Thermal effect on the dissolution of mercury from two dental amalgams

Various factors affect dissolution of mercury from dental amalgams. In this study we examined the effect of temperature on the release of mercury from two dental amalgams, namely an admixed high-copper amalgam (Contour) and a new tin- and copper-free amalgam (Composil). Ten cylindrically-shaped specimens of each type of amalgam were used in this investigation, and were divided into two equal groups. The five specimens in each group were each incubated in 10 ml purified water at either 37 degrees C or 60 degrees C, with a change of water every 24 h over an 8-day period. The quantity of mercury released from each amalgam specimen during each incubation period was expressed as micrograms cm-2 24 h-1. The amount of mercury released was estimated by cold-vapour atomic spectrometry. The results demonstrate that specimens incubated at 60 degrees C released significantly larger amounts of mercury than specimens incubated at 37 degrees C for both types of amalgam. The release of mercury by Composil was significantly greater than that by Contour (P less than or equal to 0.0001) for both temperatures studied. Raising the incubation temperature caused a disproportionate increase in mercury release from Composil compared to Contour.