Читать книгу Orthodontic Treatment of Impacted Teeth - Adrian Becker - Страница 99

In the case of obstructive impaction, logic dictates the removal of the body that is obstructing the natural eruptive potential of the tooth. This is normally performed by the surgeon and often without recourse to adjunctive orthodontics. Although the procedure often succeeds, this course of action is far from foolproof.

In Chapter 6 we examine the reliability of spontaneous eruption, which results from the different surgical procedures involved in the treatment of impacted incisors. For the present discussion, we must recognize that there is a significant number of cases in which eruption does not occur within a reasonable time‐frame.

Following the removal of the obstruction, be it a supernumerary tooth, an odontome, residual deciduous roots or even an infra‐occluded primary tooth, the position of most unerupted teeth will eventually improve. However, many of these teeth may not erupt without assistance. The failure to erupt may be due to certain factors, including the extent of their displacement, the character of the healing tissues or other factors relating to the erstwhile obstruction.

A hard tissue body, such as a supernumerary tooth, occupies significant space in the alveolus. A compound odontoma will generally consist of a random mix of dental tissues and, together with its accompanying dental follicle, in many instances occupies even more space. The result is gross displacement of the developing bud of the normal tooth, both in terms of overall distance from its normal location and in the alteration of the orientation of its long axis. The root and/or crown of a tooth of the normal series will likely be deflected, whether mesially, distally, lingually or buccally. It may also be displaced superiorly (in the upper jaw) or inferiorly (in the lower). All these possible deflections will compromise its chances of spontaneous eruption. Cramped circumstances will have developed between the pathological entity and the adjacent teeth and between (a) the entity and the floor of the nose or (b) the lower border of the mandible (see Chapter 13). A further developmental risk is the forming of abnormally shaped roots on otherwise normal teeth. Such an abnormal consequence will itself cause deviated eruption paths and even prevent spontaneous eruption altogether. However, provided that the integrity of their periodontal ligament (PDL) is not compromised and the odontoma extracted, they may be successfully erupted with orthodontic appliances.

The failure of an impacted tooth to erupt will inevitably disturb the eruption patterns of the adjacent teeth, which, as a result, will then assume abnormal relationships to one another. Such relationships are usually characterized by tipping and space loss. The overall result of this is that this situation creates a secondary physical impediment to the eruption of the impacted tooth.