LAUSR

AIM To evaluate the clinical non-inferiority of a 3-day-protocol of systemic antibiotics adjunctive to subgingival instrumentation (SI) compared to a 7-day-protocol in patients with stage III/IV grade C periodontitis. METHODS 50 systemically healthy patients (32.7±4.3 years) with aggressive periodontitis (stage III/IV grade C periodontitis) were treated by SI and adjunctive amoxicillin and metronidazole randomly assigned to group A: (n=25) 500mg antibiotics 3-times-daily for 3 days, followed by placebo 3-times-daily for 4 days, or group B: (n=25) 500mg AB 3-times-daily for 7 days. Clinical, microbial and immunological parameters were assessed at baseline, 3 and 6 months, and patient-related outcomes after 2 weeks. The primary outcome variable was the number of residual sites with PD≥6mm at 6 months. RESULTS For the primary outcome variable (the number of residual sites with PD≥6mm at 6 months), the null hypothesis was rejected and demonstrated the non-inferiority of the 3d AB protocol compared to 7d AB (the upper limits of the 95%CI for ITT: [-2.572; 1.050] and PP: [-2.523; 1.318] were lower than the assumed margin of Δ=3.1). Comparable clinical improvements were obtained for all parameters with both antibiotic protocols (p>0.05). All investigated periodontopathogens and pro-inflammatory host-derived markers were statistically significantly reduced, without differences between the treatments (p>0.05). CONCLUSION These findings indicate that in patients with aggressive periodontitis (stage III/IV grade C periodontitis), a 3-day systemic administration of amoxicillin and metronidazole adjunctive to SI may lead to non-inferior clinical outcomes after 6-months with fewer adverse events compared to a 7-day-protocol.