Putative periodontal pathogens colonizing oral mucous membranes in denture-wearing subjects with a past history of periodontitis.

The prevalence of selected putative periodontal pathogens colonizing oral mucous membranes was investigated in 26 denture-wearing subjects with a history of periodontitis. The microbiota of the oral cavity of these subjects was examined on average 9.3 years after extraction (range: 1-40 years). Samples were taken from several locations on the oral mucous membranes, from saliva and from plaque attached to the upper and lower denture. Actinobacillus actinomycetemcomitans was not detected in any of the 26 edentulous subjects. Porphyromonas gingivalis was detected in 2 subjects (proportion of cultivable flora: 0.002% and 12.5%). Prevotella intermedia was recovered from 7 subjects with a mean proportion of 0.5% (range < 0.001%-6.3%). Analysis showed that subjects harbouring P. intermedia were wearing full dentures for a longer period of time (mean: 20.2 years) than subjects in which P. intermedia could not be detected (mean: 6.6 years). This result suggests that the absence of P. intermedia shortly after extraction may reflect only a temporary event. Other Prevotella species were found in 22 subjects, constituting < 2% of the total cultivable flora (range 0.01%-10.5%). In conclusion, the low prevalence of P. gingivalis and the absence of A. actinomycetemcomitans, suggest that the oral cavity of edentulous subjects may not be regarded as a habitat for these species. The preferable habitat of the Prevotella spp. seems to be the oral mucous membranes, possibly with the exception of P. intermedia.