Effect of surface finish on the flexural strength of feldspathic and aluminous dental ceramics.

The effects of surface finish on flexural strength of a feldspathic porcelain, aluminous porcelain, and a computer aided design-computer aided machining porcelain (Vitabloc MKI) were examined. A total of 105 bars of the feldspathic ceramic were made, randomly divided into seven groups, and sintered according to manufacturer's recommendations. The groups consisted of as-fired, self-glazed, overglazed, ground, polished, ground/annealed, and polished/annealed. A total of 45 bars of the aluminous ceramic and Vitabloc MKI were made and randomly divided into three groups: as-fired, ground, and polished. Overglazing, grinding, and polishing all significantly increased (P < .05) the flexural strength (four-point-bend test) of the tested materials (15% to 30%).