Subgingival microflora in bleeding and nonbleeding pockets.

The subgingival flora of bleeding and nonbleeding 4-6 mm pockets was investigated using phase-contrast microscopy. Subgingival plaque was sampled from 11 patients with generalized moderate periodontitis. 4 subgingival samples were obtained from each patient, 2 from sites that bled upon standardized probing force and 2 from sites that did not. The amounts of gingival inflammation, supragingival plaque, attachment level and pocket depth were also assessed at each site. The %s of 4 bacterial morphotypes were assessed using phase-contrast microscopy. No significant differences were found in the %s of cocci, motile rods, or spirochetes between bleeding and nonbleeding sites. Significant correlations were found, however, between the % of spirochetes and probing depth, attachment level, and gingival inflammation. The observations indicate that the use of bleeding on probing may not be justified as an indicator of infection by those "periodontopathic" bacteria identifiable by phase-contrast microscopy. However, limitations in the microscopic method may have prevented us from observing differences between the 2 types of sites on a species level.