Differences between the sexes in post-surgical pain.

It has been shown that women have a lower pain threshold and lower tolerance to some forms of experimental pain then men. However, the evidence that clinical pain is perceived differently by the two sexes is not yet as strong. The placement of intraoral implants is a highly controlled surgical procedure that we have used to investigate this possibility. Forty-eight edentulous (without teeth) subjects (27 females), aged from 35 to 63 years, received two titanium implants in the anterior mandible under local anesthesia. After the surgery, subjects completed a pain diary three times each day, rating pain intensity and unpleasantness on 100 mm visual analog scales (VAS). Once a day, they chose verbal descriptors from the McGill Pain Questionnaire (MPQ). Age of subjects, duration of surgery, the amount of local anesthetic used and the amount of pain medication taken were not statistically different for the two groups (P>/=0.32). Results showed that the senior surgeon produced significantly less pain than a 4th year resident (P=0.04). Although there were no significant differences between sexes for mean daily ratings of intensity or unpleasantness over time (P>/=0.10), most women experienced the highest intensity of pain during the day, while most men had higher pain in the evening (P=0.025). Also, the relative unpleasantness (unpleasantness/intensity ratio) increased significantly with time for males, but not for females (P=0.016). Males and females did not differ in the total number of words chosen from the MPQ (P=0.61), or in the averaged Pain Rating Index (PRI) (P=0.53). However, women used significantly more evaluative words than men (P=0.04), suggesting that woman found the overall intensity greater. These results indicate that women find post-surgical pain more intense than males, but that men are more disturbed than women by low levels of pain that last several days.