Effect of antibiotic prophylaxis for preventing infectious complications following impacted mandibular third molar surgery. A randomized controlled trial.

BACKGROUND The objective of this study was to determine the effect of antibiotic prophylaxis in preventing postoperative infections after extraction of impacted mandibular third molars. MATERIAL AND METHODS A Parallel-group, randomized, blind, placebo-controlled trial was performed. 154 patients were randomly allocated to 2 groups; experimental (n=77) receiving 2g amoxicillin 1 hour prior to surgery and control (n=77) receiving placebo. Primary outcome was postoperative infections and secondary outcome was the need for rescue analgesia. RESULTS 4.5% of patients developed postoperative infections, five patients of the control group (4 alveolar osteitis, 1 surgical site infection) and two of the experimental group (1 alveolar osteitis, 1 surgical site infection). Difference between groups was not statistically significant, RR=0.4 (95%CI 0.08-1.99, 𝘱=0.41) NNTB=26. Rescue analgesia intake was significantly higher in the control group (41 vs 18 patients of experimental group) RR=0.49 (95%CI 0.32-0.75, 𝘱<0.05) NNTB=3. CONCLUSIONS The use of 2g amoxicillin 1 hour before surgery was not effective in significantly reducing the risk of postoperative infections from impacted mandibular third molars extraction, when compared to placebo. Nevertheless, antibiotic prophylaxis was associated with a reduced need for rescue analgesia.