriano B, A.

    1996-01-01

    This research was carried out to develop the most adequate technique to immobilize low and medium-activity radioactive waste. different brands of national cement were used, portland and pozzolanic cement. Prismatic and cylindrical test tubes were prepared with different water/cement (W/C) relationship. Additives such a as clay and bentonite were added in some other cases. Later, the properties of these test tubes were evaluated. Properties such as: mechanical resistance, immersion resistance, lixiviation and porosity resistance. Cement with the highest mechanical resistance values, 62,29 MPa was pozzolanic cement for a W/C relationship of 0,35. It must be mentioned that the other types of cements reached a mechanical resistance over 10 MPa, a value indicated by the international standards for transportation and storage of low and medium-activity radioactive waste at a superficial level. However, in the case of immersion resistance, Sol cement (portland type I) with a W/C relationship of 0,35 reached a compression resistance over 61,92 MPa; as in the previous cases, the other cements reached a mechanical resistance > 10 MPa. Regarding porosity, working with W/C relationships = 0,35 0,40 and 0,45, without additives and with additives, the percentage of porosity found for all cements is lower than 40% percentage indicated by international standards. With regard to the lixiviation test, pozzolanic cement best retained Cesium-137 and Cobalt-60, and increased its advantages when bentonite was added, obtaining a lixiviation rate of 2,02 x E-6 cm/day. Sol cement also improved its properties when bentonite was added and obtained a lixiviation rate of 2,84 x E-6 cm/day for Cesium-137. However, Cobalt-60 is almost completely retained with the 3 types of cement with or without additives, reaching the limits indicated by the international standards for the lixiviation rate of beta-gamma emitter < 5,00E-4 cm/day. Characterizing the final product involves the knowledge of its

  20. Tympanoplasty with ionomeric cement

    DEFF Research Database (Denmark)

    Kjeldsen, A D; Grøntved, A M

    2000-01-01

    with isolated erosion of the long incus process have been treated with a new surgical technique in which the ossicular chain was rebuilt with ionomeric cement. The results in hearing performance (mean pure-tone average (PTA) 0.5, 1 and 2 kHz) were evaluated pre- and post-surgery, and compared to those...... of > 10 dB, in 4 there was a slight improvement and in 2 a decline. The difference was not statistically significant. Hearing improvement using ionomeric cement in type II tympanoplasty was satisfactory. Reconstruction of the ossicular chain with ionomeric cement is recommended, as the procedure is easy...

  1. Antagonist effects of calcium on borosilicate glass alteration

    Energy Technology Data Exchange (ETDEWEB)

    Mercado-Depierre, S. [CEA Marcoule, DTCD SPDE LCLT, 30207 Bagnols sur Cèze (France); Angeli, F., E-mail: frederic.angeli@cea.fr [CEA Marcoule, DTCD SPDE LCLT, 30207 Bagnols sur Cèze (France); Frizon, F. [CEA Marcoule, DTCD SECM LP2C, 30207 Bagnols sur Cèze (France); Gin, S. [CEA Marcoule, DTCD SPDE LCLT, 30207 Bagnols sur Cèze (France)

    2013-10-15

    Graphical abstract: Display Omitted -- Highlights: •Kinetic study of glass alteration is investigated in calcium-enriched solutions. •New insights into silicon–calcium interactions in glass/cement systems are proposed. •Glass alteration is controlled by pH, Ca concentration and reaction progress. •Evidence of antagonist effects according to the importance of these parameters. -- Abstract: Numerous studies have been conducted on glass and cement durability in contact with water, but very little work to date has focused directly on interactions between the two materials. These interactions are mostly controlled by silicon–calcium reactivity. However, the physical and chemical processes involved remain insufficiently understood to predict the evolution of coupled glass–cement systems used in several industrial applications. Results are reported from borosilicate glass alteration in calcium-rich solutions. Our data show that four distinct behaviors can be expected according to the relative importance of three key parameters: the pH, the reaction progress (short- or long-term alteration) and the calcium concentration. Glass alteration is thus controlled by specific mechanisms depending on the solution chemistry: calcium complexation at the glass surface, precipitation of calcium silicate hydrates (C–S–H) or calcium incorporation in the altered layer. These findings highlight the impact of silicon–calcium interactions on glass durability and open the way for a better understanding of glass–cement mixing in civil engineering applications as well as in nuclear waste storage.

  2. Antagonist effects of calcium on borosilicate glass alteration

    International Nuclear Information System (INIS)

    Mercado-Depierre, S.; Angeli, F.; Frizon, F.; Gin, S.

    2013-01-01

    Graphical abstract: Display Omitted -- Highlights: •Kinetic study of glass alteration is investigated in calcium-enriched solutions. •New insights into silicon–calcium interactions in glass/cement systems are proposed. •Glass alteration is controlled by pH, Ca concentration and reaction progress. •Evidence of antagonist effects according to the importance of these parameters. -- Abstract: Numerous studies have been conducted on glass and cement durability in contact with water, but very little work to date has focused directly on interactions between the two materials. These interactions are mostly controlled by silicon–calcium reactivity. However, the physical and chemical processes involved remain insufficiently understood to predict the evolution of coupled glass–cement systems used in several industrial applications. Results are reported from borosilicate glass alteration in calcium-rich solutions. Our data show that four distinct behaviors can be expected according to the relative importance of three key parameters: the pH, the reaction progress (short- or long-term alteration) and the calcium concentration. Glass alteration is thus controlled by specific mechanisms depending on the solution chemistry: calcium complexation at the glass surface, precipitation of calcium silicate hydrates (C–S–H) or calcium incorporation in the altered layer. These findings highlight the impact of silicon–calcium interactions on glass durability and open the way for a better understanding of glass–cement mixing in civil engineering applications as well as in nuclear waste storage

  3. Fluoride release/recharging ability and bond strength of glass ...

    African Journals Online (AJOL)

    2015-08-17

    Aug 17, 2015 ... 2017 Nigerian Journal of Clinical Practice | Published by Wolters Kluwer - ... Objectives: The aim of this in vitro study was to evaluate the microtensile bond strength (μTBS) of different glass ... Glass ionomer cements (GICs) have often been used as the ... with nano‑fluoride‑/hydroxyapatite or resin‑modified.

  4. A Study of the Effect of Recycled Mix Glass on the Mechanical Properties of Green Concrete

    Directory of Open Access Journals (Sweden)

    Aseel B. Al-Zubaidi

    2017-12-01

    Full Text Available In this paper we utilized mixing of different types of recycled glass such as (neon glass, brown glass, and green glass that has high percentage of silicon dioxide (SiO2 with different concentrations. Utilization these landfall materials can be considered as keeping on resources. Different waste glasses used as a partial replacement of cement with different concentrations 11%, 13%, and 15% of cement weight for each type, and study the effect of it on the mechanical properties of concrete. After mixing, casting, and curing in water at (20±2°C for (7, 14, and 28 days, the mechanical properties showed that the compressive strength and flexural showed highest results at 13% from cement weight of neon glass, whereas splitting tensile strength showed the highest value at the same percentage, but from green glass.

  5. A review of glass-ionomers: From conventional glass-ionomer to bioactive glass-ionomer

    Directory of Open Access Journals (Sweden)

    Maryam Khoroushi

    2013-01-01

    Full Text Available Materials used in the body, especially the materials used in various oral cavity regions should be stable and passive without any interactions with the body tissues or fluids. Dental amalgam, composite resins and dental cements are the materials of choice with such properties. The first attempts to produce active materials, which could interact with the human body tissues and fluids were prompted by the concept that fluoride-releasing materials exert useful effects in the body. The concept of using the "smart" materials in dentistry has attracted a lot of attention in recent years. Conventional glass-ionomer (GI cements have a large number of applications in dentistry. They are biocompatible with the dental pulp to some extent. GI is predominantly used as cements in dentistry; however, they have some disadvantages, the most important of which is lack of adequate strength and toughness. In an attempt to improve the mechanical properties of the conventional GI, resin-modified glass-ionomers have been marketed, with hydrophilic monomers, such as hydroxyethyl methacrylated (HEMA. Some recent studies have evaluated GI with bioactive glass in its structure to validate the claims that such a combination will improve tooth bioactivity, regeneration capacity and restoration. There is ever-increasing interest in the application of bioactive materials in the dental field in an attempt to remineralize affected dentin. The aim of this review article is to evaluate these materials and their characteristics and applications.

  6. Retentive force and microleakage of stainless steel crowns cemented with three different luting agents.

    Science.gov (United States)

    Yilmaz, Yucel; Dalmis, Anya; Gurbuz, Taskin; Simsek, Sera

    2004-12-01

    The aim of this investigation was to compare the tensile strength, microleakage, and Scanning Electron Microscope (SEM) evaluations of SSCs cemented using different adhesive cements on primary molars. Sixty-three extracted primary first molars were used. Tooth preparations were done. Crowns were altered and adapted for investigation purpose, and then cemented using glass ionomer cement (Aqua Meron), resin modified cement (RelyX Luting), and resin cement (Panavia F) on the prepared teeth. Samples were divided into two groups of 30 samples each for tensile strength and microleakage tests. The remaining three samples were used for SEM evaluation. Data were analyzed with one-way ANOVA and Tukey test. The statistical analysis of ANOVA revealed significant differences among the groups for both tensile strength and microleakage tests (p 0.05). This study showed that the higher the retentive force a crown possessed, the lower would be the possibility of microleakage.

  7. the Danish cement industry

    OpenAIRE

    la Cour, Lisbeth Funding; Møllgård, Peter

    2001-01-01

    We test econometrically whether the sole Danish producer of cement holds a dominant position in the Danish market for (grey) cement. In import penetration tests, we find that its pricing and quantity decisions are independent of import price and quantity, implying that it can act to a considerable extent independently of its competitors. We also test whether it can act independently of its customers and find that its demand is inelastic with respect to its price. It thus holds a dominant posi...

  8. Photon Interaction Studies with Some Glasses and Building Materials

    International Nuclear Information System (INIS)

    Singh, Harvinder; Singh, Kulwant; Sharma, Gopi; Nathuram, R.; Sahota, H.S.

    2002-01-01

    Mass attenuation coefficients of some shielding materials, namely, Bakelite, black cement, white cement, plaster of paris, and concrete were determined at 356-, 511-, 662-, 1173-, and 1332-keV energies, and those of glasses containing oxides of B, Cd, Pb, and Bi were determined only at 662 keV using a narrow beam transmission method. These coefficients of glasses were then used to determine their interaction cross sections, effective atomic numbers, and electron densities. Good agreement was observed between the experimental and theoretical values. It has been proven that glasses have a potential application as a transparent radiation shielding

  9. An in vitro radiographic analysis of the density of dental luting cements as measured by CCD-based digital radiography.

    Science.gov (United States)

    Antonijevic, Djordje; Jevremovic, Danimir; Jovanovic, Svetlana; Obradovic-Djuricic, Kosovka

    2012-05-01

    According to the ISO, the radiopacity of luting cements should be equal to or greater than that of aluminum. The aim of this in vitro study was to determine the radiopacity of 13 commercially available dental luting cements and compare them with human enamel and dentin. Five classes of luting cements were evaluated: zinc phosphate (Cegal N and Harvard Zinc Phosphate), zinc polycarboxylate (Harvard Polycarboxylate and Hoffmann's Carboxylate), glass ionomers (Ketac Cem Easymix, Ketac Cem Radiopaque, and Fuji I), resin-modified glass ionomer (Rely X Luting), and resin cements (Multilink Automix, Variolink II, Speed CEM, Rely X Unicem Automix, and three shades of Variolink Veneer). Tooth slices served as controls. Five specimens of each material measuring 8 mm in diameter and 1 mm thick were prepared and radiographed alongside tooth slices and an aluminum stepwedge using a Trophy RVG sensor. The radiopacity values were expressed in mm Al and analyzed by the ANOVA and Tukey tests (P cements examined except Variolink Veneer had significantly higher radiopacities than that of dentin. Rely X Unicem Automix, glass ionomer, and resin-modified glass-ionomer cements demonstrated radiopacities that were not significantly different with respect to enamel. Zinc phosphate, zinc polycarboxylate, and three of the resin cements presented radiopacity values that were significantly greater than that of enamel. Almost all the investigated materials presented an acceptable radiopacity. Radiopacity of dental cements seems to depend more on the presence of elements with high atomic numbers than on the type of the material.

  10. Characterization of Incorporation the Glass Waste in Adhesive Mortar

    Science.gov (United States)

    Santos, D. P.; Azevedo, A. R. G.; Hespanhol, R. L.; Alexandre, J.

    Ehe search for reuse generated waste in urban centers, intending to preserve natural resources, has remained fairly constant, both in context of preventing exploitation of resources as the emplacement of waste on the environment. Glass waste glass created a serious environmental problem, mainly because of inconsistency of its flows. Ehe use of this product as a mineral additive, finely ground, cement replacement and aggregate is a promising direction for recycling. This work aims to study the influence of glass waste from cutting process in adhesive mortar, replacing part of cement. Ehe glass powder is used replacing Portland cement at 10, 15 and 20% by mass. Ehe produced mortars will be evaluated its performance in fresh and hardened states through tests performed in laboratory. Ehe selected feature is indicated by producers of additive and researchers to present good results when used as adhesive mortar.

  11. Glass consistency and glass performance

    International Nuclear Information System (INIS)

    Plodinec, M.J.; Ramsey, W.G.

    1994-01-01

    Glass produced by the Defense Waste Processing Facility (DWPF) will have to consistently be more durable than a benchmark glass (evaluated using a short-term leach test), with high confidence. The DWPF has developed a Glass Product Control Program to comply with this specification. However, it is not clear what relevance product consistency has on long-term glass performance. In this report, the authors show that DWPF glass, produced in compliance with this specification, can be expected to effectively limit the release of soluble radionuclides to natural environments. However, the release of insoluble radionuclides to the environment will be limited by their solubility, and not glass durability

  12. Class II glass ionomer cermet tunnel, resin sandwich and amalgam restorations over 2 years.

    Science.gov (United States)

    Wilkie, R; Lidums, A; Smales, R

    1993-08-01

    This study compared the clinical behavior of a glass ionomer (polyalkenoate) silver cermet, a posterior resin composite used with the "tunnel" technique, a posterior resin composite used with the "closed sandwich" technique, and a high-copper amalgam for restoring small, proximal surface carious lesions. Two dentists placed 86 restorations in the posterior permanent teeth of 26 adults treated at a dental hospital. Restorations were assessed at 6-month intervals over 2 years for gingivitis adjacent to them, the tightness of proximal contacts, occlusal wear, surface voids, roughness and cracking, surface and marginal staining, and marginal fracture. Small filling defects, surface voids and occlusal wear were obvious with the cermet material, with surface crazing and cracking present in 48% of the tunnel restorations. Two of the posterior resin composites, but none of the amalgam restorations, also failed. The cermet cannot be recommended as a long-term permanent restorative material in situations where it is likely to be subjected to heavy occlusal stresses and abrasive wear.

  13. Influence of zeolite and cement additions on mechanical behavior of sandy soil

    Directory of Open Access Journals (Sweden)

    Hossein Mola-Abasi

    2016-10-01

    Full Text Available It is well known that the cemented sand is one of economic and environmental topics in soil stabilization. In this instance, a blend of sand, cement and other materials such as fiber, glass, nanoparticle and zeolite can be commercially available and effectively used in soil stabilization in road construction. However, the influence and effectiveness of zeolite on the properties of cemented sand systems have not been completely explored. In this study, based on an experimental program, the effects of zeolite on the characteristics of cemented sands are investigated. Stabilizing agent includes Portland cement of type II and zeolite. Results show the improvements of unconfined compressive strength (UCS and failure properties of cemented sand when the cement is replaced by zeolite at an optimum proportion of 30% after 28 days. The rate of strength improvement is approximately between 20% and 78%. The efficiency of using zeolite increases with the increases in cement amount and porosity. Finally, a power function of void-cement ratio and zeolite content is demonstrated to be an appropriate method to assess UCS of zeolite-cemented mixtures.

  14. Colloidal glasses

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Colloidal glasses. Glassy state is attained when system fails to reach equilibrium due to crowding of constituent particles. In molecular glasses, glassy state is reached by rapidly lowering the temperature. In colloidal glasses, glassy state is reached by increasing the ...

  15. SUSTENTAÇÃO DE ESMALTE COM IONÔMEROS DE VIDRO E RESINA COMPOSTA: EFEITO NA RESISTÊNCIA À FRATURA DAS CÚSPIDES DE DENTES RESTAURADOS SUPPORTING ENAMEL WITH GLASS IONOMER CEMENT AND COMPOSITE RESIN: EFFECT ON FRACTURE RESISTANCE OF CUSPS OF RESTORED TEETH

    Directory of Open Access Journals (Sweden)

    Angelo Stefano SECCO

    1997-10-01

    Full Text Available Este estudo determinou a resistência e o tipo de fratura do esmalte suportado pelos materiais restauradores ionômeros de vidro convencional e modificado por resina e resina composta, bem como a influência dessa técnica restauradora na resistência das cúspides dos dentes. A remoção da estrutura dental para o preparo de cavidades tipo classe II e a presença de esmalte socavado diminuiram significativamente a resistência das cúspides dos dentes em relação ao dente hígido (p This study determined the resistance to fracture and its pattern for enamel supported with conventional and modified glass ionomer cements, and composite resin restorative materials, as well as the influence of these restorative techniques on cuspal strength of teeth. Removal of dental structure by class II cavity preparations and unsupported enamel had decreased significantly the cuspal strength in relation to healthy teeth (p < 0.01. Restorative materials used to support enamel reduced the fracture rate of restored cusps, but did not increase the fracture resistance values statistically. All tested groups presented alterations in the fracture pattern

  16. Cement for Oil Well Cementing Operations in Ghana

    African Journals Online (AJOL)

    Michael

    For Portland cement to qualify as oil well cement, the chemical and physical properties must meet ..... Reservoir Engineering, Stanford University,. Stanford, California, pp. ... Construction”, PhD Thesis, Kwame Nkrumah. University of Science ...

  17. Surface roughness of orthodontic band cements with different compositions

    Directory of Open Access Journals (Sweden)

    Françoise Hélène van de Sande

    2011-06-01

    Full Text Available OBJECTIVES: The present study evaluated comparatively the surface roughness of four orthodontic band cements after storage in various solutions. MATERIAL AND METHODS: Eight standardized cylinders were made from 4 materials: zinc phosphate cement (ZP, compomer (C, resin-modified glass ionomer cement (RMGIC and resin cement (RC. Specimens were stored for 24 h in deionized water and immersed in saline (pH 7.0 or 0.1 M lactic acid solution (pH 4.0 for 15 days. Surface roughness readings were taken with a profilometer (Surfcorder SE1200 before and after the storage period. Data were analyzed by two-way ANOVA and Tukey's test (comparison among cements and storage solutions or paired t-test (comparison before and after the storage period at 5% significance level. RESULTS: The values for average surface roughness were statistically different (pRMGIC>C>R (p0.05. Compared to the current threshold (0.2 µm related to biofilm accumulation, both RC and C remained below the threshold, even after acidic challenge by immersion in lactic acid solution. CONCLUSIONS: Storage time and immersion in lactic acid solution increased the surface roughness of the majority of the tested cements. RC presented the smoothest surface and it was not influenced by storage conditions.

  18. Cement paste prior to setting: A rheological approach

    Energy Technology Data Exchange (ETDEWEB)

    Bellotto, Maurizio, E-mail: maurizio.bellotto@bozzetto.it

    2013-10-15

    The evolution of cement paste during the dormant period is analyzed via small amplitude oscillation rheological measurements. Cement paste, from the very first moments after mixing cement and water, shows the formation of an elastic gel whose strength is rapidly increasing over time. Up to the onset of Portlandite precipitation G′(t) increases by more than 2 orders of magnitude and in the acceleratory period G′(t) continues steadily to increase. A microstructural modification is likely to occur between the dormant and the acceleratory period. At low deformations in the linearity domain the storage modulus G′(ω) exhibits a negligible frequency dependence. At higher deformations cement paste shows a yield stress which increases on increasing paste concentration. The presence of superplasticizers decreases the yield stress and increases the gelation threshold of the paste. Above the gelation threshold the evolution of cement paste with superplasticizers follows similar trends to the neat paste. -- Highlights: •The gelation of cement paste during the dormant period is analyzed via rheometry. •The observed evolution is proposed to be related to the pore structure refinement. •Similarities are observed with colloidal gels and colloidal glasses.

  19. Surface hardness of hybrid ionomer cement after immersion in antiseptic solution

    Directory of Open Access Journals (Sweden)

    Anita Yuliati

    2006-06-01

    Full Text Available Hybrid ionomer cement or resin modified glass ionomer cement is a developed form of conventional glass ionomer cement. This hybrid ionomer cement can be eroded if in direct contact with acid solution which will affect surface hardness. The aim of this study is to learn surface hardness of hybrid ionomer cement after immersion in methyl salicylate 0.06% (pH 3.6 and povidon iodine 1% (pH 2.9 solution. Sample of hybrid ionomer cement with 5 mm diameter and 3 mm thickness was immersed in sterile aquadest solution (control, methyl salicylate pH 3.6, povidon iodine pH 2.9 for 1 minute, 7 and 14 minutes. Surface hardness was measured with Micro Vickers Hardness Tester. The obtained data was analyzed statistically with ANOVA followed by LSD test. The result of hybrid ionomer cement after immersion in sterile aquadest, methyl salicylate 0.06% pH 3.6 and povidon iodine 1% pH 2.9 for one minute, showed no significant difference; while immersion for 7 and 14 minutes showed a significant difference. The conclusion states that hybrid ionomer cement after 14 minutes immersion in povidon iodine 1% pH 2.9 has the lowest surface hardness.

  20. Effect of Luting Cements On the Bond Strength to Turkom-Cera All-Ceramic Material

    Science.gov (United States)

    Al–Makramani, Bandar M. A.; Razak, Abdul A. A.; Abu–Hassan, Mohamed I.; Al–Sanabani, Fuad A.; Albakri, Fahad M.

    2018-01-01

    BACKGROUND: The selection of the appropriate luting cement is a key factor for achieving a strong bond between prepared teeth and dental restorations. AIM: To evaluate the shear bond strength of Zinc phosphate cement Elite, glass ionomer cement Fuji I, resin-modified glass ionomer cement Fuji Plus and resin luting cement Panavia-F to Turkom-Cera all-ceramic material. MATERIALS AND METHODS: Turkom-Cera was used to form discs 10mm in diameter and 3 mm in thickness (n = 40). The ceramic discs were wet ground, air - particle abraded with 50 - μm aluminium oxide particles and randomly divided into four groups (n = 10). The luting cement was bonded to Turkom-Cera discs as per manufacturer instructions. The shear bond strengths were determined using the universal testing machine at a crosshead speed of 0.5 mm/min. The data were analysed using the tests One Way ANOVA, the nonparametric Kruskal - Wallis test and Mann - Whitney Post hoc test. RESULTS: The shear bond strength of the Elite, Fuji I, Fuji Plus and Panavia F groups were: 0.92 ± 0.42, 2.04 ± 0.78, 4.37 ± 1.18, and 16.42 ± 3.38 MPa, respectively. There was the statistically significant difference between the four luting cement tested (p < 0.05). CONCLUSION: the phosphate-containing resin cement Panavia-F exhibited shear bond strength value significantly higher than all materials tested. PMID:29610618

  1. Silicate glasses

    International Nuclear Information System (INIS)

    Lutze, W.

