Galvanic corrosion of dental cobalt-chromium alloys and dental amalgam in artificial saliva.

When two or more metals or alloys are placed in contact with one another inside the oral cavity, galvanic coupling may occur which may lead to galvanic corrosion. Galvanic corrosion may release elements from the alloy into the oral cavity with possible harm to the patient. This in vitro study was conducted to determine the extent of galvanic corrosion where different dental amalgams and Co-Cr alloy combinations were placed in contact with artificial saliva as an electrolyte. The tests were conducted with potential measurements as well as potentiodynamic and potentio-static polarisation techniques. Results showed that the galvanic corrosion current density is much lower than the corrosion current density, indicating that galvanic coupling of the samples does not have a substantial effect on the overall corrosion of the samples. The corrosion potential differences between three of the four couples were above the minimum 50 mV potential difference, which is considered a potential harmful level, with only the Wironium Plus and Dispersalloy combination being under 50 mV potential difference. It is concluded that: Galvanic corrosion does not pose a greater threat to the alloys than ordinary corrosion. A Wironium Plus and Dispersalloy combination may be the safest where a Co-Cr and amalgam combination is required in the mouth of a patient.