Teeth are usually filled or restored because of tooth decay. Composite fillings are usually used in front teeth and are also often used in back teeth, although amalgam (a mixture of silver, tin, and mercury) is still sometimes used in back teeth. A local anaesthetic may be used to make the tooth and gum numb. The decayed area of tooth is drilled away and the hole is shaped to secure the filling; often, the hole is lined with a substance to protect the tooth pulp. The filling is then pushed into the hole as a soft paste. With composite fillings, a special curing light is used to harden the filling. Amalgam fillings harden naturally within a few hours.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.