Bacterial variability within diseases periodontal sites.

The purpose of this study was to examine the variability in bacterial proportions between individual periodontal sites in patients with chronic periodontitis by means of differential dark-field microscopy. Fourteen patients with untreated, moderate to advanced disease were included. Probing depth, plaque and gingival index scores were recorded for each patient. Microbial samples were collected from the tooth surface with the greatest proving depth in each sextant and examined individually by dark-field microscopy. The results indicated that proportions of spirochetes and motile rods at any given probing depth varied considerably, ranging from those expected at healthy sites to those expected at diseased sites. In accordance with previous studies, mean percentages of spirochetes tended to vary directly with increased PD, PlI and GI scores, while mean percentages of coccoid cells tended to follow a reverse pattern. However, no significant correlations could be demonstrated when measurements from individual sites were analyzed. Most of the variance in the data was due to differences between subjects rather than differences between sites. It is postulated that the large variance between subjects and sites is due in part to the cyclical nature of the disease and to the lack of synchrony between remissions and exacerbations at different sites and in different patients.