    1988-01-01

    Vitrification of liquid high-level radioactive wastes has received the greatest attention, world-wide, compared to any other HLW solidification process. The waste form is a borosilicate-based glass. The production of phosphate-based glass has been abandoned in the western world. Only in the Soviet Union are phosphate-based glasses still being developed. Vitrification techniques, equipment and processes and their remote operation have been developed and studied for almost thirty years and have reached a high degree of technical maturity. Industrial demonstration of the vitrification process has been in progress since 1978. This chapter is a survey of world-wide research and development efforts in nuclear waste glasses and its production technology. The principal glasses considered are silicate glasses which contain boron, i.e., borosilicate glasses

  2. Effect of bioglass 45S5 addition on properties, microstructure and cellular response of tetracalcium phosphate/monetite cements

    Energy Technology Data Exchange (ETDEWEB)

    Stulajterova, R., E-mail: rstulajterova@saske.sk; Medvecky, L.; Giretova, M.; Sopcak, T.; Kovalcikova, A.

    2017-04-15

    Tetracalcium phosphate/nanomonetite (TTCPMH) cement composites with 7.5 and 15 wt% addition of melt-derived 45S5 bioactive glass were prepared by mechanical homogenization of powder components and 2% NaH{sub 2}PO{sub 4} solution was used as a hardening liquid. The properties of composites with the acidic (Ca/P ratio equal 1.5) or basic (Ca/P ratio equal 1.67) TTCPMH component were compared. Addition of glass component caused rapid rise in pH of composites up to 10. In microstructure of basic cement composite, the large bioglass particles weakly bounded to surrounding cement matrix were found contrary to a more compact microstructure of acidic cement composites with the high number of spherical silica particles. Both the significant refinement of hydroxyapatite particles and the change to needle-like morphology with rise in the content of bioglass were identified in hydroxyapatite coatings created during soaking of composites in phosphate buffered saline. In acidic cement mixtures, the increase of compressive strength with an amount of bioglass was found whereas the opposite tendency was revealed in the case of basic cement mixtures. The higher concentrations of ions were verified in solutions after immersion of acidic cement composites. The severe cytotoxicity of extracts and composite cement substrates containing 15 wt% of bioglass demonstrated adverse effects of both the ionic concentrations and unappropriate surface texture on proliferation of mesenchymal stem cells. The enhanced ALP activities of cells cultured on composite cements confirmed the positive effect of bioactive glass addition on differentiation of mesenchymal stem cells. - Highlights: • Novel B45S5 bioglass/tetracalcium phosphate/nanomonetite cement composites • Cement basicity negatively affected their microstructure. • Acid composite cements had higher compressive strengths than basic composites. • Fast differentiation of MSC to osteoblast line on composite with 7.5 wt% of bioglass

  3. Concrete = aggregate, cement, water?

    International Nuclear Information System (INIS)

    Jelinek, J.

    1990-01-01

    Concrete for the Temelin nuclear power plant is produced to about 70 different formulae. For quality production, homogeneous properties of aggregates, accurate proportioning devices, technological discipline and systematic inspections and tests should be assured. The results are reported of measuring compression strength after 28 days for different concrete samples. The results of such tests allow reducing the proportion of cement, which brings about considerable savings. Reduction in cement quantities can also be achieved by adding ash to the concrete mixes. Ligoplast, a plasticizer addition is used for improving workability. (M.D). 8 figs

  4. Technology Roadmaps: Cement

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-07-01

    To support its roadmap work focusing on key technologies for emissions reductions, the International Energy Agency (IEA) also investigated one particular industry: cement. Cement production includes technologies that are both specific to this industry and those that are shared with other industries (e.g., grinding, fuel preparation, combustion, crushing, transport). An industry specific roadmap provides an effective mechanism to bring together several technology options. It outlines the potential for technological advancement for emissions reductions in one industry, as well as potential cross-industry collaboration.

  5. Reducing cement's CO2 footprint

    Science.gov (United States)

    van Oss, Hendrik G.

    2011-01-01

    The manufacturing process for Portland cement causes high levels of greenhouse gas emissions. However, environmental impacts can be reduced by using more energy-efficient kilns and replacing fossil energy with alternative fuels. Although carbon capture and new cements with less CO2 emission are still in the experimental phase, all these innovations can help develop a cleaner cement industry.

  6. Cement Mason's Curriculum. Instructional Units.

    Science.gov (United States)

    Hendirx, Laborn J.; Patton, Bob

    To assist cement mason instructors in providing comprehensive instruction to their students, this curriculum guide treats both the skills and information necessary for cement masons in commercial and industrial construction. Ten sections are included, as follow: related information, covering orientation, safety, the history of cement, and applying…

  7. Cementation of liquid radioactive waste

    International Nuclear Information System (INIS)

    Efremenkov, V.

    2004-01-01

    The cementation methods for immobilisation of radioactive wastes are discussed in terms of methodology, chemistry and properties of the different types of cements as well as the worldwide experience in this field. Two facilities for cementation - DEWA and MOWA - are described in details

  8. Cementing a wellbore using cementing material encapsulated in a shell

    Energy Technology Data Exchange (ETDEWEB)

    Aines, Roger D.; Bourcier, William L.; Duoss, Eric B.; Spadaccini, Christopher M.; Cowan, Kenneth Michael

    2016-08-16

    A system for cementing a wellbore penetrating an earth formation into which a pipe extends. A cement material is positioned in the space between the wellbore and the pipe by circulated capsules containing the cement material through the pipe into the space between the wellbore and the pipe. The capsules contain the cementing material encapsulated in a shell. The capsules are added to a fluid and the fluid with capsules is circulated through the pipe into the space between the wellbore and the pipe. The shell is breached once the capsules contain the cementing material are in position in the space between the wellbore and the pipe.

  9. Cementing a wellbore using cementing material encapsulated in a shell

    Energy Technology Data Exchange (ETDEWEB)

    Aines, Roger D.; Bourcier, William L.; Duoss, Eric B.; Floyd, III, William C.; Spadaccini, Christopher M.; Vericella, John J.; Cowan, Kenneth Michael

    2017-03-14

    A system for cementing a wellbore penetrating an earth formation into which a pipe extends. A cement material is positioned in the space between the wellbore and the pipe by circulated capsules containing the cement material through the pipe into the space between the wellbore and the pipe. The capsules contain the cementing material encapsulated in a shell. The capsules are added to a fluid and the fluid with capsules is circulated through the pipe into the space between the wellbore and the pipe. The shell is breached once the capsules contain the cementing material are in position in the space between the wellbore and the pipe.

  10. The mechanical effect of the existing cement mantle on the in-cement femoral revision.

    LENUS (Irish Health Repository)

    Keeling, Parnell

    2012-08-01

    Cement-in-cement revision hip arthroplasty is an increasingly popular technique to replace a loose femoral stem which retains much of the original cement mantle. However, some concern exists regarding the retention of the existing fatigued and aged cement in such cement-in-cement revisions. This study investigates whether leaving an existing fatigued and aged cement mantle degrades the mechanical performance of a cement-in-cement revision construct.

  11. Cementing quality evaluation with ultrasonic logs in fiberglass casings; Avaliacao da qualidade do cimento em revestimentos de fibra de vidro

    Energy Technology Data Exchange (ETDEWEB)

    Campos, Wellington; Lazaro, Andre F. [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2008-07-01

    The sonic and ultrasonic profiles are used as the main tools in assessing the cementing quality between formation and casing in oil wells. This assessment is important, because, if there is a failure in the primary cementing, both the structural integrity and zone isolation will be compromised. The sonic profiles are based on the acoustic energy attenuation in casing, cement and formation, while the ultrasonic profiles are based on the resonance of the wave pulse within the media where they travel (casings, cement and formation). The attenuation and resonance are due to the difference in the way the wave travel within these media. The acoustic impedance is the quantification of this difference, determining the refraction and reflection between the environments, and wave attenuation as well. In steel casings, this difference is meaningful, allowing the captured signals (reflected pulses) to be interpreted as good adhesion between cement and casing, or a lack of adhesion at some interval. In fiber glass casings, the impedance contrast between glass and cement is small and not detectable with the CBL/VDL sensors. The CBL/VDL tools provide an inefficient assessment of the quality of the cementing. The ultrasonic profile does not have this problem, theoretically. The goal of this work is to demonstrate and recommend the ultrasonic tool as the main instrument to assess the cementation quality in fiber glass casings. (author)

  12. Recycle Glass in Foam Glass Production

    DEFF Research Database (Denmark)

    Petersen, Rasmus Rosenlund; König, Jakob; Yue, Yuanzheng

    The foam glass industry turn recycle glass into heat insulating building materials. The foaming process is relative insensitive to impurities in the recycle glass. It is therefore considered to play an important role in future glass recycling. We show and discuss trends of use of recycled glasses...... in foam glass industry and the supply sources and capacity of recycle glass....

  13. Resistance against bacterial leakage of four luting agents used for cementation of complete cast crowns.

    Science.gov (United States)

    Zmener, Osvaldo; Pameijer, Cornelis H; Hernández, Sandra

    2014-02-01

    To assess the sealing properties of four luting materials used for cementation of full cast crowns. 40 human premolars were prepared with a chamfer finish line. Stone dies were fabricated and copings were waxed, invested and cast in gold. Ten samples (n = 10) were randomly assigned to four groups. In two groups, resin modified glass-ionomer cements were used, ACTIVA BioACTIVE-CEMENT/BASE/LINER and FujiCem2; the third group received the self-adhesive resin cement Embrace WetBond, while the fourth group served as control with a zinc phosphate cement. After cementation, excess cement was removed followed by bench-set for 10 minutes. All samples were stored in water at 37 degrees C and subjected to thermal cycling (x2000 between 5 and 55 degrees C). Subsequently the occlusal surface was reduced exposing the dentin. After sterilization the specimens were subjected to bacterial microleakage with E. faecalis in a dual chamber apparatus for a period of 60 days. Bacterial leakage was checked daily. Data were analyzed using the Kaplan-Meyer survival test. Significant pairwise differences were analyzed using the Log Rank test and the Fishers' exact test at P < 0.05. ACTIVA BioACTIVE-CEMENT/BASE/LINER, FujiCem2 and Embrace WetBond showed the lowest microleakage scores and differed statistically significantly (P < 0.05) from zinc phosphate cement.

  14. Evaluation of retentive strength of four luting cements with stainless steel crowns in primary molars: An in vitro study.

    Science.gov (United States)

    Parisay, Iman; Khazaei, Yegane

    2018-01-01

    Stainless steel crown (SSC) is the most reliable restoration for primary teeth with extensive caries. Retention is of great importance for a successful restoration and is provided by various factors such as luting cements. The aim of this study was to evaluate the retentive strength of SSC cemented with four different luting cements. In this in vitro study, A total of 55 extracted primary first molars were selected. Following crown selection and cementation (one with no cement and four groups cemented with resin, glass ionomer, zinc phosphate, and polycarboxylate), all the specimens were incubated and thermocycled in 5°C-55°C. Retentive properties of SSCs were tested with a mechanical test machine. First dislodgement of each specimen and full crown removal were recorded. One-way ANOVA test followed by least significant difference test and Kruskal-Wallis test was used for retentive strength comparison at the level of significance of P cemented with zinc phosphate exhibited higher retentive strength as compared to glass ionomer and polycarboxylate ( P cement showed the most promising results; thus, it can be preferably used for cementation of the teeth with no grossly broken down crowns.

  15. Effect of surface treatment of prefabricated posts on bonding of resin cement

    DEFF Research Database (Denmark)

    Sahafi, Alireza; Peutzfeld, Anne; Asmussen, Erik

    2004-01-01

    This in vitro study evaluated the effect of various surface treatments of prefabricated posts of titanium alloy (ParaPost XH), glass fiber (ParaPost Fiber White) and zirconia (Cerapost) on the bonding of two resin cements: ParaPost Cement and Panavia F by a diametral tensile strength (DTS) test...... the start of mixing the resin cement, the specimen was freed from the mold and stored in water at 37 degrees C for seven days. Following water storage, the specimen was wet-ground to a final length of approximately 3 mm. The DTS of specimens was determined in a Universal Testing Machine. The bonding...

  16. In vitro evaluation of microleakage of various types of dental cements

    Directory of Open Access Journals (Sweden)

    Medić Vesna

    2010-01-01

    Full Text Available Introduction. Microleakage is defined as the clinically undetectable seepage of oral fluids containing bacteria and debris between cement layer and tooth restoration. Objective. This in vitro study investigated the effect of different dental cements (zinc-phosphate, polycarboxylate, glass-ionomer and resin cement on microleakage in different ceramic crown systems (metal ceramic crown, metal ceramic crown with a porcelain margin, Empress 2 and In Ceram all-ceramic crowns fixed on extracted human teeth. Methods. One hundred and sixty intact human premolars were randomized to four groups of forty teeth each, according to the different ceramic crown systems. They were prepared in a standardized manner for metal-ceramic and all-ceramic crowns. Crowns were made following a standard laboratory technique, and each group of crowns were divided into four groups according to the different cement agents and cemented on their respective abutments. The specimens were subjected to thermocycling, placed in methylene blue solutions, embedded in resin blocks and vertically cut in the bucco-oral and meso-distal direction. The microleakage in the area of tooth-cement interface was defined as linear penetration of methylene blue and was determined with a microscope to assign microleakage scores using a five-point scale. Results. A significant association was found between a cement type and degree of microleakage (p=0.001. No statistically significant differences were found among the different ceramic crown systems luted with the same dental cement. The smallest degree of microleakage was observed in specimens luted with resin cement (X=1.73, followed by glass-ionomer cement (X=2.45 and polycarboxylate cement (X=3.20. The greatest degree of microleakage was detected in the crowns fixed with zincphosphate cement (X=3.33. Conclusion. The investigated dental cements revealed different sealing abilities. The use of resin cement resulted in the percentage of 0

  17. The biocompatibility of modified experimental Portland cements with potential for use in dentistry.

    Science.gov (United States)

    Camilleri, J

    2008-12-01

    To evaluate the biocompatibility of a group of new potential dental materials and their eluants by assessing cell viability. Calcium sulpho-aluminate cement (CSA), calcium fluoro-aluminate cement (CFA) and glass-ionomer cement (GIC; Ketac Molar), used as the control, were tested for biocompatibility. Using a direct test method cell viability was measured quantitatively using alamarBluetrade mark dye, and an indirect test method where cells were grown on material elutions and cell viability was assessed using methyltetrazolium (MTT) assay as recommended by ISO 10 993-Part 5 for in vitro testing. Statistical analysis was performed by analysis of variance and Tukey multi-comparison test method. Elution collected from the prototype cements and the GIC cured for 1 and 7 days allowed high cell activity after 24 h cell exposure, which reduced after 48 h when compared to the nontoxic glass-ionomer control, but increased significantly after 72 h cell contact. Elutions collected after 28 days revealed reduced cell activity at all cell exposure times. Cells placed in direct contact with the prototype materials showed reduced cell activity when compared with the control. Cell growth was poor when seeded in direct contact with the prototype cements. GIC encouraged cell growth after 1 day of contact. The eluted species for all the cements tested exhibited adequate cell viability in the early ages with reduced cell activity at 28 days. Changes in the production of calcium hydroxide as a by-product of cement hydration affect the material biocompatibility adversely.

  18. Influência da aplicação de flúor sobre a rugosidade superficial do ionômero de vidro Vitremer e adesão microbiana a este material Influence of the application of fluoride on the superficial roughness of Vitremer glass ionomer cement and microbial adhesion to this material

    Directory of Open Access Journals (Sweden)

    Denise PEDRINI

    2001-03-01

    Full Text Available Os cimentos ionoméricos representam importante opção de material restaurador em Odontologia e sua adesão à estrutura dental, diminuindo a infiltração marginal, somada à liberação de flúor, inibindo o metabolismo de microrganismos acidogênicos e favorecendo a remineralização dental, podem diminuir a ocorrência de cárie secundária. A aplicação tópica de géis acidulados ou neutros contendo flúor tem sido largamente utilizada em Odontologia. No entanto, este procedimento pode afetar a integridade dos materiais restauradores, aumentando sua rugosidade e a retenção de placa bacteriana. Dessa forma, o presente estudo avaliou o período de tempo no qual o cimento ionomérico Vitremer mantém sua capacidade inibitória sobre Streptococcus mutans ATCC 25175 e a adesão dos mesmos sobre a superfície do material, bem como a influência da aplicação tópica de flúor acidulado e neutro sobre esses parâmetros microbiológicos e as características superficiais daquele material. Verificou-se que a atividade antimicrobiana do cimento ionomérico Vitremer se mantém por aproximadamente quatro dias e não é recuperada com o uso de flúor gel acidulado ou neutro. Observou-se, também, que Streptococcus mutans ATCC 25175 adere ao material restaurador testado sendo que a aplicação tópica de flúor não influenciou esta adesão. As características superficiais desses materiais não se alteraram com a aplicação dos géis.Glass ionomer cements are important options in restorative and preventive dentistry due to their adhesion to the tooth surface and to fluoride release, which can decrease the risk of recurrent caries. The topical use of acidulated and neutral fluoride gels has been frequent in dentistry. However, this procedure can adversely affect the surface of restorative materials, increasing their roughness and the retention of dental plaque. Thus, this study evaluated the period in which Vitremer glass ionomer cement maintains

  19. Effects of a glass-ionomer cement on the remineralization of occlusal caries: an in situ study Efeito de um cimento de ionômero de vidro sobre a remineralização de cárie na superfície oclusal: estudo in situ

    Directory of Open Access Journals (Sweden)

    Mônica Tostes Amaral

    2006-04-01

    Full Text Available This work evaluated the remineralization of demineralized enamel of pits and fissures of human third molars sealed with a glass ionomer cement (Fuji IX, GC Corporation - Japan or with a Bis-GMA sealant (Delton - Dentsply. Ten volunteers participated in this in situ study that consisted of two thirty-day periods using intra-oral devices, with a week’s interval in between. Four experimental treatment procedures and one control were randomly assigned to the volunteers’ specimens: Group I, no treatment, control; Group II, artificial caries process; Group III, same treatment as Group II, but sealed with Delton (Dentsply; Group IV, same treatment as Group II, but sealed with Fuji IX (GC Corporation - Japan; Group V, same treatment as Group II and no sealing. Groups I and II were not submitted to the oral environment and served as controls. After a period of 30 days in the oral environment, the specimens were removed from the devices, embedded in acrylic resin, ground flat and polished. Then, Knoop hardness tests were performed, with a 25 g static load applied for 15 seconds. The measurements were made from the base of the fissure up to an opening of 600 µm, pre-established between the inclines of the cusps. Three indentations were then made, located at 25, 75, and 125 µm in depth from the outer enamel margin and 100 µm apart from each other (Micromet 2003. The Brieger F and Bonferroni’s tests were applied to the measurements. It was concluded that sealing with the glass ionomer cement Fuji IX was capable of making the enamel of pits and fissures more resistant by increasing the value of Knoop hardness.Esta pesquisa avaliou a remineralização do esmalte de fóssulas e fissuras de terceiros molares humanos previamente desmineralizados e selados com um cimento de ionômero de vidro (Fuji IX, GC Corporation - Japão ou com um selante de Bis-GMA (Delton-Dentsply. Dez voluntários participaram deste estudo in situ que consistiu de dois per

  20. Effects of fibers on expansive shotcrete mixtures consisting of calcium sulfoaluminate cement, ordinary Portland cement, and calcium sulfate

    Directory of Open Access Journals (Sweden)

    H. Yu

    2018-04-01

    Full Text Available The mining industry often uses shotcrete for ground stabilization. However, cracking within shotcrete is commonly observed, which delays production schedules and increases maintenance costs. A possible crack reduction method is using expansive shotcrete mixture consisting of calcium sulfoaluminate cement (CSA, ordinary Portland cement (OPC, and calcium sulfate (CS to reduce shrinkage. Furthermore, fibers can be added to the mixture to restrain expansion and impede cracking. The objective of this paper is to study the effects of nylon fiber, glass fiber, and steel fiber on an expansive shotcrete mixture that can better resist cracking. In this study, parameters such as density, water absorption, volume of permeable voids, unconfined compressive strength (UCS, splitting tensile strength (STS, and volume change of fiber-added expansive mixtures were determined at different time periods (i.e. the strengths on the 28th day, and the volume changes on the 1st, 7th, 14th, 21st, and 28th days. The results show that addition of fibers can improve mixture durability, in the form of decreased water absorption and reduced permeable pore space content. Moreover, the expansion of the CSA-OPC-CS mixture was restrained up to 50% by glass fiber, up to 43% by nylon fiber, and up to 28% by steel fiber. The results show that the STS was improved by 57% with glass fiber addition, 43% with steel fiber addition, and 38% with nylon fiber addition. The UCS was also increased by 31% after steel fiber addition, 26% after nylon fiber addition, and 16% after glass fiber addition. These results suggest that fiber additions to the expansive shotcrete mixtures can improve durability and strengths while controlling expansion. Keywords: Shotcrete, Restrained expansion, Fibers, Calcium sulfoaluminate cement (CSA, Ordinary Portland cement (OPC, Calcium sulfate (CS

  1. Cosmos & Glass

    DEFF Research Database (Denmark)

    Beim, Anne

    1996-01-01

    The article unfolds the architectural visions of glass by Bruno Taut. It refers to inspirations by Paul Sheerbart and litterature and the Crystal Chain, also it analyses the tectonic univers that can be found in the glass pavillion for the Werkbund exposition in Cologne....

  2. Glass Glimpsed

    DEFF Research Database (Denmark)

    Lock, Charles

    2015-01-01

    Glass in poetry as it reflects the viewer and as its power of reflection are both reduced and enhanced by technology.......Glass in poetry as it reflects the viewer and as its power of reflection are both reduced and enhanced by technology....

  3. Spin glasses

    CERN Document Server

    Bovier, Anton

    2007-01-01

    Spin glass theory is going through a stunning period of progress while finding exciting new applications in areas beyond theoretical physics, in particular in combinatorics and computer science. This collection of state-of-the-art review papers written by leading experts in the field covers the topic from a wide variety of angles. The topics covered are mean field spin glasses, including a pedagogical account of Talagrand's proof of the Parisi solution, short range spin glasses, emphasizing the open problem of the relevance of the mean-field theory for lattice models, and the dynamics of spin glasses, in particular the problem of ageing in mean field models. The book will serve as a concise introduction to the state of the art of spin glass theory, usefull to both graduate students and young researchers, as well as to anyone curious to know what is going on in this exciting area of mathematical physics.

  4. Cytotoxicity Comparison of Harvard Zinc Phosphate Cement Versus Panavia F2 and Rely X Plus Resin Cements on Rat L929-fibroblasts.

    Science.gov (United States)

    Mahasti, Sahabi; Sattari, Mandana; Romoozi, Elham; Akbar-Zadeh Baghban, Alireza

    2011-01-01

    Resin cements, regardless of their biocompatibility, have been widely used in restorative dentistry during the recent years. These cements contain hydroxy ethyl methacrylate (HEMA) molecules which are claimed to penetrate into dentinal tubules and may affect dental pulp. Since tooth preparation for metal ceramic restorations involves a large surface of the tooth, cytotoxicity of these cements would be more important in fixed prosthodontic treatments. The purpose of this study was to compare the cytotoxicity of two resin cements (Panavia F2 and Rely X Plus) versus zinc phosphate cement (Harvard) using rat L929-fibroblasts in vitro. In this experimental study, ninety hollow glass cylinders (internal diameter 5-mm, height 2-mm) were made and divided into three groups. Each group was filled with one of three experimental cements; Harvard Zinc Phosphate cement, Panavia F2 resin cement and Rely X Plus resin cement. L929- Fibroblast were passaged and subsequently cultured in 6-well plates of 5×10(5) cells each. The culture medium was RPMI_ 1640. All samples were incubated in CO2. Using enzyme-linked immune-sorbent assay (ELISA) and (3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) (MTT) assay, the cytotoxicity of the cements was investigated at 1 hour, 24 hours and one week post exposure. Statistical analyses were performed via two-way ANOVA and honestly significant difference (HSD) Tukey tests. This study revealed significant differences between the three cements at the different time intervals. Harvard cement displayed the greatest cytotoxicity at all three intervals. After 1 hour Panavia F2 showed the next greatest cytotoxicity, but after 24-hours and oneweek intervals Rely X Plus showed the next greatest cytotoxicity. The results further showed that cytotoxicity decreased significantly in the Panavia F2 group with time (pHarvard cement group failed to showed no noticeable change in cytotoxicity with time. Although this study has limitations, it provides

  5. Mineral resource of the month: hydraulic cement

    Science.gov (United States)

    van Oss, Hendrik G.

