Predominant Obligate Anaerobes in Necrotic Pulps of Human Deciduous Teeth

The purpose of this study was to investigate the bacterial composition of necrotic pulps of human deciduous teeth by sampling the split surfaces of freshly extracted teeth and culturing the bacteria present with good anaerobic isolation techniques. Significantly more bacteria were recovered after the incubation in an anaerobic chamber than after aerobic incubation in air with 30 per cent CO2. Of 276 bacterial isolates, 251 (91 per cent) were obligate anaerobes. These findings suggest that the environment of necrotic pulps in human deciduous teeth is anaerobic and thus favours the growth of anaerobes. Among the 251 obligate anaerobes isolated, strains belonging to the genera Peptostreptococcus (25 per cent), Propionibacterium (19 per cent), Eubacterium (17 per cent) and Fusobacterium (13 per cent) were major parts of the bacterial flora of the lesions of human deciduous teeth. Bifidobacterium (2 per cent), Lactobacillus (1 per cent), Actinomyees (1 per cent) and Veillonella (0.7 per cent) were minor parts of the flora. The microflora of necrotic pulps of human deciduous teeth is in some respects similar to that reported for the deep layers of dentinal lesions of adults.