Molecular analysis of bacterial community inhabiting in carious dentin lesion

Objective: The aim of this study is to clarify the structure of bacterial community in carious dentin in adults. Methods: Carious dentin, the surface of which was removed, was collected from six patients aged from 28 to 76 visiting Kyushu University Hospital. Bacterial DNA was directly extracted from carious dentin samples and the 16S rRNA gene was amplified using bacterial universal primer by PCR. The amplicons were analyzed by two molecular approaches, terminal restriction fragments length polymorphism (T-RFLP) analysis and cloning and sequencing analysis. Results: The T-RFLP profiles showed that terminal restriction fragments corresponding to Lactobacillus species were most predominant in 5 of 6 subjects. L. crispatus, L. vaginalis, L. gasseri, L. oris were identified in the cloning and sequencing analysis of the 16S rRNA gene. Conclusion: This study revealed that multiple species of Lactobacillus predominantly inhabit in carious dentin lesion. These bacteria might play an important role in the development of dental caries in the adults.