NATURAL DISTRIBUTION OF 5 BACTERIA ASSOCIATED WITH PERIODONTAL-DISEASE

The purpose of this study was to determine the prevalence and distribu tion of 5 bacterial pathogens in subgingival plaque, their relationshi p with each other and probing depth. Plaque was collected from 6905 si tes in 938 subjects. A bacterial concentration fluorescence immunoassa y and bacterial specific monoclonal antibodies were used to determine the presence and level of P. gingivalis (Pg), A. actinomycetemcomitans (Aa), P. intermedia (Pi), E. corrodens (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 th ese 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 subj ect (27.2%). While 64.0% of the sites were without any of the 5 bacter ial species evaluated, 20.2% had only 1 of the 5 bacterial species eva luated. The remaining 15.8% of sites had at least 2 bacteria species p resent. 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 t hese bacterial pathogens at > 5 mm probing depth (p less-than-or-equal -to 0.01). Mean probing depth at molar sites without a specific bacter ia was greater (p less-than-or-equal-to 0.01) in subjects with a speci fic bacterium compared to molar sites in subjects without the bacteria . The observation that these 5 bacterial species frequently inhabit th e subgingival environment, yet are not associated with advanced diseas e, suggest that a susceptible host is required, in addition to a ''pat hogenic bacteria'', before disease progression may occur.