Final answer:
Dentists use metal or tooth colored material to reduce a tooth when filling cavities, such as amalgam or composite resin.
Step-by-step explanation:
Dentists use metal or tooth colored material to reduce a tooth when filling cavities. One common material used is an amalgam which is a solid solution composed mainly of silver, tin, and copper with mercury. Another option is to use a tooth-colored composite resin which matches the natural color of the tooth.