Microbiome Analysis of Three Sample Types Obtained From Mixed Dentition Children With Different Caries Statuses: A Cross-Sectional Survey

Abstract Background: Both supragingival plaque and saliva are commonly sampled for analysis of microbial communities. However, it remains unclear whether saliva can replace supragingival plaque for microbial studies of caries. There are limited studies on whether the microbiota of healthy first permanent molar (FPM) differs in different caries statuses of deciduous teeth. Herein, the PacBio Sequel platform was used to identify microbiome between three types of oral samples. Additionally, we compared the microbia between children with caries and healthy children in the same kind of microhabitat.Methods: In total, 30 children (aged 7–9 years) were enrolled in this study; 15 of them had dental caries. DNA was extracted from supragingival plaques of deciduous molars, supragingival plaques of maxillary FPMs, and saliva, and the v1–v9 regions of 16S rRNA was amplified. Additionally, PacBio sequencing and bioinformatic analyses were performed.Results: The salivary microbial alpha diversity were lower than that of the supragingival plaque on the teeth, but three was no difference between deciduous teeth and FPMs. Nonmetric multidimensional scaling analysis showed that the saliva samples were mainly scattered in the left side, whereas most plaque samples were distributed on the right. In the same microhabitat , there was no difference in microbial alpha and beta diverty between children with caries and healthy children. For the samples of the deciduous teeth, Streptococcus mutans, Propionibacterium acidifaciens, and Veillonella dispar were more abundant in the children with caries than healthy children, and the first two bacteria showed a positive correlation. For the samples of the FPMs, Selenomonas noxia was more abundant in healthy children than children with caries. But no differentially abundant microorganism were identified between the saliva subgroups. Conclusion:The microbial composition and struction of supragingival plaque was different from that of saliva, and supragingival plaque was found to be the best candidate for studying caries etiology. Streptococcus mutans, Veillonella dispar, and Propionibacterium acidifaciens are highly associated with the existence of deciduous caries. The microbia of the supragingival plaque on the healthy FPMs resemble when the caries status of the deciduous teeth was different, except for the abundance of Selenomonas noxia.