In vitro corrosion of dental amalgam phases.

The effects of corrosion on the major phases of dental amalgam microstructure have been studied in vitro on samples prepared by electroplating mercury on Ag3Sn. Tests were made in synthetic saliva, and samples were examined in a scanning electron microscope before and after the exposure. Simple immersion had little effect on the phases. Contact of amalgam with gold increased the probability of deterioation of the gamma2 phase. By anodic polarization beyond the breakdown potential, the gamma2 phase was selectively dissolved. Under conditions simulating a crevice, the gamma2 phase was dissolved and the gamma1 phase suffered morphological changes.