Journal of Dental Research, Vol 71, 1151-1155, Copyright © 1992 by International & American Associations for Dental Research Online Journals
Effectiveness of oxide films in reducing mercury release from amalgams
J. L. Ferracane, T. Hanawa and T. Okabe
Department of Dental Materials Science, Oregon Health Sciences University, Portland 97201.
The release of mercury from four freshly-triturated amalgams into air,
argon, and moist air environments was quantitated at three different
temperatures. Although a measurable amount of mercury was released from
dental amalgam, the evaporation rate was immediately reduced by several
phenomena, the most important being the formation of an oxide film on the
surface. This hypothesis was supported by the fact that release rates were
elevated in an inert argon environment, but declined dramatically once air
was introduced and oxidation could occur. The further amalgamation of
"free" mercury, as well as the presence of water vapor, also contributed to
the reduced release rates observed during aging. Mercury release was
reduced to a negligible level within three to four hours after trituration.
Only one of the amalgams, Tytin, demonstrated a thermal dependence for
mercury release in air. The results of this study suggest that the exposure
to mercury vapor from a freshly placed amalgam restoration would be
negligible in consideration of the normal estimated daily intake from all
other sources.
