title: Effects of stress and relaxation on pain perception in subjects with pain-free occlusional disharmony compared with healthy controls.
abstract: OBJECTIVE
  The significance of occlusal disharmony for the development of painful temporomandibular disorder (TMD) is controversial. The ongoing biomechanical strain caused by occlusal disharmony might lead to sensitization processes in the nociceptive system. Understanding these processes might be an important step toward understanding the possible relationship between occlusal disharmony and TMD. In this study, we therefore investigated whether subjects with occlusal disharmony (n = 22) differ from healthy controls (n = 26) in their pain perception and pain modulation by stress and relaxation.
  
  
  METHODS
  Trigeminal and extratrigeminal experimental pain perception (pinprick, heat, and pressure pain) was assessed before and after stress (mental arithmetic) and relaxation (viewing of low-arousal pictures).
  
  
  RESULTS
  There were no group differences in pain perception at baseline or during the stress task. Compared with controls, the occlusal disharmony group exhibited an inadequate reduction in pain perception during relaxation, which was significant for the extratrigeminal site (P < 0.01) and reached a trend for significance at the trigeminal site (P = 0.1).
  
  
  CONCLUSIONS
  These results suggest that subjects with occlusal disharmony show signs of disturbed endogenous pain inhibition during relaxation.
  
  
  CONCLUSIONS
  There is evidence for the presence of sensitization of the nociceptive system in subjects with occlusal disharmony. Possibly, deficient inhibition of extratrigeminal and trigeminal pain perception by relaxation might contribute to the development of TMD or other chronic pain disorders.
authors.affiliation: Department of Neurology, University of Münster, Münster, Germany; Department of Neurology, University of München, München, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Ruscheweyh
authors.forename: T
authors.initials: T
authors.lastname: Becker
authors.forename: Y
authors.initials: Y
authors.lastname: Born
authors.forename: R
authors.initials: R
authors.lastname: Çolak-Ekici
authors.forename: M
authors.initials: M
authors.lastname: Marziniak
authors.forename: S
authors.initials: S
authors.lastname: Evers
authors.forename: A L
authors.initials: AL
authors.lastname: Gerlach
authors.forename: A
authors.initials: A
authors.lastname: Wolowski
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008310:Malocclusion / Q000150:complications / Q000503:physiopathology*; D058748:Pain Perception; D012063:Relaxation / Q000502:physiology*; D013315:Stress, Psychological / Q000150:complications / Q000503:physiopathology*; D014276:Trigeminal Nerve; D055815:Young Adult
keywords: endogenous pain inhibitory systems; experimental pain testing; relaxation; stress; temporomandibular disorder