Non-surgical periodontal treatment in conjunction with 3 or 7 days systemic administration of amoxicillin and metronidazole in severe chronic periodontitis patients. A placebo-controlled randomized clinical study

Aim To evaluate the effect of 3 or 7 days systemic administration of amoxicillin (AMX) and metronidazole (MET) or placebo as adjunct to non‐surgical periodontal treatment in severe chronic periodontitis patients. Methods One hundred and two patients with severe chronic periodontitis [e.g. ≥1 site with probing pocket depth (PD) ≥ 6 mm per quadrant] were randomly divided into three equally sized groups and treated with either scaling and root planing within 24 h (SRP) + placebo (Group A) or SRP + AMX + MET (both 500 mg × 3 times daily) for 3 days (Group B) or SRP + AMX + MET (both 500 mg × 3 times daily) for 7 days (Group C). PD, clinical attachment level (CAL), bleeding on probing (BOP), full‐mouth plaque scores (FMPS) and gingival bleeding index (GBI) were assessed prior to treatment (baseline), and at 3 and 6 months post‐treatment. The primary outcome variable was the difference (Δ) in the number of sites with PD ≥ 6 mm. Results Ninety‐one patients completed the study. At both 3 and 6 months, all three treatment protocols resulted in statistically significant improvements compared to baseline for all evaluated clinical parameters (p