The presence of black-pigmented Gram-negative anaerobes in the oral cavity of edentolous 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 > 107 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.