Influence of relative humidity and low temperature hydrothermal degradation on fretting wear of Y-TZP dental ceramics

Dental pieces are subjected to constant friction due to grinding during mastication and mouth disorders such as bruxism. Therefore, wear resistance of Y-TZP materials used for dental prostheses must be investigated. In this work, the influence of humidity and low temperature hydrothermal degradation (LTD) in 3Y-TZP ceramics subjected to fretting has been evaluated. A 100% r.h. reduces the effects of wear due to the lubricative effect of water, compared to those at ambient r.h. COF, wear volume and damage are considerably lowered at a r.h. of 100%. Exposure to degradation conditions for 25 h increased the vulnerability to wear damage of LAVA grade Y-TZP sintered at 1400 °C since the critical grain size of 300 nm was exceeded.