Metronidazole alone or with amoxicillin as adjuncts to non-surgical treatment of chronic periodontitis: a 1-year double- blinded, placebo-controlled, randomized clinical trial Feres M, Soares GMS, Mendes JAV, Silva MP, Faveri M, Teles R, Socransky SS, Figueiredo LC . Metronidazole alone or with amoxicillin as adjuncts to non-surgical treatment of chronic periodontitis: a 1-year double-blinded, placebo-controlled, randomized clinical trial. J Clin Periodontol 2012; 39: 1149– 1158. doi: 10.1111/jcpe.12004. Abstract 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% chlorhexi- dine twice a day (BID) for 2 months. Subjects were clinically monitored at base- line, 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 dif- fer 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. Magda Feres 1 , Geisla Mary Silva Soares 1 , Juliana Alethusa Velloso Mendes 1 , Maike Paulino Silva 1 , Marcelo Faveri 1 , Ricardo Teles 2,3 , Sigmund S. Socransky 2 and Luciene Cristina Figueiredo 1 1 Department of Periodontology, Dental Research Division, Guarulhos University, Guarulhos, Sa ˜o Paulo, Brazil; 2 The Forsyth Institute, Cambridge, MA, USA; 3 Department of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, MA, USA Key words: amoxicillin; chronic periodontitis; metronidazole; periodontal disease; periodontal treatment; scaling and root planing Accepted for publication 2 August 2012 The benefits of systemic antibiotics in periodontal treatment have consis- tently been demonstrated in the periodontal literature (Herrera et al. 2002, Haffajee et al. 2003a). The Conflict of interest and source of funding statement The authors declare that they have no conflict of interests. This study was supported by Research Grant #07/55291-9 from Fundac¸a˜o de Amparo a` Pesquisa do Estado de Sa˜o Paulo (FAPESP, Brazil). © 2012 John Wiley & Sons A/S 1149 J Clin Periodontol 2012; 39: 1149–1158 doi: 10.1111/jcpe.12004