When teeth in the lower jaw need to be extracted one potential complication is injury to the inferior alveolar nerve. This nerve actually sits within the jaw bone and can course very close to or even touch the roots of lower teeth. Injury to this nerve is very rare and when injured it is usually temporary, lasting several months, but can be permanent. The nerve supplies sensation to the lower lip, chin, teeth and gums on that side of the lower jaw and an injury can cause numbness, hypersensitivity, or even pain in the areas supplied by this nerve. During your pre-operative evaluation by your doctor, the proximity to between the tooth and the nerve can be determined. Sometimes a CT scan needs to be obtained to fully determine this relationship. If it is discovered that extracting the tooth completely would result in a higher risk of injury to the nerve then a coronectomy can be performed.
A coronectomy is an intentional partial tooth extraction. The tooth is sectioned into upper and lower halves. The top portion of the tooth is removed and the lower portion, or roots, are left behind. The gums are closed over the remaining roots of the tooth isolating it from the oral cavity. A post-operative x-ray is taken to confirm the position of the remaining roots after the surgery. Recovery from this procedure is very similar to having the entire tooth extracting. In most cases the roots become encased in the lower jaw bone and never cause problems again. In some instances the roots can become infected and may need to be extracted but this is only in a small number of cases. In some instances, after a coronectomy the remaining roots may migrate toward the oral cavity. If this occurs and the roots actually penetrate through the gums then they would need to be extracted but at this point they are far from the nerve and pose only a very small risk of injury to the nerve.