Tooth fracture in vivo and in vitro.

The incidence, causes and methods of investigating tooth fracture are reviewed. This is a problem of increasing clinical significance, with many predisposing factors. Large restorations and extensive carious lesions tend to be associated with most fractures, with fracture incidence being higher in first permanent molars than other tooth types, especially in the lower jaw. Tooth anatomy influences fracture incidence, as does the functional force applied to cusps. Fracture risk in restored teeth may be reduced by cuspal coverage. Traditional tooth fracture investigations using destructive techniques provide valuable information; however, replica and nondestructive techniques are also of value.