Impact of systemic antimicrobials combined with anti-infective mechanical debridement on the microbiota of generalized aggressive periodontitis: a 6-month RCT.

Aim: To compare the effects of systemic amoxicillin (AMX) plus metronidazole (MET) or placebos combined with anti-infective mechanical debridement on the sub-gingival microbiota of generalized aggressive periodontitis (GAP).

Material And Methods: The study was a 6-month randomized, double-blinded, placebo-controlled clinical trial. Thirty-one subjects received full-mouth ultrasonic debridement followed by scaling and root planing with chlorhexidine rinsing, brushing and irrigation. During mechanical therapy, subjects received systemic AMX (500mg)+MET (250mg) or placebo, t.i.d. for 10 days. Sub-gingival samples were obtained from each patient and analysed for their composition by checkerboard at baseline, 3 and 6 months post-therapy. Significant differences between groups over time were examined by General Linear Model of Repeated Measures.

Results: High levels of periodontal pathogens, as well as some "non-periodontal" species were observed. Most of the periodontal pathogens decreased significantly over time (p<0.05), whereas "non-periodontal" bacteria tended to increase in both groups. Sites that showed attachment loss and probing depth increase harboured higher levels of Dialister pneumosintes, Campylobacter rectus, Fusobacterium necrophorum, Prevotella tannerea and Peptostreptococcus anaerobius than sites that improved after both therapies (p<0.05).

Conclusions: Systemic AMX+MET or placebos adjunctive to anti-infective mechanical debridement were comparable in lowering periodontal pathogens up to 6 months after treatment. Species not commonly associated with GAP were less affected by both therapies.