Journal of Dental Research, Vol 64, 854-859, Copyright © 1985 by International & American Associations for Dental Research Online Journals
Corrosion evaluation of gold-based dental alloys
P. P. Corso Jr, R. M. German and H. D. Simmons Jr
Three commercial gold-based dental alloys and three constant-nobility
ternary alloys (Au-Ag-Cu) were evaluated for corrosion using a quantitative
test battery. Integration of the current density, in a de-aerated solution
of 1% NaCl along the approximate potential range found in the mouth (-300
mV to +300 mV vs. SCE), yields a quantitative rank ordering of the test
alloys. The results are combined with prior findings on other commercial
alloys to demonstrate the interaction of nobility and microstructure.
Nobility determines the overall corrosion resistance for gold-based alloys.
However, because of mutual insolubility, alloying with copper induces
silver segregation, resulting in a higher corrosion rate at a given
nobility. Thus, microstructure has an influence on corrosion, but heat
treatments are largely ineffective in altering the basic corrosion
characteristics. The test techniques, in combination with tarnish
evaluations, provide a quantitative battery for alloy evaluation. The
results indicate the combinations of nobility, microstructure, and
environment most likely to avoid corrosion difficulties.
