Galvanic Corrosion Conditions — MFDS Part 1 MCQ
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Correct answer: C — Two dissimilar metallic restorations are electrically connected while exposed to saliva
Explanation lettering: B = shown as A · E = shown as B · A = shown as C · C = shown as E
A is correct. Galvanic corrosion requires an electrochemical cell: dissimilar conductive metals with different electrode potentials, an electrical connection between them, and an electrolyte such as saliva. The less noble metal acts preferentially as the anode and undergoes accelerated corrosion. Restorations made from the same gold alloy have little or no galvanic potential difference. Ceramic is non-conductive and therefore cannot form the metallic electrical pathway required for a galvanic couple. Dissimilar metals that are not electrically connected do not complete the electronic circuit. A single cobalt-chromium restoration may undergo other forms of corrosion, but it does not by itself constitute a galvanic couple.
Reference: Jansen van Vuuren LJ, Odendaal JSJ, Pistorius PC. Galvanic corrosion of dental cobalt-chromium alloys and dental amalgam in artificial saliva. SADJ. 2008;63(1):34–38. https://pubmed.ncbi.nlm.nih.gov/18543740/