    2012-01-01

    Hydraulic cements are the binders in concrete and most mortars and stuccos. Concrete, particularly the reinforced variety, is the most versatile of all construction materials, and most of the hydraulic cement produced worldwide is portland cement or similar cements that have portland cement as a basis, such as blended cements and masonry cements. Cement typically makes up less than 15 percent of the concrete mix; most of the rest is aggregates. Not counting the weight of reinforcing media, 1 ton of cement will typically yield about 8 tons of concrete.

  6. Study of the influence of chemical composition on the pozzolanicity of soda-lime glass microparticles

    International Nuclear Information System (INIS)

    Sales, R.B.C.; Mohallem, N.D.S.; Aguilar, M.T.P.

    2014-01-01

    The use of residues presents interesting possibilities for obtaining eco-efficient concretes. Research has investigated the use of glass residue in Portland cement composite, whether as an aggregate or a supplementary material. However, there is still no consensus on the influence of the chemical composition of glass on the behaviour of the composites in which it is used. This paper aims to analyse the influence of this composition on the performance of cement composites produced with microparticles of colourless and amber glass. Pozzolanicity was assessed by means of direct tests (modified Chapelle and electrical conductivity) and indirect tests (chemical characterization, X-ray diffraction, thermo analysis and pozzolanic activity index). Most of the results show that microparticles of both types of glass display pozzolanic activity, with no significant differences between them. This indicates the potential for the use of glass microparticles as a supplementary material in cement composites. (author)

  7. Cement-latex grouting mortar for cementing boreholes

    Energy Technology Data Exchange (ETDEWEB)

    Kateev, I S; Golyshkina, L A; Gorbunova, I V; Kurochkin, B M; Vakula, Ya V

    1980-01-01

    The need for the development of cement-latex grouting mortar for the purpose of separating strata when reinforcing boreholes at deposits in the Tatar Associated SSR is evaluated. Results of studies of the physical and mechanical properties of cement-latex grouting mortar systems (mortar plus brick) are presented. Formulas for preparing cement-latex grouting mortor are evaluated and results of industrial tests of such mortars shown.

  8. US cement industry

    Energy Technology Data Exchange (ETDEWEB)

    Nisbet, M.A.

    1997-12-31

    This paper describes the cement and concrete industry, and provides data on energy use and carbon dioxide emissions. The potential impact of an energy tax on the industry is briefly assessed. Opportunities identified for reducing carbon dioxide emissions include improved energy efficiency, alternative fuels, and alternative materials. The key factor in determining CO{sub 2} emissions is the level of domestic production. The projected improvement in energy efficiency and the relatively slow growth in domestic shipments indicate that CO{sub 2} emissions in 2000 should be about 5% above the 1990 target. However, due to the cyclical nature of cement demand, emissions will probably be above target levels during peak demand and below target levels during demand troughs. 7 figs., 2 tabs.

  9. Chemical environment in cements

    International Nuclear Information System (INIS)

    Glasser, F.B.; Angus, M.J.; McCulloch, C.E.; Macphee, D.; Rahman, A.A.

    1984-01-01

    The alkalinity of Portland cements is responsible for precipitation and low solubility of many radwastes species. The sources of alkalinity are evaluated and two chemical models, based on experimental and theoretical data presented enabling the effect of blending agents (PFA, silica fume, etc.) to be evaluated and the alkalinity of the system at longer ages predicted. The data take the form of a solubility model which is applicable to non-heat generating wastes. 7 refs., 10 figs

  10. Performance of Cement Containing Laterite as Supplementary Cementing Material

    Directory of Open Access Journals (Sweden)

    Abbas Bukhari, Z. S.

    2013-03-01

    Full Text Available The utilization of different industrial waste, by-products or other materials such as ground granulated blast furnace slag, silica fume, fly ash, limestone, and kiln dust, etc. as supplemen- tary cementing materials has received considerable attention in recent years. A study has been conducted to look into the performance of laterite as Supplementary Cementing Materials (SCM. The study focuses on compressive strength performance of blended cement containing different percentage of laterite. The cement is replaced accordingly with percentage of 2 %, 5 %, 7 % and 10 % by weight. In addition, the effect of use of three chemically different laterites have been studied on physical performance of cement as in setting time, Le-Chatlier expansion, loss on ignition, insoluble residue, free lime and specifically compressive strength of cement cubes tested at the age of 3, 7, and 28 days. The results show that the strength of cement blended with laterite as SCM is enhanced. Key words: Portland cement, supplementary cementing materials (SCM, laterite, compressive strength KUI – 6/2013 Received January 4, 2012 Accepted February 11, 2013

  11. Marginal ridge fracture resistance, microleakage and pulpal response to glass ionomer/glass cermet partial tunnel restorations.

    Science.gov (United States)

    Prabhu, N T; Munshi, A K; Shetty, T R

    1997-01-01

    Sixty sound premolars which were to be extracted for orthodontic treatment purposes were restored either with glass ionomer cement or glass cermet cements after partial tunnel preparation, and prior to the extraction after a time interval of 30 and 60 days respectively. The teeth were then subjected to marginal ridge fracture resistance, microleakage study using dye penetration and histological evaluation of the pulpal response to these materials. Both the materials exhibited increase in marginal ridge fracture resistance at 60 days, with minimal degree of microleakage and were biologically compatible with the dental pulp.

  12. Barium aluminate cement: its application

    International Nuclear Information System (INIS)

    Drozdz, M.; Wolek, W.

    1975-01-01

    The technology of manufacturing barium aluminate cement from barium sulfate and alumina, using a rotary kiln for firing the clinker is described. The method of granulation of the homogenized charge was used. Conditions of using the ''to mud'' method in industry were indicated. The physical and chemical properties of barium aluminate cement are determined and the quality of several batches of cement prepared on a semi-industrial scale and their suitability for making highly refractory concretes are tested. The optimal composition of the concretes is determined as a function of the mixing water and barium aluminate cement contents. Several experimental batches of concretes were used in the linings of furnaces in the steel industry. The suitability of these cements for use in fields other than steelmaking is examined. It is established that calcium aluminate cement has certain limited applications [fr

  13. Acoustic probing of elastic behavior and damage in weakly cemented granular media

    Science.gov (United States)

    Langlois, V.; Jia, X.

    2014-02-01

    We investigate the elastic behavior and damage of weakly cemented granular media under external load with ultrasound. The cementation controlled experiments are performed by freezing the capillary liquid at the bead contact in a dense glass or polymeric [poly(methyl methacrylate)] bead pack wet by tetradecane of volume fraction ϕ = 0.1%-4%. When the pendular rings are solidified, an abrupt increase by a factor of 2 in the compressional wave velocity is observed. We interpret the data in terms of effective medium models in which the contact stiffnesses are derived by either a bonded contact model [P. J. Digby, J. Appl. Mech. 48, 803 (1981), 10.1115/1.3157738] or a cemented contact model [J. Dvorkin, A. Nur, and H. Yin, Mech. Mater. 18, 351 (1994), 10.1016/0167-6636(94)90044-2]. The former fails to quantitatively account for the results with a soft cement relative to the grain, whereas the latter considering the mechanical properties of the cement does apply. Moreover, we monitor the irreversible behavior of the cemented granular packs under moderate uniaxial loading (cemented materials is accompanied by a compressional wave velocity decrease up to 60%, likely due to the fractures induced at the grain-cement interfaces.

  14. Relining effects on the push-out shear bond strength of glass fiber posts

    Directory of Open Access Journals (Sweden)

    Adriana Rosado Valente ANDRIOLI

    Full Text Available Abstract Introduction The correct use of glass fiber posts in endodontically treated teeth is essential for the clinical success of restorative treatment. Objective This study evaluated the push-out shear bond strength of relined (R or non-relined (NR glass fiber posts, cemented with self-adhesive resin cement [RelyXTM U100 (U100] and conventional resin cement [RelyXTM ARC (ARC]. Material and method Sixty human single-rooted teeth were endodontically treated and divided into ARC-NR; U100-NR; ARC-R; U100-R groups. The teeth were sectioned into cervical, middle and apical thirds, and subjected to the push-out test. Bond strength was analyzed by the Friedman test; cement and post types were compared by the Mann Whitney test. The pattern of failures was evaluated with digital camera through images at 200x magnification, and was classified as adhesive (at the cement/dentin or cement/post interface, cohesive (cement or post, and mixed failures. Result In ARC-NR, bond strength values were higher in the cervical third; in U100-NR and ARC-R they were similar between the thirds. In U100-R, in the cervical and middle thirds the bond strength values were similar, and there was lower value in the apical third. For non-relined glass fiber posts, the highest mean bond strength values were observed with self-adhesive resin cement. Whereas, relined posts cemented with conventional resin cement had stronger cement layer in comparison with non-relined fiber posts. Conclusion The post relining technique was efficient in ARC-R. ARC-NR and U100-R showed improved bond strength in the cervical region of canal walls. The main failures were adhesive at the cement-post interface.

  15. Stability of reinforced cemented backfills

    International Nuclear Information System (INIS)

    Mitchell, R.J.; Stone, D.M.

    1987-01-01

    Mining with backfill has been the subject of several international meetings in recent years and a considerable research effort is being applied to improve both mining economics and ore recovery by using backfill for ground support. Classified mill tailings sands are the most commonly used backfill material but these fine sands must be stabilized before full ore pillar recovery can be achieved. Normal portland cement is generally used for stabilization but the high cost of cement prohibits high cement usage. This paper considers the use of reinforcements in cemented fill to reduce the cement usage. It is concluded that strong cemented layers at typical spacings of about 3 meters in a low cement content bulk fill can reinforce the fill and reduce the overall cement usage. Fibre reinforcements introduced into strong layers or into bulk fills are also known to be effective in reducing cement usage. Some development work is needed to produce the ideal type of anchored fibre in order to realize economic gains from fibre-reinforced fills

  16. GLASS BOX

    National Research Council Canada - National Science Library

    Curtis, Laura

    2008-01-01

    The goals of this effort were to develop Glass Box capabilities to allow for the capturing of analyst activities and the associated data resources, track and log the results of automated processing...

  17. CLAY SOIL STABILISATION USING POWDERED GLASS

    Directory of Open Access Journals (Sweden)

    J. OLUFOWOBI

    2014-10-01

    Full Text Available This paper assesses the stabilizing effect of powdered glass on clay soil. Broken waste glass was collected and ground into powder form suitable for addition to the clay soil in varying proportions namely 1%, 2%, 5%, 10% and 15% along with 15% cement (base by weight of the soil sample throughout. Consequently, the moisture content, specific gravity, particle size distribution and Atterberg limits tests were carried out to classify the soil using the ASSHTO classification system. Based on the results, the soil sample obtained corresponded to Group A-6 soils identified as ‘fair to poor’ soil type in terms of use as drainage and subgrade material. This justified stabilisation of the soil. Thereafter, compaction, California bearing ratio (CBR and direct shear tests were carried out on the soil with and without the addition of the powdered glass. The results showed improvement in the maximum dry density values on addition of the powdered glass and with corresponding gradual increase up to 5% glass powder content after which it started to decrease at 10% and 15% powdered glass content. The highest CBR values of 14.90% and 112.91% were obtained at 5% glass powder content and 5mm penetration for both the unsoaked and soaked treated samples respectively. The maximum cohesion and angle of internal friction values of 17.0 and 15.0 respectively were obtained at 10% glass powder content.

  18. The effect of temperature on compressive and tensile strengths of commonly used luting cements: an in vitro study.

    Science.gov (United States)

    Patil, Suneel G; Sajjan, Mc Suresh; Patil, Rekha

    2015-02-01

    The luting cements must withstand masticatory and parafunctional stresses in the warm and wet oral environment. Mouth temperature and the temperature of the ingested foods may induce thermal variation and plastic deformation within the cements and might affect the strength properties. The objectives of this study were to evaluate the effect of temperature on the compressive and diametral tensile strengths of two polycarboxylate, a conventional glass ionomer and a resin modified glass ionomer luting cements and, to compare the compressive strength and the diametral tensile strength of the selected luting cements at varying temperatures. In this study, standardized specimens were prepared. The temperature of the specimens was regulated prior to testing them using a universal testing machine at a crosshead speed of 1 mm/min. Six specimens each were tested at 23°C, 37°C and 50°C for both the compressive and diametral tensile strengths, for all the luting cements. All the luting cements showed a marginal reduction in their compressive and diametral tensile strengths at raised temperatures. Fuji Plus was strongest in compression, followed by Fuji I > Poly F > Liv Carbo. Fuji Plus had the highest diametral tensile strength values, followed by Poly F = Fuji I = Liv Carbo, at all temperatures. An increase in the temperature caused no significant reduction in the compressive and diametral tensile strengths of the cements evaluated. The compressive strength of the luting cements differed significantly from one another at all temperatures. The diametral tensile strength of resin modified glass ionomers differed considerably from the other cements, whereas there was no significant difference between the other cements, at all the temperatures.

  19. Using dehydrated cement paste as new type of cement additive

    NARCIS (Netherlands)

    Yu, R.; Shui, Z.H.; Dong, J

    2013-01-01

    This paper presents an experimental study, including evaluation and modification, on using dehydrated cement paste (DCP) as a new type of cement additive. After a series of processes, normal DCP (N-DCP) was produced as before and a modified form of DCP (M-DCP) was produced as well. The cementitious

  20. The use of glass powder in making batako

    Science.gov (United States)

    Nursyamsi, N.; Indrawan, I.

    2018-02-01

    Along with the increase in construction materials, innovation is needed to lessen the use of them, and one of them is by using cement [1]. In this research, it is reduced by glass powder; the reason for using it as the substitution of cement is that some chemical elements in cement are similar to those in glass powder such as SiO2, A12o3, Fe2O3, and CaO. The glass powder used was the one who passed sieve no. 100 and was hampered in sieve no. 200. It passed sieve no. 200 with its composition of 0%, 10%, 15%, 20%, 25%, and 30% from the volume of the use of cement. The specimen would treat within 28 days before the testing of compressive strength, water absorption, and tensile strength [2]. The variation which produced optimum result would mix with the foaming agent as the material for reducing the weight of the specimen. After that, the test of compressive strength, water absorption, and tensile strength on the installment of batako walls were done. The data analyzed by using SNI 02-0349-1989[3] reference about concrete brick for wall installment. The variation of 20% of glass powder passing sieve no. 200 gave optimum result. A specimen of the variation on glass powder of 20% which passed sieve no. 200 and the foaming agent was higher than the compressive strength of the specimen which used glass powder substitution of 0% of passing sieve no. 200 and foaming agent. The compressive strength of batako walls which used the batako construction with glass powder substitution of 20% of passing sieve no. 200 and the foaming agent was also higher than the compressive strength of the assaying object which used glass powder substitution of 0% of passing sieve no. 200 and foaming agent.

  1. Effects of Cement, Abutment Surface Pretreatment, and Artificial Aging on the Force Required to Detach Cantilever Fixed Dental Prostheses from Dental Implants.

    Science.gov (United States)

    Kappel, Stefanie; Chepura, Taras; Schmitter, Marc; Rammelsberg, Peter; Rues, Stefan

    To examine the in vitro effects of different cements, abutment surface preconditioning, and artificial aging on the maximum tensile force needed to detach cantilever fixed dental prostheses (FDPs) from dental implants with titanium abutments. A total of 32 tissue-level implants were combined with standardized titanium abutments. For each test group, eight cantilever FDPs were fabricated using selective laser melting (cobalt-chromium [CoCr] alloy). The inner surfaces of the cantilever FDPs and half of the abutments were sandblasted and then joined by use of four different cements (two permanent and two semi-permanent) in two different amounts per cement. Subgroups were tested after either artificial aging (thermocycling and chewing simulation) or 3 days of water storage. Finally, axial pull off-tests were performed for each abutment separately. Cement type and surface pretreatment significantly affected decementation behavior. The highest retention forces (approximately 1,200 N) were associated with sandblasted abutments and permanent cements. With unconditioned abutments, temporary cements (Fu cement (Fu ≈ 100 N), resulted in rather low retention forces. Zinc phosphate cement guaranteed high retention forces. After aging, retention was sufficient only for cementation with zinc phosphate cement and for the combination of sandblasted abutments and glass-ionomer cement. When glass-ionomer cement is used to fix cantilever FDPs on implants, sandblasting of standard titanium abutments may help prevent loss of retention. Retention forces were still high for FDPs fixed with zinc phosphate cement, even when the abutments were not pretreated. Use of permanent cements only, however, is recommended to prevent unwanted loosening of cantilever FDPs.

  2. Reinforcement of cement-based matrices with graphite nanomaterials

    Science.gov (United States)

    Sadiq, Muhammad Maqbool

    Cement-based materials offer a desirable balance of compressive strength, moisture resistance, durability, economy and energy-efficiency; their tensile strength, fracture energy and durability in aggressive environments, however, could benefit from further improvements. An option for realizing some of these improvements involves introduction of discrete fibers into concrete. When compared with today's micro-scale (steel, polypropylene, glass, etc.) fibers, graphite nanomaterials (carbon nanotube, nanofiber and graphite nanoplatelet) offer superior geometric, mechanical and physical characteristics. Graphite nanomaterials would realize their reinforcement potential as far as they are thoroughly dispersed within cement-based matrices, and effectively bond to cement hydrates. The research reported herein developed non-covalent and covalent surface modification techniques to improve the dispersion and interfacial interactions of graphite nanomaterials in cement-based matrices with a dense and well graded micro-structure. The most successful approach involved polymer wrapping of nanomaterials for increasing the density of hydrophilic groups on the nanomaterial surface without causing any damage to the their structure. The nanomaterials were characterized using various spectrometry techniques, and SEM (Scanning Electron Microscopy). The graphite nanomaterials were dispersed via selected sonication procedures in the mixing water of the cement-based matrix; conventional mixing and sample preparation techniques were then employed to prepare the cement-based nanocomposite samples, which were subjected to steam curing. Comprehensive engineering and durability characteristics of cement-based nanocomposites were determined and their chemical composition, microstructure and failure mechanisms were also assessed through various spectrometry, thermogravimetry, electron microscopy and elemental analyses. Both functionalized and non-functionalized nanomaterials as well as different

  3. Physical properties and comparative strength of a bioactive luting cement.

    Science.gov (United States)

    Jefferies, Steven; Lööf, Jesper; Pameijer, Cornelis H; Boston, Daniel; Galbraith, Colin; Hermansson, Leif

    2013-01-01

    New dental cement formulations require testing to determine physical and mechanical laboratory properties. To test an experimental calcium aluminate/glass-ionomer cement, Ceramir C and B (CC and B), regarding compressive strength (CS), film thickness (FT), net setting time (ST) and Vickers hardness. An additional test to evaluate potential dimensional change/expansion properties of this cement was also conducted. CS was measured according to a slightly modified ISO 9917:2003 for the CC and B specimens. The samples were not clamped while being exposed to relative humidity of great than 90 percent at 37 degrees C for 10 minutes before being stored in phosphate-buffered saline at 37 degrees C. For the CS, four groups were tested: Group 1-CC and B; Group 2-RelyX Luting Cement; Group 3-Fuji Plus; and Group 4-RelyX Unicem. Samples from all groups were stored for 24 hours before testing. Only CCandB was tested for ST and FT according to ISO 9917:2003. The FT was tested 2 minutes after mixing. Vickers hardness was evaluated using the CSM Microhardness Indentation Tester using zinc phosphate cement as a comparison material. Expansion testing included evaluating potential cracks in feldspathic porcelain jacket crowns (PJCs). The mean and standard deviation after 24 hours were expressed in MPa: Group 1 equals 160 plus or equal to 27; Group 2 equals 96 plus or equal to 10; Group 3 equals 138 plus or equal to 15; Group 4 equals 157 plus or equal to 10. A single-factor ANOVA demonstrated statistically significant differences between the groups (P less than 0.001). Pair-wise statistical comparison demonstrated a statistically significant difference between Groups 1 and 2. No statistically significant differences were found between other groups. The FT was 16.8 plus or equal to 0.9 and the ST was 4.8 plus or equal to 0.1 min. Vickers hardness for Ceramir C and B was 68.3 plus or equal to 17.2 and was statistically significantly higher (P less than 0.05) than Fleck's Zinc Phosphate

  4. Biomass for green cement

    Energy Technology Data Exchange (ETDEWEB)

    Cumming, R. [Lafarge Canada Inc., Calgary, AB (Canada)

    2006-07-01

    Lafarge examined the use of waste biomass products in its building materials and provided background information on its operations. Cement kiln infrastructure was described in terms of providing access to shipping, rail and highways; conveying and off-loading equipment; having large storage facilities; and, offering continuous monitoring and stack testing. The presentation identified the advantages and disadvantages of a few different biomass cases such as coal; scrap tires; non-recyclable household waste; and processed biomass. A chart representing landfill diversion rates was presented and the presentation concluded with a discussion of energy recovery and recycling. 1 tab., figs.

  5. Influence of curing conditions on durability of alkali-resistant glass ...

    Indian Academy of Sciences (India)

    Glass fibres in concrete material often increase the flexural strength. However, these fibres when in contact with cement are altered by alkali reactions due to the presence of portlandite. This study presents the results of investigation to show the effect of curing conditions on the durability of alkali-resistant glass fibres in ...

  6. Two-year survival of glass ionomer sealanTs placed as parT of ...

    African Journals Online (AJOL)

    2010-09-09

    Sep 9, 2010 ... Two-year survival of glass ionomer sealanTs placed as parT of proximal aTraumaTic. resToraTive ... absTracT. Objective: To evaluate after two years, the survival rate of glass ionomer cement (gic) ... or symptoms of periodontal disease, and clinically the ..... saliva contamination on the bond of dentine resin-.

  7. Fracture resistance of metal-free composite crowns-effects of fiber reinforcement, thermal cycling, and cementation technique.

    Science.gov (United States)

    Lehmann, Franziska; Eickemeyer, Grit; Rammelsberg, Peter

    2004-09-01

    The improved mechanical properties of contemporary composites have resulted in their extensive use for the restoration of posterior teeth. However, the influence of fiber reinforcement, cementation technique, and physical stress on the fracture resistance of metal-free crowns is unknown. This in vitro study evaluated the effect of fiber reinforcement, physical stress, and cementation methods on the fracture resistance of posterior metal-free Sinfony crowns. Ninety-six extracted human third molars received a standardized tooth preparation: 0.5-mm chamfer preparation and occlusal reduction of 1.3 to 1.5 mm. Sinfony (nonreinforced crowns, n=48) and Sinfony-Vectris (reinforced crowns, n=48) crowns restoring original tooth contour were prepared. Twenty-four specimens of each crown type were cemented, using either glass ionomer cement (GIC) or resin cement. Thirty-two crowns (one third) were stored in humidity for 48 hours. Another third was exposed to 10,000 thermal cycles (TC) between 5 degrees C and 55 degrees C. The remaining third was treated with thermal cycling and mechanical loading (TCML), consisting of 1.2 million axial loads of 50 N. The artificial crowns were then vertically loaded with a steel sphere until failure occurred. Significant differences in fracture resistance (N) between experimental groups were assessed by nonparametric Mann-Whitney U-test (alpha=.05). Fifty percent of the Sinfony and Sinfony-Vectris crowns cemented with glass ionomer cement loosened after thermal cycling. Thermal cycling resulted in a significant reduction in the mean fracture resistance for Sinfony crowns cemented with GIC, from 2037 N to 1282 N (P=.004). Additional fatigue produced no further effects. Fiber reinforcement significantly increased fracture resistance, from 1555 N to 2326 N (P=.001). The minimal fracture resistance was above 600 N for all combinations of material, cement and loading. Fracture resistance of metal-free Sinfony crowns was significantly increased by

  8. Process of preparing hydraulic cement

    Energy Technology Data Exchange (ETDEWEB)

    1919-12-11

    A process of preparing hydraulic cement from oil shale or shale coke is characterized in that the oil shale or shale coke after the distillation is burned long and hot to liberate the usual amount of carbonic acid and then is fine ground to obtain a slow hardening hydraulic cement.

