The Strength of Alumina and Magnesia Core Crowns.

Alumina and magnesia core crowns were constructed using different techniques. In two groups of crowns the platinum foil matrix was removed; in two groups the foil remained in the crowns; and in two groups the internal surface of the cores was glazed after removal of the foil. All crowns were diametrally loaded to failure. Crowns with magnesia cores that were internally glazed were significantly stronger than all other groups tested. The increase in diametral strength, however, was considerably less dramatic than modulus of rupture data using the same materials. [ABSTRACT FROM AUTHOR]