Adjunctive use of locally delivered 2% minocycline in the nonsurgical treatment of peri-implantitis: a multicenter randomized placebo-controlled trial

Objectives: This randomized, single-blind, placebo-controlled multicenter trial aimed to evaluate the clinical, radiographic, microbiologic, and patient-reported efficacy of locally delivered adjunctive 2 % minocycline hydrochloride in the nonsurgical treatment of peri‑implantitis. Methods: Forty-eight participants were randomized, and 46 (test, n = 22 [subgingival debridement + minocycline ointment]; control, n = 24 [subgingival debridement + placebo]) were included in the per-protocol efficacy analysis after two post-randomization withdrawals in the test group. Interventions were performed at baseline and weeks 1, 2, and 3. Clinical, radiographic, and microbiological parameters were assessed over a 12-week period, along with patient-reported outcomes including discomfort and oral health–related quality of life (OHRQoL). Results: At 12 weeks, the test group showed lower baseline-adjusted probing pocket depth values and less frequent bleeding on probing than the control group. In the microbiologic analysis, adjunctive minocycline was associated with lower levels of selected peri‑implant pathogens at 8 weeks (p < 0.05), whereas between-group differences were less consistent at 12 weeks. Radiographic findings should be interpreted cautiously because the follow-up period was too short to support conclusions regarding structural stability. Early swelling was lower in the test group at 3 weeks than in the control group (p < 0.05), but no significant between-group differences were observed in OHRQoL improvement. Conclusion: Locally delivered adjunctive 2 % minocycline may provide short-term clinical benefits and exploratory microbiologic improvements when used with nonsurgical peri‑implantitis therapy. However, the 12-week follow-up herein does not allow conclusions regarding long-term radiographic stability, sustained local efficacy, or definitive disease resolution. Clinical significance: Adjunctive locally delivered 2 % minocycline may provide short-term clinical benefits in nonsurgical peri‑implantitis therapy while limiting systemic antibiotic exposure.