An amalgam is a combination of a metal with mercury (Hg). The amalgams have the characteristic that when slightly heated they are soft and easily workable, and they become very hard when set. They are used for filling where it is not possible to employ high temperatures.
Dental amalgams are prepared by mixing mercury with finely divided alloys composed of varying proportions of silver, tin, and copper. Amalgams used in dental work require the following composition: Ag, 65% minimum, Cu, 6% maximum, Zn, 2% maximum, and Sn, 1% minimum.
