Comportamento biomecânico de compósitos resinosos em lesões cervicais não cariosas: Análise laboratorial

Abstract

Objective: To analyze the biomechanical performance of four direct resin solutions in non-carious cervical lesions (NCCL), when submitted or not to the biocorrosive process. Method: Two in vitro studies were carried out, based on 4 resinous groups: Tetric N-Ceram® - RN Group; Tetric N-Ceram® Bulk Fill-RB; Tetric N-Flow® + Tetric N-Ceram®-RFN; and Tetric N-Ceram® Bulk Fill + Tetric N-Ceram®-RBN, and a non-ST-restorative treatment group was added for the 2nd study. Eighty circular specimens were made for the test of roughness (ER) and weight (EP), and forty rectangular specimens for the test of flexural strength (RF), divided into 4 resinous groups. In the 2nd study, NCCLs were made in 80 bovine teeth distributed in the 4 restorative groups, and the ST. All were subdivided, and half of them submerged in a biocorrosive challenge (c). ER and EP analyzes were performed for the circular specimens and RF for the rectangular specimens. All bovine specimens were subjected to mechanical (300,000 cycles, 50 N, 2 Hz) and thermal (5ºC, 37ºC and 55ºC, 4,000 cycles) simulated aging and a constant compressive load applied to the palatal surface at 1mm/min until failure. /break (RFR). The results of the RE, EP and RF were submitted to statistical analysis by one-way ANOVA and Tukey post hoc, to analyze the group effect and the paired t test to analyze the initial and final means (ER and EP). The RFR (material and medium effect) was evaluated by the two-way ANOVA test, with Tukey's post hoc, and the failure mode by the Fisher's exact test. All at a 5% statistical significance level. Result: There was an increase in roughness in the RB group when in acidified medium (p=0.008). There were no differences in weight change between the studied groups. The RFN group in the salivary medium showed the highest flexural strength (p=0.037), however it showed a significant reduction when submitted to the acid challenge. The RBN group presented the best fracture resistance regardless of the medium, while the ST group had the worst. Conclusion: Low pH beverage negatively affects biomechanical properties of restorative materials in non-carious cervical lesions.