White in colour, composite fillings are synthetic resins that are used to fill a cavity after all of the tooth decay has been removed. Unlike Amalgam fillings, composite fillings are bonded to the dentin and enamel of the tooth and thus require less removal of tooth structure then metal fillings. Composite fillings are used to restore a tooth to its original appearance and function. Composite fillings are quickly replacing metal fillings as the primary means to replace a cavity in your tooth resulting from bacteria.