Background: The goal was to evaluate the clinical outcome of non-surgical retreatment at molar furcation sites by ultrasonic debridement with or without adjunctive application of locally delivered doxycycline, and to explore factors affecting the healing results.
Methods: This study involves 32 patients with chronic periodontitis, who received initial pocket/root debridement by ultrasonic instrumentation, followed by random assignment to retreatment of remaining pathologic sites at 3 months by ultrasonic instrumentation with or without adjunctive local application of an 8.8% doxycycline gel. Clinical examinations of plaque, probing depth (PD), relative attachment level, furcation involvement, and bleeding after furcation probing were performed initially, before retreatment at 3 months (baseline), and 3 and 9 months after retreatment. The primary efficacy variable was reduction in the degree of furcation involvement. A multilevel logistic model was used to evaluate the impact of patient and tooth site related factors on the main outcome variable.
Results: The retreatment including locally delivered doxycycline resulted in closure of 50% of degree I furcation sites, compared to 29% for sites treated with mechanical debridement only (P >0.05). Of the degree II furcation sites, 17% in the test and 11% in the control group were reduced in depth (P >0.05). The logistic multilevel model with "furcation improvement" as the dichotomous outcome variable revealed that local application of doxycycline had no statistically significant effect. The odds ratio for ?furcation improvement? was 0.80 (95% confidence interval [CI], 0.65 to 0.99) for 1-mm increase of initial vertical PD, 0.36 (95% CI, 0.17 to 0.80) for initial furcation involvement degree II compared to degree I, and 0.24 (95% CI, 0.08 to 0.72) for smokers compared to non-smokers.
Conclusion: Improvement in molar furcation involvement after non-surgical periodontal therapy was not enhanced by adjunctive locally applied doxycycline and negatively affected by increased vertical PD and tobacco smoking.