Background: The aim of the present randomized, double-masked, placebo-controlled, parallel-arm study was to examine the effectiveness of a 3-month regimen of subantimicrobial dose doxycycline (SDD) in combination with scaling and root planing compared to scaling and root planing alone on levels of gingival crevicular fluid (GCF) extracellular matrix metalloproteinase inducer (EMMPRIN) in patients with chronic periodontitis.
Methods: GCF samples were collected, and clinical parameters, including probing depth (PD), clinical attachment level, gingival index (GI), and plaque index, were recorded. Thirty chronic periodontitis subjects were randomized to receive SDD or placebo. The SDD group received SDD (20 mg, twice a day) for 3 months plus scaling and root planing, whereas the placebo group took placebo capsules twice a day for 3 months and received scaling and root planing. The subjects were reevaluated at 3 and 6 months. At each visit, all clinical parameters were measured and GCF was sampled. GCF EMMPRIN levels were determined by Western immunoblotting assay. Intragroup comparisons were tested by the Friedman test followed by the Wilcoxon signed-rank test to analyze the significance of changes over time. The Mann-Whitney test was used to determine differences between the SDD and placebo groups.
Results: Significant improvements were observed in all clinical parameters in the SDD group over the 6-month study period (P <0.025). The SDD group showed a significantly greater reduction in mean PD scores at 6 months and in mean GI scores at 3 and 6 months than the placebo group (P <0.05). From baseline to 6 months, the GCF EMMPRIN levels were reduced significantly in the SDD group (P <0.025). The GCF EMMPRIN level in the SDD group was significantly lower than that of the placebo group at 3 and 6 months (P <0.05).
Conclusions: SDD therapy in combination with scaling and root planing reduced GCF EMMPRIN levels and improved clinical periodontal parameters in subjects with chronic periodontitis. The ability of SDD to downregulate, in vivo, the GCF levels of EMMPRIN, a unique upregulator of matrix metalloproteinase expression, is one of its beneficial host-modulatory properties. These results expand the usefulness of SDD therapy as an adjunct to scaling and root planing in the long-term management of periodontal disease.