IADR Abstract Archives
Luting Materials, Preparation And Loading Effects On Stress In Veneers
Objectives: The aim of this study was to evaluate the effect of the polymerization shrinkage, functional loading and mechanical properties of different luting materials on the shrinkage stress and residual occlusal stress of ultrathin 0.3-mm ceramic laminate veneers (CLV) with and without tooth preparation.
Methods: Three resin cements: RelyX Veneer (RV), Allcem Veneer APS (AV), Variolink Esthetic LC (VE), and one flowable resin composite: Tetric N-Flow (TF) were tested for post-gel shrinkage (Shr) using strain-gauge test, Knoop hardness (KHN) and Elastic modulus (E) using hardness indentation, compressive strength (CS) and diametral tensile strength (DTS) which were used to determine the modified von Mises stresses (mvm) by finite element analysis. IPS e.max CAD discs 0.3-mm thick were made for simulating the effects of light attenuation. Eight two-dimensional finite element models (Marc-Mentat, MSC Software) of a maxillary central incisor were generated to evaluate the shrinkage stress during the light-activated polymerization of different materials for luting ultrathin 0.3-mm CLVs with or without tooth preparation and the stress during functional loading. Collected data from Shr, KHN and E were submitted to 2-way ANOVA and Tukey test (α=.05). CS and DTS were submitted to 1-way ANOVA (α=.05).
Results: TF had lower Shr when interposing ceramic disc (0.31%). The highest CS was observed for TF and lowest for VE. The AV had the highest DTS showing no significant differences to RV and TF (P>.05); VE had the lowest DTS being significantly different from the other groups (P<.05). TF showed the highest and VE the lowest KHN values while no significant differences were found in E values for RV and TF (P>.05) which showed the highest and VE the lowest values (P<.05). Both preparation techniques showed similar stress distribution for shrinkage or occlusal loading with increased stress concentration on the incisal edge for both and cervical for tooth preparation models with RV presenting the highest and VE the lowest stresses values (MPa).
Conclusions: Flowable composite had better mechanical properties than resin cements. The stress distribution from shrinkage and occlusal loading were similar for both techniques with or without tooth preparation.
Methods: Three resin cements: RelyX Veneer (RV), Allcem Veneer APS (AV), Variolink Esthetic LC (VE), and one flowable resin composite: Tetric N-Flow (TF) were tested for post-gel shrinkage (Shr) using strain-gauge test, Knoop hardness (KHN) and Elastic modulus (E) using hardness indentation, compressive strength (CS) and diametral tensile strength (DTS) which were used to determine the modified von Mises stresses (mvm) by finite element analysis. IPS e.max CAD discs 0.3-mm thick were made for simulating the effects of light attenuation. Eight two-dimensional finite element models (Marc-Mentat, MSC Software) of a maxillary central incisor were generated to evaluate the shrinkage stress during the light-activated polymerization of different materials for luting ultrathin 0.3-mm CLVs with or without tooth preparation and the stress during functional loading. Collected data from Shr, KHN and E were submitted to 2-way ANOVA and Tukey test (α=.05). CS and DTS were submitted to 1-way ANOVA (α=.05).
Results: TF had lower Shr when interposing ceramic disc (0.31%). The highest CS was observed for TF and lowest for VE. The AV had the highest DTS showing no significant differences to RV and TF (P>.05); VE had the lowest DTS being significantly different from the other groups (P<.05). TF showed the highest and VE the lowest KHN values while no significant differences were found in E values for RV and TF (P>.05) which showed the highest and VE the lowest values (P<.05). Both preparation techniques showed similar stress distribution for shrinkage or occlusal loading with increased stress concentration on the incisal edge for both and cervical for tooth preparation models with RV presenting the highest and VE the lowest stresses values (MPa).
Conclusions: Flowable composite had better mechanical properties than resin cements. The stress distribution from shrinkage and occlusal loading were similar for both techniques with or without tooth preparation.
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