Background: Previous studies have shown that subantimicrobial dose doxycycline (SDD) is of clinical benefit in the treatment of chronic periodontitis (CP). The aim of this study was to further assess the role of SDD as an adjunct to scaling and root planing (SRP) in the treatment of CP.
Methods: A double-blind, randomized, placebo-controlled, multicenter clinical study was conducted to test the efficacy of SDD (20 mg doxycycline B.I.D.) in combination with SRP in subjects with moderate to severe CP. Two-hundred ten subjects were treated with a standardized episode of SRP and randomized to receive either adjunctive SDD or placebo for 9 months. Efficacy parameters included per-subject mean changes in clinical attachment level (CAL) and probing depth (PD) from baseline, and the total number of sites with attachment gains and probing depth reductions > or = 2 mm and > or = 3 mm from baseline.
Results: In periodontal sites with PD 4 to 6 mm and > or = 7 mm (N = 209, intent-to-treat population), mean improvements in CAL and PD were greater following SRP with adjunctive SDD than SRP with placebo, achieving statistical significance in all baseline disease categories at month 9 (P < 0.05). At month 9, 42.3% of sites in the SDD group demonstrated CAL gain > or = 2 mm compared to 32.0% of sites in the placebo group (P < 0.01). CAL gain > or = 3 mm was seen in 15.4% of sites in the SDD group compared to 10.6% of sites in the placebo group (P < 0.05). When considering the same thresholds of change in PD, 42.9% of sites in the SDD group compared to 31.1% of sites in the placebo group demonstrated PD reduction > or = 2 mm (P < 0.01), and 15.4% of sites in the SDD group compared to 9.1% of sites in the placebo group demonstrated PD reduction > or = 3 mm (P < 0.01).
Conclusion: Adjunctive subantimicrobial dose doxycycline enhances scaling and root planing. It results in statistically significant attachment gains and probing depth reductions over and above those achieved by scaling and root planing with placebo.