Copper-rich and conventional amalgam restorations after clinical use.

The comparison of clinically retrieved conventional and copper-rich amalgam restorations demonstrated that there are at least two distinct types of compounds that form in vivo in amalgam restorations, tin-rich layers on the exposed surface of many amalgams and tin-chlorine and smaller amounts of stannous oxide products in the interior. In the systems rich in copper, corrosion was confined to the surface and a few isolated areas. The relatively small changes found in the systems rich in copper could account for the superior marginal integrity reported for copper-rich amalgams in clinical trials.