Vitamin D Levels and Temporomandibular Disorders: A Bidirectional Two-Sample Mendelian Randomization Analysis.

Area of Science:

• Genetics
• Nutritional Science
• Oral Health

Background:

• The relationship between vitamin D and temporomandibular disorders (TMDs) is under investigation but remains inconclusive.
• Mendelian randomization (MR) offers a method to explore potential causal links using genetic variants.

Purpose of the Study:

• To investigate the potential causal effect of vitamin D on the risk of developing TMDs.
• To examine if TMDs have a causal impact on vitamin D levels.

Main Methods:

• A bi-directional Mendelian randomization (MR) analysis was conducted using genome-wide association study (GWAS) data for vitamin D and TMDs in a European population.
• Inverse variance weighted (IVW) was the primary analysis method, supplemented by MR Egger and Weighted median.
• Sensitivity analyses, including Cochran's Q test and MR-PRESSO, were performed to ensure result robustness.

Main Results:

• Higher vitamin D levels were causally associated with an increased risk of TMDs in the European population (OR = 1.316, P = 0.005).
• No significant causal effect of TMDs on vitamin D levels was observed (β = -0.00738, P = 0.568).

Conclusions:

• This study suggests a potential causal link where higher vitamin D levels may increase TMDs risk.
• No evidence supports a causal relationship where TMDs influence vitamin D levels.
• Findings should be interpreted with caution due to potential selection bias in the TMDs patient sample.