The Effect of Adjunctive Low-dose Doxycycline Therapy on Clinical Periodontal Parameters and Crevicular Fluid Matrix Metalloproteinase-8 Levels in Chronic Periodontitis

Objective: The aim of the present randomized, double-blind, placebo-controlled study was to examine the effectiveness of LDD in combination with mechanical therapy on gingival crevicular fluid (GCF) matrix metalloproteinase-8 (MMP-8) levels and clinical parameters in patients with chronic periodontitis over a 12-month period. 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 patients were randomized either to low-dose doxcycline (LDD) or to placebo groups. LDD group received low dose doxycycline (20 mg) b.i.d for 3 months plus scaling and root planing (SRP), while placebo group was given placebo capsules b.i.d for 3 months plus SRP. The patients were evaluated every three months during 12 months study period. At each visit, all clinical parameters and GCF sampling were repeated. GCF MMP-8 levels were determined by a time-resolved immunofluorescence assay. Treatment group comparisons were tested by the Friedman test followed by Wilcoxon signed rank test to analyse significance of changes over time. The Mann-Whitney test was used to determine differences between both groups. Results: Significant improvements were observed in all clinical parameters in both groups over the 12-month period (p<0.01). LDD group exhibited more clinical improvements in PD and GI scores compared to placebo group at all time points, which was found to be statistically significant at 9-month and 12-month (p<0.05). From baseline to 12-month, GCF MMP-8 levels were significantly reduced in both groups (p<0.01). GCF MMP-8 level in LDD group was significantly lower than that of placebo group at 6-month (p<0.05). Conclusion: These results provide an additional information about the usefulness of the LDD therapy as an adjunct to mechanical therapy in the long-term management of periodontal disease. Supported by grants from TEKES, the Wilhelm and Else Stockman Foundation and Turkish Colgate Research Fund.