One year results of a randomized controlled clinical study evaluating the effects of non-surgical periodontal therapy of chronic periodontitis in conjunction with three or seven days systemic administration of amoxicillin/metronidazole

BACKGROUND: To evaluate the clinical outcomes 12 months after systemic administration of amoxicillin (AMX) and metronidazole (MET) adjunctive to subgingival debridement (SD) in patients with severe chronic periodontitis (sChP). MATERIAL AND METHODS: 102 patients with sChP were treated randomly as follows: SD within 2 consecutive days and placebo for 7 days (group A), SD+AMX+MET (both 500mg x3 times daily TID) for 3 days (group B), SD+AMX+MET (both 500mg x 3 TID) for 7 days (group C). At baseline, at 3-, 6-, and 12-months post-treatment probing pocket depth (PD), clinical attachment level (CAL), furcation involvement, bleeding on probing (BOP), full-mouth plaque score (FMPS) were determined. The reduction in the number of sites with PD≥6mm was defined as main outcome variable. RESULTS: 75 patients completed the study. At 12 months, all three treatment groups showed statistically significant improvements (p<0.001) of mean PD, CAL, BOP and number of sites with PD≥6mm compared to baseline. Mean residual PD were statistically significantly lower and CAL gain statistically significantly greater in the two antibiotic groups as compared to placebo. While PD reductions (p = 0.012) and CAL gain (p = 0.017) were statistically significantly higher in group C compared to group A, only the 3-day AB group showed statistically significantly fewer sites with PD≥6mm at 12 m (p = 0.003). The reduction in the number of sites with PD≥6 mm (primary outcome) showed no statistical significant differences between the 3 treatment groups. However, in both antibiotic groups significantly more patients compared to the placebo group reached a low risk for disease progression at 12 months (≤4 sites with PD≥5mm). CONCLUSION: At 12 months, both adjunctive antibiotic protocols resulted in statistically significantly greater clinical improvements compared to placebo.