Injuries to Permanent Dentition Symposium
Ridge Preservation/Decoronation

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Abstract

Dentoalveolar ankylosis of a tooth is a serious complication in growing individuals. The ankylosed root is continuously resorbed and replaced by bone, and an infraposition of the damaged tooth will develop. The normal alveolar development will be disrupted in this way, and prosthetic treatment will be compromised. Therefore, an ankylosed tooth should be removed before future orthodontic and/or prosthetic therapy is jeopardized. This article will present a method, decoronation, to remove an ankylosed tooth in such a way that the alveolar ridge is preserved and give guidelines for the timing to intervene. The decoronation method is described, and a possible explanation for the favorable outcome is discussed. Different aids to decide the time for intervention are presented. The alveolar ridge was maintained in buccal/palatinal direction, and the bone level increased after decoronation in patients treated before or during pubertal growth periods. The bone level also increased in those treated after this period but not at the same rate, and in a few patients it was unchanged. The clinical finding that decoronation can maintain or reestablish normal alveolar conditions is important for successful implant insertion later.

Section snippets

Treatment Options

A buildup may be a treatment option if the patient has passed the pubertal growth spurt and the infraposition is minimal. In growing individuals this is not recommended. The infraposition will increase, and buildups must be repeated, resulting in a long clinical crown with no esthetic success.

Surgical repositioning has been suggested when the ankylosed area is minimal (5). However, the long-term prognosis is poor, because the reduced marginal bone level is unchanged, and further ankylosis might

Decoronation Technique

A mucoperiosteal flap is raised at the place of the ankylosed tooth, and the crown is removed with a diamond bur under continuous saline irrigation (Fig. 2A). The root filling is removed with an endodontic file, and the coronal part of the root surface is reduced to approximately 2 mm below the marginal bone (Fig. 2B).

The empty root canal is thoroughly rinsed with saline solution and allowed to fill with blood (Fig. 2C). This is very important because the blood clot is organized from the

How Does Decoronation Work?

The marginal collagen fiber system and periodontal fibers formed during eruption of teeth play an important role in the development of the alveolar ridge (25).

When 2 adjacent teeth are erupting, bone apposition occurs on top of the interdental septum via forces from both the periodontal and gingival fibers. The forces from these marginal fibers form an active alveolar periosteum.

When a tooth becomes ankylosed, the periodontal fibers are partly or totally replaced by bone in the ankylosed area,

Timing of Decoronation

In young patients there are advantages in retaining an akylosed tooth for as long as possible as a space maintainer. However, it is important to intervene before the effect of infraposition makes a final prosthetic solution difficult because of the arrested alveolar bone growth. Therefore, it is important to keep in mind that progression of infraposition varies individually 26, 27. The rate of infraposition is correlated to the age when ankylosis is diagnosed and to the growth intensity of the

Long-term Results of Early Ankylosed, Decoronated Incisors

Decoronations of 103 ankylosed incisors in 95 patients were performed between 1978 and 1999 at the Department of Pediatric Dentistry at Eastmaninstitutet in Stockholm, Sweden (unpublished data). The patient's age at trauma varied from 6.8–17.8 years (mean, 10.7; median, 10.4), and age at decoronation varied from 9.3–22 years (mean, 14.9; median, 15). Most patients were followed for 4 years after decoronation.

The bone level increased after decoronation in patients treated before or during

Summary

  • The clinical consequences of dentoalveolar ankylosis are complicated in growing patients. Therefore, treatment planning should be multidisciplinary.

  • Early diagnosis of ankylosis is important, and progression of infraposition must be followed up.

  • Timing of decoronation is important and should be planned regarding the age of the patient, the patient's growth intensity, and growth pattern.

  • The predictable success of decoronation supports the indication for replantation of avulsed teeth in children

Acknowledgments

The author denies any conflicts of interest related to this study.

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