In vitro corrosion behavior of 13 prosthodontic alloys.

The corrosion behavior of 12 high-gold, low-gold, palladium-silver, and nickel-chromium alloys was tested using electrochemical techniques. A 22-carat-gold alloy was used as a control. High-gold alloys were extremely resistant to corrosion, but the resistance of the alloys decreased with decreasing mobility (from high-gold, to palladium-silver, to low-gold, to nickel-chromium alloys). Tests were also made to determine the type of corrosive attack; nickel-chromium alloys exhibited pitting, and palladium-silver alloys demonstrated the selective dissolution of the silver-rich phases. The corrosion resistance of noble alloys was far superior to that of nickel-chromium-based alloys; therefore, the palladium-silver alloys, which have a moderate price range, may be more suitable for restorations.