Fracture analysis of the veneering ceramic on marginal ridge of bilayer zirconium crowns Y-TZP with conventional and modified infraestructure: in vitrum study

Abstract

Zirconium bilayered crowns are an excellent alternative in esthetic restorative dentistry. Nevertheless, chipping and delamination is the weakest link in this type of restorations. Considering the hypothesis that giving a better support to the layering ceramic is going to improve its performance in this matter, and in vitro study of continuous axial load until failure applied to 20 bilayer zirconium crowns with two different core designs: 10 conventional (0.8 uniform thickness), 10 modified (1 mm thickness and 2.5 mm height in lingual and proximal areas) cemented on resin dies was done. Mean value for crowns with conventional core is 611.3 N (S.D. 191.2 N) and for modified core is 727.5 N (S.D. 173.7 N). Parametric tests and T-Student comparison was used to analyze data. Results are that bilayered zirconium crowns with modified core had 15% more fracture resistance than with conventional core accepting the null hypothesis.