Predominant cultivable microflora of plaque on removable dentures in patients with healthy oral mucosa.

Plaque from the fitting surface of upper full dentures in eight patients with healthy palatal mucosa was studied. To characterize the predominant cultivable flora, 916 isolates (100-128 from each sample) were subcultured from anaerobic roll-tubes. Streptococci constituted 0-81 per cent (median, 41 per cent) of the isolates with varying proportions of Streptococcus milleri, Streptoccus mutans, Streptococcus salivarius, Streptococcus mitior and Streptococcus sanguis. Staphylococcus aureus made up 0-13 per cent (median, 6 per cent). Gram-positive rods constituted 1-74 per cent (median, 33 per cent). Among these, Actinomyces israelii, Actinomyces naeslundii, Actinomyces viscosus and Actinomyces odontolyticus were the most common species, whereas lactobacilli were isolated only from two samples, constituting 21 and 48 per cent. Among Gram-negative bacteria, only Veillonella parvula was common, constituting 3-20 per cent (median, 10 per cent). Gram-negative rods were isolated only from three samples in small proportions making up 0-6 per cent (median, 0 per cent) of the flora. Forty-seven isolates (5 per cent) were lost. Cultures for yeasts on Sabouraud agar were positive for five samples and the yeast counts corresponded to 0-0.45 per cent (median, 0.002 per cent) of the total viable counts. The microflora of denture plaque is highly variable and is to a large extent similar to that of some forms of dental plaque.