Metronidazole and amoxicillin as adjuncts to scaling and root planing for the treatment of type 2 diabetic subjects with periodontitis: 1‐year outcomes of a randomized placebo‐controlled clinical trial

Aim To evaluate the clinical and microbiological effects of the use of metronidazole ( MTZ ) + amoxicillin ( AMX ) as adjuncts to scaling and root planing ( SRP ) for the treatment of chronic periodontitis (ChP) in type 2 diabetic subjects. Material and Methods Fifty‐eight type 2 diabetic subjects ( n  = 29/group) with generalized ChP were randomly assigned to receive SRP alone or with MTZ [400 mg/thrice a day (TID)]+AMX (500 mg/TID) for 14 days. Subgingival biofilm samples were analyzed by qPCR for the presence of seven periodontal pathogens. Subjects were monitored at baseline, 3, 6 and 12 months post‐therapies. Results The group receiving SRP + MTZ + AMX presented greater mean probing depth ( PD ) reduction and clinical attachment gain, a lower number of sites with PD ≥5 mm (primary outcome variable) and a reduced number of subjects with ≥9 of these residual pockets than the control group at 1‐year post‐therapy ( p  < 0.05). The antibiotic‐treated group also presented reduced levels and greater decreases of the three red complex species, Eubacterium nodatum and Prevotella intermedia, compared to the control group at 1 year ( p  < 0.05). Conclusions The adjunctive use of MTZ + AMX significantly improved the clinical and microbiological outcomes of SRP in the treatment of type 2 diabetic subjects with ChP.