Salivary Microbiome Variation in Early Childhood Caries of Children 3–6 Years of Age and Its Association With Iron Deficiency Anemia and Extrinsic Black Stain

Abstract

ECC is a common clinical manifestation of the oral cavity in childhood and Iron deficiency-anemia (IDA) is a high-risk factor but extrinsic black stain on the tooth surface is a protective factor for caries. There is limited information about oral microecological change in early children who suffer from ECC with IDA and extrinsic black stain (BS). This study enrolled 136 children aged 3-6 years. Dental caries and teeth BS were examined. Saliva was collected for 16S rRNA gene and fingertip blood were for Hemoglobin test. There are 93 ECC including 13 with IDA (IDA ECC) and 80 without IDA (NIDA ECC) and 43 caries free (CF) including 17 with BS (BSCF) and 26 without BS (NBS CF). Statistical analysis of microbiota data showed differences of the oral flora in different groups. The oral flora of the IDA ECC group had a high diversity, while the BSCF group had a low diversity. The bacterial genera Bacillus, Moraxella, and Rhodococcus were enriched in the IDA ECC while Neisseria was enriched in the NIDA ECC. Neisseria only exhibited high abundance in the BSCF, and the remaining genera exhibited high abundance in the NBSCF. Interestingly, the BSCF had the same trend as the NIDA ECC, and the opposite trend was observed with IDA ECC. We established random forest classifier using these biomarkers to predict disease outcomes. The random forest classifier achieved the best accuracy in predicting the outcome of caries, anemia and black stain using seven, one and eight biomarkers, respectively; and the accuracies of the classifiers were 93.35%, 94.62% and 95.23%, respectively. Our selected biomarkers can achieve good prediction, suggesting their potential clinical implications.

Bacterial profile in children with early childhood caries

“…Phylum Proteobacteria, Firmicutes, Bacteroidetes, Fusobacteria, and Actinobacteria appeared to dominate in the two groups of children. [15][16][17][18]23,24 Phylum Firmicutes had a higher percentage of children with ECC but had less diversity than CF children. [15][16][17][18] Phylum Firmicutes is one of the most powerful taxonomies because it includes many bacteria with diverse characteristics (phylogenetic, phenotypic, chemotaxonomic, and pathogenic).…”

“…[15][16][17][18]23,24 Phylum Firmicutes had a higher percentage of children with ECC but had less diversity than CF children. [15][16][17][18] Phylum Firmicutes is one of the most powerful taxonomies because it includes many bacteria with diverse characteristics (phylogenetic, phenotypic, chemotaxonomic, and pathogenic). 29 Phylum Firmicutes was dominated first by the Order Lactobacillales of the genus Streptococcus (Streptococcus mutans and Streptococcus sobrinus) and Lactobacillus salivarius (Lactobacillus salivarius, Lactobacillus fermentum, Lactobacillus gasseri, and Lactobacillus mucosae).…”

Epidemiological and Microbiome Characterization of Black Tooth Stain in Preschool Children

“…ANOSIM analyses of the plaque microbiota also indicated significant differences in β diversity in the three plaque groups. Han et al analyzed the salivary microbiome diversity and reported significant differences in the microbial diversity of the BTS and control groups (7). Chen et al performed 16S rRNA sequencing and reported no statistically significant differences in the diversity and Unweighted Unifrac PCoA in the supragingival plaque microbiome between children with (n = 10) and without (n = 10) BTS (31).…”

“…Another study indicated that the stains contain iron and copper in trace amounts along with a substantial proportion of organic matter (41). The formation of a sulfur and metal ion complex was considered responsible for pigmentation corresponding to zones of high concentrations of sulfur and iron/copper (7). Whether the presence of iron or copper is associated with BTS in primary dentition is still unclear and requires further investigations.…”

“…BTS affects primary and permanent dentition and is equally prevalent (1-20%) in both genders (5,6). The black pigmentation is caused by the formation of ferric compounds (such as ferric sulfide) as a result of interactions between hydrogen sulfide (produced by periodontal microorganisms) and iron present in saliva or gingival fluid (7). Therefore, oral microorganisms, particularly chromogenic bacteria (such as Actinomyces and Prevotella) are associated with the formation of black pigments and BTS in primary dentition (8)(9)(10).…”