  9. Health hazards of cement dust

    International Nuclear Information System (INIS)

    Meo, Sultan A.

    2004-01-01

    ven in the 21st century, millions of people are working daily in a dusty environment. They are exposed to different types of health hazards such as fume, gases and dust, which are risk factors in developing occupational disease. Cement industry is involved in the development of structure of this advanced and modern world but generates dust during its production. Cement dust causes lung function impairment, chronic obstructive lung disease, restrictive lung disease, pneumoconiosis and carcinoma of the lungs, stomach and colon. Other studies have shown that cement dust may enter into the systemic circulation and thereby reach the essentially all the organs of body and affects the different tissues including heart, liver, spleen, bone, muscles and hairs and ultimately affecting their micro-structure and physiological performance. Most of the studies have been previously attempted to evaluate the effects of cement dust exposure on the basis of spirometry or radiology, or both. However, collective effort describing the general effects of cement dust on different organ and systems in humans or animals, or both has not been published. Therefore, the aim of this review is to gather the potential toxic effects of cement dust and to minimize the health risks in cement mill workers by providing them with information regarding the hazards of cement dust. (author)

  10. Ceramic microspheres for cementing applications

    NARCIS (Netherlands)

    2011-01-01

    A method and apparatus for manufacturing ceramic microspheres from industrial slag. The microspheres have a particle size of about 38 microns to about 150 microns. The microspheres are used to create a cement slurry having a density of at least about 11 lbs/g. The resultant cement slurry may then be

  11. Ceramic microspheres for cementing applications

    NARCIS (Netherlands)

    2010-01-01

    A method and apparatus for manufacturing ceramic microspheres from industrial slag. The microspheres have a particle size of about 38 microns to about 150 microns. The microspheres are used to create a cement slurry having a density of at least about 11 lbs/g. The resultant cement slurry may then be

  12. Ceramic microspheres for cementing applications

    NARCIS (Netherlands)

    2012-01-01

    A method and apparatus for manufacturing ceramic microspheres from industrial slag. The microspheres have a particle size of about 38 microns to about 150 microns. The microspheres are used to create a cement slurry having a density of at least about 11 lbs/g. The resultant cement slurry may then be

  13. Corrosion resistant cemented carbide

    International Nuclear Information System (INIS)

    Hong, J.

    1990-01-01

    This paper describes a corrosion resistant cemented carbide composite. It comprises: a granular tungsten carbide phase, a semi-continuous solid solution carbide phase extending closely adjacent at least a portion of the grains of tungsten carbide for enhancing corrosion resistance, and a substantially continuous metal binder phase. The cemented carbide composite consisting essentially of an effective amount of an anti-corrosion additive, from about 4 to about 16 percent by weight metal binder phase, and with the remaining portion being from about 84 to about 96 percent by weight metal carbide wherein the metal carbide consists essentially of from about 4 to about 30 percent by weight of a transition metal carbide or mixtures thereof selected from Group IVB and of the Periodic Table of Elements and from about 70 to about 96 percent tungsten carbide. The metal binder phase consists essentially of nickel and from about 10 to about 25 percent by weight chromium, the effective amount of an anti-corrosion additive being selected from the group consisting essentially of copper, silver, tine and combinations thereof

  14. Mechanical behavior of a bi-layer glass ionomer

    NARCIS (Netherlands)

    Bonifácio, C.C.; de Jager, N.; Kleverlaan, C.J.

    2013-01-01

    Objective A high-viscosity consistency of the glass-ionomer cement (GIC) may lead to poor adaptation into the cavity. The use of a flowable GIC layer seemed to improve its adaptation in approximal restorations in vitro. In this study we assessed the flexural strength of a two-layered GIC, using a

  15. Alkali-activated blast furnace slag-zeolite cements and concretes

    International Nuclear Information System (INIS)

    Rakhimov, R.; Rakhimova, N.

    2012-01-01

    The aim of this work has been the study of alkali-activated slag-zeolite cements and concretes based on them. Various compositions have been tested and some characteristics such as the compressive strength have been measured versus zeolite additions. A table lists the specific surface area and particle size distributions of different cements. The conclusions of the study are the following. First, alkali-activated slag cements and concretes based on them are effective for immobilization of radioactive wastes and the production of building structures, designed for high radiation load. Secondly, zeolite-containing mineral additions are able to increase the immobilization capacity and radiation resistance of alkali-activated blast furnace slag cements and concretes. Thirdly, the efficiency of different zeolite-containing additions - 10% to increase alkali-activated blast furnace slag-zeolite cement strength was established. It is with alkaline components of water-glass, sodium carbonate, sodium sulphate. Fourth, the effective way of introducing zeolite additions in alkali-activated blast furnace slag-zeolite cement is inter-grinding of the slag and addition. Increase in strength of alkali-activated blast furnace slag-zeolite cement stone is 40% higher than that of the stone of a mixture of separately milled components. Fifth, Alkali-activated blast furnace slag-zeolite cements with zeolite-containing additions with a compressive strength of 10.1 to 140 MPa; alkali-activated blast furnace slag-zeolite cements mortars with compressive strength from 35.2 to 97.7 MPa; alkali-activated blast furnace slag-zeolite cements concretes with compressive strength up to 84.5 MPa and frost resistant up to 800 cycles were obtained

  16. Cytotoxicity and biocompatibility of Zirconia (Y-TZP posts with various dental cements

    Directory of Open Access Journals (Sweden)

    Hyeongsoon Shin

    2016-08-01

    Full Text Available Objectives Endodontically treated teeth with insufficient tooth structure are often restored with esthetic restorations. This study evaluated the cytotoxicity and biological effects of yttria partially stabilized zirconia (Y-TZP blocks in combination with several dental cements. Materials and Methods Pairs of zirconia cylinders with medium alone or cemented with three types of dental cement including RelyX U200 (3M ESPE, FujiCEM 2 (GC, and Panavia F 2.0 (Kuraray were incubated in medium for 14 days. The cytotoxicity of each supernatant was determined using 3-(4,5-dimethylthiazole-2-yl-2,5-diphenyltetrazolium bromide (MTT assays on L929 fibroblasts and MC3T3-E1 osteoblasts. The levels of interleukin-6 (IL-6 mRNA were evaluated by reverse transcription polymerase chain reaction (RT-PCR, and IL-6 protein was evaluated by enzyme-linked immunosorbent assays (ELISA. The data were analyzed using one-way ANOVA and Tukey post-hoc tests. A p < 0.05 was considered statistically significant. Results The MTT assays showed that MC3T3-E1 osteoblasts were more susceptible to dental cements than L929 fibroblasts. The resin based dental cements increased IL-6 expression in L929 cells, but reduced IL-6 expression in MC3T3-E1 cells. Conclusions Zirconia alone or blocks cemented with dental cement showed acceptable biocompatibilities. The results showed resin-modified glass-ionomer based cement less produced inflammatory cytokines than other self-adhesive resin-based cements. Furthermore, osteoblasts were more susceptible than fibroblasts to the biological effects of dental cement.

  17. Glass compositions

    Energy Technology Data Exchange (ETDEWEB)

    France, P W

    1985-05-30

    A fluoride glass for use in the production of optical fibres has an enhanced D/H ratio, preferably such that OD:OH is at least 9:1. In the example, such a glass is prepared by treating with D/sub 2/O a melt comprising 51.53 mole per cent ZrF/sub 4/, 20.47 mole per cent BaF/sub 2/, 5.27 mole per cent LaF/sub 3/, 3.24 mole per cent AlF/sub 3/, and 19.49 mole per cent LiF.

  18. The Retentive Strength of Cemented Zirconium Oxide Crowns after Dentin Pretreatment with Desensitizing Paste Containing 8% Arginine and Calcium Carbonate

    Science.gov (United States)

    Pilo, Raphael; Harel, Noga; Nissan, Joseph; Levartovsky, Shifra

    2016-01-01

    The effect of dentin pretreatment with Desensitizing Paste containing 8% arginine and calcium carbonate on the retention of zirconium oxide (Y-TZP) crowns was tested. Forty molar teeth were mounted and prepared using a standardized protocol. Y-TZP crowns were produced using computer-aided design and computer-aided manufacturing (CAD-CAM) technology. The 40 prepared teeth were either pretreated with Desensitizing Paste or not pretreated. After two weeks, each group was subdivided into two groups, cemented with either Resin Modified Glass Ionomer Cement (RMGIC) or Self Adhesive Resin Cement (SARC)). Prior to cementation, the surface areas of the prepared teeth were measured. After aging, the cemented crown-tooth assemblies were tested for retentive strength using a universal testing machine. The debonded surfaces of the teeth and crowns were examined microscopically at 10× magnification. Pretreating the dentin surfaces with Desensitizing Paste prior to cementation did not affect the retention of the Y-TZP crowns. The retentive values for RMGIC (3.04 ± 0.77 MPa) were significantly higher than those for SARC (2.28 ± 0.58 MPa). The predominant failure modes for the RMGIC and SARC were adhesive cement-dentin and adhesive cement-crown, respectively. An 8.0% arginine and calcium carbonate in-office desensitizing paste can be safely used to reduce post-cementation sensitivity without reducing the retentive strength of Y-TZP crowns. PMID:27023532

  19. The Retentive Strength of Cemented Zirconium Oxide Crowns after Dentin Pretreatment with Desensitizing Paste Containing 8% Arginine and Calcium Carbonate

    Directory of Open Access Journals (Sweden)

    Raphael Pilo

    2016-03-01

    Full Text Available The effect of dentin pretreatment with Desensitizing Paste containing 8% arginine and calcium carbonate on the retention of zirconium oxide (Y-TZP crowns was tested. Forty molar teeth were mounted and prepared using a standardized protocol. Y-TZP crowns were produced using computer-aided design and computer-aided manufacturing (CAD-CAM technology. The 40 prepared teeth were either pretreated with Desensitizing Paste or not pretreated. After two weeks, each group was subdivided into two groups, cemented with either Resin Modified Glass Ionomer Cement (RMGIC or Self Adhesive Resin Cement (SARC. Prior to cementation, the surface areas of the prepared teeth were measured. After aging, the cemented crown-tooth assemblies were tested for retentive strength using a universal testing machine. The debonded surfaces of the teeth and crowns were examined microscopically at 10× magnification. Pretreating the dentin surfaces with Desensitizing Paste prior to cementation did not affect the retention of the Y-TZP crowns. The retentive values for RMGIC (3.04 ± 0.77 MPa were significantly higher than those for SARC (2.28 ± 0.58 MPa. The predominant failure modes for the RMGIC and SARC were adhesive cement-dentin and adhesive cement-crown, respectively. An 8.0% arginine and calcium carbonate in-office desensitizing paste can be safely used to reduce post-cementation sensitivity without reducing the retentive strength of Y-TZP crowns.

  20. Glass: a candidate engineered material for management of high level nuclear waste

    International Nuclear Information System (INIS)

    Mishra, R.K.; Kaushik, C.P.

    2011-01-01

    While the commercial importance of glass is generally recognized, a few people are aware of extremely wide range of glass formulations that can be made and of the versatility of this engineered material. Some of the recent developments in the field of glass leading to various technological applications include glass fiber reinforcement of cement to give new building materials, substrates for microelectronics circuitry in form of semiconducting glasses, nuclear waste immobilization and specific medical applications. The present paper covers fundamental understanding of glass structure and its application for immobilization of high level radioactive liquid waste. High level radioactive liquid waste (HLW) arising during reprocessing of spent fuel are immobilized in sodium borosilicate glass matrix developed indigenously. Glass compositions are modified according to the composition of HLW to meet the criteria of desirable properties in terms. These glass matrices have been characterized for different properties like homogeneity, chemical durability, thermal stability and radiation stability. (author)

  1. Effect of thermocycling on the bond strength of a glass-infiltrated ceramic and a resin luting cement Efeito da ciclagem térmica sobre a resistência de união entre uma cerâmica infiltrada com vidro e um cimento resinoso

    Directory of Open Access Journals (Sweden)

    Osvaldo Daniel Andreatta Filho

    2003-03-01

    Full Text Available The aim of the present study was to evaluate the effect of thermocycling on the bond strength between the surface of the glass-infiltrated alumina ceramic In-Ceram (VITA and the Panavia F resin cement (Kuraray CO.. Four 5x6x6mm In-Ceram blocks were obtained. One of the 6x6mm faces of each block was conditioned with Cojet - System (tribochemical silica coating, ESPE-3M and then luted under a constant 750g pressure with Panavia F cement to another identical face of a resin composit block (Clearfil AP-X, Kuraray obtained by reproduction of the ceramic one from Express (3M addition curing silicone impressions. The four sets so formed by ceramic, luting cement and resin have been each one serially sectioned in 20 sticks so that the adhesive surface in each presented 1mm² of area. The samples were divided in 2 groups (n=10: G1- stored for 7 days in deionized water at 36 ± 2ºC; G2 - thermocycled 1500 times between 5 and 55ºC dwell times. The microtensile tests were accomplished in an universal testing machine (EMIC at a crosshead speed of 0,5 mm/min. The results showed that the mean tensile bond strength values (MPa for the group G2: (22,815 ± 5,254 had not statistically differ of the values of group G1: (25,628 ± 3,353 (t = 1,427; gl = 18; p-value = 0,171, at the level of a= 5%. It can be concluded that the thermocycling technique used in the present experiment had not produced statistically significant differences between the bond strength results of the specimens obtained by the two used techniques.O objetivo deste estudo foi avaliar o efeito da ciclagem térmica sobre a resistência de adesão entre a superfície da cerâmica In-Ceram Alumina (VITA e o cimento resinoso Panavia F (Kuraray. Foram confeccionados quatro blocos de cerâmica In-Ceram com dimensões de 5x6x6mm. Uma das faces com 6x6mm de cada bloco cerâmico, após condicionamento com o sistema Cojet (ESPE-3M (jateamento com óxido de alumínio/jateamento com óxido de s

  2. 21 CFR 888.4200 - Cement dispenser.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cement dispenser. 888.4200 Section 888.4200 Food... DEVICES ORTHOPEDIC DEVICES Surgical Devices § 888.4200 Cement dispenser. (a) Identification. A cement dispenser is a nonpowered syringe-like device intended for use in placing bone cement (§ 888.3027) into...

  3. Avaliação da microinfiltração marginal e profundidade de penetração dos cimentos de ionômero de vidro utilizados como selantes oclusais Evaluation of marginal microleakage and depth of penetration of glass ionomer cements used as occlusal sealants

    Directory of Open Access Journals (Sweden)

    Marina de Lourdes Calvo Fracasso

    2005-09-01

    Full Text Available OBJETIVE: the aim of this study was to conduct an in vitro comparison of marginal microleakage (MM and the depth of penetration (DP of glass ionomer cements (GIC and a resin sealant (RS into occlusal pit and fissures. METHODS: for that purpose, 60 intact third molars were equally distributed to 5 groups: G1 - 37% phosphoric acid / Delton; G2 - 40% polyacrylic acid / Ketac-Molar / nail varnish; G3 - Fuji Plus conditioner / Fuji Plus/ nail varnish; G4 -37% phosphoric acid / Vitremer / Finishing gloss; G5 -37% phosphoric acid / Vitremer prepared with a 1:4 ratio of powder / Finishing gloss. The teeth were submitted to a thermal treatment corresponding to 300 cycles (15 sec, 5/55(0C, followed by complete coating with nail varnish, except for 1mm beyond the contour of the sealant. Afterwards, the teeth were immersed in 0.5% basic fuchsine for 24 hours. Thereafter, the teeth were sectioned in buccolingual direction and microscopically analyzed (150x magnification by means of predetermined scores. The results were subject to the Kruskal-Wallis test. RESULTS: there was no statistical difference between the materials tested in relation to the DP, being that all groups displayed nearly complete filling of the fissures. No sealant material was able to prevent dye penetration; however, the GICs provided better results of MM, with significant difference when compared to the RS. CONCLUSION: all materials investigated presented a satisfactory degree of penetration into the fissures; however, the glass ionomer cements displayed better performance in the marginal microleakage test compared to the resin sealant.OBJETIVO: o objetivo deste estudo foi comparar in vitro a microinfiltração marginal (MM e o grau de profundidade de penetração (DP de cimentos de ionômero de vidro (CIV e um selante resinoso (SR em fossas e fissuras oclusais. MATERIAIS E MÉTODOS: para tanto, 60 terceiros molares hígidos foram igualmente distribuídos em 5 grupos: G1- ácido fosf

  4. Application of Glass Fiber Reinforced Cement in Exhibition Decoration Project

    Science.gov (United States)

    Wang, Yao

    2018-02-01

    Through the study of GRC material and its application field, the aesthetic characteristics and functional characteristics of GRC materials are demonstrated. The decorative application and technology of GRC material in an art exhibition center are highlighted. The design, application and construction technology of GRC curtain wall and ceiling board in the interior and exterior decoration of art exhibition hall are discussed in detail. The unique advantages of GRC materials in exhibition engineering decoration are fully reflected. In practical design application, the application principle and method are summarized, and an application procedure is formed. The research proves that GRC materials in the art of building decoration engineering has an underrated advantage.

  5. Tunnel restorations using glass ionomer or glass cermet: in vitro marginal ridge fracture and microleakage.

    Science.gov (United States)

    Shetty, R; Munshi, A K

    1996-01-01

    The purpose of this in vitro study was to compare the marginal ridge fracture resistance and microleakage following restorations of partial tunnel preparations using glass ionomer and glass cermet cements. Sixty eight sound premolars were selected for this study and were divided randomly into six groups. A standardized partial tunnel preparation was done on all the teeth except specimens belonging to Group I. The partial tunnel preparations of Groups III & V were restored with glass ionomer and that of Groups IV & VI were restored with glass cermet. The teeth belonging to Groups I, II, III & IV were subjected to marginal ridge fracture resistance testing. The teeth of Groups V & VI were tested for microleakage after immersing them in 5% methylene blue solution for 4 hours. The results indicated that the teeth restored with glass cermet were marginally better than that with glass ionomer in terms of marginal ridge fracture resistance. Both the materials failed to reinforce the marginal ridge to the level of an intact tooth. The microleakage which occurred around both the materials were statistically insignificant, but on comparison glass ionomer showed better results. Hence, glass ionomer is preferred as a restorative material for partial tunnel preparations because of additional inherent advantages like superior esthetics and fluoride leachability.

  6. Effects of abutment diameter, luting agent type, and re-cementation on the retention of implant-supported CAD/CAM metal copings over short abutments.

    Science.gov (United States)

    Safari, Sina; Hosseini Ghavam, Fereshteh; Amini, Parviz; Yaghmaei, Kaveh

    2018-02-01

    The aim of this study was to evaluate the effects of abutment diameter, cement type, and re-cementation on the retention of implant-supported CAD/CAM metal copings over short abutments. Sixty abutments with two different diameters, the height of which was reduced to 3 mm, were vertically mounted in acrylic resin blocks with matching implant analogues. The specimens were divided into 2 diameter groups: 4.5 mm and 5.5 mm (n=30). For each abutment a CAD/CAM metal coping was manufactured, with an occlusal loop. Each group was sub-divided into 3 sub-groups (n=10). In each subgroup, a different cement type was used: resin-modified glass-ionomer, resin cement and zinc-oxide-eugenol. After incubation and thermocycling, the removal force was measured using a universal testing machine at a cross-head speed of 0.5 mm/min. In zinc-oxide-eugenol group, after removal of the coping, the cement remnants were completely cleaned and the copings were re-cemented with resin cement and re-tested. Two-way ANOVA, post hoc Tukey tests, and paired t-test were used to analyze data (α=.05). The highest pulling force was registered in the resin cement group (414.8 N), followed by the re-cementation group (380.5 N). Increasing the diameter improved the retention significantly ( P =.006). The difference in retention between the cemented and recemented copings was not statistically significant ( P =.40). Resin cement provided retention almost twice as strong as that of the RMGI. Increasing the abutment diameter improved retention significantly. Re-cementation with resin cement did not exhibit any difference from the initial cementation with resin cement.

  7. Effects of abutment diameter, luting agent type, and re-cementation on the retention of implant-supported CAD/CAM metal copings over short abutments

    Science.gov (United States)

    Safari, Sina; Amini, Parviz; Yaghmaei, Kaveh

    2018-01-01

    PURPOSE The aim of this study was to evaluate the effects of abutment diameter, cement type, and re-cementation on the retention of implant-supported CAD/CAM metal copings over short abutments. MATERIALS AND METHODS Sixty abutments with two different diameters, the height of which was reduced to 3 mm, were vertically mounted in acrylic resin blocks with matching implant analogues. The specimens were divided into 2 diameter groups: 4.5 mm and 5.5 mm (n=30). For each abutment a CAD/CAM metal coping was manufactured, with an occlusal loop. Each group was sub-divided into 3 sub-groups (n=10). In each subgroup, a different cement type was used: resin-modified glass-ionomer, resin cement and zinc-oxide-eugenol. After incubation and thermocycling, the removal force was measured using a universal testing machine at a cross-head speed of 0.5 mm/min. In zinc-oxide-eugenol group, after removal of the coping, the cement remnants were completely cleaned and the copings were re-cemented with resin cement and re-tested. Two-way ANOVA, post hoc Tukey tests, and paired t-test were used to analyze data (α=.05). RESULTS The highest pulling force was registered in the resin cement group (414.8 N), followed by the re-cementation group (380.5 N). Increasing the diameter improved the retention significantly (P=.006). The difference in retention between the cemented and recemented copings was not statistically significant (P=.40). CONCLUSION Resin cement provided retention almost twice as strong as that of the RMGI. Increasing the abutment diameter improved retention significantly. Re-cementation with resin cement did not exhibit any difference from the initial cementation with resin cement. PMID:29503708

  8. Crown and bridge cements: clinical applications.

    Science.gov (United States)

    Bunek, Sabiha S; Powers, John M

    2012-12-01

    Cement selection can be confusing because factors such as substrate, the type of restoration, and patient needs must be considered. Some substrates require additional treatment before cementation. This article describes the most commonly used traditional crown and bridge cements (GI and RMGI) used for metal and metal-ceramic restorations, and resin cements used for all-ceramic restorations. Advantages, disadvantages, indications, and contraindications of cements have been reviewed. Recommended uses of cements for metal, ceramic, and laboratory composite restorations have been presented. General guidelines for surface treatment ot silica- and zirconia-based restorations when using resin cements have been discussed.

  9. Cement/slag chemistry studies

    International Nuclear Information System (INIS)

    Glasser, F.P.; Macphee, D.; Atkins, M.; Beckley, N.; Carson, S.O.; Wilding, C.R.; McHugh, G.

    1988-01-01

    The performance of cement-based matrices intended for radwaste immobilization is assessed. The long-term performance of the matrix is characterized by thermodynamic evaluation of experimental data. The results are presented in a general form, amenable to a range of specific formulations. The interaction of specific radwaste components with cements has been studied, using Iodine as an example. It occurs as both I - and IO 3 - species, but these differ sharply in sorption characteristics. The effect of ionizing radiation of the pH and E h of cement matrices is reported. (author)

  10. Cements in Radioactive Waste Disposal

    International Nuclear Information System (INIS)

    Glasser, F.P.

