Abstract: PURPOSE: To investigate the effects of antimicrobial agents on preventing local infection following impacted mandibular third molar extraction. METHODS: In this prospective, randomized , comparative, single-blind clinical trial, a total of 1 600 patients were randomized into 4 groups: control group (CG) with no treatment; chlorhexidine gluconate group (CHX) with 0.2% chlorhexidine gluconate rinse for 5 days postoperatively; amoxicillin group (AMX）with amoxicillin administration for 3 days postoperatively; chlorhexidine gluconate+amoxicillin group (CHX+AMX) with 0.2% chlorhexidine gluconate rinse for 5 days and amoxicillin administration for 3 days postoperatively. Postoperative complications including alveolar osteitis (AO) and surgical site infection (SSI) as well as postoperative reactions including pain,swelling and trismus were recorded 1, 3, 7 and 14 d after surgery. SPSS19.0 software package was used for statistical analysis. RESULTS: A total of 1 452 patients completed the study with 35 AO（2.41%）and 65 SSI（4.47%）. Eleven AO（3.03%）and 22 SSI（6.06%）were observed in CG group; 10 AO（2.78%）and 17 SSI（4.72%）were observed in CHX group; 8 AO（2.21%）and 15 SSI（4.14%）were observed in AMX group; 6 AO（1.63%）and 11 SSI（3.00%）were observed in CHX+AMX group. However,no significant difference was found in the rate of local infection and postoperative reactions among the four groups (P>0.05). CONCLUSIONS: The application of amoxicillin and 0.12% chlorhexidine gluconate can not reduce the rate of postoperative local infection after impacted mandibular third molar extraction.

Key words: Amoxicillin, Chlorhexidine gluconate, Third molar, Infection