Strength of a feldspar ceramic according to the thickness and polymerization mode of the resin cement coating

Abstract

The aim of this study was to evaluate, in vitro, the biaxial flexural strength (ISO 6872) of a feldspathic ceramic (VM7, Vita Zahnfabrik)coated with a resin cement with different thicknesses and polymerization mode. Control groups consisted in VM7 with and withoutacid etching with 10% hydrofluoric acid for 1 min. Experimental groups comprised VM7 etched, silanated and coated with VariolinkII (Ivoclar Vivadent) cement, that was polymerized through the porcelain in light-cure and dual-cure modes, with thickness ≤150 μmor >150 μm. The specimens (n=15) were subjected to the biaxial flexural strength essay and analyzed fractographically. Parametric(Dunnet, Anova 2-way, Tukey) and non-parametric tests (Weibull) were used to evaluate results. Ceramic disks coated with resincements of either activation modes and thicknesses exhibited higher flexural strength while the Weibull moduli did not presentsignificant differences for a confidence interval of 95%.