A material used to fill a cavity after the removal of a tooth decay is called a filling. Fillings can be made from many types of material like amalgam, composite resins, gold, ceramics, etc. Amalgam is the easiest to be used, fastest and least costly material that could be used for filling.
We first numb the area around the tooth to be filled with a local aesthetic. Then the decayed area is removed using a drill or laser or air abrasion as per your preference and the extent of decay. After removal of the decay, the space is prepared for filling by cleaning the cavity of bacteria and debris. Finally the filling is placed and the area is finished and polished.
Fillings help avoid worsening of tooth decay and in turn avoid its associated problems like abscess, pain and bone loss.