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Orthodontic treatment with ankylosis

We tell you what ankylosis is and whether orthodontic treatment is possible with this diagnosis
Extensive experience in solving complex cases
Treatment time — from 1 year

One of the factors that significantly complicates orthodontic treatment is the presence of ankylosed teeth. In this article, the leading orthodontist of the clinic, Marina Anatolyevna Dubovskaya, talks about what ankylosis is and how to correct the bite orthodontically with such a diagnosis.

What is ankylosis?

First, let's understand the structure of the tooth. Normally, the root of the tooth is connected to the bone tissue by the periodontal ligament — a thin (0.2 mm on average) layer consisting of vessels, nerves, periodontal fibers and intercellular substance. This ligament provides cushioning for the tooth — it transfers the chewing load to the bone and protects the tooth from being overloaded when chewing. It is this ligament that allows the tooth to be moved during orthodontic treatment. It slowly stretches and realigns itself depending on the direction of tooth movement.

If for some reason the periodontal ligament is missing, the tooth fuses with the bone and becomes one with it. This pathological process is called ankylosis.

Causes of Ankylosis

Ankylosis occurs if the microcirculation in the periodontal ligament is compromised. The ligament is not necessarily destroyed completely, a small area may be damaged where the root fuses with the bone. This adhesion will already make it impossible to move the tooth during orthodontic treatment.

Causes of ankylosis can include:

  • Tooth injury, which results in ligament necrosis.
  • Chemical damage to the ligament due to canal treatment using resorcinol-formalin.
  • Genetic predisposition.

How to diagnose ankylosis?

Suspecting ankylosis is quite difficult, even with a complete diagnosis using a CBCT image. The fact is that the periodontal gap is not always visible on X-rays. If the tooth is ankylosed partially — on a small part of the root, it is almost impossible to detect it on the image.

An ankylosed tooth can be suspected by the following external signs and tests:

  • The tooth is slightly different in height from the neighboring teeth in the dentition and does not close with the antagonist tooth. For the patient, it looks like the tooth has not fully erupted.
  • The tooth differs in color — has a pinkish tinge after treatment with resorcinol-formalin. If the patient has ever had such treatment, then the probability of ankylosis increases.
  • The tooth may be retained, i.e. not erupted or partially erupted. It is the ankylosis in this case that prevents the tooth from erupting normally.
  • Percussion — lightly tapping the tooth with a dental probe. If the tooth is fused to the bone, the sound will be more «sonorous» than normal teeth.

The presence of these signs is not proof of ankylosis.

The most characteristic sign of ankylosis is the immobility of the tooth and the inability to move it. This can be detected:

  • During orthodontic treatment, if the tooth does not make the planned movements. The orthodontist can usually notice this as early as 2-3 visits after the bracket system has been placed.
  • During the surgical procedure, when the doctor in the hole performs luxation — tries «jiggle» the tooth from side to side, but the tooth does not move.

Only with a combination of factors and tests can a definitive diagnosis of «ankylosis» be made.

Orthodontic treatment for ankylosis

The success of orthodontic treatment is 90% dependent on proper treatment planning. And therefore ankylosis makes the task doubly difficult.

Firstly, an ankylosed tooth cannot be moved, that is, any movement of teeth must be planned based on the fact that one of the teeth itself will not move anywhere, and will prevent the movement of neighboring ones.

Secondly, due to the difficulty of diagnosing ankylosis, it may not be seen before starting orthodontic treatment. If a tooth is found in the process, the orthodontist is forced to plan treatment anew with new introductory.

How does orthodontic treatment proceed if ankylosis is detected at the diagnostic stage?

First, the doctor needs to do the calculations and make sure that with a fixed tooth, he or she can achieve an optimal result. If this is possible, the doctor excludes the ankylosed tooth from the orthodontic system. No bracket is placed on it and the tooth is not connected to the arch. In cases where the clinical situation allows, the ankylosed tooth can be used as an absolute support — pulling teeth to it. The same principle is used for treatment and planning if the patient has implants. After orthodontic treatment is complete, the shape of the ankylosed tooth can be corrected with a crown.

If the ankylosed tooth will not allow an acceptable treatment result, it will be extracted. However, this is not an easy task for surgeon and patient, as removing a tooth that has become one with the bone can be traumatic.

How does orthodontic treatment proceed if ankylosis is detected during treatment?

If on 2-3 activations the orthodontist notices that the teeth do not make the planned movements or make «strange» movements — this is a signal that some of the teeth are ankylosed. Only an orthodontist can realize that something is going wrong; it will be difficult for the patient to determine the nature of the movements on his/her own.

In this case, the orthodontist will perform a spot diagnosis: evaluate x-rays, perform percussion, and, if necessary, involve a dental surgeon or general practitioner to confirm the diagnosis.

When ankylosis is confirmed, the orthodontist will need to revise the treatment plan.

When ankylosis is confirmed, the orthodontist needs to review the treatment plan. He or she needs to understand whether a good result can be achieved with a completely immobile tooth or whether extraction will be necessary. The doctor's task at this stage is not only to plan further treatment, but also to explain clearly to the patient what has happened and what further action is possible.

Continued treatment for ankylosis depending on the system

  • During the treatment on braces, the orthodontic lock is removed from the ankylosed tooth, and it is excluded from the arch. If the tooth is used as a support, a button can be glued to it and an elastic band or chain can be stretched.

  • If ankylosis is detected on aligners, the orthodontist needs to re-create a virtual treatment plan (clinic check), on the basis of which a new set of caps will be printed.

Results of orthodontic treatment with ankylosis

The patient complained about the aesthetics of the smile.

The Damon Q metal bracket system was chosen as the treatment equipment. At the diagnostic stage, the ankylosed tooth was not detected.

After braces were placed 4 months later, atypical movements of teeth 1.5 and 1.4 were detected. — they «embedded», i.e. moved higher relative to the contact plane. The cause was ankylosed 1.6.

In this case, it was sufficient to turn off 1.6 from the arc to achieve the result.

We are not afraid of difficulties and when we receive similar cases, we are even happy to receive a new orthodontic challenge. In this case, we were able to achieve an optimal functional and aesthetic result even with an ankylosed tooth. For an ideal and stable result, the ankylosed tooth is recommended to be restored with a crown.

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Updated 30.12.2023