Impacted wisdom teeth are anatomically close to the inferior alveolar nerve, which runs in a canal in the lower jaw bone. The inferior alveolar nerve provides sensation to the lower teeth, gum tissue, lip, and chin area. In some circumstances, the wisdom teeth may be in very close proximity to the nerve. Hence extraction may irritate the nerve, leading to temporary or prolonged partial or complete numbness.
If the lower wisdom teeth appear to ‘run across the canal on a panorex (a 2-D X-ray), then a 3-D cone beam CT scan should be obtained for proper diagnosis and visualization. A modified technique known as coronectomy or partial extraction therapy (PET) may be recommended for impacted lower wisdom teeth near the nerve. This technique involves the removal of the top part of the tooth while preserving the roots in place. The site often heals uneventfully with no risk of numbness to the patient.