Читать книгу Orthodontic Treatment of Impacted Teeth - Adrian Becker - Страница 104

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 canine extracted and the canine exposed. (e) An eyelet has been bonded to the most accessible location on the crown of the canine, with the twisted wire connector hanging loosely. (f) The surgical flap was re‐sutured back to its former place, the loop of the auxiliary archwire in its passive (vertical) mode, after ligation over the main archwire. (g) The twisted ligature connector from the eyelet has been drawn through a small piercing in the flap, located immediately opposite the eyelet above it. (h) The vertical loop of the auxiliary archwire is turned inwards and latched by the shortened connector, in contact with the palatal mucosa.

The crown of the impacted canine was exposed using a wide flap, but with minimal removal of bone. The deciduous canine was extracted. The unexposed crown lay between the root apices of the central incisors. Due to the obstruction caused by the roots of both the central and lateral incisors of the right side, it had traversed the anatomical midline, from where it had no available direct route to its appropriate place in the dental arch.

An attachment was bonded by the orthodontist, while haemostasis was maintained by the surgeon. The location for the bonding, chosen by the orthodontist, was the anatomically distal aspect of the rotated crown of the canine. This was also the most superficial and accessible site. A twisted steel ligature pigtail had been tied into the eyelet prior to its placement and was intended as the means of transferring extrusive force to the tooth.

The flap was pierced at the point where the flap covered the eyelet, to accommodate the ligature pigtail in its desired position, close to the midline. The pigtail was pushed through the pierced hole, before the flap was fully replaced and re‐sutured.

An auxiliary labial archwire, with a vertical loop, was ligated at this point in piggyback fashion over the heavier base arch and its loop turned inwards and upwards. It was securely latched, in light horizontal contact, to the palatal mucosa, by the shortened and bent‐over twisted ligature. Active vertical extrusive force would now erupt the tooth vertically downward, towards the tongue. From that point, a direct approach to the archwire could then be made, without interference by the incisor root.

In a situation where a palatal canine is located very high up in the maxilla, at the level of and close to the midline and to the incisor apices, an open exposure is contraindicated. There is every likelihood that the exposure will close over in the immediate post‐surgical period, together with the possibility of loss of vitality of one or more of the incisors. The canine seen in Figure 5.6 was located across the midline and between the central incisor apices. The tooth was subsequently drawn posteriorly and vertically downwards, exiting in the mid‐palate and thereby avoiding damaging the incisor apices and permitting lateral movement to its place in the arch. The initial activation was performed at the surgeon’s chairside, immediately following completion of the exposure procedure.