Effects of Ion Exchange on Hardness and Fracture Toughness of Dental Ceramics

Dental ceramics generally fail because of the growth of microscopic surface flaws that form during processing or finishing or that result from surface impact during service. The ion-exchange process has been shown to be effective in improving the flexural strength of most dental porcelains through the development of a compressive surface layer. The Vickers hardness and crack resistance of several commercial dental ceramics were determined by indentation techniques. The results of this investigation indicate that ion-exchange reinforcement can significantly improve the resistance of the ceramic surface to crack propagation with little effect on apparent surface hardness.