Microscopy and X-ray microanalysis of subcutaneously implanted conventional and high-copper dental amalgam powders in the guinea pig.

With each material, there was only a mild early inflammatory response; particles were taken up by macrophages and giant cells. By 1.5 to 3 months, chronic granulomas had developed. With conventional amalgam, there were early changes in the intracellular material, associated with the rapid degradation of Sn-Hg particles, corresponding to the gamma 2 phase. Thereafter, intracellular particles from both types of amalgam underwent progressive degradation, producing halos of secondary material containing Ag and S. Apart from an initial loss of Cu and Sn from some high-Cu amalgam particles, there were no qualitative differences in the later changes between the two materials, although conventional amalgam particles appeared to degrade faster. With both, vast numbers of fine secondary particles containing Ag and S became widely distributed throughout the lesions and gave rise to macroscopic tattooing of the skin. Secondary material and small degrading primary particles from both types of amalgam were detected in the submandibular lymph nodes where they caused localized staining.