There are two types of filling materials available.
1) Tooth coloured filling and
2) Silver filling
Tooth coloured filling is made up of a nontoxic composite resin that can be exactly matched to your existing natural tooth colour. This material bonds to the tooth creating a tight, superior fit to the natural tooth. Composite resins are a better alternative because it is tooth coloured which helps to create a long lasting beautiful smile. Fortunately, silver fillings can safely be replaced with tooth coloured restorations.
People use to have Silver/ Amalgam fillings in their mouth. But there are many disadvantages of using it as it contains 50 percent of mercury, a highly toxic and harmful metal which causes minor to lethal following complications and hence avoided by the dentist now a days but still in some cases it is indicated.