Metagenomic Analysis of the Buccal Microbiome by Nanopore Sequencing Reveals Structural Differences in the Microbiome of a Patient with Molar Incisor Hypomineralization (MIH) Compared to a Healthy Child—Case Study

Molar incisor hypomineralization (MIH) is a qualitative developmental defect that affects the enamel tissue of permanent molars and can also occur in permanent incisors. Enamel affected by MIH has reduced hardness, increased porosity, and a higher organic content than unaffected enamel. These characteristics predispose the enamel to accumulation of bacteria and a higher prevalence of caries lesions. Through a groundbreaking metagenomic analysis of the buccal mucosal sample from a patient with MIH, we explored the intricacies of its microbiome compared to a healthy control using state-of-the-art nanopore long-read sequencing. Out of the 210 bacterial taxa identified in the MIH microbiome, we found <i>Streptococcus</i> and <i>Haemophilus</i> to be the most abundant genera. The bacteria with the highest read counts in the patient with MIH included <i>Streptococcus mitis</i>, <i>Haemophilus parainfluenzae</i>, <i>Streptococcus pneumoniae</i>, <i>Rothia dentocariosa</i>, and <i>Gemella haemolysans</i>. Our results revealed a striking contrast between healthy and MIH affected children, with a higher dominance and number of pathogenic species (<i>S. pneumoniae</i>, <i>H. influenzae</i>, and <i>N. meningitidis</i>) and reduced diversity in the MIH-affected patient. This distinct microbial profile not only sheds light on MIH-affected patients, but paves the way for future research, inspiring deeper understanding and larger scale studies.