Characterization of the oral microbiome and gut microbiome of dental caries and extrinsic black stain in preschool children

A lower prevalence of dental caries (hereafter termed "caries") has been observed in children with dental extrinsic black stain (EBS). We investigated the epidemiologic characterization of EBS and explored the possible role of the oral microbiome (OM) and gut microbiome (GM) in EBS formation and caries prevention. In an epidemiologic survey, 2,675 children aged 3-6 years were included. Thirty-eight of these children (7 children had both caries and EBS, 10 had EBS only, 11 had caries only, and 10 were healthy children) were recruited for 16S rRNA sequencing and collection of samples of supragingival plaque and feces. Collected plaque samples were divided into four groups: BCP (EBS+, caries+), BP (EBS+, caries-), CP (EBS-, caries+), and P (EBS-, caries-). Fecal samples were also divided into four groups: BCF (EBS+, caries+), BF (EBS+, caries-), (EBS-, caries+), and F (EBS-, caries-). EBS was observed in 12.10% of this population. Children with EBS had a significantly reduced prevalence of caries and a lower mean value of decayed-missing-filled teeth (dmft;