Avaliação da resistência à fratura de coroas CAD-CAM sobre pilares sólidos

Abstract

The aim of the study was to evaluate the fracture resistance of ceramic crowns using Cerec CAD-CAM system on solid pillars. Sixty replica synocta implant and RN solid abutment were embedded in acrylic resin, being randomly assigned (n=20 per group). Three types of ceramics were used: Mark II (feldspar), IPS Empress CAD (leucite) and IPS e.max CAD (lithium disilicate). The crowns were fabricated by CAD-CAM system using the Cerec software version 4.1. After receiving glaze and were cemented with RelyX U200 cement under load of 1 Kg Half of the specimens of each ceramic was subjected to endurance EMIC DL-2000 test fracture in a universal testing machine with a speed of 1 mm / minute and the other half after 1,000,000 cycles of mechanical stress with a load of 100 N. According to two-way ANOVA, the interaction between the material and mechanical cycling was significant (p = 0.0001). According to Tukey test (&#945; = 5%) the fracture toughness without mechanical cycling and mechanical cycling, respectively, of Mark II (405N/454N) was statistically lower than ceramic IPS Empress CAD (1169N/1240N) and IPS e.max CAD (1378N/1025N) (p < 0.05). The ceramic IPS Empress CAD and IPS e.max CAD not differ statistically (p > 0.05). There was no statistical difference in the resistance to cyclic loading with and without fracture to the Mark II and IPS Empress CAD (p > 0.05, Student's t test) ceramics. For ceramic IPS e.max CAD, the fracture resistance without mechanical cycling was statistically superior to that obtained with cycling (p < 0.05). The ceramic IPS Empress CAD and IPS e.max CAD showed higher fracture resistance compared to ceramic Mark II. The cyclic loading negatively influenced only IPS e.max CAD.