OBJECTIVE

The aim of this randomized double-blind and placebo-controlled study was to assess if periodontal treatment with or without systemic antibiotic would change the mean level of Archaea.

METHODS

Fifty-nine (59) subjects were randomly assigned to receive scaling and root planing (SRP) alone or combined with metronidazole (MTZ; 400 mg/TID) or either with MTZ and amoxicillin (AMX; 500 mg/TID) for 14 days. Clinical and microbiological examinations were performed at baseline and at 6 months post-SRP. Six subgingival plaque samples per subject were analysed for the presence and levels of Archaea using quantitative polymerase chain reaction.

RESULTS

Scaling and root planing alone or combined with MTZ or MTZ + AMX significantly reduced the prevalence of subjects colonized by Archaea at 6 months post-therapy, without significant differences among groups (P > .05). Both therapies led to a statistically significant decrease in the mean percentage of sites colonized by Archaea (P < .05). The MTZ and MTZ + AMX group had a significantly lower mean number of sites colonized by Archaea and lower levels of these micro-organisms at sites with probing depth ≥5 mm at 6 months compared with SRP group (P < .05).

CONCLUSION

Periodontal treatments including adjunctive MTZ or MTZ + AMX are more effective than mechanical treatment alone in reducing the levels and prevalence of sites colonized by Archaea in subjects with chronic periodontitis.