Microbiome in Early Childhood Caries: Caries Severity-Dependent Insights

Objectives: Children with early childhood caries (ECC) show different caries severities and susceptibility in different tooth types and location in the oral cavity. The study aimed to investigate changes in the oral microbiome in ECC subjects stratified according to the severity of caries and types of teeth and tooth surfaces involved. Materials and Methods: Supragingival plaque from the upper and lower anterior regions in the oral cavity of subjects were collected in 3 groups of increasing caries severity (G1-Molar (M) caries only; G2- Molar and Upper Anterior (UA) caries; and G3-M + UA + lower anterior (LA) caries were obtained followed by microbiome analysis. Results: Alpha-diversity analyses showed inter- but no intra-individual statistically significant differences between the UA and LA (p-value ˂ 0.001, LA˃UA), and a significant difference between the microbiome of the three caries groups (p-value ˂ 0.001). There were significant beta-diversity differences between G1 and G2 (p < 0.05) and in the composition and diversity among the three groups (p-value ˂ 0.001). Actinomyces, Saccharibacteria_genera_inserta_sedis and Eikenella had increased differential abundance in G1 vs G3 and Fusobacterium was less abundant in G2 compared to the other groups. Conclusions: There were clear distinct differences in tooth-site specific and caries-severity microbiome diversity patterns and bacterial abundance profiles in S-ECC children. Clinical Relevance: This study provides new information towards the refinement of an ECC clinical phenotype stratification, a step that will contribute to increased uniformity in future microbiome studies of children with ECC.