Corrosion of Ni-Cr-Mo alloys for fixed dental prostheses in an aqueous solution of 0.05% NaF and in commercial mouthwashes by means of EIS.

Ni-Cr-Mo alloys have been popular in dental prostheses due to their favorable mechanical and corrosion resistant properties, making them economically viable. The present study investigates the corrosion behavior of three distinct Ni-Cr-Mo alloys in fluoride-containing environments, which mimic typical oral hygiene products. Specifically, we evaluate alloys SC (73% Ni, 14% Cr, 8.5% Mo, among other elements), SB (61% Ni, 25% Cr, and 10.5% Mo), and W (65% Ni, 22.5% Cr, and 9.5% Mo), subjecting them to processes in 0.05% NaF and NaCl solutions. The evaluation methods include metallography, immersion procedures, and sophisticated electrochemical impedance spectroscopy (EIS). The results indicate that alloy SC, characterized by higher nickel and lower chromium content, displayed poor passivation, thus experiencing a continual rise in current density as potential increased. Conversely, the other alloys demonstrated effective passivation within a notable range, indicating better overall corrosion resistance. The findings suggest significant implications for the selection of alloy compositions in dental applications, emphasizing the need to consider corrosion resistance when subjected to common oral substances.