Microbiology of molar-incisor hypomineralization lesions. A pilot study

Objective: An insufficient mineralization (hypomineralization) in the teeth during the maturation stage of amelogenesis cause defects in 3-44% of children. Here, we describe for the first time the microbiota associated with these defects and compared it to healthy teeth within the same subjects. Methods: Supragingival dental plaque was sampled from healthy and affected teeth from 25 children with molar-incisor hypomineralization (MIH). Total DNA was extracted and the 16S rRNA gene was sequenced by Illumina sequencing in order to describe the bacterial composition. Results: We detected a higher bacterial diversity in MIH samples, suggesting better bacterial adhesion or higher number of niches in those surfaces. We found the genera Catonella, Fusobacterium, Campylobacter, Tannerella, Centipeda, Streptobacillus, Alloprevotella and Selenomonas associated with hypomineralized teeth, whereas Rothia and Lautropia were associated with healthy sites. Conclusion: The higher protein content of MIH-affected teeth could favour colonization by proteolytic microorganisms. The over-representation of bacteria associated with endodontic infections and periodontal pathologies suggests that, in addition to promote caries development, MIH could increase the risk of other oral diseases.