This section considers the broad principles which underpin the decision to remove or not to remove an unerupted or partially erupted third molar tooth. Specific indications are considered in greater detail in section 3.

As a general principle, teeth should not be removed without due cause. This applies to third molars as much as it does to any other teeth. All forms of surgery, whether under local anaesthesia or general anaesthesia, carry some risk of complications - at worst, death - and there is an inevitable and measurable morbidity associated with surgical removal of teeth. Even in the best of hands, unpredictable accidents can occur and when very large numbers of teeth are being considered in the population this must happen to the occasional patient. Quite apart from this, there is a question of cost to the Health Service as well as to the patient. There needs, therefore, to be a distinct reason for the removal of third molar teeth and this reason should be clearly identified.

2.1 For which patients is removal not advisable?

2.1.1

It is self evident that there is no strong indication for removing third molars which are completely asymptomatic and disease free except under special circumstances (see section 2.2), as the risks of intervention may lead to complications both minor and major. ^{17, 18, 19, 20, 21, 22, 23, 24} Non-intervention avoids these risks and may preserve potentially functional teeth and the bony ridge. The teeth might also be used for transplantation purposes. Evidence level Ia

There is general agreement that, where there is adequate space, unerupted teeth should be left in situ to erupt and that during childhood even impacted teeth may change their position. It is not possible to predict accurately which asymptomatic teeth will erupt^{25, 26, 27} and there is little evidence that the teeth become significantly more difficult technically to remove with age, or that more complications occur by leaving them in situ. However, it should be remembered that as the patient grows older there is an increased risk of surgical morbidity.²⁸ Evidence level Ia

Third molars which would be judged to erupt successfully and have a functional role in the dentition should not be removed.

Third molars should not be removed in patients whose medical history renders the removal an unacceptable risk to the overall health of the patient or where the risk exceeds the benefit.

In patients where the surgical removal of a single third molar tooth is planned under local anaesthesia the simultaneous extraction of asymptomatic contralateral teeth should not normally be undertaken.

2.1.2

In the case of deeply impacted third molars without evidence of pathology, especially when completely covered by soft tissue and/or bone, there is a risk of significant loss of periodontal support from the adjacent second molar following surgery to remove these teeth. There are therefore definite indications for leaving these teeth in situ. The same is not true for partially erupted impacted teeth, where there is good evidence that they are likely at sometime to cause symptoms.^{25, 29, 30} Evidence level Ia

Deeply impacted third molars in patients with no history or evidence of pertinent local or systemic pathology (other than the exceptions identified in sections 2.2 and 3) should not be removed.

2.1.3

Where the patient has no symptoms and the third molar is buried, pathology-free and in close relationship with the inferior dental nerve or where there is a very atrophic mandible with little risk of trauma then it is considered good practice to leave the third molar in situ.^{3, 31} Evidence level IV

Third molars should not be removed in patients where the risk of surgical complications is judged to be unacceptably high, or where fracture of an atrophic mandible may occur.

2.2 For which patients is removal advisable?

There are some definite indications for removal of third molars. For example, where infection can be predicted and therefore avoided, where there has been recurrent pain and discomfort with the likely use of antibiotics, and where there have been multiple episodes of conservative treatment, then removal of third molars should be the usual consequence. In these circumstances, timely removal of the third molar reduces the cost to the patient, time off work, and the risks associated with repeated conservative treatment, e.g. with antibiotics. Other situations where it is in the patient's best interests to have early removal of third molars include those who are in occupations where they may have to work in situations isolated from expert treatment, or when medical or surgical conditions are likely to arise leading to difficulty or risk with their removal.

2.2.1

There is some evidence to suggest that a decision should be made to remove third molars where there is a likelihood of infection. There is no evidence that it is in the patient's best interests to wait until infection arises.^{4, 32, 33} Evidence level III and IV

Removal is advised in patients who are experiencing or have experienced significant infection associated with unerupted or impacted third molar teeth.

2.2.2

If the patient has had infection or is very likely to have infection, e.g. a partially erupted tooth, and is likely to be in a position in which he or she cannot obtain access to surgical care then early removal may be appropriate. The consensus is that it is better to remove the cause of the infection than repeatedly to treat it with antibiotics. ^{11, 18, 31} Evidence level IV

Removal of third molars is advised in patients with predisposing risk factors whose occupation or lifestyle precludes ready access to dental care.

2.2.3

Teeth at risk of infection which could result in osteoradionecrosis or endocarditis should be removed. Although the risks of these conditions developing may be small, their serious nature precludes the retention of a potentially infected third molar. ^{7, 34} Evidence level IV

Removal is advised in patients with a medical condition when the risk of retention outweighs the potential complications associated with removal of third molars (e.g. prior to radiotherapy or cardiac surgery).

2.2.4

There is a consensus view that where the third molar may complicate orthognathic surgery or another surgical procedure to the jaw, then it is reasonable to remove that tooth, provided the risks of complications and the severity of those complications do not outweigh the benefits. ^{16, 34} Evidence level IV

Removal of third molars may be considered in patients who have agreed to a tooth transplant procedure, orthognathic surgery, or other relevant local surgical procedure.

2.2.5

Disease-free non-functional upper third molars would normally be removed under general anaesthesia when impacted lower third molars are to be extracted and when the risks of retention and a further general anaesthetic outweigh the risks associated with their removal.^{16, 18, 31, 34, 35} Diminishing use of general anaesthesia makes this less of a consideration than in the past, but where a general anaesthetic has to be given there are obvious risks attached to this procedure and if it has to be repeated this increases that risk. Evidence level IV

Where a general anaesthetic is to be administered for the removal of at least one third molar, consideration should be given to the simultaneous removal of the opposing or contralateral third molars when the risks of retention and a further general anaesthetic outweigh the risks associated with their removal.