Ankylosis of teeth

Tooth ankylosis refers to a fusion between a tooth and underlying bony support tissues. In some species, this is a normal process that occurs during the formation or maintenance of the dentition. By contrast, in humans tooth ankylosis is pathological, whereby a fusion between alveolar bone and the cementum of a tooth occurs.

In humans, this is a rare phenomenon in deciduous dentition and even more uncommon in permanent teeth. Ankylosis occurs when partial root resorption is followed by repair with either cementum or dentine that unites the tooth root with the alveolar bone, usually after trauma. However, root resorption does not necessarily lead to tooth ankylosis and the causes of tooth ankylosis remain uncertain to a large extent. However, it is evident that the incident rate of ankylosis in deciduous teeth is much higher than that of permanent teeth.

Risk factors of tooth ankylosis can be generally classified into genetic factors and dental trauma. Diagnostic methods of tooth ankylosis include the use of clinical examinations, x-ray and cone beam computerized tomography (CBCT). Tooth ankylosis could have several symptoms, with decreased tooth count being the most prominent one. Factors like gender and sex may also lead to the incidence of certain signs, yet the full mechanisms have not been well evaluated. In general, the non-growing subjects and growing subjects would exhibit different signs and symptoms.

Individuals suffering from ankylosis of deciduous teeth risk of losing these teeth due to the failure of the tooth eruption during facial growth and would lead to a series of functional and esthetic problems. After diagnosis with clinical examination or CBCT image, tooth ankylosis is often treated by removing the crown of the affected tooth. Early orthodontic interception is also confirmed to be effective in promoting the recovery of the lost space as well as allowing the eruption of the teeth. It is current under the investigation of its probability being used as a prevention of tooth ankylosis.