The results of this study show that proportions of serotype b of A. actinomycetemcomitans are significantly greater in culture-positive patients with aggressive periodontitis than those with chronic periodontitis.

To prevent the onset or progression of periodontitis, we must understand when periodontal pathogens are first harbored and how they develop the biofilm that causes periodontal disease. The purpose of this study was to determine the relationship between clinical status and selected periodontal pathogens in subgingival plaque in school children. This study was conducted with 95 school children, 8-11 years old. The presence and distribution of eight selected periodontal pathogens sampled from the maxillary right first molar were determined by an indirect immunofluorescent technique and compared with clinical parameters. Of the 95 sites sampled, only one site had all eight pathogens and five sites did not have any of the eight pathogens. The mean number of positive pathogens per site was 3.5 +/- 1.8 and mean percentage of positive pathogens was 3.82 +/- 4.22%. The number and total percentage of positive pathogens were strongly correlated with the Plaque Index (PI). In addition, the number of positive pathogens was correlated to the presence of subgingival calculus. The most frequently found pathogens were Campylobacter rectus (84.2%) and Eikenella corrodens (83.2%), and the least, Actinobacillus actinomycetemcomitans serotype c (7.4%). Of the eight pathogens, the frequency and distribution of Porphyromonas gingivalis were significantly correlated with PI and the presence of calculus. In addition, seven sites with both P. gingivalis and Bacteroides forsythus showed a correlation with gingival inflammation. In conclusion, the presence of P. gingivalis or P. gingivalis and B. forsythus may be a risk marker to be sought in screening for the onset of periodontal disease.

The present results suggest that the clinical parameters associated with attachment loss differ between generations and that gingival inflammation is likely associated with the onset of periodontitis more strongly than progression of periodontitis, whereas PD and/or AL are associated with the progression of periodontitis.

The results indicated that T. forsythensis and C. rectus might be able to be used as risk markers for the onset of periodontitis.

Since the distribution of E. corrodens is significantly higher in JP, post-JP, and PP, E. corrodens might play an important role in the occurrence or progression of periodontitis in young patients.