Guideline 43: Management of Unerupted and Impacted Third Molar Teeth

Management of Unerupted and Impacted Third Molar Teeth
Summary of recommendations

Removal of unerupted and impacted third molars is not advisable:

In patients whose third molars would be judged to erupt successfully and have a functional role in the dentition.

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 with deeply impacted third molars with no history or evidence of pertinent local or systemic pathology.

In patients where the risk of surgical complications is judged to be unacceptably high, or where fracture of an atrophic mandible may occur.

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.

Removal of unerupted and impacted third molars is advisable:

In patients who are experiencing or have experienced significant infection associated with unerupted or impacted third molar teeth.

In patients with predisposing risk factors whose occupation or lifestyle precludes ready access to dental care.

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).

In patients who have agreed to a tooth transplant procedure, orthognathic surgery, or other relevant local surgical procedure.

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.

There are strong indications for removal when:

There have been one or more episodes of infection such as pericoronitis, cellulitis, abscess formation; or untreatable pulpal/periapical pathology.

There is caries in the third molar and the tooth is unlikely to be usefully restored, or when there is caries in the adjacent second molar tooth which cannot satisfactorily be treated without the removal of the third molar.

There is periodontal disease due to the position of the third molar and its association with the second molar tooth.

In cases of dentigerous cyst formation or other related oral pathology.

In cases of external resorption of the third molar or of the second molar where this would appear to be caused by the third molar.

Other indications for removal:

For autogenous transplantation to a first molar socket.
In cases of fracture of the mandible in the third molar region or for a tooth involved in tumour resection.
An unerupted third molar in an atrophic mandible.
Prophylactic removal of a partially erupted third molar or a third molar which is likely to erupt may be appropriate in the presence of certain specific medical conditions.
Atypical pain from an unerupted third molar is a most unusual situation and it is essential to avoid any confusion with temporomandibular joint or muscle dysfunction before considering removal.
An acute exacerbation of symptoms occurring while the patient is on a waiting list for surgery may be managed by extraction of the opposing maxillary third molar.
A partially erupted or unerupted third molar, close to the alveolar surface, prior to denture construction or close to a planned implant.

Clinical assessment

Clinical assessment should be carried out with the aim of assessing the status of the third molars and excluding other causes of the symptoms. A complete examination should include assessment of:

the eruption status of the third molar
the presence of local infection
caries in, or resorption of, the third molar and the adjacent tooth
periodontal status
orientation and relationship of the tooth to the inferior dental canal
occlusal relationship
temporomandibular joint function
regional lymph nodes.
Any associated pathology should also be noted.

Radiological assessment is essential prior to surgery, but does not require to be carried out at the initial examination.

Routine radiographic examination of unerupted third molars is not recommended.

The following information should be noted in relation to lower third molars:

the type and orientation of impaction and the access to the tooth
the crown size and condition
the root number and morphology, including the presence of apical hooks
the alveolar bone level, including the depth and the point of elevation and density
the follicular width
the periodontal status, together with that of the adjacent tooth
The relationship or proximity of upper third molars to the maxillary antrum and of lower third molars to the inferior dental canal.

The following signs have been demonstrated to be associated with a significantly increased risk of nerve injury during third molar surgery:

diversion of the inferior dental canal
darkening of the root where crossed by the canal
interruption of the white lines of the canal.

In the presence of any of these findings, great care should be taken in surgical exploration and the decision to treat should be carefully reviewed. The patient should be advised of the risk.

If on the initial radiograph there is a suggestion of an intimate relationship between the roots of the lower third molar and the inferior dental canal, a second radiograph should be taken using different project geometry.

Clinical management

After referral but prior to surgery interim measures may include systemic antibiotic administration, chlorhexidine mouth rinses, operculectomy, local dressing and lavage.

Referring practitioners should contact the surgeon to expedite treatment if a patient on a waiting list experiences recurrent bouts of infection.

The whole tooth should be removed and wound toilet completed. Any suspected pathological material should be sent for a histopathology report.

Resorbable sutures may be used at any time but in particular where no review is planned.

The limited evidence available is insufficient to make a recommendation on the routine use of antibiotics for third molar removal. However, in severe cases where there is acute infection at the time of operation, significant bone removal, or prolonged operation, antibiotics should not be withheld.

Preoperative steroids should be considered (unless contraindicated) where there is a risk of significant postoperative swelling.

Common complications associated with treatment

Haemorrhage must be controlled at the time of surgery. Soft tissue bleeding may require haemostatic agents, bipolar diathermy and/or sutures. Occasionally, a small amount of bone wax is necessary to control bleeding from bone, but this must be used with caution. Haematoma formation outwith the socket can occur and may require drainage.

Patients should be informed that bruising is common and self-limiting and will usually resolve within two weeks of surgery.

Where signs of systemic involvement are present (pyrexia, regional lymphadenopathy) antibiotics should be prescribed.

When a retained root fragment gives rise to symptoms, it should be removed.

Appropriate instruments should be in place prior to elevation to help minimise the occurrence of displacement. Where displacement occurs, every effort should be made at the time of surgery to recover the displaced tooth, but referral to a specialist centre may be required.

Where wound dehiscence occurs without the development of pain and infection, patients should be advised to continue wound toilet, e.g. hot salty mouthwashes and socket syringing.

Patients should be told about damage to adjacent teeth at the time of surgery or, if under sedation or general anaesthetic, when they are fully conscious. The consequences of this damage should be explained to the patient and recorded in the patient's notes. If repair is required, the operator should arrange appropriate management.

Serious complications associated with treatment

Fracture of the mandible should be noted at the time of surgery and repaired if necessary. If the operator is unable to do this, he/she must arrange immediate referral.

Tuberosity fractures may occur and should be treated at the time of surgery. If the operator is unable to do this, he/she must arrange an immediate referral.

Oro-antral communication identified at the time of surgery should be repaired, usually with a buccal advancement flap. Antibiotic therapy is advisable and the patient should avoid nose blowing.

Any broken instrument should be removed at the time of the operation. If not retrievable, the patient should be told and this recorded in the notes.

Complete transection of the lingual or inferior dental nerves requires immediate nerve repair by an experienced surgeon. Where there is partial damage, gentle debridement and the maintenance of good apposition of the ends is normally undertaken. The patient should be informed of the situation.

Late recognition of nerve damage may require further surgical exploration.

Follow up

A review appointment is required:

Where non-resorbable sutures have been placed
Where complications arise
At the patient's or surgeon's request

Patient information

At the time of the operation, the patient should know:

How to contact the surgeon in case of emergency
How to look after their mouth postoperatively
Possible complications and side effects of the operation in general and any problems specific to the operation undertaken
Any drug therapy required
Whether a review appointment is required and if so, when
That the referring practitioner will receive a letter postoperatively.