RESUMEN
OBJECTIVE: The objective of this study was to investigate the association between the antimicrobial and clinical efficacy of minocycline hydrochloride microspheres when used adjunctively with scaling and root planing. METHODS: 127 subjects with moderate-to-advanced chronic periodontitis were randomly assigned to receive either minocycline microspheres plus scaling and root planing (n = 62) or scaling and root planing alone (n = 65). Deoxyribose nucleic acid analysis and clinical data were obtained at baseline and 30 days after treatment. End points included changes in the mean sum of red complex bacteria, pocket depth, number of deep pockets, bleeding on probing, and clinical attachment level from baseline to day 30. Regression analysis determined the association between microbiological and clinical efficacy. RESULTS: Minocycline microspheres plus scaling and root planing reduced pocket depth, the number of deep pockets and bleeding on probing, and increased clinical attachment level significantly more than scaling and root planing alone (p < 0.05). Comparing minocycline microspheres plus scaling and root planing with scaling and root planing alone, the number needed to treat for a 2 mm pocket depth reduction difference was 6.5. Pocket depth reduction correlated significantly with a decrease in the numbers and proportions of red complex bacteria. Minocycline microspheres significantly improved all clinical parameters compared to scaling and root planing alone. CONCLUSIONS: The addition of minocycline microspheres to scaling and root planing led to a greater reduction in the proportions and numbers of red complex bacteria. The reduction in pocket depth was significantly correlated with the reduction of the proportions and numbers of red complex bacteria. Additionally, there were statistically greater improvements in all clinical parameters examined.