In vitro evaluation of physico-chemical and mechanical properties of resin cements light cured through ceramics of different thicknesses

Abstract

The longevity of ceramic veneers depends, between other factors, on the physicochemical and mechanical properties of the resin cements used to its cementation. The objective of the present study will be to evaluate the influence of different configurations/thicknessess of lithium disilicate reinforced ceramics, on the degree of conversion, microhardness and color stabiity of a light curing resin cement. In order to evaluate these aspects, 56 specimens of resin cements will be light cured through ceramics, following the 7 experimental groups (n=8):lithium disilicate reinforced monolithic ceramics (E-max CAD) with 0.6, 1.2 and 2mm of thickness; and lithium dissilicate reinforced monolithic ceramics associated with 0.2mm thickness veneer ceramics (0.4+0.2, 1+1.2mm and 1.8+0.2mm), as well as a control group, without ceramic interposition. These specimens will be assessed through Degree of Conversion (FTIR), microhardness and colorimetric tests in the following evaluation times: before light curing (FTIR only), immediately after, after 24 hours and 7 days. After this period, specimens artificial aging will be performed through specimen immersion in 60ºC deionized water during 24 hours in order to assess the color stability. For statistical analysis, considering results normality, a 3-way variance analysis (ANOVA) and Tukey's test will be applied; if the results do not pass in normality test, the Kruskal-Wallis test will be applied, both with 5% significance level. (AU)