[Anaerobes in infected canals: a preliminary study].

Anaerobes of 17 infected canals with periapical periodontitis were studied. Most of root flora were not only anaerobes but also aerobes. Anaerobes were predominant in chronic periapical periodontitis. Major anaerobes isolated from canals were peptostreptococcus, B. melaninogenicus and B. oralis. The chi-square results indicated that the peptostreptococcus were significantly related to apical radiolucency and B. melaninogenicus were significantly related to percussion or foul smell. Animal experiment results showed that rats inoculated with mixed flora developed many abscesses. But the monoinfected rats had infiltration of PMNs, dilation and hypermia of vessels. B. melaninogenicus, B. oralis and mixed flora had liquefied gelatin and indicated these bacteria had collagenase which could dissolve collagen fibers and significantly related to destroy of collagen fibers and bone in periapical tissues.