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Dental Restorative Materials (dental + restorative_material)
Selected AbstractsThe post-amalgam era: a selection of materials and their longevity in the primary and young permanent dentitionsINTERNATIONAL JOURNAL OF PAEDIATRIC DENTISTRY, Issue 3 2003H. Forss Summary. Objectives. During the last decade there has been a rapid change in the selection of dental restorative materials as the use of amalgam has decreased. The aim of this study was to obtain information on children's restorative dental care in Finland and to analyse the longevity of failed restorations. Design. A random sample of public dental health care centres was drawn from the registers and the dentists working there were asked to record information for each restoration they placed during a three-day period. The survey data comprised a total of 2186 restorations in patients younger than 17 years. Results. Of the children in need of restorative treatment, only a few had previous amalgam restorations. Primary caries was the main reason for restorative treatment in both primary and permanent dentitions (80% and 83%, respectively). In primary teeth, the most common restorative material was resin-modified glass ionomer cement (57·4%), whereas in permanent teeth, composite resin dominated (58·7%). Amalgam was not used at all in the primary dentition and in only 0·6% of permanent teeth. Eighteen per cent of treatments in primary and 12% in permanent teeth were replacements of previous fillings. The mean age of failed glass ionomer restorations was 2·8 years (n = 101) in the primary dentition, and 3·5 years (n = 54) in the permanent dentition. Conclusions. Until better restorative materials are developed, more attention should be paid to the prevention of dental caries as well as to the proper handling of alternative materials. [source] Curing Dental Resins and Composites by PhotopolymerizationJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 6 2000JEFFREY W. STANSBURY PHD ABSTRACT The development and continued evolution of photopolymerizable dental materials, particularly dental composite restoratives, represent a significant, practical advance for dentistry. The highly successful integration of the light-activated curing process for dental applications is described in this review. The basic mechanisms by which the photoinitiators efficiently convert monomers into polymers are discussed along with the variety of factors that influence the photopolymerization process. The conventional camphorquinone-amine visible light photoinitiator system used in most dental restorative materials is illustrated in addition to some alternative initiator systems that have been studied for dental materials applications. CLINICAL SIGNIFICANCE Photopolymerization has become an integral component of the practice of dentistry. A better appreciation of the photopolymerization process as well as its potential and limitations may aid the dentist in the delivery of both esthetic and restorative dental care. [source] The effect of Coca-Cola and fruit juices on the surface hardness of glass,ionomers and ,compomers'JOURNAL OF ORAL REHABILITATION, Issue 11 2004M. Aliping-McKenzie summary, The interaction of tooth-coloured dental restorative materials (a conventional glass,ionomer, two resin-modified glass,ionomers and two compomers) with acidic beverages has been studied with the aim of investigating how long-term contact affects solution pH and specimen surface hardness. For each material (ChemFil Superior, ChemFlex, Vitremer Core Build-Up/Restorative, Fuji II LC, Dyract AP and F2000) disc-shaped specimens were prepared and stored in sets of six in the following storage media: 0·9% NaCl (control), Coca-Cola, apple juice and orange juice. After time intervals of 1 day, 1 week, 1 month, 3 months, 4 months, 6 months and 1 year, solution pH and Vickers Hardness Number were determined for each individual specimen. Differences were analysed by anova followed by Student,Newman,Keuls post hoc analysis. All materials were found to reduce the pH of the 0·9% NaCl, but to increase the pH of the acidic beverages. The conventional glass,ionomers dissolved completely in apple juice and orange juice, but survived in Coca-Cola, albeit with a significantly reduced hardness after 1 year. The other materials survived in apple juice and orange juice, but showed greater reductions in surface hardness in these beverages than in Coca-Cola. Fruit juices were thus shown to pose a greater erosive threat to tooth coloured materials than Coca-Cola, a finding which is similar to those concerning dentine and enamel towards these drinks. [source] Long-term cytotoxicity of resin-based dental restorative materialsJOURNAL OF ORAL REHABILITATION, Issue 1 2002S. Bouillaguet Highly filled composites, Ormocers (organically modified ceramics) and ,smart' materials have been developed to overcome the polymerization shrinkage problems of conventional composite materials. The purpose of the current study was to investigate the effect of longer-term (up to 8 weeks) ageing of these resin-based dental restorative materials and determine the effect of post-curing on cytotoxicity. Twelve discs of each material (Colombus/IDR, Definite/Degussa, Ariston pHc/Vivadent) were either light-cured (Lc) or light-cured and post-cured (Pc). For cytotoxicity testing, the discs were placed in contact with cell culture medium (DMEM) and incubated at 37 °C. Extracts from composite materials were collected after 24 h and weekly over a time period of 8 weeks. Cytotoxicity of the eluates to cultured fibroblasts (Balb/c3T3) were measured by the succinic dehydrogenase (SDH) activity (MTT assay) and the results expressed in percentage of negative controls (Teflon discs). The results showed that ageing significantly influenced the cytotoxicity of the materials. Except for Ariston pHc, materials were less cytotoxic after 8 weeks of ageing than they were in early intervals and post-curing was not generally useful in reducing cytotoxicity. The Ariston pHc was initially moderately toxic, but then become highly cytotoxic for 5 weeks before returning to initial levels. The current study demonstrated the importance of assessing the cytotoxicity of resin composite materials at multiple times. [source] A Quantum-Mechanical QSAR Model to Predict the Refractive Index of Polymer MatricesMOLECULAR INFORMATICS, Issue 10 2006Andrew Abstract Refractive index (RI) is an important optical property for polymer matrices, especially when the color or tint of the cured material is of interest. This is certainly the case for dental restorative applications. In this work, results are presented for a quantitative,structure activity relationship derived from relevant semiempirical quantum mechanical information. This model