Decay of tooth which forms due to carelessness and absence of proper routine check up every year. This decay is removed using a diamond bur and finally restored with a filling material. The common type of filling material used in dentistry are silver amalgam and tooth cloured restorative materials, each restorative material has its own means of retention of the filling material, such a way the cavity should be modified to suit the need, traditionally the restorative material of choice was amalgam, which needed the tooth to be prepared mechanically by undercuts for the filling material to stay there, amalgam is still one of the best material suited in areas close to gums, since their biocompatibility to gums are the best and strength wise they are still the best.
Taking into factors such as esthetics especially in front of tooth, silver was trouble some, which led to the usage of tooth coloured filling material which matched in cosmetic appearance.
The cavity preparation in such tooth is different form the conventional amalgam restoration, since the retention of the filling material was dependent on micro-mechanical retention, the advantage of tooth coloured filling material was less tooth reduction is needed compared to amalgam restoration.
The defects of such tooth coloured filling material was that they are not ideal filling material in deep cvites where a protection with sufficient base is needed, since the remaining dentine thickness is less, tooth coloured filling material is not a suitable filling material where the cavity as well has sub gingival margins.