Orthodontic Treatment of Impacted Teeth. Adrian Becker

the PDL to attack the naked dentinal root surface and thereby create a focus of invasive cervical root resorption. The etchant should be applied by the orthodontist in gel form on the end of a fine sponge bud or fine instrument. It should be left in place for 15 seconds and thereafter drawn off by the surgeon through the fine suction tip, before the surface is rinsed again with saline to remove the last traces of acid.

      Continued use of the fine tip for a few more seconds will draw air over the surface of the crown of the tooth, until it is dry and the typical white matt appearance of the etched surface becomes apparent. The surface is now ready for bonding. Many practitioners may feel concern about the adequacy of the desiccation and may also prefer to be sure that no salt crystals remain from the dried saline. Experience shows that this concern is without foundation. Nevertheless, to allay these doubts, a final rinse with atomized water from the triple syringe may be carried out and followed by a fine compressed air stream, thereby doubly ensuring the appropriate degree of dryness of the enamel surface. Care must be taken that the compressed air stream be very gentle, in order to avoid splashing up blood from the surgical area, contaminating the enamel and causing bond failure. Oddly enough, the use of a suitably adapted electric hair dryer has the advantage of providing a gentle and waterless stream of warm air, which may be more effective in drying the etched enamel surface and is a method favoured by some clinicians.

      The prepared eyelet attachment has a pliable base. An attachment of appropriate size should be selected and manually adapted by the orthodontist with pliers to conform to the target bonding site. A cut length of 0.012 in. (0.3 mm) or 0.014 in. (0.35 mm) soft stainless steel ligature wire is threaded through the eyelet and, with the use of mosquito or Matthieu forceps, is twisted into a medium‐tight and firm pigtail, which should swing freely in the eyelet. Although any type of bonding agent may be used, we have found that light‐activated systems are easier to handle in these circumstances than chemically activated systems.

      The subject of attachments is discussed in more detail in Chapter 2. Nevertheless, one or two points are pertinent in the present context regarding bonding under conditions of surgical exposure.

      The choice of the appropriate implement to be used, to carry the attachment to its place and to hold it there until setting has occurred, is also important. Many operators prefer to use mosquito or Matthieu forceps; however, freeing the instruments from the attachments is only possible to achieve by changing the hand grip and unlocking the ratchet that holds the beaks closed. These manoeuvres produce considerable jolting and jarring of the attachment and could cause loss of the delicate control needed for successful, accurate placement. Experience has shown that it is better to use reverse‐action bonding tweezers, which, once the attachment has been placed, may be much more gently disengaged, to be left unsupported during the curing process.

The viscosity of the bonding paste should be adequate to prevent any ‘floating’ movement. However, if continuous pressure is desired during the setting period, one may place a ligature director, with its notch engaged, astride the eyelet loop and under light pressure. The freeing of the ligature director, once setting is complete, is achieved simply by merely withdrawing the instrument in the direction of its long axis, without generating any undue lateral jarring. It is always advisable, before requesting the surgeon to re‐suture the flap, to test the strength of the newly bonded attachment by giving the pigtail ligature a firm tug.

      As part of the original orthodontic treatment plan, an accurate radiographic assessment of the position of the impacted tooth will have been made and an approach to its orthodontic resolution formulated. With the impacted tooth in full view during the exposure procedure, the orthodontist must re‐evaluate the earlier assessment and confirm or revise the traction direction accordingly. If the traction is to be directed in line with the prepared place in the dental arch, then the pigtail ligature will be swivelled on the eyelet until it points in that direction. The surgeon will then suture the flap back over the wire, leaving its end freely protruding through the cut and sutured edges.

      As will be discussed in Chapter 7 with regard to a palatally impacted maxillary canine, sometimes the direction of the traction cannot be pointed straight to the labial archwire, due to the proximity of the roots of adjacent teeth. In such a case, the wire may initially need to be drawn vertically downwards towards the tongue, or posteriorly towards the molars. To achieve this, the pigtail, which cannot be drawn through the sutured edges of the flap, will rather be taken through the middle of the palatal area. This means that the reflected flap will need to be divided into two, one on each side of the pigtail (Figure 5.6g). A better alternative, prior to the replacement and suturing of the flap, is to pass the pigtail through a small pierced pinhole in the palatal flap mucosa. When suturing is finished and the palatal area completely closed off, the orthodontist should shorten the pigtail and turn it up into a hook or a circle, to be attached to an active palatal arch, ballista, auxiliary archwire or elastomeric chain, according to preference and suitability.

      The replacement of the flap will once again conceal the impacted tooth. However, before it is hidden by the closure, it is prudent to photograph the tooth and its attachment (Figure 5.6d, e). This will be appreciated at a later stage, when the patient returns for routine orthodontic adjustment and further activation of the traction mechanism. It will enable subsequent decisions related to the direction of orthodontic traction to be made with greater reliability.

      Traction should be applied immediately after the closure has been achieved and regardless of which traction method is used. This will help to reduce later manipulation of the ligature pigtail, which is very helpful, particularly during the first couple of post‐surgical months. Such manipulation is unpleasant and even painful for the patient as the pigtail passes through the soft tissues.

      There is much to be said for the first adjustment being fully exploited, with the application of appropriate traction while a local anaesthetic is still operational, i.e. at the time of surgical exposure. Subsequent manipulation may then only be necessary for two or three additional adjustment visits, before the tooth is erupted and before the pigtail becomes free from the soft tissue. If, prior to the surgery, an auxiliary labial archwire or a ‘ballista’ spring in its passive mode has been tied into the arch, as already recommended, then lightly pushing the loop from its vertical, inactive position towards the mid‐palate and turning the pigtail ligature around it will provide appropriate light and continuous extrusive force. This will be active over a wide range of movement and will remain active for many weeks. Similarly, an auxiliary palatal arch may be slotted into the palatal horizontal molar tubes then raised, to be held by the pigtail ligature. Whichever of these devices is used, this orthodontic manoeuvre should take no more than a minute or two and can be done while the surgical instruments are being cleared away.

      With the procedure described, and attachment placement performed by the orthodontist and with moisture control under the care of the surgeon, the bonding has been shown to be very reliable [3]. However, this has not always been the prevailing opinion. In the past, bonding in the presence of an open and bleeding wound, involving both soft and hard tissues, was strenuously resisted, since it was thought to be inconsistent with the attainment of a dry and uncontaminated field. This mistaken opinion on the part of the orthodontist was probably born more out of a reluctance to be present at the surgical episode than out of any experience of a high incidence of failure in attachment bonding in these circumstances.

      From the discussion here, it will be abundantly clear that the presence of the orthodontist at the surgical intervention has multiple positive aspects:

       The orthodontist is able to see the exact position of the crown, the direction of the long axis and the deduced location of the root apex.

       The height of the tooth and its relation to adjacent roots may be noted and the orthodontist will be able to confirm the strategic plan for its resolution by direct visualization.

       The orthodontist will be in a position to decide, from the mechano‐therapeutic aspect, exactly where