Efficacy of Local Application of a Combined Metronidazole and Minocycline Ointment in the Non‐Surgical Treatment of Peri‐Implantitis: A Preclinical In Vivo Study

AIM: To evaluate the adjunctive effect of locally delivered metronidazole-minocycline (Met/Mc) versus minocycline (Mc) ointment and mechanical debridement alone in non-surgical treatment of peri-implantitis. MATERIALS AND METHODS: Peri-implantitis was induced through ligature in a canine model. Implants were allocated to mechanical debridement (control), Mc or Met/Mc. Probing depth (PD), bleeding on probing (BOP), marginal bone levels (MBLs) and immunohistochemical parameters (CD3, CD20, IgG) were assessed over 12 weeks. RESULTS: Both Met/Mc and Mc showed significantly greater PD reductions than control (Δ -5.33 ± 1.35 mm and -3.67 ± 1.89 mm vs. -0.04 ± 1.80 mm; p < 0.0001 and p = 0.0004). BOP and MBL reductions were significantly greater in Met/Mc than Mc and control (BOP: Δ -5.67 ± 0.71 vs. -3.22 ± 2.54 vs. -0.78 ± 1.99, p = 0.020; MBL: Δ -2.41 ± 1.21 vs. -0.80 ± 0.21 vs. +0.64 ± 0.93 mm, p = 0.0035). Met/Mc showed significantly lower CD3, CD20 and IgG than the control and lower CD20 and IgG than Mc (all p < 0.05). CONCLUSION: In this preclinical model, adjunctive Met/Mc ointment yielded greater clinical and radiographic improvements than both comparators, accompanied by reduced B-cell and plasma-cell infiltration. These findings provide preclinical proof of concept, however, warranting clinical confirmation.