Natural distribution of 5 bacteria associated with periodontal disease

The purpose of this study was to determine the prevalence and distribution of 5 bacterial pathogens in subgingival plaque, their relationship with each other and probing depth. Plaque was collected from 6905 sites in 938 subjects. A bacterial concentration fluorescence immunoassay and bacterial specific monoclonal antibodies were used to determine the presence and level of P. gingivalis (Pg), A. actinomycetemcomitans (Aa), P. intermedia (Pi), E. carrodens (Ec) and F. nucleatum (Fn) in each plaque sample. The prevalence in subjects was lowest for Pg (32%) and highest for Ec (49%). The site‐based frequency distribution of these bacterial species ranged from 10.3% for Pg to 18.7% for Ec. Pi and Ec were the bacterial combination most often found together in a subject (27.2%). While 64.0% of the sites were without any of the 5 bacterial species evaluated, 20.2% had only 1 of the 5 bacterial species evaluated. The remaining 15.8% of sites had at least 2 bacteria species present. There was a general linear association of the detection level of bacterial species and probing depth. The odds ratios were 3.9 (Pg). 3.0 (Aa), 4.0 (Pi). 2.7 (Ec) and 2.8 (Fn) of finding high levels of these bacterial pathogens at > 5 mm probing depth (p≤ 0.01). Mean probing depth at molar sites without a specific bacteria was greater (p≤ 0.01) in subjects wish a specific bacterium compared to molar sites in subjects without the bacteria. The observation that these 5 bacterial species frequently inhabit the subgingival environment, yet are not associated with advanced disease, suggest that a susceptible host is required, in addition to a “pathogenic bacteria”, before disease progression may occur.