Comparison between the prophylactic effects of amoxicillin 24 and 48 hours pre-operatively on surgical site infections in Japanese patients with impacted mandibular third molars: A prospective cohort study

Introduction According to the guidelines, the dosage for mandibular wisdom tooth extraction (MWTE) varies within the administration period. There is a 24-fold difference between the minimum and maximum doses. If an appropriate antimicrobial can be administered without increasing incidence of surgical site infection (SSI), it may lead to a global action plan on antimicrobial resistance (AMR). Therefore, we prospectively surveyed incidence of SSI post-operatively and use of oral antibiotics (OA) for MWTE. Methods Subjects were patients who underwent MWTE in our dental outpatient clinic from May 2019 to April 2020. Two groups were formed depending on type of administration period they received: 24 h and 48 h after surgery. The following information was collected: (1) patient factors (age, gender, body mass index, presence/absence of preoperative medication, diagnosis, impacted wisdom tooth status; (2) surgical factors (operative time, presence/absence of closure, presence/absence of hemostat, doctor career, type and frequency of painkiller); (3) relationship between administration period of OA and SSI occurrence; and (4) details of SSI. Results Three hundred forty subjects were analyzed, all of which used amoxicillin. There were 106 cases in 24 h group and 234 cases in 48 h group. The total incidence of SSI was 1.1% (4/340 cases), with 0.9% (1/106 cases) in 24 h group and 1.3% (3/234 cases) in 48 h group; there was no difference between the two groups. Conclusion Our study suggests that amoxicillin (250 mg/dose every 8 h x 3 doses beginning 1 h before surgery) might be sufficient in preventing SSI in Japanese dental patients without SSI risk factors.