Efeito da configuração do preparo cavitário e da composição cerâmica na distribuição de tensão, deformação e resistência à fratura de onlays confeccionadas por meio de CAD/CAM

Abstract

The aim of this study was to evaluate the effect of two cavity preparation on fracture resistande of two CAD/CAM ceramic on Finite Element Analysis, Coronal deformation, Fracture Resistance and Fracture Mode over human molar teeth restored with esthetic indirect restoration. Forty-eight human molars were select and randomly divided into the following four groups (n=12): Group 1: conventional onlay (with occlusal and proximal box), leucite glass ceramic (IPS-Empress CAD, Ivoclar Vivadent); group 2: conservative onaly (without occlusal and proximal box), leucite glass ceramic (IPS-Empress CAD, Ivoclar Vivadent); group 3: convencional onlay, lithium-disilicate glass ceramic (IPS e.max CAD, Ivoclar Vivadent); group 4: conservative onlay, lithium-disilicate glass ceramic (IPS e.max CAD, Ivoclar Vivadent). Cuspal deformation (μS) was measured at 100N and Maximum fracture load by strain gauges (n = 7 teeth), Fracture Resistance (N) was measured by axial compression test and Fracture mode were recorded based on the degree of tooth structure and restoration damagemin four types (n = 12 teeth) and the Stress distributions was mesasure for all groups on Finite Element Analysis. The CS, Fracture resistance and Fracture mode were statistically analyzed using Tukey test and ANOVA two-way (p = 0.05). The Coronal deformation (CD) at 100N the Tukey s test showed that leucite ceramic restorations had significantly higher deformation than lithium-disilicate ceramic restorations, irrespective of cavity preparation (P<0.001). At maximum fracture load showed that lithium-disilicate ceramic restorations had significantly higher deformation than leucite ceramic restorations, irrespective of cavity preparation (P<0.001). The Fracture resistance and Fracture mode showed that the presence of box had no significant effect for leucite ceramic restoration (P=0.375), however the presences of box on disilicate ceramic restorations reduced significantly the fracture resistance (P<0.001). The disilicate ceramic restorations had significantly higher fracture resistance than leucite ceramic restoration (P <0.001) irrespective of cavity preparation. Fracture mode distributions showed that the leucite disilicate ceramic resulted in more severe fracture mode irrespective of cavity preparation. Whithin the limitations of this study, it was observed that the conservative onlay increase fracture resistence and the complex restored with a leucite-reinforced ceramics has less coronal deformation and fracture mode.