Читать книгу Orthodontic Treatment of Impacted Teeth - Adrian Becker - Страница 103

The contrasting approach to surgical exposure is the closed eruption technique. This technique involves an orthodontic attachment bonded at the time of the exposure, with the tissues being fully re‐sutured back to their former place, thereby re‐covering the impacted tooth. The technique was first described by Hunt [27] and McBride [4, 5, 28] and is a procedure that may be used regardless of the height or mesiodistal displacement of the tooth.

In the case of a buccally impacted tooth, a surgical flap is raised from the attached gingiva at the crest of the ridge, with appropriate vertical releasing cuts, and is elevated as high as is necessary to expose the unerupted tooth. An eyelet or button attachment is then bonded and the flap fully sutured back to its former place [7]. The twisted stainless steel ligature wire (or gold chain, as preferred by some clinicians), which has been tied or linked to the attachment, is then drawn inferiorly through the sutured edges of the fully replaced flap. The surgical wound is thereby completely closed and the impacted tooth with its new bonded attachment is sealed off from the oral environment. Because it is fully closed, spontaneous eruption will not occur. Accordingly, active orthodontic force will need to be applied to the tooth to bring about its eruption [29]. In the following period of several weeks or months and after complete healing of the repositioned surgical flap has occurred, the tooth will progress towards and through the area of the attached gingiva and will create its own portal, through which it will exit the tissues and erupt into the mouth. In so behaving, it very closely simulates normal eruption and results in a similar clinical outcome in terms of its clinical appearance and objective periodontal parameters. It will usually be difficult to distinguish from any normally and spontaneously erupting tooth.

Crescini et al. [30] described a modification of the closed eruption technique, which they called the ‘tunnel’ technique, specifically relating to maxillary permanent canines. The aim of this aptly named method is even further to mimic the natural eruption process by applying extrusive force to move the impacted canine directly through the socket of the recently extracted deciduous canine (Figure 5.5). In this procedure, a full buccal flap is raised from the attached gingiva at the neck of the deciduous canine and adjacent teeth, in order to expose the surface of alveolar bone, and the deciduous canine is extracted. The twisted steel ligature or gold chain, which is linked to the bonded eyelet, is then threaded into the apical area of the newly vacated socket of the deciduous canine and drawn downwards to exit through its coronal end. No buccal bone need be removed beyond that immediately overlying the crown of the exposed canine. The flap is then sutured back to its former position, leaving only the end of the ligature/gold chain visible through the socket of the deciduous canine.

Fig. 5.5 Crescini’s tunnel variation of the closed eruption technique. (a) A very high labial canine was exposed with a full‐flap exposure, which included the gingival margin of the extracted deciduous canine. The canine was exposed and, below it, a bridge of buccal bone was left intact. (b) An attachment was bonded to the palatal aspect of the permanent canine and its pigtail ligature directed through the socket vacated by the extracted deciduous tooth. (c) The flap was sutured to its former place and vertical traction drew the tooth down, retaining the alveolar bone on its labial side.

Courtesy of Dr E Ketzhandler.

It will, however, be quite clear that this method is only indicated when the crown of the permanent canine is at a significant distance above and directly superior to the apex of the deciduous canine and when its orientation is close to the vertical. It cannot be employed when there is mesial or distal displacement of the impacted canine, overlapping the adjacent lateral incisor or the first premolar. Neither is it appropriate when the tooth is more than slightly palatal to the line of the arch.

It will be appreciated, too, that the socket of the deciduous canine is much narrower than the broad permanent canine crown. Moreover, normal healing of most of the more occlusal portion of the socket will have occurred and bone regenerated, much before the canine even reaches its more occlusal lower levels. One must assume, therefore, that the tooth will meet with resistance not only from the mature peripheral alveolar socket bone in the apical areas of the socket wall, but also from the more recently infiltrated young alveolar bone, which must be resorbed to make way for the eruption of the tooth. By retaining the buccal bridge of bone during surgery (given the conservative attitude to bone removal in general), the tooth will come down through an uncompromised bony matrix. The final outcome will show the aligned tooth to have excellent bony support, in terms of both its width and the level of the alveolar crest.

In considering the location and orientation of most impacted maxillary canines, each method of surgical exposure has its advantages and its drawbacks. These are apparent in relation to efficacy of treatment and post‐surgical recovery, as well as regarding the overall treatment outcome in relation to aesthetics, periodontal prognosis and stability of the final result. An ‘aggressive’ canine that is located within the resorption crater that it has carved into the root of the adjacent incisor is a case in point. It is almost certain that an open surgical exposure would cause the loss of vitality of that incisor. However, a carefully performed closed exposure can usually be expected to enable the incisor to maintain its vitality. Similarly, the open surgical exposure method is not advised for severely ectopic canines, canines that are found in the more difficult sites, such as high above the apices of the other teeth, or those in locations where open surgery would involve leaving denuded root surfaces of adjacent teeth exposed to the oral environment. The deeper and more distant the impacted tooth is located within the jaw bone, the more radical is the bone resection that is required in order to ensure that the exposed crown of the tooth will not heal over in the weeks that follow. Open exposures in these more difficult situations are also more likely to adversely affect the patient’s quality of life in the immediate post‐surgical weeks, in terms of pain, recurrent bleeding, taste, halitosis and general function [20].