Abstract
The purpose of this study was to investigate the effectiveness of leucite crystals ion-exchanged with rubidium on the mechanical properties of glassy porcelain. For ion-exchange, a mixture of high-pure natural leucite (KAlSi2O6) powder and RbNO3 were heat-treated at 450°C (RLa) or 650°C (RLb) for 1 hour. The density of leucite increased as a result of the rubidium ion-exchange treatment. Polymorphic transformation temperatures of the ion-exchanged leucites were low compared with the unmodified leucite. Composite porcelains were prepared by blending each leucite (30vol%) with “Component No.3” frit of Weinstein et al. patent. The flexural strength and fracture toughness of the glass-only and composite porcelains were measured by a three-point bending test and indentation technique. ANOVA and post hoc multiple comparisons test revealed that the flexural strength and fracture toughness of the composite porcelain containing RLa were significantly higher (p<.05 and p<.01, respectively) than those of the other groups. The results suggested that the rubidium-ion-exchanged leucite (RLa) could be a better reinforcing agent for dental porcelain.
