Microbial flora of sinus tracts and root canals of non-vital teeth.

The occurrence of bacteria in 12 endodontically induced periodontal lesions associated with sinus tracts was examined. The microbial flora encountered in the sinus tract was compared with that of the root canal of the involved teeth which had not experienced any prior endodontic therapy. All microbiological samples taken from the sinus tract and from the root canal system contained bacteria. Seventy-one strains were detected in the extraradicular lesions. Of the anaerobic species, Fusobacterium nucleatum (7 strains), Prevotella intemedia (4 strains) and P. oralis (4 strains) were most frequently found. In the group of the facultative anaerobes Streptococcus spp. were predominant. Ninety-four strains were isolated from the root canal system of the 12 teeth. P. intermedia (6 strains), P. buccae (5 strains), F. nucleatum (5 strains) and Lactobacillus plantarum (5 strains) were most common. In 9 cases, species present in the root canal could be revealed in the extraradicular lesions. It was concluded that a variety of microorganisms were capable of colonizing endodontically induced, extraradicular lesions clinically characterized by sinus tracts.