Bulk fracture of amalgam restorations--a 5-year controlled clinical trial.

Summary A controlled clinical study, containing 720 posterior amalgam restorations placed in a group of 103 adult patients by three dentists, was used for examination of the influences on the incidence of occlusal and approximal bulk fractures. These fractures were evaluated from black and white photographs, taken annually, of the occlusal surface of the restorations over a 5-year period, using a three point photorating scale for both fracture sites. The influence of the dentist as well as the influence of the alloy and tooth type were statistically analysed. The results of these analyses demonstrated that the dentist, as well as the alloy and tooth type, have a statistically significant influence on the incidence of bulk fracture of amalgam restorations.