When extracting lower wisdom teeth, coronectomy is a treatment option involving removing the crown of the lower wisdom tooth, whilst keeping the roots in place in healthy patients. This option is given to patients as an alternative to extraction when the wisdom teeth are in close association with the inferior alveolar nerve, and so used to prevent damage to the nerve which may occur during extraction.

Advantages

Reduces risk of neuropathy compared with full extraction. The risk of altered sensation is significantly lower than convention surgical removal of mandibular third molars. Approximately 0.65% of individuals encounter postoperative deficits in the Inferior alveolar nerve (IAN) following coronectomy, a significantly lower occurrence compared to the 5.10% observed after conventional extraction procedures. Patients undergoing coronectomy are anticipated to experience easier recovery from IAN deficits compared to those undergoing extractions. Limited studies indicate a 100% recovery rate in coronectomy patients, whereas only 66% of patients undergoing extraction recover within one month. 62.2% of the roots will migrate post-coronectomy, erupting away from the inferior alveolar canal. This makes extraction of the remaining roots safer.

Disadvantages

There is a 5% chance of failure of coronectomy, the root will become mobilized during transection. In 5% of the cases, follicle remnants will form deep periodontal pockets which will lead to infection.

Indications

Coronectomy should be considered if there are signs that the patient is at a high risk of nerve damage during extraction:

Contraindications

Procedure

Preoperative assessment

The patient

The patient should be aware of the potential risks of the procedure such as:

Radiography

A plain film radiograph allows the proximity of the tooth to the inferior alveolar canal to be assessed. The plain film can be assessed to identify the tooth as high risk If there is; loss of the lamina dura, darkening of the canal and grooving of the root. If the mandibular third molar is deemed to be high risk, a cone beam CT (CBCT) is taken in addition to the plain film. The justification of additional radiography can be justified by the surgeon as it allows them to gain further information regarding the tooth roots and the inferior alveolar canal should the roots be mobilised when transecting.

Consent

Verbal consent must be attained by the surgeon prior to the procedure of a coronectomy. Additionally consent must be gained if removal of the roots is required due to mobilisation. The patient should be informed of early and late infection meaning the roots may need removing.

Operative technique

Post operative complications

Early

If the patient presents with dry socket, irrigate with chlorohexidine mouthwash and place resorbable dressing such as Alvogyl. If the patient has recurrent infection, consideration to remove the roots should be noted.

Late

In a few cases the remaining roots may erupt which can minimise the morbidity of the inferior alveolar nerve, however the roots may be in close contact to the inferior alveolar nerve requiring surgical separation.