Comparação de diferentes ensaios mecânicos para avaliar a resistência adesiva a uma cerâmica Y-TZP

Abstract

This study aimed to evaluate the bond strength using different test types for bonding evaluation, between a yttrium tetragonal zirconia polycrystals (Y-TZP) ceramic and composite resin, considering two types of Y-TZP surface treatments. Three hundred and sixty Y-TZP blocks, received one of the two surface treatments (N= 180): UT- control (untreated) and SS- silica coating + silanization. Specimen of composite resin were made in different geometries and cemented with resin cement to Y-TZP blocks. The 180 specimens for each surface treatment were divided into six subgroups (n = 30) according to the configuration of bond test: tensile (TBS); microtensile (μTSB); shear (SBS); microshear (μSBS); push-out (PSH) and micropush-out (μPSH). For data analysis were used Weibull parameters, Weibull modulus (m) and resistance characteristic (σ0), to check the dispersion and magnitude of the resistance data, One-way ANOVA test to evaluate the results with normal distribution and Mann-Whitney for those with non-normal distribution. Both the surface treatment s type and specimen size showed a statistically significant difference between groups (p = 0.00). Independent of the type of surface treatment, microtensile test and microshear had higher values than their equivalent macro test. On contrary, push-out presented higher values in the macro tests. The tests that showed higher m and σ0, were: PSH, μPSH, μTBS and μSHS. Silica coating + silanization significantly increased bond strength. Push-out, micropush-out, microshear and microtensile tests have proved to be more appropriate for evaluating bond strength, although the microtensile be inapplicable for Y-TZP untreated, due to the impossibility of obtaining the bar shaped specimens during cutting.