predicts the RI for a wide variety of polymer matrices using representative structures of polymers, including resin components of several currently used dental restorative materials. The AM1 semiempirical method was used for calculations due to its speed and general reliability. Several structural subunits of the polymer chains were used for the QSAR analysis, but dimer moieties produced the best results for some 60 polymers. The final QSAR model was composed of a multilinear equation that featured the highest occupied molecular orbital , the lowest unoccupied molecular orbital gap and a polarizability index as the two descriptors best able to account for the variation in the data. The final model had R2=0.963, R2cv=0.959, F=740, and s2=0.0002. Other quality indicators for the correlation and the individual descriptors were within acceptable limits. The presence of electronically related descriptors is encouraging, as these are conceptually tied to the phenomenon of RI. The difference between a theoretically predicted value for poly(propylene oxide) and its monomer was 0.04, as compared to 0.09 from experimental data. [source] The interactions of tooth colored dental restorative materials with aqueous lactic acidPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2003Dr Sevil, ahmal Abstract In this study, the interaction of packable composite and ormocer with aqueous lactic acid solutions were determined and changes compared with those for a polyacid modified resin composite and a glass ionomer. For each material, namely Solitaire, Z-100, Definite, Dyract AP and Vitremer, eight cylindrical specimens of 6,mm diameter and 12,mm height were prepared and weighed. They were stored individually in 20,cm3 0.02 mol,1 lactic acid solution for 1 week, then the pH was determined and the specimens reweighed. This was repeated at 1 week intervals until the specimens were 6 weeks old. The results of this study showed that; polyacid modified resin composites and resin-modified glass-ionomers were capable of increasing the pH of lactic acid solutions. The same groups showed an increase in mass during the first week. Composite resins and ormocer showed less increase in mass than the others. Copyright © 2003 John Wiley & Sons, Ltd. [source] Understanding the kinetics and network formation of dimethacrylate dental resinsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2001Lale G. Lovell Abstract Dimethacrylate monomers are commonly used as the organic phase of dental restorative materials but many questions remain about the underlying kinetics and network formation in these highly crosslinked photopolymer systems. Several novel experimental and modeling techniques that have been developed for other multifunctional (meth)acrylates were utilized to gain further insight into these resin systems. Specifically, this work investigates the copolymerization behavior ofbis-GMA (2,2-bis[p-(2-hydroxy-3-methacryloxyprop-1-oxy)-phenyl]propane) and TEGDMA (triethylene glycol dimethacrylate), two monomers typically used for dental resin formulations. Near-infrared spectroscopy, electron paramagnetic resonance spectroscopy, as well as dynamic mechanical and dielectric analysis were used to characterize the kinetics, radical populations, and structural properties of this copolymer system. In addition, a kinetic model is described that provides valuable information about the network evolution during the formation of this crosslinked polymer. The results of these numerous studies illustrate that all of the aforementioned techniques can be readily applied to dental resin systems and consequently can be used to obtain a wealth of information about these systems. The application of these techniques provides insight into the complex polymerization kinetics and corresponding network formation, and as a result, a more complete understanding of the anomolous behaviors exhibited by these systems, such as diffusion controlled kinetics and conversion dependent network formation, is attained. Copyright © 2001 John Wiley & Sons, Ltd. [source] Proliferative activity of cells from remaining dental pulp in response to treatment with dental materialsAUSTRALIAN DENTAL JOURNAL, Issue 1 2010AN Lutfi Abstract Background:, The biological examination of pulp injury, repair events and response of dental pulp stem cells to dental restorative materials is important to accomplish restorative treatment, especially to commonly used dental materials in paediatric dentistry, such as glass ionomer cement (GIC) and calcium hydroxide (Ca(OH)2) lining cement. Methods:, Healthy patients aged between 9 to 11 years with carious primary molars without pulp exposure were selected and divided into two groups: Group 1 (teeth restored with GIC) and Group 2 (teeth lined using Ca(OH)2 and restored with GIC). The proliferative activity of stem cells of teeth between these two groups was compared using colourimetric cell proliferation reagent, alamarBlue. Immunocytochemistry and flow cytometry confirmation were performed using mesenchymal stem cell markers, CD105 and CD166. Results:, The proliferative activity using alamarBlueÔ assay showed that cells derived from the remaining dental pulp of exfoliated deciduous teeth were positive for CD105 and CD166 and exhibited no difference between the two groups. Conclusions:, It can be concluded that the use of Ca(OH)2 or GIC as a lining material in indirect pulp capping procedures has the same effect on cells derived from the remaining dental pulp of exfoliated deciduous teeth which have responded favourably to the restorative treatments. [source] Protein dynamics of bovine dentin phosphophorynCHEMICAL BIOLOGY & DRUG DESIGN, Issue 2 2005K.J. Cross Abstract:, Bovine dentin phosphophoryn (BDP), a protein rich in aspartyl (Asp) and o -phosphoseryl [Ser(P)] residues, is synthesized by odontoblasts and believed to be involved in matrix-mediated biomineralization of dentin. The elucidation of the structure,function relationship of phosphophoryn has been a challenge because of its high-molecular weight, high negative charge, repetitive sequence, and lability. We have used the dynamic behavior of the 1H NMR signal at 600 MHz to provide insight into the molecular dynamics of phosphophoryn. Our results indicate that phosphophoryn is a molecule of uniformly high mobility, thus belonging to a recently identified class of intrinsically disordered proteins that are characterized by sequences of low complexity and rich in polar and charged residues. The significance of our results is that phosphophoryn, because of its uniform nature has the potential to be replaced by biomimetic synthetic peptide analogs that together with amorphous calcium phosphate may lead to the development of novel, nontoxic, apatite-based dental restorative materials. [source] | ||||||||||