Pyrosequencing analysis of oral microbiota shifting in various caries states in childhood

Dental caries is one of the most prevalent childhood diseases worldwide, but little is known about the dynamic characteristics of oral microbiota in the development of dental caries. To investigate the shifting bacterial profiles in different caries states, 60 children (3-7-year-old) were enrolled in this study, including 30 caries-free subjects and 30 caries-active subjects. Supragingival plaques were collected from caries-active subjects on intact enamel, white spot lesions and carious dentin lesions. Plaques from caries-free subjects were used as a control. All samples were analyzed by 454 pyrosequencing based on 16S rRNA gene V1-V3 hypervariable regions. A total of 572,773 pyrosequencing reads passed the quality control and 25,444 unique phylotypes were identified, which represented 18 phyla and 145 genera. Reduced bacterial diversity in the cavitated dentin was observed as compared with the other groups. Thirteen genera (including Capnocytophaga, Fusobacterium, Porphyromonas, Abiotrophia, Comamonas, Tannerella, Eikenella, Paludibacter, Treponema, Actinobaculum, Stenotrophomonas, Aestuariimicrobium, and Peptococcus) were found to be associated with dental health, and the bacterial profiles differed considerably depending on caries status. Eight genera (including Cryptobacterium, Lactobacillus, Megasphaera, Olsenella, Scardovia, Shuttleworthia, Cryptobacterium, and Streptococcus) were increased significantly in cavitated dentin lesions, and Actinomyces and Corynebacterium were present at significant high levels in white spot lesions (P < 0.05), while Flavobacterium, Neisseria, Bergeyella, and Derxia were enriched in the intact surfaces of caries individuals (P < 0.05). Our results showed that oral bacteria were specific at different stages of caries progression, which contributes to informing the prevention and treatment of childhood dental caries.