A high proportion of children and adults will suffer from traumatic dental injuries (TDIs) caused by sudden impact forces to teeth generated by falls, fights, sports-related injuries and traffic accidents. Immediate treatment and an accurate differential diagnosis of the type of TDI is needed to ensure the tooth is given the most appropriate treatment. The starting point is always to assess if the tooth has been completely avulsed from its socket and replanted. If the tooth has not been avulsed, the displacement of the tooth and its mobility beyond normal limits should be tested. If several teeth move as one unit, it is characteristic of an alveolar fracture. If a single tooth moves and a fracture can been seen in a radiographic, it is characteristic of a root fracture. If no root fracture can be identified in a radiograph, it suggests that the tooth has had an extrusion. A tooth which appears to be in an abnormal position because of protrusion or retrusion, has suffered from lateral luxation. A tooth which is abnormally located by intrusion out of its socket into alveolar bone, has suffered from intrusion. If the tooth has not been displaced, but is loose, has suffered from subluxation. If the tooth has not been displaced, but is not loose, and has percussion tenderness, it has suffered concussion. If the tooth has not been displaced, it is not loose, and has no percussion tenderness, it has suffered concussion. If the tooth has not been displaced, it is not loose, and has no percussion tenderness, and it has suffered a fracture above the gingiva which exposed the pulp, the tooth has suffered a complicated crown fracture. If a tooth has a crown-root fracture that has not exposed pulp, it has suffered an uncomplicated crown fracture. If a tooth has a crown-root fracture that has exposed pulp, it has suffered a complicated crown fracture. If the extent of the fracture is so minimal that no tooth structure has been lost, the tooth has suffered an infraction. If the tooth has no discernible symptoms of trauma, then it can be assumed that the tooth has no injury.