<unk> s are a type of fracture of a tooth. They can be characterized by an incomplete or complete fracture line that extends through the long axis of the<unk>  toward the apex.<unk> s represent between 2 and 5 percent of crown/root fractures. The greatest incidence occurs in endodontically treated teeth, and in patients older than 40 years of age. The occurrence of a complete<unk>  is often catastrophic for the individual tooth as tooth extraction is usually the only reasonable treatment.<unk>  is more likely where teeth have undergone extensive prior treatment. It is thought that excessive removal of dentine during procedures such as<unk>  canal treatment weakens the tooth. For this reason excessive canal shaping should be avoided. Fracturing may be caused by excessive forces placed on the tooth, such as during compaction of gutta-percha during the obturation phase of endodontics. Trauma can also cause crack formation.
Vertical root fracture
Disc protrusion
Binaural fusion
Epidural abscess
Spiral fracture
Pulp canal obliteration
Hyoid bone fracture
Intracapsular fracture