title: The Association Between Headaches and Temporomandibular Disorders is Confounded by Bruxism and Somatic Symptoms.
abstract: OBJECTIVE
  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 have been diagnosed: self-reported headache, (probable) migraine, (probable) tension-type headache, and secondary headache attributed to TMD. The presence of TMD was subdivided into 2 subtypes: painful TMD and function-related TMD. The associations between the subtypes of TMD and headaches were evaluated by single regression models. To study the influence of possible confounding factors on this association, the regression models were extended with age, sex, bruxism, stress, depression, and somatic symptoms.
  
  
  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 symptoms. For probable migraine, both somatic symptoms and bruxism confounded the initial association found with painful TMD.
  
  
  CONCLUSIONS
  The findings of this study imply that there is a central working mechanism overlapping TMD and headache. Health care providers should not regard these disorders separately, but rather look at the bigger picture to appreciate the complex nature of the diagnostic and therapeutic process.
authors.affiliation: *Education of Physiotherapy, ACHIEVE-Centre of Applied Research, Faculty of Health, Amsterdam University of Applied Sciences ‡Department of Rehabilitation, Academic Medical Center, University of Amsterdam §Department of Oral Health Sciences, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, Research Institute MOVE Amsterdam, Amsterdam †Radboud University Medical Center, Research Institute for Health Sciences, IQ Healthcare, Nijmegen ∥Department of Oral-Maxillofacial Surgery, Prosthodontics and Special Dental Care ¶Physical Therapy Science, Clinical Health Sciences, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Hedwig A
authors.initials: HA
authors.lastname: van der Meer
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Speksnijder
authors.forename: Raoul H H
authors.initials: RHH
authors.lastname: Engelbert
authors.forename: Frank
authors.initials: F
authors.lastname: Lobbezoo
authors.forename: Maria W G
authors.initials: MWG
authors.lastname: Nijhuis-van der Sanden
authors.forename: Corine M
authors.initials: CM
authors.lastname: Visscher
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002012:Bruxism / Q000150:complications* / Q000503:physiopathology; D005260:Female; D006261:Headache / Q000150:complications* / Q000503:physiopathology; D020773:Headache Disorders / Q000150:complications* / Q000503:physiopathology; D006801:Humans; D008297:Male; D000071896:Medically Unexplained Symptoms; D008875:Middle Aged; D012189:Retrospective Studies; D057566:Self Report; D013705:Temporomandibular Joint Disorders / Q000150:complications* / Q000503:physiopathology; D055815:Young Adult