The failure of surface-treated Y-TZP dental ceramics

摘要

The effects of dental grinding, sandblasting and aging on the biaxial flexural strength of Y-TZP ceramics containing 3 mol % yttria were evaluated. Dental grinding at a high rotation speed lowers the mean strength, whereas sandblasting may provide a powerful tool for surface strengthening. Fractographic examination of ground specimens revealed that failure originated from radial cracks extending up to 50 μm from the grinding groves into the bulk of the material. However, no evidence of grinding-induced surface cracks could be obtained by SEM analysis of the ground samples, prepared by a standard bonded-interface technique. Sandblasting, in contrast, introduces lateral cracks, which are not detrimental to the strength of YTZP ceramics. The failure of these samples was initiated from a lateral crack linked to subsurface cracks. Fracture of samples, which were subjected to aging in an aqueous environment, originated form the interface between the transformed surface layer and the tetragonal core.