Uncovering the gut microbiota's role in temporomandibular joint disorders: A bidirectional Mendelian randomization study.

Previous studies have revealed the association between gut microbiota (GM) and temporomandibular joint inflammation, which leads to temporomandibular joint disorders (TMD). However, the causality of the associations remains unknown. This Mendelian randomization (MR) study aims to clarify the causal relationships between GM and TMD. We employed a two-sample MR approach to analyze GM data from the MiBioGen consortium, including 18,340 participants and 211 taxa, and TMD data from the FinnGen consortium R10 release, including 6314 cases and 222,498 controls. Various MR methods, including inverse-variance weighted (IVW), MR-Egger, and weighted median analyses, alongside comprehensive sensitivity analyses, were used to assess causality. After comprehensive sensitivity analyses, the study found causal links between 6 certain GM at the genus level and TMD, including Eubacterium fissicatena group (IVW's odds ratio [OR] = 1.18; 95% confidence interval [CI]: 1.02-1.37; P = .027), Catenibacterium (IVW's OR = 1.33; 95% CI: 1.11-1.59; P = .002), Oxalobacter (IVW's OR = 0.85; 95% CI: 0.75-0.97; P = .013), Ruminococcaceae NK4A214 (IVW's OR = 0.80; 95% CI: 0.66-0.99; P = .036), and Senegalimassilia (IVW's OR = 0.75; 95% CI: 0.59-0.96; P = .024). Following replication verification analysis, Catenibacterium (FDR = .04) at the genus level were positively correlated to the risk of TMD. The reverse MR analysis revealed that TMD had no significant effect on the 6 GMs. The findings of this MR study support a strong and negative causal association between genus Catenibacterium and TMD, highlighting potential targets for the prevention and treatment of TMD.