Clonality of Black-pigmented Anaerobes Isolated from Infected Root Canals and Subgingival Plaque in 12 Patients

Abstract

The purpose of this study was to investigate the clonal types of black-pigmented anaerobes isolated from infected root canals and subgingival plaque. Twelve patients, who had single-rooted teeth with selected chronic apical periodontitis and had not undergone endodontic treatment, were chosen for thisstudy. Microbiological specimens from the root canals were collected with three sizes of H-files, and thosefrom six subgingival sites of the same teeth were collected with paper points. The isolates were identified by the 16S rRNA gene-directed PCR method, and the gene types were determined by the arbitrarily primed PCR (AP-PCR) method. Porphyromonas gingivalis and Prevotella nigrescens were the most frequently isolated species from the root canals (41.7%) and from subgingival plaque samples (50.0%) in 12 patients, respectively. Four patients simultaneously harbored the same species in the root canal and subgingival plaque (three patients harbored P. nigrescens and one patient P. gingivalis). The AP-PCR patterns of isolates from the root canal and subgingival plaque were identical in at least three out of 12 patients. These results support the hypothesis that the pocket is one of the possible sources of root-canal infection.