Objectives: Previous studies have demonstrated the clinical benefits of sub-antimicrobial dose doxycycline (SDD) in the treatment of chronic periodontitis (CP). The aim of this study was to retrospectively evaluate the role of SDD as an adjunct to scaling and root planing (SRP) in the treatment of smokers and non-smokers with CP.
Material and Methods: A meta-analysis of two previously reported clinical studies was undertaken. Both were 9-month, double-blind, randomized, placebo-controlled, multi-centre clinical trials that investigated the efficacy of SDD (20 mg doxycycline twice daily) in combination with SRP in subjects with moderate–severe CP. 36.9% of the combined study population were smokers. Three hundred and ninety-two subjects were included in the meta-analysis, which evaluated 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 PD reductions 2 and 3 mm from baseline in four subgroups: smokers/SDD; smokers/placebo; non-smokers/SDD; non-smokers/placebo.
Results: A hierarchical treatment response was observed, with non-smokers who received SDD demonstrating the greatest CAL gains and PD reductions. Smokers who received placebo demonstrated the smallest clinical improvements following treatment. Smokers who received SDD demonstrated an intermediate treatment response that was broadly equivalent to that seen in non-smokers who received placebo. In sites with baseline PD 4–6 mm, month 9 CAL gains were 19–45% better in non-smokers who received SDD compared with all other subgroups (p<0.05), and were 21% greater in smokers who received SDD compared with smokers who received placebo (p<0.05). Furthermore, month 9 PD reductions were 21–53% greater in non-smokers who received SDD compared with all other subgroups (p<0.01), and were 26% greater in smokers who received SDD compared with smokers who received placebo (p<0.05).
Conclusion: Adjunctive SDD enhances therapeutic outcomes compared with SRP alone, resulting in clinical benefit in both smokers and non-smokers with CP.