Over recent years there has been debate over the advisability of removing symptom-free wisdom teeth or leaving them in place. The trend in recent years has been to be conservative in the management of these teeth and this has been driven, to some extent, by the incidence of complications associated with their surgical removal, and particularly the small, but measurable, risk of damage to the inferior dental nerve or the lingual nerve.
The controversy surrounding wisdom teeth has led to the publication of guidelines, the most recent of which are 'Management of unerupted and impacted third molar teeth' a National Clinical Guideline from the Scottish
Criteria for removal of wisdom teeth Pericoronitis spread ot infection from pericoronitis treatment of pericoronitis Clinical assessment Radiographic assessment Clinical management preoperative information techniques lower third molars upper third molars Postoperative care Complications of surgery
Table 27.2 Indications for removal of wisdom teeth
External or internal resorption Wisdom tooth in tumour resection
Intercollegiate Guidelines Network (SIGN) and 'Removal of wisdom teeth' guidance from the National Institute for Clinical Excellence (NICE). These guidelines inform the decision on whether to remove wisdom teeth.
Surgical removal of impacted third molars, it is recommended, should be limited to patients with evidence of pathology. These are listed in Table 27.2 and will be discussed in turn. Further possible indications to be considered are listed in Table 27.3.
Table 27.3 Further possible indications for removal of third molars
Denture or implant design
Access to dental care
Orthognathic surgery or reconstructive surgery
Use of general anaesthesia
Age of patient
The most common reason for recommending removal of wisdom teeth is that patients have experienced significant infection associated with them. This usually manifests itself as pericoronitis and a discussion of the clinical features and management of this will follow. Pericoronitis is only an indication for extraction if the first episode is very acute or there has been more than one episode.
Untreatable caries, pulpal or periapical pathology
Another common indication for removal of wisdom teeth is the development of caries either in the wisdom tooth itself or in the adjacent second molar. This occurs because the patient is unable to clean the distal aspect of the second molar or the area around the wisdom tooth, which is often partially erupted. This leads to the accumulation of food debris and plaque and then caries of the adjacent tooth surfaces. This may lead to untreatable pulpal or periapical pathology.
As a result of the unsatisfactory relationship between the second and third molars, the area is prone to periodontal disease, which may compromise the second molar. This can be improved by the removal of the third molar.
When third molars are unerupted they may be the source of a dentigerous cyst, which can enlarge considerably before giving rise to symptoms. The risk of developing these cysts is low but is also unpredictable and gives rise to a clinical dilemma of how often radiographic assessment of unerupted third molars is necessary to diagnose a cyst before its size makes the management more complicated.
A less common reason for removal of third molars is external resorption of the second molar due to pressure from the unerupted third molar. As with the formation of the dentigerous cyst, this resorption can be extensive before the patient experiences symptoms. Internal resorption within the wisdom tooth is also an indication for removal.
If an impacted wisdom tooth is associated with a tumour at the angle of the mandible, or is within the tumour resection margins, it should be removed.
When a patient presents with a heavily restored or carious first molar tooth and a partially erupted third molar tooth it is possible to transplant the third molar into the socket of the first molar. This procedure is complicated by the difficulty of removing the third molar without damage and also because the root morphology of these teeth is different, which causes problems accommodating the third molar in its new site. Once transplanted, the tooth will often require to be splinted for a period and, with a low success rate, this procedure is rarely carried out.
If a fracture of the mandible through the angle occurs, an opportunity may arise to remove the third molar when surgical access is being made to treat the fracture itself. Some authorities consider that unerupted third molars should be removed in those individuals who participate in contact sports like rugby and boxing, in whom the risk of mandibular fracture is increased.
It has been argued that an unerupted third molar in an already atrophic mandible might be a potential site for fracture and consideration should be given to removing it in a controlled manner before a fracture occurs.
Denture or implant design
Restorative dentists can request the removal of unerupted third molar teeth to facilitate denture design or the accurate placement of implants.
Where patients are in a situation where they do not have easy access to dental care, it is appropriate to consider the removal of potentially troublesome third molar teeth. This could for example, include submariners or occupations that involve working in isolated areas where dental help may be difficult to find. With modern means of travel and communication, this reason for removing third molar teeth has assumed less significance.
Removal of third molars may be indicated in certain medical conditions, such as prior to cardiac surgery or in those scheduled to have radiotherapy of the jaw. Removal of third molars following radiotherapy increases the likelihood of the development of osteoradionecrosis, and is therefore better carried out before such treatment (see Ch. 36).
Orthodontic treatment plans may include the removal of impacted lower and upper third molars in an attempt to prevent or reduce imbrication of the incisor teeth. There is no evidence, however, that third molars contribute to this problem (see Ch. 31).
Third molars may also need removed when orthognathic surgery is being planned, particularly with procedures such as sagittal split osteotomy (see Ch. 13).
More rigorous criteria for removal of lower third molars can lead to further difficulties in determining whether symptom-free third molar teeth on the other side of the mouth should be removed when general anaesthesia or sedation is being used for the removal of a symptomatic third molar tooth. The fact that the tooth is present is not sufficient reason to remove it while the patient is anaesthetised. However, as in all situations regarding third molars, all four teeth should be subject to a risk-benefit analysis.
Finally, removing third molars in young fit patients and not leaving them until an older age when the bone is denser and more difficult to manage, and when the patient may have medical problems related to older age groups, is still a common point of view. Contrary to this argument is the view that the small but significant morbidity following removal of wisdom teeth supports a more conservative approach, and so removal for this reason alone can no longer be condoned. The more conservative approach is now more commonly adopted but many oral surgeons are mindful that they may be storing up difficulties for later years, both for their patients and for their surgical successors. Time alone will answer this question
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