An electrolytic current, often referred to as "galvanic" current, can occur in the mouth between dental restorations made of different metals, such as amalgam fillings and gold alloy crowns. This phenomenon is based on the principles of galvanic or electrogalvanic action, which occur when metals with different electric potentials come into contact in a conductive environment.

Amalgam fillings, also known as silver fillings, are dental restorations made from a mixture of metals, including silver, tin, copper, and mercury.