|Classification and external resources|
Tooth ankylosis is the pathological fusing of cementum or dentine of a tooth root to the alveolar bone. Ankylosis of teeth is uncommon, it more often occurs in deciduous teeth than permanent teeth.
Tooth ankylosis can be recognised clinically by the loss of physiological mobility, and a high P note.
It may also be detected radiographically, loss of periodontal ligament space and evidence of replacement resorption. Ankylosis usually initially occurs on the labial and lingual root surfaces making radiographic detection in the early stages difficult.
Early diagnosis allows the practitioner to plan for future complications.
Deciduous (baby) teeth
Ankylosis of deciduous teeth may rarely occur. The most commonly affected tooth is the mandibular (lower) second deciduous molar. Partial root resorption first occurs and then the tooth fuses to the bone. This prevents normal exfoliation of the deciduous tooth and typically causes impaction of the permanent successor tooth. As growth of the alveolar bone continues and the adjacent permanent teeth erupt, the ankylosed deciduous tooth appears to submerge into the bone, although in reality it has not changed position. Treatment is by extraction of the involved tooth, to prevent malocclusion, periodontal disturbance or dental caries.
Permanent (adult) teeth
In healthy teeth, the periodontal ligament (PDL) fibroblasts block osteogenic cells within the periodontium by releasing locally acting regulators. This separates the tooth root from alveolar bone . Damage to the PDL disrupts this process resulting bone growth across the periodontal space and fusion with the root. It may occur following dental trauma, especially re-implanted or severely intruded teeth. Increasing the extra oral dry time increases the likelihood of ankylosis. The probability also increases with the severity of intrusion. There is no known treatment to arrest the process. Ankylosis itself is not a reason to remove a permanent tooth, however teeth which must be removed for other reasons are made significantly more difficult to remove if they are ankylosed. Ankylosis in growing patients can result in infra occlusion of teeth, this can lead to an aesthetic and functional deficit.
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