Association of Caries Increments and Oral Microbiome Among Young Adults

Objectives: Dental caries is one of the worldwide diseases. Some specific pathogens are well known, such as Mutans streptococci [main species: Streptococcus mutans (S. mutans) and S. sobrinus]. Recent cross-sectional studies suggest that the microbial diversity and microbiomes component are associated with dental caries using a next-generation sequencing. However, it remains unclear which oral microbiome diversity and component affect increase in dental caries among young adults. The purpose of this 3-year prospective cohort study was to explore the relationship between increase in dental caries and oral microbiome among Japanese university students.
Methods: We analyzed 487 students who volunteered to receive oral examinations and answer the questionnaire at baseline (2013) and follow-up (2016). Of these targeted students, the salivary samples were randomly collected from 55 students and analyzed using the next-generation sequencing. The students were divided into two groups: active group (Δ decayed, missing, filled teeth (ΔDMFT) score>0) and non-active group (ΔDMFT=0).
Results: A total of 196 OTUs were obtained from the samples. Of these, 13 phyla, 21 classes, 32 orders, 48 families, 72 genera and 156 species were identified. The microbial diversity in the active group (n=14) was similar with that in the non-active group (n=41). Based on linear discriminant analysis effect size algorithm (LEfSe) analysis, the relative abundances of Alloprevotella and Dialister in genera, and Alloprevotella sp, Haemophilus sp, Prevotella pleuritis, Dialister pneumosintes, and Haemophilus haemolyticos in species were significantly greater in the active group than in the non-active group (p<0.05, t-test).
Conclusions: The prospective cohort study revealed that diversity of salivary microbiome between the active and non-active groups were similar. Some bacterial taxonomic clades showed the significant difference in Japanese university students, which may contribute to new strategies for preventing dental caries.