Effect of sandblasting, grinding, polishing and glazing on the flexural strength of two pressable all-ceramic dental materials

Objectives. During laboratory fabrication procedures and/or clinical adjustments, pressable materials: IPS Empress and Empress 2, may be ground, polished or sandblasted. These treatments may affect their strength by introducing microscopic flaws and defects. This study investigates the effect of these procedures on the mean flexural strength of these materials. Methods. One hundred and forty disc specimens (14 mm×1 mm) of IPS Empress and Empress 2 were prepared, and divided into seven groups of 20 specimens for each material. Groups were untreated, polished, polished and glazed, ground, ground and glazed, sandblasted, sandblasted and glazed. Surface roughness, mean biaxial flexural strength and Weibull modulus were appraised, and a scanning electron microscope was used to describe surface features. Statistical significance among groups of population was analysed using one-way Anova and Tukey's multiple comparison tests. Results. Untreated and sandblasted groups showed significantly the highest roughness values, and polished the lowest for each material ( p