    2013-01-01

    The use of cement and concrete to immobilise radioactive waste is complicated by the wide- ranging nature of inorganic cementing agents available as well as the range of service environments in which cement is used and the different functions expected of cement. For example, Portland cement based concretes are widely used as structural materials for construction of vaults and tunnels. These constructions may experience a long pre-closure performance lifetime during which they are required to protect against collapse and ingress of water: strength and impermeability are key desirable characteristics. On the other hand, cement and concrete may be used to form backfills, ranging in permeability. Permeable formulations allow gas readily to escape, while impermeable barriers retard radionuclide transport and reduce access of ground water to the waste. A key feature of cements is that, while fresh, they pass through a fluid phase and can be formed into any shape desired or used to infiltrate other materials thereby enclosing them into a sealed matrix. Thereafter, setting and hardening is automatic and irreversible. Where concrete is used to form structural elements, it is also natural to use cement in other applications as it minimises potential for materials incompatibility. Thus cement- mainly Portland cement- has been widely used as an encapsulant for storage, transport and as a radiation shield for active wastes. Also, to form and stabilise structures such as vaults and silos. Relative to other potential matrices, cement also has a chemical immobilisation potential, reacting with and binding with many radionuclides. The chemical potential of cements is essentially sacrificial, thus limiting their performance lifetime. However performance may also be required in the civil engineering sense, where strength is important, so many factors, including a geochemical description of service conditions, may require to be assessed in order to predict performance lifetime. The

  11. Cements in Radioactive Waste Disposal

    Energy Technology Data Exchange (ETDEWEB)

    Glasser, F. P. [University of Aberdeen, Scotland (United Kingdom)

    2013-09-15

    The use of cement and concrete to immobilise radioactive waste is complicated by the wide- ranging nature of inorganic cementing agents available as well as the range of service environments in which cement is used and the different functions expected of cement. For example, Portland cement based concretes are widely used as structural materials for construction of vaults and tunnels. These constructions may experience a long pre-closure performance lifetime during which they are required to protect against collapse and ingress of water: strength and impermeability are key desirable characteristics. On the other hand, cement and concrete may be used to form backfills, ranging in permeability. Permeable formulations allow gas readily to escape, while impermeable barriers retard radionuclide transport and reduce access of ground water to the waste. A key feature of cements is that, while fresh, they pass through a fluid phase and can be formed into any shape desired or used to infiltrate other materials thereby enclosing them into a sealed matrix. Thereafter, setting and hardening is automatic and irreversible. Where concrete is used to form structural elements, it is also natural to use cement in other applications as it minimises potential for materials incompatibility. Thus cement- mainly Portland cement- has been widely used as an encapsulant for storage, transport and as a radiation shield for active wastes. Also, to form and stabilise structures such as vaults and silos. Relative to other potential matrices, cement also has a chemical immobilisation potential, reacting with and binding with many radionuclides. The chemical potential of cements is essentially sacrificial, thus limiting their performance lifetime. However performance may also be required in the civil engineering sense, where strength is important, so many factors, including a geochemical description of service conditions, may require to be assessed in order to predict performance lifetime. The

  12. Does cement mantle thickness really matter?

    OpenAIRE

    Caruana, J.

    2008-01-01

    The thickness of the cement mantle around the femoral component of total hip replacements is a contributing factor to aseptic loosening and revision. Nevertheless, various designs of stems and surgical tooling lead to cement mantles of differing thicknesses. This thesis is concerned with variability in cement thickness around the Stanmore Hip, due to surgical approach, broach size and stem orientation, and its effects on stress and cracking in the cement. The extent to which cement mantle thi...

  13. Glass: Rotary Electric Glass Furnace

    Energy Technology Data Exchange (ETDEWEB)

    Recca, L.

    1999-01-29

    Compared to conventional gas-fired furnaces, the new rotary electric furnace will increase energy efficiency while significantly reducing air emissions, product turnaround time, and labor costs. As this informative new fact sheet explains, the thousand different types of glass optical blanks produced for the photonics industry are used for lasers, telescopes, cameras, lights, and many other products.

  14. Alternative Fuels in Cement Production

    DEFF Research Database (Denmark)

    Larsen, Morten Boberg

    The substitution of alternative for fossil fuels in cement production has increased significantly in the last decade. Of these new alternative fuels, solid state fuels presently account for the largest part, and in particular, meat and bone meal, plastics and tyre derived fuels (TDF) accounted...... for the most significant alternative fuel energy contributors in the German cement industry. Solid alternative fuels are typically high in volatile content and they may differ significantly in physical and chemical properties compared to traditional solid fossil fuels. From the process point of view......, considering a modern kiln system for cement production, the use of alternative fuels mainly influences 1) kiln process stability (may accelerate build up of blockages preventing gas and/or solids flow), 2) cement clinker quality, 3) emissions, and 4) decreased production capacity. Kiln process stability...

  15. Experimental studies on a new bioactive material: HAIonomer cements.

    Science.gov (United States)

    Yap, A U J; Pek, Y S; Kumar, R A; Cheang, P; Khor, K A

    2002-02-01

    The lack of exotherm during setting, absence of monomer and improved release of incorporated therapeutic agents has resulted in the development of glass ionomer cements (GICs) for biomedical applications. In order to improve biocompatibility and biomechanically match GICs to bone, hydroxyapatite-ionomer (HAIonomer) hybrid cements were developed. Ultra-fine hydroxyapatite (HA) powders were produced using a new induction spraying technique that utilizes a radio-frequency source to spheriodize an atomized suspension containing HA crystallites. The spheriodized particulates were then held at 800 degrees C for 4 h in a carbolite furnace using a heating and cooling rate of 25 degrees C/min to obtain almost fully crystalline HA powders. The heat-treated particles were characterized and introduced into a commercial glass ionomer cement. 4 (H4), 12 (H12) and 28 (H28) vol% of fluoroalumino silicate were substituted by crystalline HA particles that were dispersed using a high-speed dispersion technique. The HAIonomer cements were subjected to hardness, compressive and diametral tensile strength testing based upon BS6039:1981. The storage time were extended to one week to investigate the effects of cement maturation on mechanical properties. Commercially available capsulated GIC (GC) and GIC at maximum powder:liquid ratio (GM) served as comparisons. Results were analyzed using factorial ANOVA/Scheffe's post-hoc tests and independent samples t-test at significance level 0.05. The effect of time on hardness was material dependent. With the exception of H12, a significant increase in hardness was observed for all materials at one week. A significant increase in compressive strength was, however, observed for H12 over time. At 1 day and 1 week, the hardness of H28 was significantly lower than for GM, H4, and H12. No significant difference in compression and diametral tensile strengths were observed between materials at both time intervals. Results show that HAIonomers is a

  16. Calcium Aluminate Cement Hydration Model

    Directory of Open Access Journals (Sweden)

    Matusinović, T.

    2011-01-01

    Full Text Available Calcium aluminate cement (AC is a very versatile special cement used for specific applications. As the hydration of AC is highly temperature dependent, yielding structurally different hydration products that continuously alter material properties, a good knowledge of thermal properties at early stages of hydration is essential. The kinetics of AC hydration is a complex process and the use of single mechanisms models cannot describe the rate of hydration during the whole stage.This paper examines the influence of temperature (ϑ=5–20 °C and water-to-cement mass ratio (mH /mAC = 0.4; 0.5 and 1.0 on hydration of commercial iron-rich AC ISTRA 40 (producer: Istra Cement, Pula, Croatia, which is a part of CALUCEM group, Figs 1–3. The flow rate of heat generation of cement pastes as a result of the hydration reactions was measured with differential microcalorimeter. Chemically bonded water in the hydrated cement samples was determined by thermo-gravimetry.Far less heat is liberated when cement and water come in contact for the first time, Fig. 1, than in the case for portland cement (PC. Higher water-to-cement ratio increases the heat evolved at later ages (Fig. 3 due to higher quantity of water available for hydration. A significant effect of the water-to-cement ratio on the hydration rate and hydration degree showed the importance of water as being the limiting reactant that slows down the reaction early. A simplified stoichiometric model of early age AC hydration (eq. (8 based on reaction schemes of principal minerals, nominally CA, C12A7 and C4AF (Table 1, was employed. Hydration kinetics after the induction period (ϑ < 20 °C had been successfully described (Fig. 4 and Table 2 by a proposed model (eq. (23 which simultaneously comprised three main mechanisms: nucleation and growth, interaction at phase boundary, and mass transfer. In the proposed kinetic model the nucleation and growth is proportional to the amount of reacted minerals (eq

  17. Reuse of ground waste glass as aggregate for mortars.

    Science.gov (United States)

    Corinaldesi, V; Gnappi, G; Moriconi, G; Montenero, A

    2005-01-01

    This work was aimed at studying the possibility of reusing waste glass from crushed containers and building demolition as aggregate for preparing mortars and concrete. At present, this kind of reuse is still not common due to the risk of alkali-silica reaction between the alkalis of cement and silica of the waste glass. This expansive reaction can cause great problems of cracking and, consequently, it can be extremely deleterious for the durability of mortar and concrete. However, data reported in the literature show that if the waste glass is finely ground, under 75mum, this effect does not occur and mortar durability is guaranteed. Therefore, in this work the possible reactivity of waste glass with the cement paste in mortars was verified, by varying the particle size of the finely ground waste glass. No reaction has been detected with particle size up to 100mum thus indicating the feasibility of the waste glass reuse as fine aggregate in mortars and concrete. In addition, waste glass seems to positively contribute to the mortar micro-structural properties resulting in an evident improvement of its mechanical performance.

  18. Rheological measurements on cement grouts

    International Nuclear Information System (INIS)

    Dalton, M.J.

    1986-06-01

    This report describes the techniques which have been developed at Winfrith for assessing the rheological properties of cement grouts. A discussion of the theory of rheology and its application to cement is given and the methodology for calibrating a special paddle measuring system for a commercial viscometer is described. The use of the system for determining flow curves, equilibrium viscosity, viscosity as a function of shearing time and structure changes is also discussed. (author)

  19. Cement pulmonary embolism after vertebroplasty.

    Science.gov (United States)

    Sifuentes Giraldo, Walter Alberto; Lamúa Riazuelo, José Ramón; Gallego Rivera, José Ignacio; Vázquez Díaz, Mónica

    2013-01-01

    In recent years, the use of vertebral cementing techniques for vertebroplasty and kyphoplasty has spread for the treatment of pain associated with osteoporotic vertebral compression fractures. This is also associated with the increased incidence of complications related with these procedures, the most frequent being originated by leakage of cementation material. Cement can escape into the vertebral venous system and reach the pulmonary circulation through the azygous system and cava vein, producing a cement embolism. This is a frequent complication, occurring in up to 26% of patients undergoing vertebroplasty but, since most patients have no clinical or hemodynamical repercussion, this event usually goes unnoticed. However, some serious, and even fatal cases, have been reported. We report the case of a 74-year-old male patient who underwent vertebroplasty for persistent pain associated with osteoporotic L3 vertebral fracture and who developed a cement leak into the cava vein and right pulmonary artery during the procedure. Although he developed a pulmonary cement embolism, the patient remained asymptomatic and did not present complications during follow-up. Copyright © 2012 Elsevier España, S.L. All rights reserved.

  20. Calcium Orthophosphate Cements and Concretes

    Directory of Open Access Journals (Sweden)

    Sergey V. Dorozhkin

    2009-03-01

    Full Text Available In early 1980s, researchers discovered self-setting calcium orthophosphate cements, which are a bioactive and biodegradable grafting material in the form of a powder and a liquid. Both phases form after mixing a viscous paste that after being implanted, sets and hardens within the body as either a non-stoichiometric calcium deficient hydroxyapatite (CDHA or brushite, sometimes blended with unreacted particles and other phases. As both CDHA and brushite are remarkably biocompartible and bioresorbable (therefore, in vivo they can be replaced with newly forming bone, calcium orthophosphate cements represent a good correction technique for non-weight-bearing bone fractures or defects and appear to be very promising materials for bone grafting applications. Besides, these cements possess an excellent osteoconductivity, molding capabilities and easy manipulation. Furthermore, reinforced cement formulations are available, which in a certain sense might be described as calcium orthophosphate concretes. The concepts established by calcium orthophosphate cement pioneers in the early 1980s were used as a platform to initiate a new generation of bone substitute materials for commercialization. Since then, advances have been made in the composition, performance and manufacturing; several beneficial formulations have already been introduced as a result. Many other compositions are in experimental stages. In this review, an insight into calcium orthophosphate cements and concretes, as excellent biomaterials suitable for both dental and bone grafting application, has been provided.

  1. Collaboration of polymer composite reinforcement and cement concrete

    Science.gov (United States)

    Khozin, V. G.; Gizdatullin, A. R.

    2018-04-01

    The results of experimental study of bond strength of cement concrete of different types with fiber reinforcing polymer (FRP) bars are reported. The reinforcing bars were manufactured of glass fibers and had a rebar with different types of the surface relief formed by winding a thin strip impregnated with a binder or by “sanding”. The pullout tests were carried out simultaneously for the steel reinforcing ribbed bars A400. The impact of friction, adhesion and mechanical bond on the strength of bonds between FRP and concrete was studied. The influence of the concrete strength and different operation factors on the bond strength of concrete was evaluated.

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

    Directory of Open Access Journals (Sweden)

    Matheus Coêlho Bandéca

    2010-03-01

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

  3. Nitrate glass

    International Nuclear Information System (INIS)

    Kirilenko, I.A.; Vinogradov, E.E.

    1977-01-01

    Experimental evidence on behaviour of nitrate glasses is reviewed in terms of relationships between the presence of water in vitrescent nitrate systems and the properties of the systems. The glasses considered belong to systems of Mg(NO 3 ) 2 - Nd(NO 3 ) 3 ; Hg(NO 3 ) 2 -Nd(NO 3 ) 3 ; NaNO 3 -Mg(NO 3 ) 2 -Nd(NO 3 ) 3 ; M-Zn(NO 3 ) 3 , where M is a mixture of 20% mass NaNO 3 and 80% mass Mg(NO 3 ) 2 , and Zn is a rare earth ion. Nitrate glass is shown to be a product of dehydration. Vitrification may be regarded as a resusl of formation of molecular complexes in the chain due to hydrogen bonds of two types, i.e. water-water, or water-nicrate group. Chain formation, along with low melting points of the nitrates, hinder crystallization of nitrate melts. Provided there is enough water, this results in vitrification

  4. UV irradiation improves the bond strength of resin cement to fiber posts.

    Science.gov (United States)

    Zhong, Bo; Zhang, Yong; Zhou, Jianfeng; Chen, Li; Li, Deli; Tan, Jianguo

    2011-01-01

    The purpose is to evaluate the effect of UV irradiation on the bond strength between epoxy-based glass fiber posts and resin cement. Twelve epoxy-based glass fiber posts were randomly divided into three groups. Group 1 (Cont.): No surface treatment. Group 2 (Low-UV): UV irradiation was conducted from a distance of 10 cm for 10 min. Group 3 (High-UV): UV irradiation was conducted from a distance of 1 cm for 3 min. A resin cement (CLEARFIL SA LUTING) was used for the post cementation to form resin slabs which contained fiber posts in the center. Microtensile bond strengths were tested and the mean bond strengths (MPa) were 18.81 for Cont. group, 23.65 for Low-UV group, 34.75 for High-UV group. UV irradiation had a significant effect on the bond strength (pUV irradiation demonstrates its capability to improve the bond strength between epoxy-based glass fiber posts and resin cement.

  5. Low pH Cements

    International Nuclear Information System (INIS)

    Savage, David; Benbow, Steven

    2007-05-01

    The development of low-pH cements for use in geological repositories for radioactive waste stems from concerns over the potential for deleterious effects upon the host rock and other EBS materials (notably bentonite) under the hyperalkaline conditions (pH > 12) of cement pore fluids. Low pH cement (also known as low heat cement) was developed by the cement industry for use where large masses of cement (e.g. dams) could cause problems regarding heat generated during curing. In low pH cements, the amount of cement is reduced by substitution of materials such as fly ash, blast furnace slag, silica fume, and/or non-pozzolanic silica flour. SKB and Posiva have ruled out the use of blast furnace slag and fly-ash and are focusing on silica fume as a blending agent. Currently, no preferred composition has been identified by these agencies. SKB and Posiva have defined a pH limit ≤ 11 for cement grout leachates. To attain this pH, blending agents must comprise at least 50 wt % of dry materials. Because low pH cement has little, or no free portlandite, the cement consists predominantly of calcium silicate hydrate (CSH) gel with a Ca/Si ratio ≤ 0.8. Although there are potential implications for the performance of the spent fuel and cladding due to the presence of hyperalkaline fluids from cement, the principal focus for safety assessment lies with the behaviour of bentonite. There are a number of potential constraints on the interaction of hyperalkaline cement pore fluids with bentonite, including mass balance, thermodynamic issues, mass transport, and kinetics, but none of these is likely to be limiting if conventional OPC cements are employed in repository construction. Nevertheless: Low-pH cements may supply approximately 50 % less hydroxyl ions than conventional OPC for a given volume of cement, but mass balance constraints are complicated by the uncertainty concerning the type of secondary minerals produced during cement-bentonite interaction. The change of aqueous

  6. Low pH Cements

    Energy Technology Data Exchange (ETDEWEB)

    Savage, David; Benbow, Steven [Quintessa Ltd., Henley-on-Thames (United Kingdom)

    2007-05-15

    The development of low-pH cements for use in geological repositories for radioactive waste stems from concerns over the potential for deleterious effects upon the host rock and other EBS materials (notably bentonite) under the hyperalkaline conditions (pH > 12) of cement pore fluids. Low pH cement (also known as low heat cement) was developed by the cement industry for use where large masses of cement (e.g. dams) could cause problems regarding heat generated during curing. In low pH cements, the amount of cement is reduced by substitution of materials such as fly ash, blast furnace slag, silica fume, and/or non-pozzolanic silica flour. SKB and Posiva have ruled out the use of blast furnace slag and fly-ash and are focusing on silica fume as a blending agent. Currently, no preferred composition has been identified by these agencies. SKB and Posiva have defined a pH limit {<=} 11 for cement grout leachates. To attain this pH, blending agents must comprise at least 50 wt % of dry materials. Because low pH cement has little, or no free portlandite, the cement consists predominantly of calcium silicate hydrate (CSH) gel with a Ca/Si ratio {<=} 0.8. Although there are potential implications for the performance of the spent fuel and cladding due to the presence of hyperalkaline fluids from cement, the principal focus for safety assessment lies with the behaviour of bentonite. There are a number of potential constraints on the interaction of hyperalkaline cement pore fluids with bentonite, including mass balance, thermodynamic issues, mass transport, and kinetics, but none of these is likely to be limiting if conventional OPC cements are employed in repository construction. Nevertheless: Low-pH cements may supply approximately 50 % less hydroxyl ions than conventional OPC for a given volume of cement, but mass balance constraints are complicated by the uncertainty concerning the type of secondary minerals produced during cement-bentonite interaction. The change of aqueous

  7. Development of cement material using inorganic additives

    International Nuclear Information System (INIS)

    Toyohara, Masumitsu; Satou, Tatsuaki; Wada, Mikio; Ishii, Tomoharu; Matsuo, Kazuaki.

    1997-01-01

    Inorganic admixtures to enhance the fluidity of cement material was developed. These admixtures turned into easy to immobilize the miscellaneous radioactive waste using cement material. It was found that the ζ potential of cement particles was directly proportional to the content of the inorganic admixtures in cement paste and the particles of cement were dispersed at the high ζ potential. The condensed sodium phosphate, which was the main component of the inorganic admixtures, retarded the dissolution of Ca 2+ ion from the cement, and generated the colloids by incorporating dissolved Ca 2+ ion. The cement material containing the inorganic admixtures was found to have the same mechanical strength and adsorption potential of radionuclides in comparison to normal cement materials. It was confirmed that the cement material containing the inorganic admixture was effectively filled gaps of miscellaneous radioactive waste. (author)

  8. Development of high-performance blended cements

    Science.gov (United States)

    Wu, Zichao

    2000-10-01

    This thesis presents the development of high-performance blended cements from industrial by-products. To overcome the low-early strength of blended cements, several chemicals were studied as the activators for cement hydration. Sodium sulfate was discovered as the best activator. The blending proportions were optimized by Taguchi experimental design. The optimized blended cements containing up to 80% fly ash performed better than Type I cement in strength development and durability. Maintaining a constant cement content, concrete produced from the optimized blended cements had equal or higher strength and higher durability than that produced from Type I cement alone. The key for the activation mechanism was the reaction between added SO4 2- and Ca2+ dissolved from cement hydration products.

  9. Uso das técnicas de infravermelho e de ressonância magnética nuclear na caracterização da reação ácido-base de um cimento odontológico experimental Use of infrared and magnetic nuclear resonance techniques in the characterization of the acid-base reaction of an experimental dental cement

    Directory of Open Access Journals (Sweden)

    Marcio José Bertolini

    2009-01-01

    Full Text Available Glass ionomer cements (GICs are products of the acid-base setting reaction between an finely fluoro-alumino silicate glass powder and poly(acrylic acid in aqueous solution. The sol gel method is an adequate route of preparation of the glasses used to obtain the GICs. The objective of this paper was to compare two powders: a commercial and an experimental and to investigate the structural changes during hardening of the cements by FTIR and Al MAS NMR. These analyses showed that the experimental glass powder reacted with organic acid to form the GICs and it is a promising material to manufacture dental cements.

