Distribution of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis by subject age.

The possible associations between periodontitis subject age and the distribution of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis were examined using an extensive data bank of subgingival plaque specimens analyzed using DNA probes. The results suggest that A. actinomycetemcomitans is strongly related to subjects in the youngest age group (10 to 19 years) with decreasing prevalence and concentration levels in older age groups. In contrast, P. gingivalis showed a reverse relationship to subject age with highest prevalence and concentration levels in older subjects (30 years and older) compared to subjects in younger age groups. Statistical testing of these relationships were highly significant. (P less than 0.0001).