Journal of Dental Research, Vol 69, 1786-1790, Copyright © 1990 by International & American Associations for Dental Research Online Journals
The effect of tin on the corrosion behavior of the Ag-Hg phase of dental amalgam and dissolution of mercury
M. Marek
School of Materials Engineering, Georgia Institute of Technology, Atlanta 30332-0245.
The anodic polarization behavior of the Ag-Hg matrix phase of dental
amalgam (gamma 1) and the rate of mercury dissolution were examined as a
function of the tin content. The objectives were to determine the effect of
tin on the electrochemical behavior and dissolution of mercury and to
provide evidence on whether tin dissolves in the gamma 1 phase or
precipitates as a tin-rich phase. Anodic polarization curves were recorded
for specimens of the gamma 1 phase containing 0-1.5% Sn and for the gamma 2
phase and a gamma 2-containing dental amalgam, in synthetic saliva. Mercury
dissolved in synthetic saliva in 24 h was determined for the gamma 1 phase
containing 0-1.0% Sn, with cold-vapor Atomic Absorption Spectrophotometry
used for mercury analysis. Tin induced passive behavior of the gamma 1
phase and suppressed mercury dissolution. The passive gamma 1 phase did not
exhibit a breakdown of passivity occurring at the gamma 2 phase. The
results were consistent with the tin presence in gamma 1 in a solid
solution, rather than in tin-rich precipitates, and indicated that at least
1.5% Sn can be dissolved in gamma 1 at 37 degrees C.
