Topographic distribution of black-pigmenting anaerobes before and after periodontal treatment by local delivery of tetracycline.

The purpose of this study was to determine the distribution of black-pigmenting Gram-negative bacteria in the dentition of 10 adult periodontitis patients before and after treatment by local delivery of tetracycline. The subjects were selected based on a screening for high counts of Porphyromonas gingivalis and multiple deep pockets. Subgingival microbial samples were taken from the mesial and distal aspect of every tooth (44 to 56 sites per patient) before treatment, and after one and two months. Therapy included full mouth scaling and root planing, chlorhexidine mouth rinsing and placement of tetracycline HCl fibers (Actisite) on all teeth. 63.4% of 524 baseline samples yielded total anaerobic viable counts > or = 10(6) CFU/ml; P. gingivalis was found in 59.2% and Prevotella intermedia in 56.9%. One month after treatment, the % of samples with > or = 10(6) CFU/ml was reduced to 9.4%, 5.3% were P. gingivalis- and 5.1% P. intermedia- positive. After 2 months, 9.6% samples yielded > or = 10(6) CFU/ml, 5.2% were P. gingivalis- and 9.4% P. intermedia- positive. 20 of the 39 sites with a persistence of P. gingivalis were located on second molars. Logistic regression models were utilized to explain the persistence of P. gingivalis, using site location and other clinical parameters as independent variables. These analyses indicated a strong association of site location, pocket depth and bleeding on sampling with persistence of P. gingivalis. The study shows that local delivery of tetracycline is highly effective in reducing the prevalence and proportions of black-pigmenting anaerobes within a dentition. Bleeding deep pockets of second molars have an increased risk for persistence of these anaerobes.