C24    Discuss tarnishing and corrosion of dental amalgams and how corrosion products can influence surrounding tissues as well as restorations.

Amalgam can corrode and release metal ions. The less noble the metal is, the more likely it is to corrode. The corrosion products can, under certain circumstances, migrate into surrounding tissues and cause discoloration. Elements such as mercury can also react with alloys such as gold, causing the strength of the gold alloy to decrease. The latter is only of significance if the amalgam is in direct contact with the gold (e.g. an amalgam that is used to restore a margin of an old gold crown).