INFLUENCE OF TOPICAL FLUORIDES ON CORROSION BEHAVIOR OF SILVER AMALGAM ALLOYS

Potentiodynamic polarization and cyclic voltametry measurements were e mployed to study the effect of topical fluoride preparations on corros ion of silver amalgam alloy in synthetic saliva and aqueous fluoride s olutions. Results support that small amounts of copper and indium allo yed to silver - tin amalgam enhance corrosion resistance considerably. Indiloy shifts both the open circuit potential and the anodic polariz ation curve to more positive potential values, this lead to a decrease s in the current density. The weak activity of Indiloy as compared wit h Spheraloy is attributed to the fact that the amount of yz phase (tin - mercury) present in the former is much lesser than that present in the latter. Findings also show that fluoride solutions (NaF, SnF and S nF + HCl) enhance the dissolution rate of the investigasted alloys and the polarization curves illustrate the appearance of an active - pass ive transitions. This behaviour was discussed on the basis of complex formation. Cyclic voltammograms confirm the results obtained from the potentiodynamic polarization measurements and elucidate the anodic oxi dation peaks of silver oxide and copper verifying the proposed mechani sm.