Sensory loss following third molar surgery

The prediction of sensory loss following the extraction of third molars and the monitoring of sensory return following such injury is a matter of concern for oral surgeons. These factors were assessed in 500 patients, representing 957 lower third molar extractions. The preoperative orthopantomogram (OPG) was examined and the anatomical proximity of the third molar to the inferior alveolar nerve was graded into risk groups. Other clinical factors thought to contribute to sensory loss were assessed, those factors being surgical technique, difficulty of the operation and the type of impaction. For those patients who sustained a nerve injury, the sensory loss was monitored using eight different subjective tests. The sweat test was assessed as an objective test to monitor sensory loss in the face. It was found that while there was a trend for increased sensory loss in those teeth with a closer proximity, when looked at as high and low risk there was no statistical difference between the groups (p=0.33). More importantly, cases of sensory loss occurred when they were not anticipated. There was a higher incidence of sensory loss occurring in the more difficult cases. Horizontal impactions proved to cause the highest incidence of sensory loss. The lingual split technique produced the highest incidence of mental and lingual sensory loss. The recovery of the sensory modalities showed a trend towards fine touch, pin prick, cold sensation and electrical thresholds, all returning before tests of warm sensation, sharp/dull, two point discrimination and vibration. The objective sweat test for measuring sympathetic fibre supply to the face as a measure of sensory loss was of no clinical value. It was concluded that: 1. Preoperative radiographic prediction of nerve injury from third molar surgery is inaccurate; 2. Recovery of nerve injuries was best monitored by fine touch, pin prick, cold sensation, and electrical sensory thresholds