Influence of finishing on the electrochemical properties of dental alloys.

Abstract

Dental alloy surface finishing procedures of may influence their electrochemical behavior, which is used to evaluate their corrosion resistance. We examined the polarization resistance and potentiodynamic polarization profile of the precious-metal alloys, Type 4 gold alloy and silver-palladium alloy, and the base-metal alloys, nickel-chromium alloy, cobalt-chromium alloy, and CP-titanium. Three types of finishing procedure were examined: mirror-finishing using 0.05 micron alumina particles, polishing using #600 abrasive paper and sandblasting. Dissolution of the alloy elements in 0.9% NaCl solution was also measured and compared with the electrochemical evaluation. The corrosion resistance of the dental alloys was found to relate to finishing as follows: The polarization resistance and potentiodynamic polarization behavior revealed that the corrosion resistance improved in the order of sandblasting, #600-abrasive-paper polishing, and mirror-finishing. While the corrosion potential, critical current density and passive current density varied depending on the type of finishing, the transpassive potential remained unchanged. The influence of finishing on the corrosion resistance of precious-metal alloys was less significant than on that of base-metal alloys. A mirror-finishing specimen was recommended for use in evaluation of the corrosion resistance of various dental alloys.