Temporomandibular disorders are differentially associated with headache diagnoses: a controlled study. 
Temporomandibular disorders (TMDs) are considered to be comorbid with headaches.  Earlier population studies have suggested that TMD may also be a risk factor for migraine progression.  If that is true, TMD should be associated with specific headache syndromes (eg, migraine and chronic migraine), but not with headaches overall.  Accordingly, our aim was to explore the relationship between TMD subtypes and severity with primary headaches in a controlled clinical study.  The sample consisted of 300 individuals.  TMDs were assessed using the Research Diagnostic Criteria for TMD, and primary headache was classified according to International Classification for Headache Disorders-2.  Univariate and multivariate models assessed headache diagnoses and frequency as a function of the parameters of TMD.  Relative to those without TMD, individuals with myofascial TMD were significantly more likely to have chronic daily headaches (CDHs) [relative risk (RR)=7.8; 95% confidence interval (CI), 3.1-19.6], migraine (RR=4.4; 95% CI, 1.7-11.7), and episodic tension-type headache (RR=4.4; 95% CI, 1.5-12.6).  Grade of TMD pain was associated with increased odds of CDH (P<0.0001), migraine (P<0.0001), and episodic tension-type headache (P<0.05).  TMD severity was also associated with headache frequency.  In multivariate analyses, TMD was associated with migraine and CDH (P=0.001).  Painful TMD (P=0.0034) and grade of TMD pain (P<0.001) were associated with headache frequency.  TMD, TMD subtypes, and TMD severity are independently associated with specific headache syndromes and with headache frequency.  This differential association suggests that the presence of central facilitation of nociceptive inputs may be of importance, as positive association was observed only when muscular TMD pain was involved.