Clinical and microbiological benefits of metronidazole alone or with amoxicillin as adjuncts in the treatment of chronic periodontitis: a randomized placebo-controlled clinical trial

J Clin Periodontol. 2011 Sep;38(9):828-37. doi: 10.1111/j.1600-051X.2011.01763.x. Epub 2011 Jul 15.


Aim: To evaluate the effects of the adjunctive use of metronidazole (MTZ) or MTZ+amoxicillin (AMX) in the treatment of generalized chronic periodontitis (ChP).

Materials and methods: Fifty-one subjects (n=17/group) were randomly assigned to receive scaling and root planing (SRP) only or combined with MTZ (400 mg t.i.d.) or MTZ+AMX (500 mg t.i.d.) for 14 days. Clinical and microbiological examinations were performed at baseline and 3 months post-SRP. Nine plaque samples/subject were analysed by checkerboard DNA-DNA hybridization for 40 bacterial species.

Results: Subjects receiving MTZ+AMX exhibited a greater mean gain of clinical attachment, reduction in probing depth (PD) in intermediate and deep sites and a lower percentage of sites with PD5 mm at 3 months, in comparison with those treated with SRP only (p<0.05). The major benefit from the adjunctive use of MTZ was a greater reduction in PD in deep sites. SRP+MTZ+AMX was the only treatment that significantly reduced the levels and proportions of all red complex pathogens and elicited a significantly greater beneficial change in the microbial profile in comparison with SRP only.

Conclusion: The adjunctive use of MTZ+AMX offers short-term clinical and microbiological benefits, over SRP alone, in the treatment of non-smokers subjects with generalized ChP. The added benefits of MTZ were less evident.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Amoxicillin / pharmacology
  • Amoxicillin / therapeutic use*
  • Anti-Bacterial Agents / pharmacology
  • Anti-Bacterial Agents / therapeutic use*
  • Bacterial Load / drug effects
  • Chemotherapy, Adjuvant
  • Chronic Periodontitis / drug therapy*
  • Chronic Periodontitis / microbiology
  • Chronic Periodontitis / therapy
  • DNA, Bacterial / analysis
  • Dental Plaque / microbiology
  • Dental Scaling
  • Double-Blind Method
  • Drug Combinations
  • Female
  • Humans
  • Male
  • Metronidazole / pharmacology
  • Metronidazole / therapeutic use*
  • Middle Aged
  • Numbers Needed To Treat
  • Observer Variation
  • Periodontal Pocket / drug therapy
  • Periodontal Pocket / microbiology
  • Periodontal Pocket / therapy
  • Statistics, Nonparametric


  • Anti-Bacterial Agents
  • DNA, Bacterial
  • Drug Combinations
  • Metronidazole
  • Amoxicillin