  10. Streptococcus mutans-induced secondary caries adjacent to glass ionomer cement, composite resin and amalgam restorations in vitro Cárie secundária adjacente a restaurações de cimento de ionômero de vidro, resina composta e amálgama induzida por Streptococcus mutans in vitro

    Directory of Open Access Journals (Sweden)

    Adriana Gama-Teixeira

    2007-12-01

    Full Text Available The aim of this study was to define, in vitro, the potential to inhibit secondary caries of restorative materials currently used in dental practice. Standard cavities were prepared on the buccal and lingual surfaces of fifty extracted human third molars. The teeth were randomly divided into five groups, each one restored with one of the following materials: glass ionomer cement (GIC; amalgam; light-cured composite resin; ion-releasing composite; and light-cured, fluoride-containing composite resin. The teeth were thermocycled, sterilized with gamma irradiation, exposed to a cariogenic challenge using a bacterial system using Streptococcus mutans, and then prepared for microscopic observation. The following parameters were measured in each lesion formed: extension, depth, and caries inhibition area. The outer lesions developed showed an intact surface layer and had a rectangular shape. Wall lesions were not observed inside the cavities. After Analysis of Variance and Component of Variance Models Analysis, it was observed that the GIC group had the smallest lesions and the greatest number of caries inhibition areas. The lesions developed around Amalgam and Ariston pHc restorations had an intermediate size and the largest lesions were observed around Z-100 and Heliomolar restorations. It may be concluded that the restorative materials GIC, amalgam and ion-releasing composites may reduce secondary caries formation.O objetivo deste estudo foi definir, in vitro, o potencial de materiais restauradores, usados rotineiramente na prática clínica, na inibição da cárie secundária. Cavidades padronizadas foram preparadas nas faces vestibulares e linguais de 50 terceiros molares humanos extraídos. Os dentes foram divididos aleatoriamente em 5 grupos, cada um restaurado com um dos seguintes materiais: cimento de ionômero de vidro (CIV; amálgama; resina composta fotopolimerizável; compósito que libera íons, e resina composta fotopolimeriz

  11. In vitro evaluation of marginal microleakage of class II bonded amalgam restorations using a dentin adhesive and a glass ionomer cement Avaliação in vitro da microinfiltração marginal em restaurações de amálgama tipo classe II usando adesivo dentinário e cimento de ionômero de vidro

    Directory of Open Access Journals (Sweden)

    Edmêr Silvestre PEREIRA JÚNIOR

    1999-04-01

    Full Text Available The purpose of this study was to evaluate in vitro the effectiveness of the dentin bonding system All Bond 2 associated with Resinomer (Bisco, and of Vitrebond (3M glass ionomer cement fresh-mixed, both used in the bonded amalgam technique, to prevent short-term microleakage in class II cavities restored with Dispersalloy (Dentsply, an admixed alloy. The control group utilized the Copalite (Cooley & Cooley varnish. Forty five sound human extracted premolars were used. Class II cavity preparations were made on the mesial and distal surfaces of non-carious teeth, with the gingival margins wall established 1mm under the cementum enamel junction. The specimens were divided randomly into three groups with thirty cavities in each group. The teeth were stored in distilled water for 24 hours and were thermocyled through 500 cycles in distilled water between 5°C and 55°C with a dwell time of 15 seconds. The apices and roots of the teeth were sealed. They were placed in a 37°C bath of 0.5% basic fuchsin dye for 24 hours. The teeth were washed in tap water for 24 hours and cut. The microleakage scores per restoration were averaged and three values of various test groups were subjected to the Kruskal-Wallis and Dunn test at a significance level of p O objetivo deste estudo foi avaliar in vitro a efetividade na prevenção da microinfiltração do sistema adesivo All Bond 2 associado ao Resinomer (Bisco, e do cimento de ionômero de vidro Vitrebond (3M, sem polimerização, em amálgama adesivo classe II, restauradas com Dispersalloy (Dentsply. No grupo controle utilizou-se o verniz cavitário Copalite (Cooley & Cooley. Para tanto, 45 pré-molares humanos íntegros e extraídos, com finalidade ortodôntica, receberam cavidades classe II, sendo uma na face mesial e outra na face distal de cada dente, com a parede cervical localizada a 1mm além da junção cemento-esmalte, sendo 30 cavidades em cada grupo. Após as restaurações os dentes foram estocados

  12. Finite element analysis of stresses in fixed prosthesis and cement layer using a three-dimensional model

    Directory of Open Access Journals (Sweden)

    Arunachalam Sangeetha

    2012-01-01

    Full Text Available Context: To understand the effect of masticatory and parafunctional forces on the integrity of the prosthesis and the underlying cement layer. Aims: The purpose of this study was to evaluate the stress pattern in the cement layer and the fixed prosthesis, on subjecting a three-dimensional finite element model to simulated occlusal loading. Materials and Methods: Three-dimensional finite element model was simulated to replace missing mandibular first molar with second premolar and second molar as abutments. The model was subjected to a range of occlusal loads (20, 30, 40 MPa in two different directions - vertical and 30° to the vertical. The cements (zinc phosphate, polycarboxylate, glass ionomer, and composite were modeled with two cement thicknesses - 25 and 100 μm. Stresses were determined in certain reference points in fixed prosthesis and the cement layer. Statistical Analysis Used: The stress values are mathematic calculations without variance; hence, statistical analysis is not routinely required. Results: Stress levels were calculated according to Von Mises criteria for each node. Maximum stresses were recorded at the occlusal surface, axio-gingival corners, followed by axial wall. The stresses were greater with lateral load and with 100-μm cement thickness. Results revealed higher stresses for zinc phosphate cement, followed by composites. Conclusions: The thinner cement interfaces favor the success of the prosthesis. The stresses in the prosthesis suggest rounding of axio-gingival corners and a well-established finish line as important factors in maintaining the integrity of the prosthesis.

  13. Effect of Selected Alternative Fuels and Raw Materials on the Cement Clinker Quality

    Directory of Open Access Journals (Sweden)

    Strigáč Július

    2015-11-01

    Full Text Available The article deals with the study of the effects of alternative fuels and raw materials on the cement clinker quality. The clinker quality was expressed by the content of two principal minerals alite C3S and belite C2S. The additions of alternative fuels ashes and raw materials, in principle, always increased the belite content and conversely reduced the amount of alite. The alternative fuels with high ash content were used such as the meat-bone meal, sewage sludge from sewage treatment plants and paper sludge and the used alternative raw materials were metallurgical slags - granulated blastfurnace slag, air cooled blastfurnace slag and demetallized steel slag, fluidized bed combustion fly ash and waste glass. Meat-bone meal, sewage sludge from sewage treatment plants and paper sludge were evaluated as moderately suitable alternative fuels which can be added in the amounts of 2.8 wt. % addition of meat-bone meals ash, 3.64 wt. % addition of sewage sludge ash and 3.8 wt. % addition of paper sludge ash to the cement raw mixture. Demetallised steel slag is suitable for production of special sulphate resistant cement clinker for CEM I –SR cement with addition up to 5 wt. %. Granulated blastfurnace slag is a suitable alternative raw material with addition 4 wt. %. Air cooled blastfurnace slag is a suitable alternative raw material with addition 4.2 wt. %. Waste glass is not very appropriate alternative raw material with addition only 1.16 wt. %. Fluidized bed combustion fly ash appears not to be equally appropriate alternative raw material for cement clinker burning with less potential utilization in the cement industry and with addition 3.41 wt. %, which forms undesired anhydrite CaSO4 in the cement clinker.

  14. Evaluation of pH at the Bacteria–Dental Cement Interface

    Science.gov (United States)

    Mayanagi, G.; Igarashi, K.; Washio, J.; Nakajo, K.; Domon-Tawaraya, H.; Takahashi, N.

    2011-01-01

    Physiochemical assessment of the parasite-biomaterial interface is essential in the development of new biomaterials. The purpose of this study was to develop a method to evaluate pH at the bacteria-dental cement interface and to demonstrate physiochemical interaction at the interface. The experimental apparatus with a well (4.0 mm in diameter and 2.0 mm deep) was made of polymethyl methacrylate with dental cement or polymethyl methacrylate (control) at the bottom. Three representative dental cements (glass-ionomer, zinc phosphate, and zinc oxide-eugenol cements) were used. Each specimen was immersed in 2 mM potassium phosphate buffer for 10 min, 24 hrs, 1 wk, or 4 wks. The well was packed with Streptococcus mutans NCTC 10449, and a miniature pH electrode was placed at the interface between bacterial cells and dental cement. The pH was monitored after the addition of 1% glucose, and the fluoride contained in the cells was quantified. Glass-ionomer cement inhibited the bacteria-induced pH fall significantly compared with polymethyl methacrylate (control) at the interface (10 min, 5.16 ± 0.19 vs. 4.50 ± 0.07; 24 hrs, 5.20 ± 0.07 vs. 4.59 ± 0.11; 1 wk, 5.34 ± 0.14 vs. 4.57 ± 0.11; and 4 wks, 4.95 ± 0.27 vs. 4.40 ± 0.14), probably due to the fluoride released from the cement. This method could be useful for the assessment of pH at the parasite-biomaterial interface. PMID:21933936

  15. Polymer-cement interactions towards improved wellbore cement fracture sealants

    Science.gov (United States)

    Beckingham, B. S.; Iloejesi, C.; Minkler, M. J.; Schindler, A. K.; Beckingham, L. E.

    2017-12-01

    Carbon capture, utilization, and storage (CCUS) in deep geologic formations is a promising means of reducing point source emissions of CO2. In these systems, CO2 is captured at the source and then injected to be utilized (eg. in enhanced oil recovery or as a working fluid in enhanced geothermal energy plants) or stored in geologic formations such as depleted oil and gas reservoirs or saline aquifers. While CCUS in subsurface systems could aid in reducing atmospheric CO2 emissions, the potential for CO2 leakage from these systems to overlying formations remains a major limitation and poses a significant risk to the security of injected CO2. Thus, improved materials for both initial wellbore isolation and repairing leakage pathways that develop over time are sought. One approach for the repair of cement fractures in wellbore (and other) systems is the injection of polymer materials into the fracture with a subsequent environmentally dependent (temperature, pressure, pH, etc.) densification or solidification. Here, we aim to investigate novel polymer materials for use to repair leaking wellbores in the context of CCUS. We synthesize and fully characterize a series of novel polymer materials and utilize a suite of analysis techniques to examine polymer-cement interactions at a range of conditions (namely temperature, pressure and pH). Initial findings will be leveraged to design novel polymer materials for further evaluation in polymer-cement composite cores, cement fracture healing, and the aging behavior of healed cements.

  16. Influence of the bracket on bonding and physical behavior of orthodontic resin cements.

    Science.gov (United States)

    Bolaños-Carmona, Victoria; Zein, Bilal; Menéndez-Núñez, Mario; Sánchez-Sánchez, Purificación; Ceballos-García, Laura; González-López, Santiago

    2015-01-01

    The aim of the study is to determine the influence of the type of bracket, on bond strength, microhardness and conversion degree (CD) of four resin orthodontic cements. Micro-tensile bond strength (µTBS) test between the bracket base and the cement was carried out on glass-hour-shaped specimens (n=20). Vickers Hardness Number (VHN) and micro-Raman spectra were recorded in situ under the bracket base. Weibull distribution, ANOVA and non-parametric test were applied for data analysis (pcement showing the worst performance. The CD was from 80% to 62.5%.

  17. Tensile strength of cementing agents on the CeraOne system of dental prosthesis on implants.

    Science.gov (United States)

    Montenegro, Alexandre Campos; Machado, Aldir Nascimento; Depes Gouvêa, Cresus Vinicius

    2008-12-01

    The aim of this in vitro study was to evaluate the tensile strength of titanium cylinders cemented on stainless steel abutment mock-ups by the Cerazone system. Four types of cements were used: glass ionomer, Fuji I (GC); zinc phosphate, Cimento LS (Vigodent); zinc oxide without eugenol, Rely x Temp NE (3M ESPE); and resin cement, Rely x ARC (3M ESPE). Four experimental groups were formed, each composed of 5 test specimens. Each test specimen consisted of a set of 1 cylinder and 1 stainless steel abutment mock-up. All cements tested were manipulated in accordance with manufacturers' instructions. A static load of 5 Newtons (N) for 2 minutes was used to standardize the procedure. The tensile tests were performed by a mechanical universal testing machine (EMIC DL500MF) at a crosshead speed of 0.5 mm/min. The highest bonding values resulting from the experiment were obtained by Cimento LS (21.86 MPa mean), followed by the resin cement Rely x ARC (12.95 MPa mean), Fuji I (6.89 MPa mean), and Rely x Temp NE (4.71 MPa mean). The results were subjected to analysis of variance (ANOVA) and the Student's t test. The cements differed amongst them as regards tensile strength, with the highest bonding levels recorded with zinc phosphate (Cimento LS) and the lowest with the zinc oxide without eugenol (Rely x Temp NE).

  18. Are encapsulated anterior glass-ionomer restoratives better than their hand-mixed equivalents?

    LENUS (Irish Health Repository)

    Dowling, Adam H

    2009-02-01

    The performance of encapsulated anterior GI restoratives were compared with their hand-mixed equivalents for the range of powder to liquid mixing ratios routinely encountered clinically. The clinically induced variability of powder to liquid mixing variations of an anhydrous GI restorative formulation was also compared with conventional GI restorative formulations that contained a polyalkenoic acidic liquid.

  19. Seepage/Cement Interactions

    International Nuclear Information System (INIS)

    Carpenter, D.

    2000-01-01

    The Development Plan (CRWMS M andO 1999a) pertaining to this task defines the work scopes and objectives for development of various submodels for the Physical and Chemical Environment Abstraction Model for TSPA-LA. The Development Plan (CRWMS M andO 1999a) for this specific task establishes that an evaluation be performed of the chemical reactions between seepage that has entered the drift and concrete which might be used in the repository emplacement drifts. The Development Plan (CRWMS M andO 1999a) then states that the potential effects of these water/grout reactions on chemical conditions in the drift be assessed factoring in the influence of carbonation and the relatively small amount of grout. This task is also directed at: (1) developing a conceptualization of important cement/seepage interactions and potential impacts on EBS performance, (2) performing a screening analysis to assess the importance of cement/seepage interactions. As the work progresses and evolves on other studies, specifically the Engineered Barrier System: Physical and Chemical Environment (P andCE) Model (in progress), many of the issues associated with items 1 and 2, above, will be assessed. Such issues include: (1) Describing the mineralogy of the specified cementitious grout and its evolution over time. (2) Describing the composition of the water before contacting the grout. (3) Developing reasonable upper-bound estimates for the composition of water contacting grout, emphasizing pH and concentrations for anions such as sulfate. (4) Evaluating the equilibration of cement-influenced water with backfill and gas-phase CO 2 . (5) Developing reasonable-bound estimates for flow rate of affected water into the drift. The concept of estimating an ''upper-bound'' range for reaction between the grout and the seepage, particularly in terms of pH is based on equilibrium being established between the seepage and the grout. For example, this analysis can be based on equilibrium being established as

  20. A modified PMMA cement (Sub-cement) for accelerated fatigue testing of cemented implant constructs using cadaveric bone.

    Science.gov (United States)

    Race, Amos; Miller, Mark A; Mann, Kenneth A

    2008-10-20

    Pre-clinical screening of cemented implant systems could be improved by modeling the longer-term response of the implant/cement/bone construct to cyclic loading. We formulated bone cement with degraded fatigue fracture properties (Sub-cement) such that long-term fatigue could be simulated in short-term cadaver tests. Sub-cement was made by adding a chain-transfer agent to standard polymethylmethacrylate (PMMA) cement. This reduced the molecular weight of the inter-bead matrix without changing reaction-rate or handling characteristics. Static mechanical properties were approximately equivalent to normal cement. Over a physiologically reasonable range of stress-intensity factor, fatigue crack propagation rates for Sub-cement were higher by a factor of 25+/-19. When tested in a simplified 2 1/2-D physical model of a stem-cement-bone system, crack growth from the stem was accelerated by a factor of 100. Sub-cement accelerated both crack initiation and growth rate. Sub-cement is now being evaluated in full stem/cement/femur models.

  1. Effect of Sandblasting and Type of Cement on the Bond Strength of Molar Bands on Stainless Steel Crowns.

    Science.gov (United States)

    Bawazir, Omar A; Elaraby, Alaa; Alshamrani, Hamed; Salama, Fouad S

    2015-01-01

    The purposes of this study were to: (1) compare the bond strength of molar bands cemented to stainless steel crowns (SSCs) using glass ionomer cement (GIC), resin-modified glass ionomer cement (RMGIC), or polycarboxylate cement (PXC); and (2) assess the influence of sandblasting molar bands on the mean bond strength between the band and the SSC. Sixty SSCs and 60 molar bands were used. The inner surfaces of 30 molar bands were roughened by sandblasting prior to cementation. The bond strength was measured after dislodging the SSC using a push-out test. In the nonsandblasted group, a significant difference was observed between PXC and RMGIC (P >.04). In the sandblasted group, a significant difference was observed between PXC and RMGIC (P >.02), while there was only a marginal difference between GIC and RMGIC (P >.05). The sandblasted group exhibited superior bond strength overall. However, the only significant improvement was observed for GIC (P >.03). PXC showed the highest bond strength of molar bands to SSCs, while RMGIC showed the lowest. Sandblasting the inner surface of bands enhanced the bond strength of different cements.

  2. 76 FR 76760 - Gray Portland Cement and Cement Clinker From Japan

    Science.gov (United States)

    2011-12-08

    ... and Cement Clinker From Japan Determination On the basis of the record \\1\\ developed in the subject... duty order on gray Portland cement and cement clinker from Japan would be likely to lead to... and Cement Clinker from Japan: Investigation No. 731- TA-461 (Third Review). By order of the...

  3. Cement radwaste solidification studies third annual report

    International Nuclear Information System (INIS)

    Brown, D.J.; James, J.M.; Lee, D.J.; Smith, D.L.; Walker, A.T.

    1982-03-01

    This report summarises cement radwaste studies carried out at AEE Winfrith during 1981 on the encapsulation of medium and low active waste in cement. During the year more emphasis has been placed on the work which is directly related to the solidification of SGHWR active sludge. Information has been obtained on the properties of 220 dm 3 drums of cemented waste. The use of cement grouts for the encapsulation of solid items has also been investigated during 1981. (U.K.)

  4. Characterization of cement-stabilized Cd wastes

    International Nuclear Information System (INIS)

    Maria Diez, J.; Madrid, J.; Macias, A.

    1996-01-01

    Portland cement affords both physical and chemical immobilization of cadmium. The immobilization has been studied analyzing the pore fluid of cement samples and characterizing the solid pastes by X-ray diffraction. The influence of cadmium on the cement hydration and on its mechanical properties has been also studied by isothermal conduction calorimetry and by the measure of strength and setting development. Finally, the effect of cement carbonation on the immobilization of cadmium has been analyzed

  5. Substantial global carbon uptake by cement carbonation

    OpenAIRE

    Xi, Fengming; Davis, Steven J.; Ciais, Philippe; Crawford-Brown, Douglas; Guan, Dabo; Pade, Claus; Shi, Tiemao; Syddall, Mark; Lv, Jie; Ji, Lanzhu; Bing, Longfei; Wang, Jiaoyue; Wei, Wei; Yang, Keun-Hyeok; Lagerblad, Björn

    2016-01-01

    Calcination of carbonate rocks during the manufacture of cement produced 5% of global CO2 emissions from all industrial process and fossil-fuel combustion in 20131, 2. Considerable attention has been paid to quantifying these industrial process emissions from cement production2, 3, but the natural reversal of the process—carbonation—has received little attention in carbon cycle studies. Here, we use new and existing data on cement materials during cement service life, demolition, and secondar...

  6. Color change of CAD-CAM materials and composite resin cements after thermocycling.

    Science.gov (United States)

    Gürdal, Isil; Atay, Ayse; Eichberger, Marlis; Cal, Ebru; Üsümez, Aslihan; Stawarczyk, Bogna

    2018-04-24

    The color of resin cements and computer-aided-design and computer-aided-manufacturing (CAD-CAM) restorations may change with aging. The purpose of this in vitro study was to analyze the influence of thermocycling on the color of CAD-CAM materials with underlying resin cement. Seven different CAD-CAM materials, composite resins and glass-ceramics were cut into 0.7-mm and 1.2-mm thicknesses (n=10) and cemented with a dual-polymerizing resin cement, a light-polymerizing resin cement, and a preheated composite resin (N=420). Color values were measured by using spectrophotometry. Specimens were subjected to thermocycling (5°C and 55°C; 5000 cycles). The measured color difference (ΔE) data were analyzed by using descriptive statistics. Normality of data distribution was tested by using the Kolmogorov-Smirnov test. Three-way and 1-way ANOVA followed by the Scheffé post-hoc test and unpaired 2-sample Student t test were computed to determine the significant differences among the tested parameters (α=.05). ΔE values were significantly influenced by the CAD-CAM material (η p 2 =0.85, Pcement (η P 2 =0.03, P=.003) but were not influenced by thickness (P=.179). Significant interactions were present among thickness, cement, and CAD-CAM materials (Pcement showed significantly lower ΔE values than the preheated composite resin (P=.003). Restoration materials and composite resin cement types used for cementation influence the amount of color change due to aging. Copyright © 2018 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  7. A new bio-active glass ceramic

    International Nuclear Information System (INIS)

    Shamim, A.; Arif, I.; Suleman, M.; Hussain, K.; Shah, W.A.

    1995-01-01

    Since 1960 fine ceramics such as alumina have been used side by side with metallic materials for bone and joint replacement. They have high mechanical strength and are free from corrosion problem faced by metals. However they don't bond to the natural living bone and hence are called bio-inactive. This was followed by the development of bio-active glasses and glass-ceramics which bond to the natural bone but have low mechanical strength. In the present work a new bio-active glass-ceramic, based on CaO-SiO/sub 2/-P/sub 2/O/sub 3/-MgO composition, has been developed which has mechanical strength compared to that of a bio-inactive glass ceramic and also bonds strongly to the natural bone. X-ray diffraction analysis reveals wollastanite and apatite phases in the glass ceramic. A new bio-active cement has also been developed which can be used to join broken pieces of bone or by itself at a filler. (author)

  8. Cementation unit for radioactive wastes

    International Nuclear Information System (INIS)

    Dellamano, Jose Claudio; Vicente, Roberto; Lima, Jose Rodrigues de

    2001-01-01

    This communication describes the waste cementation process and facility developed at Instituto de Pesquisas Energeticas e Nucleares - IPEN. The process is based on 200 litres batch operation, in drum mixing, with continuous cement feeding. The equipment is a single recoverable helicoidal mixer and a turning table that allows the drum to rotate during the mixing operation, simulating a planetary mixer. The facility was designed to treat contact handled liquids and wet solid wastes, but can be adapted for shielded equipment and remote operation. (author)

  9. 21 CFR 872.3275 - Dental cement.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Dental cement. 872.3275 Section 872.3275 Food and... DENTAL DEVICES Prosthetic Devices § 872.3275 Dental cement. (a) Zinc oxide-eugenol—(1) Identification... filling or as a base cement to affix a temporary tooth filling, to affix dental devices such as crowns or...

  10. Cement production from coal conversion residues

    International Nuclear Information System (INIS)

    Brown, L.D.; Clavenna, L.R.; Eakman, J.M.; Nahas, N.C.

    1981-01-01

    Cement is produced by feeding residue solids containing carbonaceous material and ash constituents obtained from converting a carbonaceous feed material into liquids and/or gases into a cement-making zone and burning the carbon in the residue solids to supply at least a portion of the energy required to convert the solids into cement

  11. Multicomponent modelling of Portland cement hydration reactions

    NARCIS (Netherlands)

    Ukrainczyk, N.; Koenders, E.A.B.; Van Breugel, K.

    2012-01-01

    The prospect of cement and concrete technologies depends on more in depth understanding of cement hydration reactions. Hydration reaction models simulate the development of the microstructures that can finally be used to estimate the cement based material properties that influence performance and

  12. CRYSTALLIZATION IN MULTICOMPONENT GLASSES

    Energy Technology Data Exchange (ETDEWEB)

    KRUGER AA; HRMA PR

    2009-10-08

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  13. Crystallization In Multicomponent Glasses

    International Nuclear Information System (INIS)

    Kruger, A.A.; Hrma, P.R.

    2009-01-01

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  14. Natural radioactivity of raw materials and products of cement manufacturing and of power plant fly ashes

    International Nuclear Information System (INIS)

    Gallyas, Miklos

    1984-01-01

    The natural radioactivity was investigated for several building materials used in Hungary, including cement, concrete, glasses, fine ceramic products, insulation materials, and also for some industrial wastes utilized as building material aggregates like slags, fly ashes etc., from their radiation health aspect. The dose commitments of the population from building materials standardized in several countries are presented. The 232 Th, 226 Ra, and 40 K contents of building materials were measured by gamma spectrometry, using NaI/Tl/scintillation detectors. The results were used to qualify cement materials and fly ash aggregates according to their origin in Hungary, from the point of view of their natural radioactivity. It was concluded that the radioactivity level of the majority of Hungarian cements are below the adopted international standards. (R.P.)

  15. Recycling of Glass

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Damgaard, Anders

    2011-01-01

    Glass is used for many purposes, but in the waste system glass is predominantly found in terms of beverage and food containers with a relatively short lifetime before ending up in the waste. Furthermore there is a large amount of flat glass used in building materials which also ends up in the waste...... system; this glass though has a long lifetime before ending up in the waste. Altogether these product types add up to 82% of the production of the European glass industry (IPCC, 2001). Recycling of glass in terms of cleaning and refilling of bottles as well as the use of broken glass in the production...... of new glass containers is well established in the glass industry. This chapter describes briefly howglass is produced and howwaste glass is recycled in the industry. Quality requirements and use of recycled products are discussed, as are the resource and environmental issues of glass recycling....

  16. Vitrified medical wastes bottom ash in cement clinkerization. Microstructural, hydration and leaching characteristics.

