Isolation and classification of anaerobic bacteria from pulp cavities of nonvital teeth in man.

The anaerobic microflora of infected pulp cavities and chronic periapical abscesses was studied. A total of 19 infected nonvital teeth were subjected to this study. The coronal surface was swabbed with 70% ethanol to remove debris and to disinfect. Material in root canal chamber was obtained by sterilized paper points and suspended in reduced transport fluid. The samples were dispersed, diluted, and inoculated on blood agar plates. Isolates were identified by colony characteristics and cellular morphology, fermentation, indole production, nitrate reduction, gelatin digestion, urease production, ability to grow aerobically, API 20A System, and API ZYM System. Anaerobic bacteria were found in 14 pulp cavities. Anaerobic gram-negative rods, Actinomyces species, and Propionibacterium species were predominant in the root canals. Mixed infection with anaerobes and facultative anaerobes were demonstrated in most of the pulpal cavities of nonvital teeth.