Hypersensitivity due to stress.

Basal, preoperative and postoperative perception thresholds and pain tolerance thresholds were studied in 32 patients undergoing minor oral surgery using monopolar stimulation of a vital anterior tooth. Significant differences were found between the perception and pain tolerance thresholds, the basal and preoperative perception and pain tolerance thresholds being higher than the postoperative thresholds. Decreased postoperative pain tolerance thresholds were found in patients with increased anxiety. The effect of premedication on the thresholds was also studied. Premedication with diazepam and pethidine caused an increase in the preoperative perception and pain tolerance thresholds but did not prevent a decrease in the postoperative perception and pain tolerance thresholds. The increase in the preoperative perception and pain tolerance thresholds caused by the premedication was equal in magnitude to the decrease in the thresholds measured immediately after surgery.