A two-sample bidirectional Mendelian randomization study on gut microbiota, dental caries, and toothache

We aimed to evaluate whether gut microbiotas have an effect on caries and toothache and explore whether dental caries and toothache have any impact on the identified significant bacterial genera. We first used genetic instruments of gut microbiota from the MiBioGen consortium to investigate the relationship with toothache and dental caries. The genome-wide association study summary data were from the UK Biobank and the FinnGen consortium, respectively. Mendelian randomization (MR) Egger regression, weighted median, inverse-variance weighted, simple mode, and weighted mode were used in the analysis. MR-PRESSO and Cochrane Q statistics were used to detect pleiotropy and heterogeneity. Furthermore, we performed a bidirectional MR analysis to examine the direction of the relationship. In our study, we identified 22 gut microbiota that were associated with toothache and dental caries. In the reverse MR analysis, the analysis suggested a strong correlation between the gut microbiome (Eubacterium nodatum group) and toothache. Our MR analysis suggested that the gut microbiota influences the occurrence of dental caries and toothache, while dental caries and toothache exert an impact on the identified significant bacterial genera.