Wetting Characteristics of a Nano Y-TZP Dental Ceramic by a Molten Feldspathic Veneer.

The purpose of this study was to evaluate the wetting behaviour of a molten feldspathic glass-ceramic which is used as a veneering layer on dental Y-TZP cores. The grain size effect of the zirconia substrate on the wettability of the veneering material was also studied. It is suggested that the presence of a weak bond at the interface could be attributed to the poor wetting of ZrO2 surface by the molten veneer. Result of the sessile drop analysis showed high contact angles of more than 110˚ at the initial states of the test. The contact angles were affected by increasing the grain size. An about 6% increase in mean of the contact angles of micro Y-TZP was determined when compared to the nano-structured bodies. It is suggested that the fine microstructure which was observed in the nano Y-TZP body enhances the physical wetting behaviour due to a probable increase in surface energy which is considered as the driving force of wetting. The enhancement which was observed in wettability of the nano-sized Y-TZP at longer times may also be originated from a chemical wetting assisted by the diffusion of the atoms through the increased defects of surface such as grain boundaries and triple junctions. [ABSTRACT FROM AUTHOR]