Comparison of fracture strength of porcelain-veneered-to-high noble and base metal alloys.

Sixty crowns were cast from a commercial high noble and base metal alloy. The porcelain applied to the crowns was fired 10 times and fractured under gradual application of load. The fracture strength of the porcelain-veneered-to-base metal and high noble alloys subjected to repeated firings was compared. The results were: The fracture strength of porcelain-veneered-to-high noble alloys remained relatively constant for five firings but decreased significantly as the firings increased to 10. Ten firings did not significantly affect the fracture strength of porcelain-veneered-to-base metal alloys. Porcelain-veneered-to-base metal alloy crowns had a higher fracture strength compared with high noble alloy crowns.