The prevalence of A. actinomycetemcomitans, P. gingivalis and P. intermedia in selected subjects with periodontitis.

The present study was carried out in a private periodontal practice. 8 clinical criteria were chosen to select patients for microbiological examination. These criteria characterize prominent features of disease which at the start, during, or in the maintenance phase of treatment suggest difficulties in the progress of the periodontal therapy. Based on these clinical characteristics, an inventory was made of the prevalence of the 3 putative periodontal pathogens: Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia. Out of 320 referred patients 91 patients did meet > or = 1 of the clinical criteria and consequently were selected for microbiological examination. Results showed that young patients (19-30 years) with periodontitis demonstrated the presence of A. actinomycetemcomitans more often (69%: p < 0.005) compared to older age cohorts. A. actinomycetemcomitans was found more often when localized breakdown (in particular in the 1st molar and incisor region) was observed and in patient who responded poorly to scaling and rootplaning. P. gingivalis and P. intermedia were most frequently recovered in patients showing primarily a bone loss pattern of angular defects of > or = 5 mm. Retrospectively, these patients were further categorized, based on full mouth radiographs, in (1) patients with primarily horizontal bone loss and (2) patients with primarily angular bony defects. Results showed that A. actinomycetemcomitans occurred less frequently in patients showing horizontal bone loss (p < 0.05).