Mechanical fatigue and hydrothermal stability of Y-TZP dental ceramics

摘要

This study was designed to evaluate the effects of dental grinding and sandblasting on the ageing and fatigue behavior of pressure less-sintered biomedical grade Y-TZP ceramic. It was found that upon dental grinding and sandblasting, the surface of the material was heavily damaged in part plastically deformed, but the amount of transformed monoclinic zirconia was low. The partitioned tetragonal zirconia grains and pre-existing monoclinic zirconia in the ground and sandblasted surfaces hindered the propagation of the diffusion-controlled transformation during subsequent ageing. Dental grinding at a high rotation speed lowered the mean strength under static loading and the survival rate under cyclic loading. Sandblasting, in contrast, resulted in surface strengthening and substantially higher survival rate under cyclic loading. For all tested groups, about 10-15 % lower survival strength values were obtained when tested in artificial saliva, compared to dry specimens, implying that stress-assisted corrosion plays an important role in the fatigue behavior of dental zirconia.