Occurrence of Porphyromonas gingivalis and Tannerella forsythensis in periodontally diseased and healthy subjects

Background: The purpose of this study was to compare the prevalence and level of Porphyromonas gingivalis (P. gingivalis) and Tannerella forsythensis (T. forsythensis) in subgingival plaque samples from both healthy individuals and periodontal patients in different age groups. Methods: A total of 498 subgingival plaque samples were studied. These samples were collected from 407 individuals diagnosed with periodontal disease (210 adult periodontitis [AP], 78 rapidly progressive periodontitis [RPP], and 19 refractory periodontitis [Ref-P] cases) and 91 healthy (H) subjects. P gingivalis and T forsythensis were detected by indirect immunofluorescent assay using species-specific polyclonal antisera to P. gingivalis strain (FDC 381) and T. forsythensis strain (FDC 335). The prevalence of P gingivalis and T forsythensis was compared by chi-square analysis. Differences in P. gingivalis and T forsythensis levels among various periodontal status and age groups was determined by one-way analysis of variance and Fisher's multiple comparison tests. The association between the presence of P gingivalis or T forsythensis in different periodontal status and age groups was measured using odds ratios. Results: P. gingivalis was found in 85.7% (P <0.0001) and T. forsythensis in 60.7% (P = 0.0002) of diseased subjects compared to 23.1% and 39.6%, respectively, in healthy subjects. P. gingivalis, but not T. forsythensis, was detected more frequently in any diseased group than in the H group in every age group (P <0.0001). No significant difference was found in the prevalence of P. gingivalis and T forsythensis among age groups, except T forsythensis was more prevalent in the age group of 40 to 59 years than in the age group <20 years (chi(2) = 3.93, P = 0.047) in the H group. The mean level of P. gingivalis and T. forsythensis was significantly higher in diseased groups than in the H group (P <0.0001). The odds ratio for P gingivalis in the AP group (25.0) was greater than any other group for P gingivalis or T forsythensis compared to the H group. Conclusions: These data suggested that P gingivalis is closely associated with the pathogenesis of periodontitis and that it may not be a normal inhabitant of periodontally healthy subjects. T forsythensis is also important in the pathogenesis of periodontal disease; however, whether it causes periodontal disease or is a secondary invader of periodontal lesions remains to be determined.