Orthodontic Treatment of Impacted Teeth. Adrian Becker

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].

       Initiation of traction

      Even though the orthodontist may or may not be present during a closed surgical technique procedure, it is nevertheless imperative that an attachment be bonded at that time. It is obviously propitious to apply the eruptive force to the impacted tooth immediately, taking full advantage of the prevailing anaesthesia. The absence of the orthodontist will place the onus to do this, squarely but unfairly, on the shoulders of the surgeon.

In contrast, when open surgery is performed, the presence of the orthodontist is unnecessary, since the aim of the surgery is merely to prepare the stage for the future placement of an attachment by the orthodontist in his or her office. Accordingly, the surgeon must complete the exposure in such a manner as to be sure that the tissues will not heal over and make the tooth inaccessible in the few post‐surgical weeks, until an attachment is bonded in the orthodontist’s office and traction begins. Since orthodontic procedures in general do not require local anaesthesia, the orthodontist is unlikely to offer it to the patient at the next orthodontic appointment, even though there is a general sensitivity of the area, even to gentle manipulation. Inevitably, because the anaesthetic will not be given and because the orthodontist is not present at the surgical procedure and because the surgeon will not apply traction at the time, there is a loss of momentum in the progress of treatment. The first visit to the orthodontist will not be for quite a long time and it is inevitable that there will be an additional delay in the commencement of traction. It is therefore beneficial, even for the open procedures, that an attachment be placed at the time of surgery and to apply traction, in order to maintain the treatment momentum.

CBCT imaging of the impacted canine, in the case shown above, pinpointed the exact location of the canine (Figure 5.6a–c) and this enabled the direction of traction to be determined. The other serial slices and 3D reconstructions performed on the material have illustrated the level of technical difficulty of resolution of the impaction and subsequent alignment of the tooth. They have, however, also shown an apparently healthy PDL and an absence of signs of resorption and other pathology, both of the canine itself and of the roots of the adjacent teeth, which would determine whether or not the tooth would respond to orthodontic forces.

Fig. 5.6 Cone beam computed tomography (CBCT) imaging slices of a palatally impacted canine that has crossed the midline, as seen on (a) a panoramic curved slice (b) a cross‐sectional slice and (c) an axial slice. The long axis of the canine is oriented approximately 10° to the horizontal. (d) A wide flap has been reflected, the deciduous