The association between headaches and temporomandibular disorders is confounded by bruxism and somatic symptoms

OBJECTIVES: The objective of this observational study was to establish the possible presence of confounders on the association between temporomandibular disorders (TMD) and headaches in a patient population from a TMD and Orofacial Pain Clinic. METHODS: Several subtypes of headaches were diagnosed: self-reported headache, (probable) migraine, (probable) tension-type headache (TTH), and secondary headache attributed to TMD. The presence of TMD was subdivided into two subtypes: painful TMD and function-related TMD. The associations between the subtypes of TMD and headaches were evaluated by single regression models. Subsequently, to study the influence of possible confounding factors on this association, the regression models were extended with age, gender, bruxism, stress, depression, and somatic complaints. RESULTS: Of the included patients (n=203), 67.5% experienced headaches. In the subsample of patients with a painful TMD (n=58), the prevalence of self-reported headaches increased to 82.8%. The associations found between self-reported headache and (1) painful TMD and (2) function-related TMD, were confounded by the presence of somatic complaints. For probable migraine, both somatic complaints and bruxism confounded the initial association found with painful TMD. DISCUSSION: The findings of this study imply there is a central working mechanism overlapping TMD and headache. Healthcare providers should not look at these disorders separately, but rather at the bigger picture to appreciate the complex nature of the diagnostic and therapeutic process