[Adaptation of composites to enamel: relation to the appearance of marginal staining].

Marginal staining is the major cause of failure of composite resin restorations. The following reasons were incriminated: The nonrespect of the integrity of the cavity limits during cavity obturation, as for instance, when a simple bevel is made. The appearance of fractures or composite bond strength failures during polishing procedures. This phenomenon can be enhanced by the use of composite finishing knives (KOMET) and by overfilling the cavity.