Cytotoxicity of amalgams.

The purpose of this study was to compare the relative cytotoxicity of amalgams and to determine whether their toxicity depends upon composition and aging time, by means of a rapid and sensitive in vitro cell culture test. Zinc-containing amalgams showed higher cytotoxicity than did any other amalgams. High-copper amalgams had the same cytotoxicity as did the low-copper amalgam. The addition of selenium did not reduce the cytotoxicity of amalgam. Moreover, excessive additions of selenium increased the cytotoxicity of amalgam compared with that of a similar selenium-free material. The cytotoxicity of amalgam was decreased with aging time, possibly due to the combined effects of surface oxidation and further amalgamation.