Do systemic amoxicillin and metronidazole during the non-surgical peri-implantitis treatment phase prevent the need for future surgical treatment? A retrospective long-term cohort study.

AIM: The aim of this retrospective long-term follow-up of a 3-month RCT was to assess whether non-surgical peri-implantitis treatment with adjunctive systemic antibiotics influenced the need for additional surgical treatment. MATERIALS AND METHODS: Patients enrolled in an aftercare programme following non-surgical peri-implantitis treatment, with or without systemic amoxicillin and metronidazole, were analysed. Data had previously been collected pre-treatment (T(0)) and 3 months after treatment (T(1)) and were additionally collected during subsequent aftercare visits, until the final assessment (T(2)). Primary outcome was the need for additional surgical peri-implantitis therapy during the aftercare programme, analysed via Kaplan-Meier analysis and Cox regression. Secondary outcomes involved clinical parameters, assessed using parametric and non-parametric tests. RESULTS: Forty-five patients (22 AB- group, 23 AB+ group) were included. The mean follow-up time between T(1) and T(2) was 35.9 months (SD = 21.0). 73.9% of the AB+ group and 50.0% of the AB- group did not receive additional surgical therapy (log-rank test, p = .110). The adjusted Cox regression model did not provide a significant result for antibiotics (beta = .441, 95% CI = 0.159-1.220, p = .115). Univariable regression analysis highlighted the influence of baseline peri-implant pocket depth on the need for surgical treatment (beta = 1.446, 95% CI = 1.035-2.020, p = .031). CONCLUSIONS: Systemic amoxicillin and metronidazole administered during non-surgical peri-implantitis treatment do not seem to prevent the need for additional surgical therapy in the long term, during a structured aftercare programme.