Vitamin D serum levels and temporomandibular disorders: A systematic review and meta-analysis

Objective: This systematic review evaluates the connection between vitamin D serum levels, deficiency, and temporomandibular disorders (TMD), offering a meta-analysis of the existing evidence in this domain. Design: The Scopus, ISI Web of Science, and Pubmed databases were searched for human studies concerning the connection between vitamin D and TMD comprising a control group. A random-effect model with forest plots was used for vitamin D serum levels mean difference (MD), vitamin D deficiency odds ratio (OR), and risk difference (RD) between subjects with and without TMD. Subgroup analysis was conducted based on ethnicity, overall risk of bias, TMD diagnosis method, and study designs. A p-value lower than 0.05 was considered significant. The certainty of the meta-evidence was evaluated according to the GRADE approach. Results: Of the 2621 identified unique records, 15 studies were included in the study, eight of which were considered for the meta-analysis. The meta-analysis revealed a significant vitamin D deficiency OR (3.85; 95 % CI: 2.35 - 5.43; Certainty: Low) and RD (22%; 95% CI: 11 % - 32%; Certainty: Very low), and vitamin D serum levels MD (-5.03 ng/mL; 95 % CI: -9.92 - -0.13; Certainty: Very low) between subjects with and without TMD. Among subgroup analyses, only the difference in vitamin D MD between Middle Eastern and European patients was significant (P < 0.01). Conclusion: Considering the low to very low certainty of the evidence, vitamin D serum levels are significantly lower, and vitamin D deficiency is significantly more prevalent in TMD patients.