Papers by Keyword: Dental Restorative Materials

Abstract: A methodology for residual stresses calculations is proposed. Common photo-curing dental restorative materials under different C-factors are considered as case studies. Reaction kinetics, curing shrinkage, and viscoelasticity map were required as input data on a structural FE solver. Post cure effects were considered in order to quantify the residual stresses coming out from natural contraction with respect to those debited to the chemical shrinkage. The analysis showed for a given test case that stresses build-up due to the thermal contraction (after the completion of restoration) are comparable with those emerging due to thermal shrinkage.

Abstract: Purpose To investigate the cariostatic effect of six restorative materials in vitro. Method Enamel blocks of bovine incisors were restored with six restorative materials (a conventional GIC, FujiIILC, Compoglass F, BeautifilII,Charisma and an experimental fluoride releasing resin composite) respectively with a gap of 270μm in width between each filling material and enamel. Then all restorations were immersed in a partially saturated acidic buffer solution at 37C for 3days. The surface enamel microhardness of the enamel blocks were measured before and after demineralization and the depth of enamel demineralization was measured using polarization microscope for each restoration.Results Enamel surface hardness of all restorations demonstrated significant reduced after demineralization ( p<0.05), and the order of hardness reduction is as follows: Charisma >BeautifilII≈Compoglass F≈Experimental Resin>FujiIILC>GIC ( p> 0.05). The order of the depth of enamel demineralization along the surface and the interface near the gap for the 5 materials is as follows: Charisma >BeautifilII≈Compoglass F ≈Experimental Resin>FujiIILC>GIC (P > 0.05). Conclusion The new fluoride releasing and recharging composite resin has the ability to prevent recurrent caries around the restoration and its ability is comparable to compomer materials.

Abstract: The aim of this study was to evaluate the suitability of CaF2 doping tricalcium silicate (Ca3SiO5, C3S) as dental restorative materials. The solid state reaction method was used to prepare CaF2 doping C3S (F-C3S) using CaCO3, SiO2 and CaF2 as the starting materials. The in vitro bioactivity, the rate of heat evolution and the compressive strength were investigated. The in vitro bioactivity was examined by soaking the pastes in simulated body fluid (SBF). The FTIR and SEM results indicated the hydroxycarbonate apatite (HCA) layers of F-C3S pastes and pure C3S pastes occurred after soaking for 1 day and 3 days, respectively. The difference in bioactivity was attributed to the formation of F-substituted apatite, which has a Ksp lower than HCA. As compared with the pure C3S, the rate of heat evolution during the hydration of F-C3S was slower. This was avail to the dimensional stability of dental restorative materials. The pastes of F-C3S had a lower early compressive strength in the early stage, but a higher compressive strength in the later stage. Our results indicated that F-C3S would be bonded better to the teeth because of the earlier formation of HCA and the higher later compressive strength. F-C3S may be a progressive candidate for dental restorative materials.

Abstract: Flexural strength of a dental material reflects its ability to withstand tensile stresses and thus the fracture risk of a filling. The flexural strength of an experimental bioceramic Calcium aluminate-based (CA) dental restorative material was measured using three different methods with a composite (Tetric Ceram), a glass ionomer cement (Fuji II) and a phosphate cement (Harward) as references. The three test methods were: a) ISO 4049 for dental composites, 3-point bend test b) EN 843-1 for ceramic materials, 3-point bend test and c) ASTM F-394, biaxial ball-on-disc for ceramic materials. The strength of the CA-material, tested in the ball-on-disc method, is close to the theoretical strength based on the microstructure of the material (max. grain size of 15 μm). The composite material and the phosphate cement were rather insensitive to the test method, while the glass ionomer cement as the CA-material showed sensitivity towards the test method. A modified biaxial test method for evaluation of strength of dental materials in a close to real-life component is proposed.

Abstract: There is little information concerning the physical properties of various commercialized water-based temporary filling materials. In this study, the setting characteristics of 5 water-based temporary filling cements, i.e., Caviton, HY-seal, Lumicon, Cavit-G, and Cavit-W, were examined. Reinforced plastic pipes were filled with the test materials, and the specimens were then immersed in distilled water at 37°C. Setting time of each specimen was determined by a penetration test using a Vicat penetrometer; and setting layer depth was measured with micrometer calipers. Cavit-W exhibited the fastest setting time, whereas Caviton and HY-seal demonstrated the slowest setting time. These results indicate that the setting properties of these materials used in this study were significantly different for each material, which showed some changes on the surface and the internal part after the start of water absorption.