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Mechanism of chloride corrosion of dental amalgam
Author(s) -
FINKELSTEIN G. F.,
GREENER E. H.
Publication year - 1979
Publication title -
journal of oral rehabilitation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.991
H-Index - 93
eISSN - 1365-2842
pISSN - 0305-182X
DOI - 10.1111/j.1365-2842.1979.tb01280.x
Subject(s) - amalgam (chemistry) , corrosion , mechanism (biology) , dentistry , chloride , chemistry , metallurgy , materials science , medicine , electrode , philosophy , epistemology
Summary Polarization of conventional dental amalgam in Ringer's solution produces a dissolution of the γ2 phase at –250 mV (SCE) and formation of Sn—Cl and Sn—O—Cl. This study was undertaken to determine the electrochemical nature of these reactions. Potentiostatic polarization scans were run at 4, 37 and 50°C in several dilutions of aerated Ringer's solution. Manipulation of reactant concentrations and electrolyte temperature produced shifts in the potentiostatic profiles. At 50°C, a γ2 dissolution peak shift to —300 mV was observed, and at 4°C the peak shifted to—200 mV. Dilution of Ringer's solution with respect to [Cl − ] over three orders of magnitude produced a linear shift in the noble direction of 500 mV. Cathodic polarization appears to be limited by the oxygen half cell reaction. Changes of [Cl − ] affect the shape of the peak, round out its approach to the current maximum. Shifts in peak potential due to temperature and concentration changes agreed with calculations based on critical pitting potential for γ2 dissolution due to a chloride reaction. Polarization profiles in pooled saliva agreed with calculated potentials based on known saliva [Cl − ].