Abstract: Objective：To investigate the effectiveness of preemptive analgesia with loxoprofen sodium orally, which was a kind of non-steroid anti-inflammatory drugs, in extractions of mandibular impacted third teeth. Methods: There were questionnaires about postoperative pain for patients whose mandibular impacted third teeth were extracted from July 2017 to August 2017 in First Clinical Division of Peking University School and Hospital of Stomatology. All the patients did their routine clinical examinations and imaging examinations. After their mandibular impacted third teeth were extracted, the questionnaires were sent to them. The questionnaires were filled in by the patients on their own and returned one week later. There were 120 questionnaires that were sent and 105 questionnaires returned, of which 98 questionnaires were filled in completely. According to the inclusive criteria and exclusion criteria, 66 questionnaires were totally selected in this study. According to the time when the patients took their loxoprofen sodium orally firstly, the patients were divided into 3 groups. The first group was for patients who didn’t take loxoprofen sodium during their extractions (non-medicine group). The second group was for patients who took 60 mg loxoprofen sodium 30 min before their extractions (preoperative group). The third group was for patients who took 60 mg loxoprofen sodium 30 min after their extractions (postoperative group). The operation time among the 3 groups was analyzed by Kruskal-Wallis method. The postoperative time points were 2, 4, 12,24 and 48 h after operation. The scores of visual analogue scales (VAS) for postoperative pain in each group at different postoperative time points were analyzed by Friedman method. At each postoperative time point, VAS scores in the different groups were analyzed by Kruskal-Wallis me-thod. The numbers of the patients taking loxoprofen sodium home and drug adverse reactions were also analyzed. Results: The operation time of the 3 groups was 15.0 (5.0,30.0) min and had no significant differences (P=0.848).VAS scores of non-medicine group 2,4, 12,24 and 48 h after operation were 1.75 (0.1,10.0), 6.25 (1.5,10.0), 2.00 (0.1,8.0), 2.00 (0.1,6.0) and 0.5 (0.1,5.5) separately and had significant differences (P<0.001).The VAS score at 4 h after operation was higher than the VAS scores at other time points after operation (P<0.005). Four hours after the operations, the VAS scores of preoperative group ［2.0 (0.1,10.0)］ and postoperative group ［2.0 (0.1,5.0)］ were lower significantly than those of non-medicine group ［6.25 (1.5,10.0)］ (P<0.001).The numbers of the patients taking loxoprofen sodium home were 9(40.9%) in non-medicine group,5(21.8%) in preoperative group and 7(33.3%) in postoperative group. The number of the patients who had drug adverse reactions in preoperative group (n=3,13.0%) and in postoperative group (n=4,19.0%) was less than the number of the patients who had drug adverse reactions in non-medicine group (n=8,36.4%). Conclusion: There were two protocols of preemptive analgesia with loxoprofen sodium orally in extractions of mandibular impacted third teeth, which were taking 60 mg loxoprofen sodium orally 30 min before the extractions and taking 60 mg loxoprofen sodium orally 30 min after the extractions. Both of the two preemptive analgesia protocols could decrease the postoperative pain significantly.

Key words: Impacted tooth, Preemptive analgesia, Non-steroidal anti-inflammatory drugs