BIOLOGICAL MOLECULES IN THE CORROSION OF DENTAL ALLOYS

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Corrosion is the primary mechanism for the tarnish, toxicity and degradation of dental alloys. The long-term objective of this study is to define the mechanism of corrosion in the oral environment. The specific aims are: (1) to determine in vitro the possible role of relevant biological molecules in the corrosion of selected dental alloys, and (2) to identify and characterize the electrochemical reaction(s) in the above corrosion process. The corrosion behavior of dental amalgams, casting golds, silver-palladium and nickel-chromium alloys will be studied by potentiostatic and potentiodynamic polarization measurements in electrolytes containing individual biological molecules, singly or in combination. Biological molecules to be examined, in addition to the major components of saliva (namely, chloride, phosphate, carbonate, etc.) will include amino acids, poly-alpha-amino acids, polypeptides and proteins. Corroded alloy surfaces will be examined and analyzed by SEM, energy dispersive X-ray spectroscopy, X-ray diffraction, NMR and FTIR in order to define precisely the alloy-electrolyte interaction. Electrolytes will be analyzed by atomic absorption spectroscopy to determine the nature and concentration of metal ions released during corrosion. These studies will, in the long run, bring about a better understanding of the corrosion process of dental alloys in vivo and its possible contribution to clinical problems associated with toxicity, tarnishing and mechanical degradation.