Background: The mixed dentition is an important transition period from primary teeth to permanent teeth. However, the caries prevalence of first permanent molar in mixed dentitions was about 30%, which almost represent the caries rate of permanent teeth in this period of time. Therefore, we assessed the oral bacterial profiles in young children (age 6-8) with mixed dentition with or without first molar caries for providing the research basis of caries etiology.
Methods: We collected samples of supragingival plaque and saliva from the children living in Guizhou, a rural isolated province in China. Then, we performed DNA extraction and purification followed by 454 pyrosequencing of the V1-V3 hypervariable regions of the 16S rRNA and compared our results with those of previous research.
Results: (i) We analyzed 48,320 unique sequences that represented 18 phyla, 29 classes, 44 orders, 74 families, 129 genera, 15,003 species-level OUT in plaque and saliva samples; (ii) longitudinally, there was the "healthy core microbiome" between healthy deciduous dentition and early mixed dentition, for example, Neisseria, Porphyromonas, Selenomonas etc.; (iii) horizontally, there also existed the "healthy core microbiome" in early mixed dentition, for example, Neisseria, Streptococcus, Prevotella etc.; (iv) the dominant bacteria detected by Lefse in caries group including Actinomycetaceae, Streptobacillus (p < 0.05) and those in caries-free group including Gammaproteobacteria, Pasteurellaceae, Aggregatibacter, Chloroflexi, (p < 0.05).
Conclusions: The oral cavity is a highly heterogeneous ecosystem with the "healthy core microbiome" in children, although microbial composition shifts along with aging. In addition, the abundance and diversity of microbiota vary between caries and caries-free groups verify the ecological plaque hypothesis.
Keywords: 454 pyrosequencing; children; healthy core microbiome; mixed dentition; plaque; saliva.
© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd. All rights reserved.