Influence of oral pH Environment in the Corrosion Resistance of Cr-Co-Mo alloy Used for Dentistry Prosthetic Components

The Cr-Co-Mo alloys are commonly used in dentistry for prosthetic components and dental implant supported prosthesis. These alloys present high corrosion resistance owing to a passive oxide film on the surface. However, the oral environment is an aggressive system, due to pH variation, chloride and fluoride ions presence, that can decrease the metal alloy corrosion resistance. Although Cr-Co-Mo alloys have been used for a long time, their electrochemical properties on different pH have not been studied yet. This study aimed to evaluate the electrochemical properties of Cr-Co-Mo alloy in NaCl 0.9% solution in different pH and mouthwash solution. To imitate the oral environment, electrolytes with a pH equal to 2, 3, and 6 were used. Corrosion studies were performed by open circuit potential observation, potentiodynamic polarization curve, chronoamperometry and electrochemical impedance. The results showed that the analyzed alloy has good corrosion resistance under experimental conditions, although the acidified NaCl 0.9% solution increased the corrosion current, particularly in cathodic potentials.