Application of newer methods to study the importance of root canal and oral microbiota in endodontics

Abstract

1. 1. Root canal specimens from fifty-seven teeth and mouth rinse specimens from forty-five patients were examined directly by phase-contrast, dark-field, and bright-field microscopy and by aerobic and anaerobic culture on agar media. Deep semifluid broth was also inoculated with root canal specimens. It was reaffirmed that microorganisms could be detected microscopically which could not be detected by cultures alone. 2. 2. The flora of open and closed teeth were compared. That of the latter was found to be a similar though restricted representation of the former. Non-beta hemolytic streptococci were found to predominate in both. Noncultivable spirochetes were found only with other mixed cultivable flora. Forms observed in root canal specimens which yielded no growth resembled more commonly observed forms, such as gram-positive cocci and rods. 3. 3. Root canal flora tabulated in relation to endodontic treatments diminished from one treatment to the next, as well as from the beginning to the end of individual treatments. 4. 4. When root canal flora were compared with clinical diagnoses, organisms were detected by all methods and to about the same extent as in all canals, regardless of diagnosis, with the possible exception of teeth with granulomatous involvement. These organisms were detected only by microscopic examination and semifluid broth cultures. 5. 5. Root canal flora and total oral flora of the patients were compared. They differed in a marked restriction of some oral forms and species from the root canals. Beta hemolytic streptococci and Staphylococcus aureus found in mouth rinses were not found in root canals. 6. 6. Indices representing predominance of forms as seen by direct microscopic examination of the oral and root canal flora and the growth of microorganisms on agar plates were recorded for comparison. Coccal forms and non-beta hemolytic streptococci were the most numerous as well as the most commonly detected microorganisms in all flora.