Influência de diferentes substratos na carga de fratura de um material restaurador híbrido

Abstract

The objective of the study was to evaluate the effect of the substrate on the fracture strength of a polymer-infiltrated ceramic network (PICN -Vita Enamic) after aging by mechanical cycling. 120 specimens were made. PICN slides were obtained from CAD / CAM blocks and cemented to disk shape substrates: dentin (EnDen); dentin analogue (EnAnDen); nickel-chromium alloy (EnNiCr); and composite resin + fiberglass post (EnRc). To compare the polymer-infiltrated ceramic to a feldspathic ceramic and an indirect resin, 20 disks of Vitablocs Mark II feldspathic ceramic (FeAnDen) and 20 disks of Opallis Lab resin (ResAnDen) were cemented to the dentin analog and subjected to the same tests than the other groups. The specimens had a final dimension of approximately 3.1 mm in thickness and 12 mm in diameter. All specimens were submitted to mechanical cycling (500,000 cycles, 2 Hz, 50 N) and tested with a compressive load in a universal testing machine (EMIC) at a speed of 0.5 mm / min. The fracture loading data were analyzed using 1-way ANOVA and Tukey test with a significance level of 95% (α = 0.05). A Weibull analysis was used to compare the groups with more than 10 specimens tested incompression. All specimens of the group FeAnDen fractured during the mechanical aging. 4 specimens of the group EnRc survived the mechanical aging, and their mean on the compression test was not statistically evaluated. In the comparison between EnDen, EnAnDen and EnNiCr, the mean of EnNiCr group was greater than the other two groups. There was no statistical difference between the means of the EnAnDen and EnDen groups. The Weibull (m) modulus of EnAnDen group (9.01) was statistically greater than EnDen group (3.15). The highest characteristic strength was obtained by EnNiCr group. Failure modes varied according to the momento of failure: failures during the cycling were mostly radial; failures during the compression test were mostly conical. The substrate influences on the compressive strength of a hybrid material after mechanical aging. The failure mode depends on the type of load applied. Polymer-content materials were more resistant to mechanical cycling compared to feldspathic ceramics.