A filling is the name of a dental procedure in which a material such as silver amalgam or a composite (white) filling is used to treat a decayed tooth. This material is inserted into the tooth where it then prevents the further spread of decay or repairs any damage.
The silver amalgam filling is the traditional type of filling which is composed of various metals such as copper, tin and mercury. This combination helps to retain the normal function of the tooth.
Composite white fillings have a natural colour which is similar to the colour of your natural teeth and so blends it well with them. Plus there have been issues raised about the safety of silver amalgam fillings due to their mercury content which has prompted some people to switch to composite fillings instead.