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Supporting Your Practice

What are the 5W’s of Ankylosis?


Young boy at dentistWHAT is it?

Ankylosis occurs when the tooth’s cementum fuses to the alveolar bone. The vertical growth and development of the tooth is delayed and therefore, is under-erupted compared to the rest of the occlusal plane. If ankylosis is not properly assessed or managed, it can lead to molar tipping, periodontal defects, over-eruption of opposing teeth as well as the loss of space in the arch.

WHO is it most prevalent in?

It is most encountered in children between the ages of 8-9 years of age. When ankylosis occurs, it is often bilateral and 67% of affected people will have two or more teeth in infraclusion. Additionally, children whose siblings have ankylosed teeth are twice as likely to be affected than the rest of the population.

WHEN does it happen?

This can occur anytime during eruption

WHERE in the mouth is it most common?

Ankylosis typically occurs in mandibular 6’s and 7’s followed by maxillary 6’s and 7’s

WHY does this occur?

The cause of ankylosis is still unclear. Some cite factors such as:

  • Localized infection
  • Trauma
  • Disturbances in local metabolism
  • Chemical or thermal irritation
  • Gaps in the periodontal membrane

HOW is it diagnosed?

The ankylosed tooth may be submerged ~1mm or more below the occlusal plane. There will be no radiographic evidence of a periodontal ligament and physiological tooth mobility will be absent. Upon percussion, these teeth produce a sharp sound.

HOW is it treated?

Patients with ankylosed teeth should be closely and regularly monitored at recall appointments. Generally, if the onset of ankylosis is early, the earlier the tooth will become submerged due to the rapid growth of bone height of the alveolus.

In mild cases, If the submergence is less than 1mm, the tooth can be monitored. If the ankylosis is moderate, consideration may be given to building up the occlusal surface of the tooth using stainless steel crowns or restorations to maintain space and counteract supraeruption of the opposing teeth. However, in the situations where ankylosis is severe, extraction and space maintenance is indicated.

Source: Dental Secrets, Elsevier, 2015

1 Comment

  1. James Noble October 29, 2015

    The term “submerged” is a misnomer, teeth don’t “submerge”, the term “infra-occluded” is more appropriate. Further, a point ankylosis may be present and the tooth may be ankylosed and the pd. will be only not visible at that point, so a PA is a guide to diagnosis, same thing with the percussion test. The definite diagnosis is orthodontic traction to determine ankylosis. If there is indeed a “point” of ankylosis, surgical lunation followed by orthodontic traction has been shown to be effective in breaking this point of ankylosis.


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