Dental amalgam is a combination of mercury with other metals and has been used for over 150 years for the treatment of tooth cavities because it is very strong and durable.
Dental amalgams are made by mixing one part of liquid mercury with one part of a mixture of other metals: mainly silver, but also tin, some copper and small amounts of zinc.
Source: GreenFacts
GreenFacts Summary on Tooth filling materials Dental amalgams & alternative materials
GreenFacts Summary on Mercury:
Deutsch: Zahnamalgam
Español: Amalgama dental
Français: Amalgame dentaire