[Influence of surface properties on the bending strength of OPTEC porcelain]

Influence of properties on bending strength of OPTEC porcelain, an experiment on four-point bending test was studied using four kinds of specimens (5 X 3 X 20) made of OPTEC porcelain (INCISAL) each of which was surface-treated; (1) glaze firing (no treatment) (2) polishing by emery paper #150 (3) polishing by alumina powder (0.3 microns) (4) glaze firing after polishing by emery paper #150 The test specimens were immersed in distilled water maintained at 37 +/- 1 degrees C broken into four-point bending at 1.0 mm/min, and their bending jig had on inner and outer span of 5 mm and 15 mm. The specimens graze fired after polishing had the highest bending strength, of 914 kg/km2, those polished with alumina powder, 831 kg/cm2, those graze 763 kg/cm2, and those polished with emery paper 705 kg/cm2. In conclusion, the bending strength of the porcelain was decreased by the surface roughness.