Are pain-related temporomandibular disorders the product of an interaction between psychological factors and self-reported bruxism?

Aims: To investigate whether pain-related temporomandibular disorders (TMD) are the product of an interaction between psychological factors and self-reported bruxism activities. Methods: Patients referred to a specialized clinic for complaints of orofacial pain and dysfunction completed a digital questionnaire prior to the first clinical visit. The patient sample was then split into a case group consisting of 268 patients diagnosed with TMD pain according to the Diagnostic Criteria for Temporomandibular Disorders (85.8% women; mean ± standard deviation [SD] age = 40.1 ± 14.5 years) and a control group consisting of 254 patients without any pain in the orofacial area (50.8% women; 46.9 ± 13.6 years). The possible moderating roles of six psychological factors (depression, somatic symptoms, anxiety, stress, optimism, and prior psychological treatment) on the relationship between selfreported bruxism and the clinical presence of TMD pain were examined. Results: Patients with TMD pain reported significantly more bruxism than patients without any report of orofacial pain. Furthermore, bruxism intensity was associated with a variety of psychological factors; however, there were no significant interactions between any of the psychological factors and bruxism with respect to the clinical presence of TMD pain. Conclusion: These findings do not support the view that the effect of bruxism on TMD pain is stronger in patients who experience higher levels of psychological distress compared to those with lower levels of distress.