Tarnish of Dental Amalgam

¹ Department of Dental Materials, Marquette University School of Dentistry, Milwaukee, Wisconsin

Amalgam which was polished 6 and 24 hours after the start of mixing was compared for brightness decrease after storage in four different media up to 30 days. No significant difference was observed between the two groups.

Immersion of polished specimens into water of 35° and 45° C. showed little difference among specimens that were polished 6 hours, 24 hours, and 1 week after mixing. At 55° C. significant decrease of luster was observed for specimens polished at 6 hours and at 24 hours, as compared with those polished after 1 week's storage. No significant difference was observed between specimens of any of the three age groups when immersed into 70° C. water. However, the brightness values dropped markedly for all specimens stored at 70° C.

The mercury content of the specimens have some relation to brightness decrease; the more residual mercury contained in the specimen, the more decrease in brightness was observed after 1 week's storage in dry air.

It would be suggested from this study that well-condensed amalgam may be safely polished at 6 hours after mixing of the amalgam.