Periodontal bacterial load: a proposed new epidemiological method for periodontal disease assessment

The purpose of this study was to identify a periodontal clinical measure that correlates with red complex bacteria usually associated with periodontal disease.

Periodontal clinical parameters were recorded in 116 postpartum women at six sites per tooth for all teeth excluding third molars. Two subgingival plaque samples per subject were collected and analyzed for 39 bacterial species using the Checkerboard DNA-DNA hybridization technique. Periodontal Bacterial Load (PBL) was calculated as the sum of all pocket depth measurements of 4 mm at sites with a Clinical Attachment Level (CAL) of 4 mm. The association of clinical and bacterial scores was analyzed using the Spearman correlation coefficient and the Kruskal-Wallis test.

The PBL was correlated with microorganisms from the red complex that included Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola, individually or grouped (p<0.05). The PBL was not associated with periodontally beneficial species from the yellow, green, purple, and blue complexes (p>0.05). The proportions and mean counts of the red complex were increased according to the quartile groups of distribution of the PBL.

PBL appears to be a reliable measure of periodontal status in postpartum women.

PBL avoids bias in the assessment of periodontal status in studies of periodontal disease.