Background: The aim of this study was to evaluate if adjunctive, locally delivered controlled-release doxycycline might improve the outcome of reinstrumentation of pathologic pockets persisting after initial periodontal therapy.
Methods: Subjects with chronic periodontitis underwent initial treatment including full-mouth ultrasonic debridement and oral hygiene instructions. At the 3-month reexamination, 32 subjects with remaining pathologic sites were assigned randomly to one of two retreatment protocols: ultrasonic instrumentation alone (control) or ultrasonic instrumentation plus application of an 8.8% doxycycline gel (test). Clinical examinations of plaque, probing depth (PD), relative attachment level (RAL), and bleeding on probing were performed before retreatment (baseline) and after 3 and 9 months. Primary efficacy variables were the percentage of closed pockets, i.e., PD < or =4 mm, and changes in PD and RAL.
Results: Baseline examination revealed no significant difference in mean PD between treatment groups. The mean PD reduction at 3 months was 0.9 mm (95% confidence interval [CI]: 0.6 to 1.2) in the control group and 1.0 mm (95% CI: 0.7 to 1.3) in the test group (P >0.05). At 9 months, both treatment groups showed a mean PD reduction of 1.1 mm. The mean RAL gain was 0.6 mm at 3 months and approximately 0.8 at 9 months for both groups. The probability of pocket closure was not improved by the adjunctive antibiotic therapy. Only factors at the tooth site level (plaque presence, furcation involvement, and presence of an intrabony defect) were identified by multilevel analysis as significant for the treatment outcome.
Conclusion: Locally delivered doxycycline failed to improve the healing outcome of reinstrumentation of periodontal pockets showing a poor initial response to pocket/root debridement.