Association between levels of target species and severe periodontitis.

Abbreviations: Aa = A. actinomycetemcomitans, Pg = P. gingivalis, Tf = T. forsythia, Td = T. denticola, and Pi = P. intermedia.
a Bacterial level 0 represents PCR-negative subjects, while the higher levels are categorized according to the tertile or quintile distribution of the number of bacterial cells in PCR-positive subjects. The cut-off values are as follows: 3.3x104 and 5.8x105 for Aa; 4.4x106, 2.6x107, 6.7x107, and 1.7x108 for Pg; 3.1x106, 8.7x106, 1.7x107, and 3.3x107 for Tf; 1.7x106, 7.6x106, 1.9x107, and 4.6x107 for Td; and 5.1x106, 2.3x107, 5.6x107, and 1.3x108 for Pi.
b Logistic regression analysis of each microorganism individually, adjusted for known confounders: age, gender, education, number of remaining teeth, smoking status, and diabetes.
c Logistic regression analysis of multiple target species, adjusted for known confounders. The lowest bacterial level that reached statistical significance (P <0.05), is in boldface.
Association between levels of target species and severe periodontitis.