Figure 6.
Profiles of the mean counts (×105) of 40 taxa in subgingival biofilm samples taken from 292 subjects with periodontitis subset into three age groups (<35, 35–64 and >64 years old) in different severity categories (“the least” severe and “the most” severe). Nine subgingival biofilm samples were taken from each subject and were analyzed separately to determine their content of 40 species of bacteria. The species were ordered and grouped according to the microbial complexes described by Socransky et al. [89]. The mean values for each species were averaged within a subject and then across subjects in each severity categories. The significance of differences among age groups into each severity category was determined using analysis of covariance (ANCOVA), adjusted for smoking, gender, baseline probing depth and geographic population. The significance of differences between pairs of comparisons was determined using Tukey’s multiple comparison test (different letters indicate significant differences between age groups).