Efeito do tipo de resina e técnica de inserção no desempenho biomecânico de restauração de molares com grande perda estrutural

Abstract

The aim of this study was to evaluate the effect of composites and filling techniques on tensile bond strength, ultimate tensile strength, elastic modulus, hardness Vickers, cuspal deflections and stress generated in molars class II. One hundred seventeen extracted molars were divided into nine groups (n = 13) resulting from the combination of two factors: 1 - composite (Filtek LS, 3MEspe) (Aelite LS Posterior, BISCO) and (Filtek Supreme, 3M-Espe), 2 Filling technique: bulk filling, 8 increments and 16 increments. Post-gel shrinkage and cuspal deflection were evaluated by strain gauge test. For analysis of the micro tensile bond strength and ultimate tensile strength was used the micro tensile test. The mode of failure of the sticks was obtained with an optical microscopy. Dynamic indentation test was used to calculate the Vickers hardness and elastic modulus of the composites at five depths of the cavity (0.5, 1.5, 2.5, 3.5 and 4.5 mm). Analysis by finite element method was developed to generate models of two-dimensional molars for definition of the stress polymerization and strain. Data from post-gel shrinkage were submitted to ANOVA One-way and Tukey's test (p<0.05); cuspal deflection for two-way ANOVA with two levels (buccal and lingual cuspal) and test Tukey's test (p<0.05); micro tensile bond strength and ultimate tensile strength for two-way ANOVA with two levels (top and bottom of the restoration) and Tukey's test; elastic modulus, Vickers hardness and stress distribution were analyzed qualitatively. Pearson correlation tests were performed between the results. The increase in the number of increments and materials with high value of post-gel contraction reflects a greater cuspal deflection. The micro tensile bond strength and ultimate tensile bond strength of the composite decreases when used bulk filling technique because does not allow adequate polymerization of the material. Materials with high elastic modulus have greater stress of polymerization for the dental structure. The validation of the finite element analysis consolidates the results of strain gauge test.