    Science.gov (United States)

    Papamarkou, S; Christopoulos, D; Tsakiridis, P E; Bartzas, G; Tsakalakis, K

    2018-04-19

    The present investigation focuses on the utilization of medical wastes incineration bottom ash (MBA), vitrified with soda lime recycled glass (SLRG), as an alternative raw material in cement clinkerization. Bottom ash is recovered from the bottom of the medical wastes incineration chamber, after being cooled down through quenching. It corresponds to 10-15 wt% of the initial medical wastes weight and since it has been classified in the category of hazardous wastes, its safe management has become a major environmental concern worldwide. MBA glasses of various syntheses were initially obtained during the MBA vitrification simultaneously with various amounts of silica scrap (20, 25 and 30 wt% correspondingly). The produced MBA glasses were in turn used for the production of Portland cement clinker, after sintering at 1400 °C, thus substituting traditional raw materials. Both evaluation of vitrification and sintering products was carried out by chemical and mineralogical analyses along with microstructure examination. The final cements were prepared by clinkers co-grinding in a laboratory ball mill with appropriate amounts of gypsum (≈5.0 wt%) and the evaluation of their quality was carried out by determining setting times, standard consistency, expansibility and compressive strength at 2, 7, 28 and 90 days. Finally, the leaching behaviour of the vitrified MBA and hydrated cements, together with the corresponding of the "as received" MBA, was further examined using the standard leaching tests of the Toxicity Characteristic Leaching Procedure (TCLP) and the EN 12457-2. According to the obtained results, the quality of the produced cement clinkers was not affected by the addition of the vitrified MBA in the raw meal, with the trace elements detected in all leachates measured well below the corresponding regulatory limits. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. Electrically conductive Portland cement concrete.

    Science.gov (United States)

    1986-01-01

    There is a need for an effective, simple-to-install secondary anode system for use in the cathodic protection of reinforced concrete bridge decks. In pursuit of such a system, carbon fibers and carbon black were incorporated in portland cement concre...

  18. Polymer reinforcement of cement systems

    International Nuclear Information System (INIS)

    Swamy, R.N.

    1979-01-01

    In the last couple of decades several cement- and concrete-based composites have come into prominence. Of these, cement-polymer composites, like cement-fibre composites, have been recognised as very promising, and considerable research and development on their properties, fabrication methods and application are in progress. Of the three types of concrete materials which incorporate polymers to form composites, polymer impregnated concrete forms a major development in which hardened concrete is impregnated with a liquid monomer which is subsequently polymerized to form a rigid polymer network in the pores of the parent material. In this first part of the extensive review of the polymer reinforcement of cement systems, the process technology of the various monomer impregnation techniques and the properties of the impregnated composite are assessed critically. It is shown that the high durability and superior performance of polymer impregnated concrete can provide an economic and competitive alternative in in situ strengthening, and in other areas where conventional concrete can only at best provide adequate performance. The review includes a section on radiation-induced polymerization. (author)

  19. Resistance to bond degradation between dual-cure resin cements and pre-treated sintered CAD-CAM dental ceramics

    Science.gov (United States)

    Osorio, Raquel; Monticelli, Francesca; Osorio, Estrella; Toledano, Manuel

    2012-01-01

    Objective: To evaluate the bond stability of resin cements when luted to glass-reinforced alumina and zirconia CAD/CAM dental ceramics. Study design: Eighteen glass-infiltrated alumina and eighteen densely sintered zirconia blocks were randomly conditioned as follows: Group 1: No treatment; Group 2: Sandblasting (125 µm Al2O3-particles); and Group 3: Silica-coating (50 µm silica-modified Al2O3-particles). Composite samples were randomly bonded to the pre-treated ceramic surfaces using different resin cements: Subgroup 1: Clearfil Esthetic Cement (CEC); Subgroup 2: RelyX Unicem (RXU); and Subgroup 3: Calibra (CAL). After 24 h, bonded specimens were cut into 1 ± 0.1 mm2 sticks. One-half of the beams were tested for microtensile bond strength (MTBS). The remaining one-half was immersed in 10 % NaOCl aqueous solution (NaOClaq) for 5 h before testing. The fracture pattern and morphology of the debonded surfaces were assessed with a field emission gun scanning electron microscope (FEG-SEM). A multiple ANOVA was conducted to analyze the contributions of ceramic composition, surface treatment, resin cement type, and chemical challenging to MTBS. The Tukey test was run for multiple comparisons (p ceramic interfacial longevity depended on cement selection rather than on surface pre-treatments. The MDP-containing and the self-adhesive resin cements were both suitable for luting CAD/CAM ceramics. Despite both cements being prone to degradation, RXU luted to zirconia or untreated or sandblasted alumina showed the most stable interfaces. CAL experimented spontaneous debonding in all tested groups. Key words:CAD/CAM ceramic, alumina, zirconia, resin cement, surface pre-treatment, sandblasting, silica-coating, chemical aging, bond degradation, microtensile bond strength. PMID:22322517

  20. [Cement augmentation on the spine : Biomechanical considerations].

    Science.gov (United States)

    Kolb, J P; Weiser, L; Kueny, R A; Huber, G; Rueger, J M; Lehmann, W

    2015-09-01

    Vertebral compression fractures are the most common osteoporotic fractures. Since the introduction of vertebroplasty and screw augmentation, the management of osteoporotic fractures has changed significantly. The biomechanical characteristics of the risk of adjacent fractures and novel treatment modalities for osteoporotic vertebral fractures, including pure cement augmentation by vertebroplasty, and cement augmentation of screws for posterior instrumentation, are explored. Eighteen human osteoporotic lumbar spines (L1-5) adjacent to vertebral bodies after vertebroplasty were tested in a servo-hydraulic machine. As augmentation compounds we used standard cement and a modified low-strength cement. Different anchoring pedicle screws were tested with and without cement augmentation in another cohort of human specimens with a simple pull-out test and a fatigue test that better reflects physiological conditions. Cement augmentation in the osteoporotic spine leads to greater biomechanical stability. However, change in vertebral stiffness resulted in alterations with the risk of adjacent fractures. By using a less firm cement compound, the risk of adjacent fractures is significantly reduced. Both screw augmentation techniques resulted in a significant increase in the withdrawal force compared with the group without cement. Augmentation using perforated screws showed the highest stability in the fatigue test. The augmentation of cement leads to a significant change in the biomechanical properties. Differences in the stability of adjacent vertebral bodies increase the risk of adjacent fractures, which could be mitigated by a modified cement compound with reduced strength. Screws that were specifically designed for cement application displayed greatest stability in the fatigue test.

  1. CO2 Capture by Cement Raw Meal

    DEFF Research Database (Denmark)

    Pathi, Sharat Kumar; Lin, Weigang; Illerup, Jytte Boll

    2013-01-01

    The cement industry is one of the major sources of CO2 emissions and is likely to contribute to further increases in the near future. The carbonate looping process has the potential to capture CO2 emissions from the cement industry, in which raw meal for cement production could be used...... as the sorbent. Cyclic experiments were carried out in a TGA apparatus using industrial cement raw meal and synthetic raw meal as sorbents, with limestone as the reference. The results show that the CO2 capture capacities of the cement raw meal and the synthetic raw meal are comparable to those of pure limestone...... that raw meal could be used as a sorbent for the easy integration of the carbonate looping process into the cement pyro process for reducing CO2 emissions from the cement production process....

  2. Leaching of tritium from a cement composite

    International Nuclear Information System (INIS)

    Matsuzuru, Hideo; Ito, Akihiko

    1978-10-01

    Leaching of tritium from cement composites into an aqueous phase has been studied to evaluate the safety of incorporation of the tritiated liquid waste into cement. Leaching tests were performed by the method recommended by the International Atomic Energy Agency. The Leaching fraction was measured as functions of waste-cement ratio (Wa/C), temperature of leachant and curing time. The tritium leachability of cement in the long term test follows the order: alumina cement portland cement slag cement. The fraction of tritium leached increases with increasing Wa/C and temperature and decreasing curing period. A deionized water as a leachant gives a slightly higher leachability than synthetic sea water. The amount leached of tritium from a 200 l drum size specimen was estimated on the basis of the above results. (author)

  3. Mechanical and thermal properties of castor oil polyurethane bone cement after gamma irradiation

    International Nuclear Information System (INIS)

    Azevedo, E.C.; Chierice, G.O.; Claro Neto, S.; Lepiesnki, C.M.; Nascimento, E.M.

    2009-01-01

    Polyurethanes from castor oil are being employed as bone cement in medical applications. In this work the thermal and mechanical properties of gamma irradiated polyurethanes derivative from castor oil were investigated by instrumented indentation, thermogravimetry and scanning electron microscopy. A slightly increase in hardness is observed only for doses as high as 100 kGy. Thermal analysis indicates stability at human body temperature. The glass transition temperature has small changes after gamma irradiation. (author)

  4. Through BHA (Bottom Hole Assembly) cementing with proprietary cementing technology

    Energy Technology Data Exchange (ETDEWEB)

    Fanguy, Charles ' Joey' ; Mueller, Dan T. [BJ Services Company, Houston, TX (United States); Garrett, J.C. [Palm Energy Partners, LLC, Metairie, LA (United States)

    2004-07-01

    There are many problems that can arise when drilling into sub-normally pressured or naturally fractured zones. Lost circulation is one problem that is commonly encountered while drilling oil and gas wells. Lost circulation can lead to increased costs associated with drilling due to rig time, spreadsheet costs, and expensive mud system losses. Cement is one of the most effective treatment options, although it is not normally considered the first option because most operators are forced to trip out of the wellbore and utilize a squeeze packer. This is not always a viable option because of potential well control issues associated with the hydrostatic pressure reduction due to the losses of the whole mud. One treatment option that is commonly overlooked is pumping cement slurries through the bottom hole assembly and drill bit. This is generally not attempted for a variety of reasons. These reasons include: I Concern about 'squeezing off' of the cement in the bit II Lack of potential quality control associated with mixing 'on the fly' III Lack of the ability to test the actual mixed slurry samples The use of a pre-mixed, storable cement slurry has eliminated the concerns associated with pumping cement slurries through mud motors, MWD tools, BHA's, and drill bits. This advanced cement technology has been successfully utilized while reducing the risks associated with these lost circulation treatments. In addition, this technology has eliminated the costs associated with using a squeeze packer and the rig time required for several trips out of the wellbore. The paper will describe the premixed slurry properties and QA/QC procedures that are required for successful through the bit operations. This paper will also provide case histories of successful through the bit operation, as well as background information leading to the treatments. The case histories include successful through the bit remediation of severe lost circulation zones and as well the

  5. Analysis of cement-treated clay behavior by micromechanical approach

    OpenAIRE

    Zhang , Dong-Mei; Yin , Zhenyu; Hicher , Pierre Yves; Huang , Hong-Wei

    2013-01-01

    International audience; Experimental results show the significant influence of cement content on the mechanical properties of cement-treated clays. Cementation is produced by mixing a certain amount of cement with the saturated clay. The purpose of this paper is to model the cementation effect on the mechanical behavior of cement-treated clay. A micromechanical stress-strain model is developed considering explicitly the cementation at inter-cluster contacts. The inter-cluster bonding and debo...

  6. Spin glasses

    International Nuclear Information System (INIS)

    Mookerjee, Abhijit

    1976-01-01

    ''Spin glasses'', are entire class of magnetic alloys of moderate dilution, in which the magnetic atoms are far enough apart to be unlike the pure metal, but close enough so that the indirect exchange energy between them (mediated by the s-d interaction between local moments and conduction electrons) dominates all other energies. Characteristic critical phenomena displayed such as freezing of spin orientation at 'Tsub(c)' and spreading of magnetic ordering, are pointed out. Anomalous behaviour, associated with these critical phenomena, as reflected in : (i) Moessbauer spectroscopy giving hyperfine splitting at Tsub(c), (ii) maxima in susceptibility and remanent magnetism, (iii) thermopower maxima and change in slope, (iv) Characteristic cusp in susceptibility and its removal by very small magnetic fields, and (v) conductivity-resistivity measurements, are discussed. Theoretical developments aimed at explaining these phenomena, in particular, the ideas from percolation and localisation theories, and the approach based on the gellations of polymers, are discussed. Finally, a new approach based on renormalisation group in disordered systems is also briefly mentioned. (K.B.)

  7. Marginal Integrity of Glass Ionomer and All Ceramic Restorations

    Science.gov (United States)

    2015-06-01

    North Carolina), scanned by the CEREC Omnicam , and milled by CEREC inLab MC XL system. 15 List of Procedures in Chronological Order 1. The...Fuji II LC, GC America, Alsip, Illinois). Forty lithium disilicate porcelain ceramic inlays will be milled from CEREC Block PC (Sirona, Charlotte...evolution of the CEREC system. Journal of the American Dental Association, 137, 7s-13s. Mount G.J. (1991). Adhesion of glass-ionomer cement in the clinical

  8. Synthesis of Portland cement and calcium sulfoaluminate-belite cement for sustainable development and performance

    Science.gov (United States)

    Chen, Irvin Allen

    Portland cement concrete, the most widely used manufactured material in the world, is made primarily from water, mineral aggregates, and portland cement. The production of portland cement is energy intensive, accounting for 2% of primary energy consumption and 5% of industrial energy consumption globally. Moreover, portland cement manufacturing contributes significantly to greenhouse gases and accounts for 5% of the global CO2 emissions resulting from human activity. The primary objective of this research was to explore methods of reducing the environmental impact of cement production while maintaining or improving current performance standards. Two approaches were taken, (1) incorporation of waste materials in portland cement synthesis, and (2) optimization of an alternative environmental friendly binder, calcium sulfoaluminate-belite cement. These approaches can lead to less energy consumption, less emission of CO2, and more reuse of industrial waste materials for cement manufacturing. In the portland cement part of the research, portland cement clinkers conforming to the compositional specifications in ASTM C 150 for Type I cement were successfully synthesized from reagent-grade chemicals with 0% to 40% fly ash and 0% to 60% slag incorporation (with 10% intervals), 72.5% limestone with 27.5% fly ash, and 65% limestone with 35% slag. The synthesized portland cements had similar early-age hydration behavior to commercial portland cement. However, waste materials significantly affected cement phase formation. The C3S--C2S ratio decreased with increasing amounts of waste materials incorporated. These differences could have implications on proportioning of raw materials for cement production when using waste materials. In the calcium sulfoaluminate-belite cement part of the research, three calcium sulfoaluminate-belite cement clinkers with a range of phase compositions were successfully synthesized from reagent-grade chemicals. The synthesized calcium sulfoaluminate

  9. The cement recycling of the earthquake disaster debris by Hachinohe Cement Co., Ltd

    International Nuclear Information System (INIS)

    Kataoka, Masayuki

    2015-01-01

    A tremendous quantity of earthquake disaster debris and tsunami sediment was resulted by the Great East Japan Earthquake on March 11, 2011. Hachinohe Cement Co., Ltd., a Sumitomo Osaka Cement subsidiary, was the first cement industry company to receive and process such waste materials outside of their usual prefecture area, while the company is performing their treatment and recycling services locally in Hachinohe City and Aomori Prefecture. This report provides an explanation about the recycling mechanism of waste materials and by-products in cement manufacturing process, and introduces an example of actual achievements for the disaster debris treatment by utilizing the cement recycling technologies at the Hachinohe Cement Plant. (author)

  10. Ground Glass Pozzolan in Conventional, High, and Ultra-High Performance Concrete

    OpenAIRE

    Tagnit-Hamou Arezki; Zidol Ablam; Soliman Nancy; Deschamps Joris; Omran Ahmed

    2018-01-01

    Ground-glass pozzolan (G) obtained by grinding the mixed-waste glass to same fineness of cement can act as a supplementary-cementitious material (SCM), given that it is an amorphous and a pozzolanic material. The G showed promising performances in different concrete types such as conventional concrete (CC), high-performance concrete (HPC), and ultra-high performance concrete (UHPC). The current paper reports on the characteristics and performance of G in these concrete types. The use of G pro...

  11. Cementing of geothermal wells. Progress report No. 12, January-March, 1979

    Energy Technology Data Exchange (ETDEWEB)

    1979-08-01

    Work to implement the program plan for the development of improved high temperature cementing materials for geothermal wells is continuing. Results from initial tests in the Dynamic Brine Exposure Testing Apparatus (D-BETA) are available. Based upon initial data, the rate at which cement coupons undergo change in the D-BETA is between that of the static tests and the dynamic exposures at East Mesa. Several cementing compositions have been formulated with chemical, physical and mechanical properties to withstand the existing geothermal conditions. The pumpability of three formulations has been demonstrated and the materials have been submitted to NBS for additional evaluation. The effect of Al/sub 2/O/sub 3/, Fe/sub 2/O/sub 3/, SO/sub 3/, Na/sub 2/CO/sub 3/ and Na/sub 2/SO/sub 4/ on different binders were studied at Colorado School of Mines. The results were found to range from deleterious to beneficial. Phosphate-bonded cements have been produced at the University of Rhode Island from a glass containing 7% Na/sub 2/O, 24% CaO, 24% Al/sub 2/O/sub 3/ and 45% SiO/sub 2/. Preliminary tests indicate that the material sets in several hours and appears to have some high temperature stability. Tests performed on hydrothermal cements indicate six formulations that are pumpable as long as three hours at 316/sup 0/C. Two formulations, Al/sub 2/O/sub 3/ and ZrO/sub 2/, have been chosen for use at temperatures above 300/sup 0/C. Polymer concentrates containing cement fillers have been found to be hydrothermally stable in 300/sup 0/C brine. Recommended standards for evaluating geothermal well cements have been developed by NBS. (MHR)

  12. Alkali-silica reactivity of expanded glass granules in structure of lightweight concrete

    International Nuclear Information System (INIS)

    Bumanis, G; Bajare, D; Korjakins, A; Locs, J

    2013-01-01

    Main component in the lightweight concrete, which provides its properties, is aggregate. A lot of investigations on alkali silica reaction (ASR) between cement and lightweight aggregates have been done with their results published in the academic literature. Whereas expanded glass granules, which is relatively new product in the market of building materials, has not been a frequent research object. Therefore lightweight granules made from waste glass and eight types of cement with different chemical and mineralogical composition were examined in this research. Expanded glass granules used in this research is commercially available material produced by Penostek. Lightweight concrete mixtures were prepared by using commercial chemical additives to improve workability of concrete. The aim of the study is to identify effect of cement composition to the ASR reaction which occurs between expanded glass granules and binder. Expanded glass granules mechanical and physical properties were determined. In addition, properties of fresh and hardened concrete were determined. The ASR test was processed according to RILEM AAR-2 testing recommendation. Tests with scanning electron microscope and microstructural investigations were performed for expanded glass granules and hardened concrete specimens before and after exposing them in alkali solution

  13. Use sulfoferritic cements in construction

    Science.gov (United States)

    Samchenko, Svetlana V.; Zorin, Dmitriy A.

    2018-03-01

    Currently, high-rise construction has received increasing attention around the world. In the big cities under construction is less space and one solution is the high-rise construction. However, high-rise buildings use special requirements, such as strength, thermal insulation, wind load and others. When concrete is exposed to continuous loads by wind or to mechanical loads, it undergoes abrasion. Resistance to this process depends on the characteristics of materials that the concrete and finishing seams are made of. Research on increasing impact and abrasion resistance of calcium sulfoferrite-based cement stone from the perspective of formation of cement stone structure will be instrumental in developing durable materials for application in high-rise construction.

  14. Concrete research using blended cements

    International Nuclear Information System (INIS)

    Butler, W.B.

    2001-01-01

    Concrete research increasingly involves the use of mixes containing one or more of the supplementary cementitious materials (SCMs), often in conjunction with chemical admixtures. The influence of materials is commonly evaluated on the basis of water/ cement or water/ binder ratio and SCM content as a percentage of total binder, with dosage level of chemical admixture varied to maintain workability. As a result, more than one variable is introduced at a time and the objectives of the research may not be achieved. The significance of water/ cement ratio and addition rates of admixtures are examined from a practical standpoint with suggestions for more appropriate means of evaluation of the influence of individual materials. Copyright (2001) The Australian Ceramic Society

  15. The density of cement phases

    International Nuclear Information System (INIS)

    Balonis, M.; Glasser, F.P.

    2009-01-01

    The densities of principal crystalline phases occurring in Portland cement are critically assessed and tabulated, in some cases with addition of new data. A reliable and self-consistent density set for crystalline phases was obtained by calculating densities from crystallographic data and unit cell contents. Independent laboratory work was undertaken to synthesize major AFm and AFt cement phases, determine their unit cell parameters and compare the results with those recorded in the literature. Parameters were refined from powder diffraction patterns using CELREF 2 software. A density value is presented for each phase, showing literature sources, in some cases describing limitations on the data, and the weighting attached to numerical values where an averaging process was used for accepted data. A brief discussion is made of the consequences of the packing of water to density changes in AFm and AFt structures.

  16. Effect of Anatomical Customization of the Fiber Post on the Bond Strength of a Self-Adhesive Resin Cement.

    Science.gov (United States)

    Rocha, Adricyla Teixeira; Gonçalves, Leticia Machado; Vasconcelos, Ana Júlia de Carvalho; Matos Maia Filho, Etevaldo; Nunes Carvalho, Ceci; De Jesus Tavarez, Rudys Rodolfo

    2017-01-01

    The aim of the study was to evaluate, by means of the push-out test, the effect of the anatomical customization of the fiber post on the bond strength of a self-adhesive resin cement. Twelve endodontically treated, human, upper central incisors were randomly divided into two groups ( n = 6): control (glass fiber posts cemented with Relyx® U200) and customized (glass fiber posts anatomically customized with translucent composite resin cemented with Relyx U200). The roots were sectioned into three slices, cervical, middle, and apical, and photographed with a digital camera attached to a stereomicroscopic loupe. The images were analyzed by software, for evaluation of the cement line. The slices were subsequently submitted to the push-out test until the post had completely extruded, and the fracture mode was analyzed with a stereomicroscopic loupe. The results showed significant differences between the groups in the different root thirds in relation to the area occupied by air bubbles ( p customized group. The customized group showed greater bond resistance than the control group and a more uniform cement layer.

  17. WHITE CEMENT IN SUSTAINABLE DEVELOPMENT

    OpenAIRE

    Y.C.P RAMANA BABU; B.SAI DOONDI; N. M .V .VAMSI KRISHNA; K.PRASANTHI

    2013-01-01

    India is one among the fast developing countries in the world in the areas of Infrastructure. Now a day, Carbon monoxide (CO) and carbon dioxide (CO2) are the temporary atmospheric pollutants in the environment chiefly emitted from the fuel burning vehicles and street lights which lead to global warming and pose a major threat tothe survival and sustainable development. This paper deals with the principal purpose of use of white cement in pavement design which will take care of the Green hous...

  18. Modernization of Byuzmeyinsky Cement Plant

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-03-01

    With an objective of saving energy and reducing greenhouse gas emission, investigations and discussions were given on a modernization project for Byuzmeyinsky Cement Factory, the only cement factory in Turkmenistan. Byuzmeyinsky Cement Factory uses the wet process which consumes a large amount of energy, is inferior in production efficiency and quality, and discharging a great amount of greenhouse effect gas. The present project will execute change of the raw material crusher into a vertical roll mill for one of the four wet kilns, and change of the facilities for raw material powder mixing and storing and clinker manufacturing into dry-type facilities using the NSP system. As a result of the discussions, the energy saving effect would be 86,321 tons of crude oil equivalent annually, and the greenhouse gas emission reducing effect would be 224,467 t-CO2 annually. The total fund amount required for the project is estimated to be 90,211,000 dollars. With regard to the profitability, the internal financial profit rate would be 9.71% after tax, and the ROE would be 18.62%, whereas the project is considered feasible. (NEDO)

  19. Use of Incineration Solid Waste Bottom Ash as Cement Mixture in Cement Production

    Science.gov (United States)

    Jun, N. H.; Abdullah, M. M. A. B.; Jin, T. S.; Kadir, A. A.; Tugui, C. A.; Sandu, A. V.

