Influence of cooling rate on flexural strength of zirconia veneered with two different veneering ceramics.

Abstract

The recent introduction of zirconia based ceramics as restorative dental materials has generated considerable interest in the dental community. Zirconia holds a unique place amongst oxide ceramics due to its excellent mechanical properties. The mechanical properties of zirconia are the highest reported for any dental ceramic, this permit a substantial reduction in core thickness. But; due to the optical opacity of these materials, they are covered with veneering ceramics with esthetic characteristics similar to the natural tooth substance. The residual stresses developed in veneered zirconia restorations can be modified using different heat treatments, and these changes are a direct result of the viscoelastic behavior of the glass veneer during various cooling rates of veneering technique. The study of flexural strength of veneered zirconia restorations using different cooling protocols is an important parameter to improve the clinical behavior and performance of veneered zirconia prostheses. This study investigated the effect of veneering techniques and cooling rate of glaze firing cycle on flexural strength of veneered zirconia specimens.