Management of Third Molar-Related Nerve Injuries: Observe or Treat?

The determination of whether to observe or treat a nerve injury following third molar surgery depends on several factors: (1) knowledge of the natural course and incidence of sensory recovery following nerve injury; (2) the history of the nerve injury; (3) the physical findings; (4) the results of diagnostic procedures to determine the type (degree) of nerve injury; (5) the characteristics of the neuropathic pain, if present; and (6) the potential benefits and risks of treatment (i.e., surgery), if indicated. A witnessed injury is best treated immediately, but no later than within 4 weeks. Observation for up to 3 months is indicated when there is a history of an unwitnessed nerve injury, the descriptive word choices and functional deficits suggest only hypoesthesia, the physical findings are negative (i.e., no dystrophic changes, evidence of self-induced injury, neuropathic pain, or triggers), and the clinical neurosensory examination shows only mild sensory impairment, because more than half of IAN and LN injuries recover before 3 months. The presence of a LN deficit after 3 months has a greater chance of being associated with a severe nerve injury, and therefore the probability of recovery is less than with an IAN deficit after 3 months. Nerve injuries persisting up to and beyond 3 months, or those associated with pain, should be evaluated for the type of injury and the character and source of the pain, if present. Treatment is indicated when after 3 months there is still moderate or severe sensory impairment or there is neuropathic pain. However, further observation may still be indicated when the risk of the treatment outweighs the benefits.