Temporomandibular Symptoms, Migraine, and Chronic Daily Headaches in the Population

Migraine is a chronic-recurrent disorder that sometimes progresses into chronic migraine, a subtype of the chronic daily headaches (CDH). Accordingly, identifying risk factors for progression is of importance.1 Most risk factors have been assessed as a dichotomous variable (present or not). More relevant is to demonstrate a dose relationship, where higher frequency or severity of exposure magnifies the risk. This has been suggested for head trauma,2 certain medications, obesity, and allodynia.1 Temporomandibular disorders (TMD) are considered to be comorbid with migraine.3,4 Since nociceptive inputs from the orofacial area may induce trigeminal sensitization,5 TMD may be a risk factor for migraine progression. Investigating associations between disorders is a prelude to the development of studies assessing causality. Accordingly, we explored the relationship between headache types and TMD, as well as number of TMD symptoms. ### Methods. This was a questionnaire-based population study, estimating prevalence rates of TMD symptoms and of primary headaches in a Brazilian urban population. Our sample (1,230 adults) was drafted from 484,422 inhabitants representative of Brazil by demographics. The 5 …