Wettability of zirconia by feldspathic veneer in dental restorations: Effect of firing atmosphere and surface roughness

Abstract

Yttria-stabilized zirconia (YSZ) has been widely used in dental applications due to its excellent properties. However, chipping of fused feldspathic veneers on the zirconia cores is prone to limit the use of YSZ in all-ceramic dental restorations. The aim of this study was to investigate the effect of some processing parameters such as roughening the core surface and the atmosphere in which the feldspathic veneer was fused on the dental zirconia core.In order to address possible reasons of the chipping issue, the wetting behavior of a molten veneer on a zirconia core was evaluated using a sessile drop method at 990°C for 0–120min. The results showed the non-wetting behavior of the materials as the contact angles was measured to be >90° at conventional processing conditions. By varying some processing parameters such as surface roughening or firing atmosphere, it was found that these factors had huge effects on the wettability. The results showed that the melt veneer had little tendency to spread on the rougher zirconia surfaces. In addition, the firing of the feldspathic veneer in vacuum significantly decreased the wetting compared with that of in the air.