The presence of black-pigmented Gram-negative anaerobes in the oral cavity of edentulous subjects

The aim of this study was to investigate whether black-pigmented Gram-negative anaerobes are part of the indigenous oral flora of edentulous subjects with or without dentures. Group I consisted of 11 subjects with dentures (mean age 63.6 years, range 52-75) and Group II consisted of 39 subjects with complete dentures in both jaws (mean age 59.3 years, range 37-80). Two microbial samples for microbiological examination were taken from each subject. One of them was from the dorsum of the tongue and the other was from saliva. Black-pigmented Gram-negative anaerobes > 10(7) cfu/ml were found in both samples. In 50 edentulous subjects, they were found more commonly from tongue (40%) than from saliva (26%). None of the subjects had Porphyromonas gingivalis. There was no statistically significant difference (P > 0.05) between the presence of black-pigmented Gram-negative anaerobes on tongue and in saliva in the two groups. Our results suggested that high levels of black-pigmented Gram-negative anaerobes may belong to the indigenous oral flora in edentulous mouths with or without dentures.