Two main options existing for tooth fillings: amalgam (silver) fillings or resin/composite (tooth-colored) fillings.
Dental amalgam is an alloy comprised of elemental mercury, silver, tin, and copper. Amalgam is extremely durable, making for long lasting fillings in areas of the mouth requiring high resistance to fracture.
Tooth-colored fillings are made of a glass filler and acrylic resin. These fillings mimic the natural tooth color but are less resistant to fracture. Most often, resin fillings are used for areas of the mouth with less chewing pressure such as on the tooth root or between teeth.