    2017-06-01

    Incineration solid waste bottom ash was use to examine the suitability as a substitution in cement production. This study enveloped an innovative technology option for designing new equivalent cement that contains incineration solid waste bottom ash. The compressive strength of the samples was determined at 7, 14, 28 and 90 days. The result was compared to control cement with cement mixture containing incineration waste bottom ash where the result proved that bottom ash cement mixture able achieve its equivalent performance compared to control cement which meeting the requirement of the standards according to EN 196-1. The pozzolanic activity index of bottom ash cement mixture reached 0.92 at 28 days and 0.95 at 90 and this values can be concluded as a pozzolanic material with positive pozzolanic activity. Calcium hydroxide in Portland cement decreasing with the increasing replacement of bottom ash where the reaction occur between Ca(OH)2 and active SiO2.

  20. Natural cement as the precursor of Portland cement: Methodology for its identification

    International Nuclear Information System (INIS)

    Varas, M.J.; Alvarez de Buergo, M.; Fort, R.

    2005-01-01

    When cements appeared in the 19th century, they took the place of traditional binding materials (lime, gypsum, and hydraulic lime) which had been used until that time. Early cements can be divided into two groups, natural and artificial (Portland) cements. Natural cements were introduced first, but their widespread usage was short-lived as they were quickly replaced by artificial cements (Portland), still the most important and predominant today. The main differences between natural and artificial cements arise during the manufacturing process. The final properties of the cements are greatly influenced by differences in the raw materials and burning temperatures employed. The aim of this paper is to assess the efficiency of traditional analytical techniques (petrographic microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR)) used to differentiate natural and artificial cements

  1. Effects of cement particle size distribution on performance properties of Portland cement-based materials

    Energy Technology Data Exchange (ETDEWEB)

    Bentz, D.P.; Garboczi, E.J.; Haecker, C.J.; Jensen, O.M.

    1999-10-01

    The original size, spatial distribution, and composition of Portland cement particles have a large influence on hydration kinetics, microstructure development, and ultimate properties of cement-based materials. In this paper, the effects of cement particle size distribution on a variety of performance properties are explored via computer simulation and a few experimental studies. Properties examined include setting time, heat release, capillary porosity percolation, diffusivity, chemical shrinkage, autogenous shrinkage, internal relative humidity evolution, and interfacial transition zone microstructure. The effects of flocculation and dispersion of the cement particles in the starting microstructures on resultant properties are also briefly evaluated. The computer simulations are conducted using two cement particle size distributions that bound those commonly in use today and three different water-to-cement ratios: 0.5, 0.3, and 0.246. For lower water-to-cement ratio systems, the use of coarser cements may offer equivalent or superior performance, as well as reducing production costs for the manufacturer.

  2. Cement replacement materials. Properties, durability, sustainability

    International Nuclear Information System (INIS)

    Ramezanianpour, Ali Akbar

    2014-01-01

    The aim of this book is to present the latest findings in the properties and application of Supplementary Cementing Materials and blended cements currently used in the world in concrete. Sustainability is an important issue all over the world. Carbon dioxide emission has been a serious problem in the world due to the greenhouse effect. Today many countries agreed to reduce the emission of CO2. Many phases of cement and concrete technology can affect sustainability. Cement and concrete industry is responsible for the production of 7% carbon dioxide of the total world CO2 emission. The use of supplementary cementing materials (SCM), design of concrete mixtures with optimum content of cement and enhancement of concrete durability are the main issues towards sustainability in concrete industry.

  3. The cement solidification systems at LANL

    International Nuclear Information System (INIS)

    Veazey, G.W.

    1990-01-01

    There are two major cement solidification systems at Los Alamos National Laboratory. Both are focused primarily around treating waste from the evaporator at TA-55, the Plutonium Processing Facility. The evaporator receives the liquid waste stream from TA-55's nitric acid-based, aqueous-processing operations and concentrates the majority of the radionuclides in the evaporator bottoms solution. This is sent to the TA-55 cementation system. The evaporator distillate is sent to the TA-50 facility, where the radionuclides are precipitated and then cemented. Both systems treat TRU-level waste, and so are operated according to the criteria for WIPP-destined waste, but they differ in both cement type and mixing method. The TA-55 systems uses Envirostone, a gypsum-based cement and in-drum prop mixing; the TA-50 systems uses Portland cement and drum tumbling for mixing

  4. Characterization of experimental cements with endodontic goal

    International Nuclear Information System (INIS)

    Dantas, A.M.X.; Sousa, W.J.B.; Oliveira, E.D.C.; Carrodeguas, R.G.; Fook, M.V. Lia; Universidade Estadual da Paraiba

    2017-01-01

    The present study aimed to characterize experimental endodontic cements using as comparative parameter MTA cement. Two experimental endodontic cements were assessed: one based on 95% tri-strontium aluminate and 5% gypsum (CE1) and another based on 50% Sr_3Al_2O_6 and 50% non-structural white cement (CE2). Experimental cements were manipulated and characterized by scanning electron microscopy (SEM), coupled to EDS mode, X-ray diffractometer (XRD) and Thermogravimetric (TG) analysis. Data analysis demonstrated that the particles of the materials used presented varied shapes and sizes, with similar elements and crystalline behavior. However, CE1 presented increased mass loss. Experimental cements presents similarities to MTA, nevertheless, further studies are encourage to determinate comparative properties with the commercially material. (author)

  5. Modelling porewater chemistry in hydrated Portland cement

    International Nuclear Information System (INIS)

    Berner, U.R.

    1987-01-01

    Extensive employment of concrete is foreseen in radioactive waste repositories. A prerequisite for modelling the interactions between concrete and formation waters is characterization of the concrete system. Available experimental data from high pressure squeezing of cement pore-water indicate that, besides the high pH due to alkali hydroxide dissolution, cement composition itself influences the solubility determining solid phases. A model which simulates the hydration of Portland cement assuming complete hydration of the main clinker minerals is presented. The model also includes parameters describing the reactions between the cement and blending agents. Comparison with measured pore-water data generally gives a consistent picture and, as expected, the model gives correct predictions for pure Portland cements. For blended cements, the required additional parameters can, to some extent, be derived from pore-water analysis. 14 references, 1 figure, 4 tables

  6. Chemistry of cements for nuclear applications

    International Nuclear Information System (INIS)

    Barrett, P.; Glasser, F.P.

    1992-01-01

    In recent times the nuclear industry has thrown up challenges which cannot be met by the application of conventional civil and materials engineering knowledge. The contributions in this volume investigate all aspects of cement performance. The scope of the papers demonstrates the current balance of activities which have as their objective the elucidation of kinetics and immobilization, determining material interactions and of assessing future performance. The papers reflect the varied goals of the sponsors who include national governments, the Commission of the European Communities and the nuclear industries. In six parts attention is paid to the durability of cement and concrete in repository environment; interactions between cement, waste components and ground water; properties and performance of cement materials; leach behavior and mechanisms, diffusional properties of cement and concrete, including porosity-permeability relationships; and thermodynamics of cementitious systems and modelling of cement performance

  7. lead glass brick

    CERN Multimedia

    When you look through the glass at a picture behind, the picture appears raised up because light is slowed down in the dense glass. It is this density (4.06 gcm-3) that makes lead glass attractive to physicists. The refractive index of the glass is 1.708 at 400nm (violet light), meaning that light travels in the glass at about 58% its normal speed. At CERN, the OPAL detector uses some 12000 blocks of glass like this to measure particle energies.

  8. The mechanical effect of the existing cement mantle on the in-cement femoral revision.

    Science.gov (United States)

    Keeling, Parnell; Lennon, Alexander B; Kenny, Patrick J; O'Reilly, Peter; Prendergast, Patrick J

    2012-08-01

    Cement-in-cement revision hip arthroplasty is an increasingly popular technique to replace a loose femoral stem which retains much of the original cement mantle. However, some concern exists regarding the retention of the existing fatigued and aged cement in such cement-in-cement revisions. This study investigates whether leaving an existing fatigued and aged cement mantle degrades the mechanical performance of a cement-in-cement revision construct. Primary cement mantles were formed by cementing a polished stem into sections of tubular steel. If in the test group, the mantle underwent conditioning in saline to simulate ageing and was subject to a fatigue of 1 million cycles. If in the control group no such conditioning or fatigue was carried out. The cement-in-cement procedure was then undertaken. Both groups underwent a fatigue of 1 million cycles subsequent to the revision procedure. Application of a Mann-Whitney test on the recorded subsidence (means: 0.51, 0.46, n=10+10, P=0.496) and inducible displacement (means: 0.38, 0.36, P=0.96) revealed that there was no statistical difference between the groups. This study represents further biomechanical investigation of the mechanical behaviour of cement-in-cement revision constructs. Results suggest that pre-revision fatigue and ageing of the cement may not be deleterious to the mechanical performance of the revision construct. Thus, this study provides biomechanical evidence to back-up recent successes with this useful revision technique. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Sustainable Development of the Cement Industry and Blended Cements to Meet Ecological Challenges

    OpenAIRE

    Sobolev, Konstantin

    2003-01-01

    The world production of cement has greatly increased in the past 10 years. This trend is the most significant factor affecting technological development and the updating of manufacturing facilities in the cement industry. Existing technology for the production of cement clinker is ecologically damaging; it consumes much energy and natural resources and also emits pollutants. A new approach to the production of blended or high-volume mineral additive (HVMA) cement helps to improve its ecologi...

  10. Pulmonary Cement Embolism following Percutaneous Vertebroplasty

    Directory of Open Access Journals (Sweden)

    Ümran Toru

    2014-01-01

    Full Text Available Percutaneous vertebroplasty is a minimal invasive procedure that is applied for the treatment of osteoporotic vertebral fractures. During vertebroplasty, the leakage of bone cement outside the vertebral body leads to pulmonary cement embolism, which is a serious complication of this procedure. Here we report a 48-year-old man who was admitted to our hospital with dyspnea after percutaneous vertebroplasty and diagnosed as pulmonary cement embolism.

  11. Low melting high lithia glass compositions and methods

    Science.gov (United States)

    Jantzen, Carol M.; Pickett, John B.; Cicero-Herman, Connie A.; Marra, James C.

    2000-01-01

    The invention relates to methods of vitrifying waste and for lowering the melting point of glass forming systems by including lithia formers in the glass forming composition in significant amounts, typically from about 0.16 wt % to about 11 wt %, based on the total glass forming oxides. The lithia is typically included as a replacement for alkali oxide glass formers that would normally be present in a particular glass forming system. Replacement can occur on a mole percent or weight percent basis, and typically results in a composition wherein lithia forms about 10 wt % to about 100 wt % of the alkali oxide glass formers present in the composition. The present invention also relates to the high lithia glass compositions formed by these methods. The invention is useful for stabilization of numerous types of waste materials, including aqueous waste streams, sludge solids, mixtures of aqueous supernate and sludge solids, combinations of spent filter aids from waste water treatment and waste sludges, supernate alone, incinerator ash, incinerator offgas blowdown, or combinations thereof, geological mine tailings and sludges, asbestos, inorganic filter media, cement waste forms in need of remediation, spent or partially spent ion exchange resins or zeolites, contaminated soils, lead paint, etc. The decrease in melting point achieved by the present invention desirably prevents volatilization of hazardous or radioactive species during vitrification.

  12. Waste glass corrosion modeling: Comparison with experimental results

    International Nuclear Information System (INIS)

    Bourcier, W.L.

    1993-11-01

    A chemical model of glass corrosion will be used to predict the rates of release of radionuclides from borosilicate glass waste forms in high-level waste repositories. The model will be used both to calculate the rate of degradation of the glass, and also to predict the effects of chemical interactions between the glass and repository materials such as spent fuel, canister and container materials, backfill, cements, grouts, and others. Coupling between the degradation processes affecting all these materials is expected. Models for borosilicate glass dissolution must account for the processes of (1) kinetically-controlled network dissolution, (2) precipitation of secondary phases, (3) ion exchange, (4) rate-limiting diffusive transport of silica through a hydrous surface reaction layer, and (5) specific glass surface interactions with dissolved cations and anions. Current long-term corrosion models for borosilicate glass employ a rate equation consistent with transition state theory embodied in a geochemical reaction-path modeling program that calculates aqueous phase speciation and mineral precipitation/dissolution. These models are currently under development. Future experimental and modeling work to better quantify the rate-controlling processes and validate these models are necessary before the models can be used in repository performance assessment calculations

  13. Tritium sorption by cement and subsequent release

    International Nuclear Information System (INIS)

    Ono, F.; Tanaka, S.; Yamawaki, M.

    1994-01-01

    In a fusion reactor or tritium handling facilities, contamination of concrete by tritium and subsequent release from it to the reactor or experimental rooms is a matter of problem for safety control of tritium and management of operational environment. In order to evaluate these tritium behavior, interaction of tritiated water with concrete or cement should be clarified. In the present study, HTO sorption and subsequent release from cement were studied by combining various experimental methods. From the basic studies on tritium-cement interactions, it has become possible to evaluate tritium uptake by cement or concrete and subsequent tritium release behavior as well as tritium removing methods from them

  14. Immobilisation of ion exchange resins in cement

    International Nuclear Information System (INIS)

    Howard, C.G.; Jolliffe, C.B.; Lee, D.J.

    1990-09-01

    The removal of activity from spent decontaminating solutions eg LOMI can be achieved using organic ion exchange resins. These resins can be successfully immobilised in cement based matrices. The optimum cement system contained 10% ordinary Portland cement 84% gg blast furnace slag, 6% microsilica with a water cement ratio of 0.5 and a dry resin loading of 36% with respect to total weight. This formulation was successfully scaled up to 200 litres giving a product with acceptable compressive strength, dimensional stability and elastic modulus. Storage of samples under water appears to have no detrimental effects on the product's properties. (author)

  15. Immobilisation of ion exchange resins in cement

    International Nuclear Information System (INIS)

    Howard, C.G.; Jolliffe, C.B.; Lee, D.J.

    1990-09-01

    The removal of activity from spent decontaminating solutions eg LOMI can be achieved using organic ion exchange resins. These resins can be successfully immobilised in cement based matrices. The optimum cement system contained 10% ordinary Portland cement, 84% gg blast furnace slag, 6% microsilica with a water cement ratio of 0.5 and a dry resin loading of 36% with respect to total weight. This formulation was successfully scaled up to 200 litres giving a product with acceptable compressive strength, dimensional stability and elastic modulus. Storage of samples under water appears to have no detrimental effects on the products' properties. (author)

  16. Use of rubber crumbs in cement concrete

    Science.gov (United States)

    Longvinenko, A. A.

    2018-03-01

    Rubber crumb obtained from worn out tires has been increasingly used over the last 15-20 years, especially in manufacture of asphalt and cement concrete mixtures. This review pays principal attention to application of the rubber crumb to cement concrete mixtures. Use of the rubber crumb in cement concrete is not as successful as in asphalt concrete mixtures, due to incompatibility problems linked to chemical composition and a significant difference in rigidity between the rubber crumb and concrete mixture aggregates. Different methods are proposed and studied to mitigate the adverse influence and increase the beneficial effects of the rubber crumb when added to cement concrete.

  17. Controls on Cementation in a Chalk Reservoir

    DEFF Research Database (Denmark)

    Meireles, Leonardo Teixeira Pinto; Hussein, A.; Welch, M.J.

    2017-01-01

    In this study, we identify different controls on cementation in a chalk reservoir. Biot’s coefficient, a measure of cementation, stiffness and strength in porous rocks, is calculated from logging data (bulk density and sonic Pwave velocity). We show that Biot’s coefficient is correlated...... that some degree of pore filling cementation occurred in Kraka (Alam, 2010). Lack of correlation between Biot’s coefficient and Gamma Ray (GR) indicates that the small amount of clay present is generally located in the pore space, thus not contributing to frame stiffness. While there was no compositional...... control on cementation via clay, we could infer that stratigraphy impacts on the diagenetic process....

  18. Immobilisation of radwaste in cement based matrices

    International Nuclear Information System (INIS)

    Glasser, F.P.; Macphee, D.; Atkins, M.; Pointer, C.; Cowie, J.; Wilding, C.R.; Mattingley, N.J.; Evans, P.A.

    1989-01-01

    The solubilities and influence on cement pH are reported for calcium aluminate and aluminosulphate hydrates. The solubility of Ca(OH) 2 is reported to 700 bars. Polymerization of C-S-H is investigated by NMR. Specific interactions of U 6+ and iodine (I - , IO 3 - ) with cement components are described. The impact of radiation on cements and the influence of higher temperature are documented. The role of dissolved Ca and CO 2 in groundwaters as dissolution media for cements are reported. (author)

  19. Integer programming of cement distribution by train

    Science.gov (United States)

    Indarsih

    2018-01-01

    Cement industry in Central Java distributes cement by train to meet daily demand in Yogyakarta and Central Java area. There are five destination stations. For each destination station, there is a warehouse to load cements. Decision maker of cement industry have a plan to redesign the infrastructure and transportation system. The aim is to determine how many locomotives, train wagons, and containers and how to arrange train schedules with subject to the delivery time. For this purposes, we consider an integer programming to minimize the total of operational cost. Further, we will discuss a case study and the solution the problem can be calculated by LINGO software.

  20. Prediction of hydroxyl concentrations in cement pore water using a numerical cement hydration model

    NARCIS (Netherlands)

    Eijk, van R.J.; Brouwers, H.J.H.

    2000-01-01

    In this paper, a 3D numerical cement hydration model is used for predicting alkali and hydroxyl concentrations in cement pore water. First, this numerical model is calibrated for Dutch cement employing both chemical shrinkage and calorimetric experiments. Secondly, the strength development of some

  1. Evaluation of cement thixotropy for the cement of oil wells in areas ...

    African Journals Online (AJOL)

    ... economical for cementing job operations in wells with loss zones. The results also show that the effect of LHF is positive, since in addition to his contribution to long term performances, especially the durability of hardened concrete, it improves the thixotropy of cement made of plaster. Keywords: cementing; lost circulation; ...

  2. Geotechnical Properties of Clayey Soil Stabilized with Cement ...

    African Journals Online (AJOL)

    ADOWIE PERE

    2017-12-31

    Dec 31, 2017 ... ... to investigate the different effects of cement-sawdust ash and cement on a ... Keywords: Cement, Saw dust, strength test subgrade material, highway construction ... characteristics of lateritic soil stabilized with sawdust ash.

  3. Glass and nuclear wastes

    International Nuclear Information System (INIS)

    Sombret, C.

    1982-10-01

    Glass shows interesting technical and economical properties for long term storage of solidified radioactive wastes by vitrification or embedding. Glass composition, vitrification processes, stability under irradiation, thermal stability and aqueous corrosion are studied [fr

  4. Microstructuring of glasses

    CERN Document Server

    Hülsenberg, Dagmar; Bismarck, Alexander

    2008-01-01

    As microstructured glass becomes increasingly important for microsystems technology, the main application fields include micro-fluidic systems, micro-analysis systems, sensors, micro-actuators and implants. And, because glass has quite distinct properties from silicon, PMMA and metals, applications exist where only glass devices meet the requirements. The main advantages of glass derive from its amorphous nature, the precondition for its - theoretically - direction-independent geometric structurability. Microstructuring of Glasses deals with the amorphous state, various glass compositions and their properties, the interactions between glasses and the electromagnetic waves used to modify it. Also treated in detail are methods for influencing the geometrical microstructure of glasses by mechanical, chemical, thermal, optical, and electrical treatment, and the methods and equipment required to produce actual microdevices.

  5. Using the low-temperature plasma in cement production

    International Nuclear Information System (INIS)

    Sazonova, N A; Skripnikova, N K

    2015-01-01

    The calculation of the raw-material mixtures and mineralogical composition of the cement clinkers which are synthezed on their base taking into account the disbalanced crystallization of the melting and glassing under conditions of the low-temperature plasma was performed. The difference of the actual values from the calculated ones is 0.69-3.73%. The composition which is characterized as the saturation coefficient 0,88; the silicate module - 3.34, the alumina module - 2.52 in melting of which the alite in amount 78.7%; 3CaO·SiO 2 - 4%; 3CaO·Al 2 O 3 - 9.8%; 12CaO·7Al 2 O 3 -2.9%; CaO free - 1% formed using the lime-stone from the quarry «Pereval» in the town of Slyudyanka and the clay from the deposit «Maximovski» in Irkutsk Region is considered as the optimal one. The structure of the melted clinker is represented as the metastable minerals of alite in the lamellar form with the dimensions up to (3-20)×(80-400) μm and the ratio of length to width 26.6-133. The elongated crystal form may stipulate the high cement activity based on the melted clinkers, which is 82.7-84.2 MPa. Valid- ing the revealed high activity of the viscous substance was confirmed by the results of the scanning electronic microscopy, X-ray phase analysis, with using of which the quantitative and qualitative analyses of the clinker minerals having the deformed crystalic lattice; were performed the morphology of the minerals in the clinker and cement stone, received on its ground, was studied. (paper)

  6. Measurement of optical glasses

    International Nuclear Information System (INIS)

    Nicolau-Rebigan, S.

    1978-11-01

    The possibilities of measurement of the optical glasses parameters needed in building optical devices especially in lasers devices are presented. In the first chapter the general features of the main optical glasses as well as the modalities of obtaining them are given. Chapter two defines the optical glass parameters, and the third chapter describes the measuring methods of the optical glass parameters. Finally, the conclusions which point out the utilization of this paper are presented. (author)

  7. Nanoscale Mobility of Aqueous Polyacrylic Acid in Dental Restorative Cements.

    Science.gov (United States)

    Berg, Marcella C; Benetti, Ana R; Telling, Mark T F; Seydel, Tilo; Yu, Dehong; Daemen, Luke L; Bordallo, Heloisa N

    2018-03-28

    Hydrogen dynamics in a time range from hundreds of femtoseconds to nanoseconds can be directly analyzed using neutron spectroscopy, where information on the inelastic and quasi-elastic scattering, hereafter INS and QENS, can be obtained. In this study, we applied these techniques to understand how the nanoscale mobility of the aqueous solution of polyacrylic acid (PAA) used in conventional glass ionomer cements (GICs) changes under confinement. Combining the spectroscopic analysis with calorimetric results, we were able to separate distinct motions within both the liquid and the GICs. The QENS analysis revealed that the self-diffusion translational motion identified in the liquid is also visible in the GIC. However, as a result of the formation of the cement matrix and its setting, both translational diffusion and residence time differed from the PAA solution. When comparing the local diffusion obtained for the selected GIC, the only noticeable difference was observed for the slow dynamics associated with the polymer chain. Additionally, over short-term aging, progressive water binding to the polymer chain occurred in one of the investigated GICs. Finally, a considerable change in the density of the GIC without progressive water binding indicates an increased polymer cross-linking. Taken together, our results suggest that accurate and deep understanding of polymer-water binding, polymer cross-linking, as well as material density changes occurring during the maturation process of GIC are necessary for the development of advanced dental restorative materials.

  8. Rietveld analysis, powder diffraction and cement

    International Nuclear Information System (INIS)

    Peterson, V.

    2002-01-01

    Full text: Phase quantification of cement is essential in its industrial use, however many methods are inaccurate and/or time consuming. Powder diffraction is one of the more accurate techniques used for quantitative phase analysis of cement. There has been an increase in the use of Rietveld refinement and powder diffraction for the analysis and phase quantification of cement and its components in recent years. The complex nature of cement components, existence of solid solutions, polymorphic variation of phases and overlapping phase peaks in diffraction patterns makes phase quantification of cements by powder diffraction difficult. The main phase in cement is alite, a solid solution of tricalcium silicate. Tricalcium silicate has been found to exist in seven modifications in three crystal systems, including triclinic, monoclinic, and rhombohedral structures. Hence, phase quantification of cements using Rietveld methods usually involves the simultaneous modelling of several tricalcium silicate structures to fit the complex alite phase. An industry ordinary Portland cement, industry and standard clinker, and a synthetic tricalcium silicate were characterised using neutron, laboratory x-ray and synchrotron powder diffraction. Diffraction patterns were analysed using full-profile Rietveld refinement. This enabled comparison of