An intrusion represents the most severe injury to the dentition as a result of the damage to gingival attachment, contusion of the periodontal ligament and bone, and, in immature teeth, damage of the tooth root forming structures (Hertwig’s epithelial root sheath). An intruded primary tooth may damage the underlying permanent tooth bud.
The intrusion is the result of a direct axial impact on the incisal edge. The tooth is pushed into the alveolar ridge, whereby the blood supply of pulp is severed (1) and the periodontal ligament is crushed (2). The tooth is locked into the bone.
Note: Tooth intrusion is associated with major risk of loss of the tooth, which in most cases is due to replacement resorption (ankylosis).
Clinically, the tooth is not in alignment in the dental arch (infraposition). In most cases it is squeezed into the jaw. Percussion elicits a hard metallic sound. There is bleeding from the periodontal sulcus.
The left central maxillary incisor is intruded in half its crown length in apical direction.
Axial view of the same patient.
Following intrusive luxation, the entire periodontal ligament will be torn, and the ligament space will not be discernable in most cases.
Radiographic imaging may include orthopantomogram (OPG), intraoral dental films or cone beam/CT imaging.