Fatigue root fracture: a spontaneous root fracture in non-endodontically treated teeth.

A series of 46 cases of root fracture with four different patterns occurring in 51 non-endodontically treated teeth were studied. All of the patients had chewing habits which induced a unique root fracture. The results of this study suggest an additional cause of root fracture that has not been described previously. Here, the new term 'fatigue root fracture' is used to describe a fracture that results from an excessive, repetitive, heavy masticatory stress applied to a tooth. The majority (80%) of cases of this kind of fracture are vertical and occur mainly (96%) in persons over the age of 40. In addition, all the teeth affected were posterior teeth, and the majority (51%) were mandibular first molars.