The effect of dental grinding and sandblasting on the biaxial flexural strength and Weibull modulus of tetragonal zirconia

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 and reliability, whereas sandblasting may provide a powerful tool for surface strengthening. The coarse-grained materials were less susceptible to grinding induced defects, presumably due to higher fracture toughness. During aging at 140 degreesC for 24 hours, an about 100 mum thick layer has transformed to monoclinic on the surface of the standard-grade Y-TZP ceramics resulting in considerable strength degradation, whereas the "corrosion resistant" materials exhibited a much higher resistance toward the low-temperature degradation. Furthermore, preexisting monoclinic zirconia in the surface of the sandblasted Y-TZP hinders the propagation of the diffusion-controlled transformation during subsequent exposure to aqueous environments.