title: Modeling of the effect of friction in the temporomandibular joint on displacement of its disc during prolonged clenching.
abstract: OBJECTIVE
  The effect of the frictional coefficient in the temporomandibular joint on the disc during prolonged clenching was examined.
  
  
  METHODS
  For this purpose, a finite element model of the temporomandibular joint based on magnetic resonance images from a volunteer subject was used. Muscle forces applied for clenching were used as a loading condition for stress analysis during 10 minutes. With respect to the frictional coefficient between articular surfaces, 3 different values ranging from micro = 0.001 to micro = 0.1 were established.
  
  
  RESULTS
  At the onset of clenching, large stresses were found in the central and lateral part of the intermediate zone in the disc, and its stress distribution was not markedly changed during 10 minutes of clenching. In the retrodiscal tissue, stress relaxation occurred during the first 2 minutes of clenching. When the frictional coefficient between articular surfaces increased, the anterior, lateral, and central points in the disc moved further forward. At the end of 10 minutes of clenching, the disc showed a more anterior position as the frictional coefficient increased.
  
  
  CONCLUSIONS
  This result indicates that increase of the frictional coefficient between the articular surfaces may be a major cause for the onset of the disc displacement.
authors.affiliation: Department of Orthodontics and Craniofacial Developmental Biology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan. etanaka@hiroshima-u.ac.jp
authors.forename: Eiji
authors.initials: E
authors.lastname: Tanaka
authors.forename: Miho
authors.initials: M
authors.lastname: Hirose
authors.forename: Jan Harm
authors.initials: JH
authors.lastname: Koolstra
authors.forename: Theo M G J
authors.initials: TM
authors.lastname: van Eijden
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Iwabuchi
authors.forename: Reiji
authors.initials: R
authors.lastname: Fujita
authors.forename: Masao
authors.initials: M
authors.lastname: Tanaka
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tanne
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D002012:Bruxism / Q000150:complications*; D003799:Dental Stress Analysis / Q000379:methods*; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D004204:Joint Dislocations / Q000209:etiology* / Q000503:physiopathology; D008410:Masticatory Muscles / Q000503:physiopathology; D013704:Temporomandibular Joint / Q000503:physiopathology; D019224:Temporomandibular Joint Disc / Q000503:physiopathology*; D013705:Temporomandibular Joint Disorders / Q000209:etiology* / Q000503:physiopathology; D013997:Time Factors