Association between the amount of treponema lecithinolyticum in subgingival dental plaque and the severity of periodontitis

The pathogenesis of periodontitis involves certain bacteria in the bacterial plaque, including Treponema lecithinolyticum (Tl). The aim of this study was to evaluate the load of T1 in pocket periodontal disease and determine how it correlates with the severity of periodontitis. We examined five subjects with pocket depths (PD) of 4 to 5 mm (group 1 (G1)) and ≥6 mm (group 2 (G2)) and subjects without periodontal disease (group 3 (G3), control). We collected 20 microbial samples (gingival crevicular fluids) from the deepest pockets (≥4 mm) by using a paper point. The bacterium load between the two groups was compared using a quantitative real-time polymerase chain reaction (qPCR). Statistical analysis was performed by using Mann-Whitney tests, Kruskal-Wallis test, and Spearman's correlation. The qPCR results showed that the amount of Tl was higher in subjects with periodontitis than in healthy controls, but the difference was not statistically significant (p ≥ 0.05). The Kruskal-Wallis test results of G1, G2, and G3 revealed that no significant differences existed. The amount of bacteria exhibited a moderately strong and positive correlation with PD and the Papilla Bleeding Index (PBI). However, a weak correlation was found when recession and loss of attachment were analyzed. In subjects with periodontal disease, PD and PBI were associated with the amount of Tl.