Effect of dental preparation and ceramic types on fracture strength and marginal adaptation of laminate veneers

Abstract

This study aims to evaluate the influence of dental preparations and two types of ceramic on the fracture resistance and marginal adaptation of teeth restored with laminate veneers. 56 central incisors were divided into 7 groups, according to the type of dental preparation: window, straight edge, overlap; and the type of ceramic: feldspathic and lithium disilicate. After cementation of veneers with resin luting cement, replicas in epoxy resin were evaluated regarding marginal gap in scanning electron microscopy (SEM). The results were statistically analyzed by ANOVA and Chi square test, with a significance level of 5%. The restored teeth resistance was significantly influenced by the type of preparation (p = 0.03) and ceramic (p = 0.011). The best performance was the lithium disilicate ceramic, associated with the straight edges and overlap preparations. Within the feldspathic ceramic group, the best strength was associated with the window preparation type. About the marginal adaptation analysis, groups with straight edge and overlap preparations associated with lithium disilicate ceramic showed no marginal gaps. The group with window preparation with lithium disilicate ceramic and group straight edge with feldspathic ceramic showed 75% of gap presence. It is concluded that, for feldspathic ceramic, the window preparation showed better fracture resistance. For lithium disilicate ceramic, the type of preparation did not influence the fracture resistance. When the incisal edge is involved, laminate veneers built with lithium disilicate ceramic associated with the straight edge or overlap preparations showed no gap formation and had the best fracture resistance.