Mechanism of improved corrosion resistance of Zn-containing dental amalgams.
The aim of this study was to determine the mechanism of improved corrosion resistance of Zn-containing dental amalgams. Two Zn-containing conventional amalgams, their Zn-free counterparts, and three experimental amalgams (SnHg, ZnHg, and SnZnHg) were evaluated by the potentiodynamic polarization technique in 1% NaCl solution. The main difference between the two types of amalgams was found in their respective breakdown potentials at which passivity was destroyed. The breakdown potential of Zn-containing amalgams was about 200 mV more positive than that of the Zn-free amalgams. The improved stability of the Zn-containing amalgams has been attributed to the formation of a previously reported Zn stannate passive film which, according to the polarization data, is more resistant to the aggressive chloride ion than tin hydroxide that forms on Zn-free amalgams. The formation of Zn stannate was not found to affect the oxygen reduction reaction, the major cathodic reaction involved in the corrosion of dental amalgams.
Sarkar
N K
NK
Department of Biomaterials, Louisiana State University, School of Dentistry, New Orleans 70119.
Park
J R
JR
D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003343:Corrosion; D003723:Dental Amalgam; D010084:Oxidation-Reduction; D013499:Surface Properties; D015032:Zinc
D003723:Dental Amalgam; D015032:Zinc