The quality of evidence is downgraded by study limitations (high loss to follow-up in relation to observed absolute effect, and selective outcome reporting)
A Cochrane review [Abstract] 1 included 18 double-blind placebo-controlled trials with a total of 2456 participants who received either antibiotics (of different kinds and dosages) or placebo, immediately before (10 studies) or just after (4 studies) tooth extraction, or both. Primary outcome was post-surgical signs of local infection, including alveolar osteitis (dry socket), pain, fever, swelling, and restricted mouth opening (trismus). Trials which reported the outcomes of endocarditis incidence, bacteraemia, or serum markers of infection only, were not included in this review. Only 5 trials reported antibiotic related adverse events per patient (n=930). All study patients were healthy individuals undergoing extraction of impacted third molars (wisdom teeth).
Based on seven studies, antibiotics reduced the risk of clinically diagnosed surgical site infection by 70 % (NNT 12). The results were similar in studies with pre- and post operative antibiotic administration. Two studies compared the pre- and postoperative administration and found no difference in local infections. The prevalence of local infection varied from 0 to 56 % in the study populations (mean 12 %). There was no difference between the groups in post-operative fever, swelling or trismus. In five studies reporting adverse effects the patients in the antibiotic group experienced twice as often drug related side effects which were generally brief and minor and required no treatment (NNH 21).
| Outcome | Number of participants (trials) | Control:Placebo | Intervention:Antibiotics | Effect size (95 % CI) |
|---|---|---|---|---|
| Local infection | 1523(10) | 118/1000 | 34/1000 | RR 0.29(0.16 to 0.50) |
| Pain 7 days after extraction | 675(3) | 126/1000 | 76/1000 | RR 0.60(0.32 to 1.11) |
| Pain intensity (VAS 1-100) | 372(4) | VAS 15 (mean) | VAS mean 8 lower | MD -8.17 (-11.90 to -4.45) |
| Fever on 7th day | 816(4) | 39/1000 | 13/1000 | RR 0.34(0.06 to 1.99) |
| Swelling on 7th day | 334(3) | 307/1000 | 282/1000 | RR 0.92(0.65 to 1.30) |
| Adverse effects 7 days after extraction | 939(5) | 49/1000 | 96/1000 | RR 1.98(1.10 to 3.59) |
It is unclear whether the evidence in this review is generalisable to those with concomitant illnesses or immunodeficiency, or those undergoing the extraction of teeth due to severe caries or periodontitis. Due to the increasing prevalence of bacteria which are resistant to treatment by currently available antibiotics, clinicians should consider carefully whether treating 12 healthy patients with antibiotics to prevent one infection is likely to do more harm than good. However, patients at a higher risk of infection are more likely to benefit from prophylactic antibiotics.
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