In vitro tarnish measurements on fixed prosthodontic alloys.

This presentation describes a battery of quantitative in vitro tarnish tests for cast dental alloys. Eleven commercial alloys representing the available nobility range in precious fixed prosthodontic alloys were used to establish typical responses to the tests. Below approximately 55 at.% noble metal content, microstructure plays a dominant role in determining tarnish resistance. Thus, through proper alloy design and heat treatment, low nobility alloys can be designed with acceptably low tarnish susceptibility. The availability of these quantitative tests will allow determination of relative tarnish resistance and aid in establishing criteria for dental alloys. Furthermore, the data and test criteria developed in this study will provide a method for comparing alloys and designing improved lower cost alloys.