Risk factors associated with temporomandibular joint disorder: A mendelian randomization analysis

BACKGROUND: Temporomandibular joint disorder (TMD), a prevalent orofacial disorder with complex aetiologies and considerable socioeconomic costs. This underscores the critical importance of developing a comprehensive understanding of the risk factors associated with TMD, as existing research is hindered by deficiencies in establishing causal relationships and the limitations of traditional research methodologies. OBJECTIVES: This research explores the causal link between certain risk factors and temporomandibular joint disorder (TMD) through Mendelian randomization (MR), providing multidimensional perspectives in addressing this worldwide health issue. METHODS: Utilizing instrumental variables, we applied advanced statistical methods, including the weighted median, inverse variance weighted (IVW) and MR-Egger, to evaluate the impact of twelve potential risk factors on TMD. RESULTS: Our results identified a significant positive association of TMD with malocclusion (p < .001), sleeping disorders (p = .006), anxiety (p = .002), major depression (p = .0002), daily cigarettes consumption (p = .029) and autoimmune diseases (p = .039). Conversely, a negative association was observed with educational attainment (p = .003). CONCLUSION: These findings suggest that malocclusion, sleeping disorders, anxiety, major depression, daily cigarettes consumption and autoimmune diseases, could potentially increase TMD risk while educational attainment might mitigate its increase. No direct causal relationships were established between serum 25-hydroxyvitamin D levels, menopause, frequent alcohol consumption, coffee intake and severely worn dentition and TMD.