The nerve that  supplies sensation to the lower lip, chin, teeth and gums sits within the lower jaw bone and can lie very close to or even touch the roots of the lower teeth. Injury to this nerve is very rare and when injured it can cause changes in sensation; this is usually temporary, lasting several months, but can be permanent. All third molar extractions carry the risk of numbness, hypersensitivity, or even pain in the areas supplied by this nerve. Unfortunately, in some patients the nerve is so close to the wisdom tooth that an extraction may not be indicated because of higher risk of injury to this nerve.

During your consultation appointment, the proximity between the tooth and the nerve will be determined, demonstrated, and discussed. The relative risk of removal of wisdom teeth will be discussed. In some cases with higher than average risk , a coronectomy procedure may be discussed as an alternative.

A coronectomy is also known as a partial tooth extraction. It is a technique-sensitive procedure best performed by your oral and maxillofacial specialists. The top part of the tooth, or the crown, is removed. The remaining part of the tooth, or the roots, which are in close proximity to the nerve, are purposely left behind, decreasing  the risk of a nerve injury. 

Recovery from a coronectomy is similar to having a wisdom tooth extraction. The main difference is the need for yearly follow up X-rays. Most of the time the bone heals over the roots and  they do not cause a problem again.  In some rare  cases, the remaining roots become symptomatic and become infected, requiring a removal during a second surgery. Over the ensuing years the roots may migrate upwards away from the nerve  and may require removal. This removal would carry a lower risk of numbness since the nerve and roots will no longer be in close approximation.