Metronidazole alone or with amoxicillin as adjuncts to non‐surgical treatment of chronic periodontitis: a 1‐year double‐blinded, placebo‐controlled, randomized clinical trial

Aim To evaluate the effects of the adjunctive use of metronidazole ( MTZ ) or MTZ  + amoxicillin ( AMX ) in the treatment of generalized chronic periodontitis (ChP). A secondary aim was to examine a possible added effect of chlorhexidine to these therapies. Methods One hundred and eighteen subjects received scaling and root planing ( SRP ) only or with MTZ [400 mg/thrice a day ( TID )] or MTZ + AMX (500 mg/ TID ) for 14 days. Half of the subjects in each group rinsed with 0.12% chlorhexidine twice a day (BID) for 2 months. Subjects were clinically monitored at baseline, 3, 6 and 12‐months post‐therapy. Results The two antibiotic groups showed lower mean number of sites with probing depth ( PD ) ≥5 mm and fewer subjects exhibiting ≥9 of these sites at 1‐year post‐treatment. Logistic regression analysis showed that antibiotics were the only significant predictors of subjects presenting ≤4 sites with PD ≥5 mm at 1 year ( MTZ + AMX : OR , 13.33; 95% CI , 3.75‐47.39/ p  = 0.0000; MTZ : OR , 7.26; 95% CI , 2.26‐23.30/ p  = 0.0004). The frequency of adverse events did not differ between the two antibiotic treatments ( p  > 0.05). The chlorhexidine subgroups showed a trend ( p  > 0.05) to present fewer residual sites ≥5 mm compared with the placebo subgroups at 1 year. Conclusion Treatment of generalized ChP is significantly improved by the adjunctive use of MTZ + AMX and MTZ .