Correlation of Red-complex Bacteria in Active Periodontal Disease Sites

Objectives: Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia, which exist as a consortium in subgingival biofilms, belong to the principal periodontopathogenic bacteria known as red complex. We aimed to examine the relationships between the quantity and prevalence of P. gingivalis, T. denticola, and T. forsythia in subgingival biofilms and local periodontal health.

Methods: The subjects in this study were 35 adult patients who visited the Kyusyu Dental College Hospital. Plaque samples were collected from 105 periodontal pocket sites. Quantitative analyses of each of the three periodontopathogenic bacteria were performed using the real-time polymerase chain reaction (PCR) with species-specific primers and hybridization probes.

Results: The plaque samples were divided into four groups, based on the presence or absence of a periodontal pocket [probing depth (PD) ≥ 4 mm] and bleeding on probing (BOP). The proportions of all three target bacteria detected in samples from active periodontal disease sites (+PD /+BOP) were markedly higher than those from the other sites. Furthermore, cell numbers of P. gingivalis, T. denticola, and T. forsythia in the subgingival plaque of each sampling site were significantly mutually correlated and were increased in the plaque of active periodontal disease sites (+PD /+BOP).

Conclusions: This study suggested that P. gingivalis, T. denticola, and T. forsythia might exist coordinately in subgingival biofilms, and that symbiotic effects of them might influence periodontal disease activity.