Electrochemical determination of the corrosion resistance of noble dental casting alloys

Abstract

Forty-four dental casting alloys and pure metals have been evaluated for corrosion resistance in an artificial saliva. The electrochemical tests included measurement of the rest potential and tracing of polarization curves. Qualitative comparisons of the normalized polarization curves, and quantitative determination of corrosion resistance, and of corrosion and breakdown potentials, provided complementary means of evaluation. Alloys were assigned two families: alloys for crowns and bridges (C&B alloys), and alloys for ceramic veneering (PFM alloys). Among these two families, groups were based on the gold-content (high and low), and on the main non-gold component: silver for C&B alloys, and palladium for PFM alloys. Pure metals and some non-noble alloys have been included as references. From this study, it clearly appears that the PFM alloys, having a higher content of noble metals, are more corrosion resistant than the C&B alloys containing copper and silver. Some relationships between noble-metal content and electrochemical parameters such as rest potential and corrosion resistance, have been identified, but the strength of the correlations is somewhat lowered by the influence of additional parameters, such as the presence of non-noble components or the nature of the microstructure. The present investigation is part of a larger study including other electrochemical parameters as well as various biocompatiblity tests on the same set of 44 alloys.