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2 The Logistics of Orthodontic Treatment for Impacted Teeth
ОглавлениеAdrian Becker
It is well known that movement of teeth adjacent to an impacted tooth will often have a positive effect on the eruptive behaviour of that tooth, particularly if the movement involves the opening of space in the dental arch [1]. By the time the space has increased to be of a suitable size and by the time the oral and maxillofacial surgeon is able to make appropriate arrangements for its surgical exposure in a busy schedule, a new periapical radiograph may indicate that the impacted tooth has significantly improved its position. In such a case, the surgery may become superfluous. Indeed, if the spontaneous eruption seems likely to occur imminently, or at least within a reasonable period, there is obvious merit in waiting for this to actually occur.
If, on the other hand, eruption looks as if it will take many months, then the orthodontist must weigh the benefits of avoiding surgery against the drawbacks involved in leaving orthodontic appliances in place for an extended period of time. As a general rule, orthodontic appliances increase the susceptibility of the teeth to caries, which is evident with the initial appearance of so‐called white spot lesions [2]. In the case of long‐term presence of appliances, there is a significant risk of proliferative inflammation of the gingivae and serious periodontal involvement. Indeed, the longer the appliances are in place, the greater the risk of damage.
There is, however, a further factor to be taken into account, because removing the appliances before treatment is completed brings with it the risk of having to replace the appliances. This may be necessitated in order to correct a malposition of the newly erupted (and erstwhile impacted) tooth. The flip side is to accept a compromised and inadequate outcome. To solve this dilemma, the clinician may elect to advise surgical exposure followed by orthodontic traction in order to expedite the eruption of the tooth and thus clear the way to complete the treatment within a very much shorter time.
A similar dilemma may arise when orthodontic treatment has provided space and surgery is undertaken to remove a physical obstacle. In such an event the elimination of the obstacle will have rendered the impaction potentially resolvable, without further treatment. However, the surgical intervention involved in removing the obstacle will offer the opportunity of anaesthetized access to the unerupted tooth. It would be a pity not to exploit that opportunity, since subsequent healing of the wound will deny that access. If that eruption does not then take place, a second surgical intervention in the same area will have been necessary and much time will have been wasted confirming that spontaneous eruption will not occur.
It is therefore quite clear that the time factor is most important. Orthodontic appliances are in place and there may be an unsightly space in the dental arch. Orthodontically aided eruption will unquestionably speed up the resolution enormously and, this being so, the patient’s best interests are to be served by including exposing and bonding the impacted tooth among the factors to be considered at the planning stage.
When the existence of an impaction is only a small part of a complex overall malocclusion, the time factor becomes more critical. It would be a reasonable estimate that a given overall orthodontic problem, by itself, may require two years of treatment. In the case of an awkwardly placed impacted tooth, the resolution of the problem may take a further year or more [3–5]. To add the luxury of a wait‐and‐see period is to add yet more time to this already extended three‐year plus period. During all this time, orthodontic appliances are being worn. The result of all this is that, while the orthodontist may well be rewarded by an improved position of the impacted tooth, a deteriorating state of oral health, due to poor oral hygiene, may deprive the achievement of all meaningful content.
Let us remind ourselves of the definitions set out in Chapter 1, in which it was noted that a ‘permanent tooth with delayed eruption [is an] unerupted tooth whose root is developed in excess of two‐thirds of its expected final length and whose spontaneous eruption may nevertheless be expected within a reasonable time’. A tooth that is not expected to erupt within a reasonable time in these circumstances is termed an impacted tooth. Thus, in the present context and despite the fact that the tooth may be expected to erupt spontaneously ‘in time’, this period may be considered ‘unreasonable’, when taking into account the likelihood of detrimental iatrogenic effects on the remainder of the dentition, engendered by this extra and often considerable waiting period. This then will reclassify the tooth (in clinical therapeutic terms) as an impacted tooth. As such, a proactive surgical exposure should be considered.
In this chapter we shall therefore discuss the manner in which the orthodontic treatment of impacted teeth needs to be modified to accommodate the special requirements of the orthodontic appliance, the specific components that may be usefully employed and the accompanying treatment strategy that will make its performance run smoothly. It is not the intention here to discuss the details of appliance therapy. These will be set out in later chapters, where we will discuss the different groups of impacted teeth that are seen in practice. However, some general principles are in order at this juncture.
