effect of postoperative amoxicillin on early bacterial colonization of peri-implant sulcus: a randomized controlled clinical trial

objectives: with side effects of antibiotics taken into consideration, the necessity of antibiotic therapy after simple implant placement procedures is still a subject of debate and the existing literature on this topic is widely controversial. the aim of this study was to assess the effect of postoperative amoxicillin therapy on early colonization of peri-implant sulcus after implant placement. materials and methods: in this randomized controlled clinical trial, 20 patients requiring simple implant placement were randomly allocated to test or control groups and received postoperative amoxicillin or placebo, respectively. microbiological samples were collected on day 0 and day 7. mann whitney and wilcoxon signed rank tests were utilized to evaluate changes in colony count of identified bacterial species between the test and control groups, and between day 0 and day 7. results: the decrease in the number of sensitive facultative species and the increase in the number of resistant anaerobes in amoxicillin group were statistically significant as compared to the placebo group (p=0.025 and p=0.005, respectively). the increase in the number of sensitive anaerobes in the placebo group as compared to amoxicillin group, and the decrease in the number of facultative gram-positive cocci as compared to the placebo group were statistically significant (p=0.011 and p=0.035, respectively). conclusions: postoperative administration of amoxicillin resulted in an increase in the number of resistant anaerobes and a decrease in the number of sensitive facultative bacteria and facultative gram-positive cocci, as compared to the placebo, but with no sign/symptom of infection in any group. keywords: dental implants; osseointegration; amoxicillin; placebos; infection; bacteria, aerobic; bacteria, anaerobic