Microbial composition of supra- and subgingival plaque in subjects with adult periodontitis

Background, aims: The purpose of the present study was to compare and relat e the microbial composition of supra and subgingival plaque in 23 adult per iodontitis subjects (mean age 51+/-14 years). Methods: A total of 1.170 samples of supra and subgingival plaque were coll ected from the mesial aspect of every tooth (up to 28 supra and 28 subgingi val samples) from each subject and evaluated for the presence and levels of 40 bacterial taxa using whole genomic DNA probes and checkerboard DNA-DNA hybridization. Clinical assessments including dichotomous measures of gingi val redness, bleeding on probing, plaque accumulation and suppuration, as w ell as duplicate measures of pocket depth and attachment level. were made a t 6 sites per tooth. The counts (levels), % DNA probe count (proportion) an d % of sites colonized (prevalence) of each species in supra and separately in subgingival plaque were computed for each subject. Significance of diff erences between supra and subgingival plaque for each species was sought us ing the Wilcoxon signed ranks test and adjusted for multiple comparisons. Results: All 40 taxa were detected in both supra and subgingival plaque, Ac tinomyces species were the most prevalent taxa in both habitats. 75 to 100% of supra and 62 to 100% of subgingival sites were colonized by at least on e of the 5 Actinomyces species. Supragingival samples exhibited significant ly higher counts of Actinomyces naeslundii genospecies 1, Actinomyces israe lii, Actinomyces odontolyticus, Neisseria mucosa, Streptococcus gordonii, C apnocytophaga ochracea and Capnocytophaga sputigena when compared with mean counts in subgingival samples taken from the same tooth surfaces. Subgingi val plaque samples presented significantly higher counts of Prevotella nigr escens, Prevotella intermedia, Bacteroides forsythus and Porphyromonas ging ivalis. Subgingival samples exhibited a significantly higher proportion of "red" and "orange complex" species, while supragingival plaque exhibited hi gher proportions of "green" and "purple" complex species as well as Actinom yces species. Suspected periodontal pathogens could be detected in supragin gival plaque From sites where subgingival samples were negative for the sam e species. Conclusions: The data indicate that supragingival plaque can harbor putativ e periodontal pathogens, suggesting a possible role of this environment as a reservoir of such species for the spread or reinfection of subgingival si tes.