title: The effects of sustained incisal clenching on the temporomandibular joint space.
abstract: OBJECTIVE
  To determine the effect of sustained incisal clenching on the width of the temporomandibular joint space.
  
  
  METHODS
  Nine normal subjects clenched on an anterior appliance for 10 min at 49 N. Sagittal tomograms were obtained during comfortable closure in the intercuspal position (ICP) (ICP-Before), comfortable closure on bite force transducer without clenching (BFT-Before), start of clenching (BFT-0), end of 5 min clenching (BFT-5), end of 10 min clenching (BFT-10), comfortable closure on the bite force transducer immediately after clenching (BFT-After) and comfortable closure in ICP after clenching (ICP-After). Joint space dimensions were automatically measured by a computerized image analysis system.
  
  
  RESULTS
  The minimum joint space dimension was significantly reduced at BFT-5 (P = 0.0381), BFT-10 (P = 0.0019) and BFT-After (P = 0.0053) in relation to BFT-Before. The condylar position was also significantly shifted upward at BFT-0 (P = 0.0422), BFT-5 (P = 0.0005), BFT-10 (P = 0.0001), and BFT-After (P = 0.0004) in relation to BFT-Before.
  
  
  CONCLUSIONS
  Sustained incisal clenching at 49 N causes significant anterior joint space reduction. We believe this is due to marked compression of the articular cartilage and disc.
authors.affiliation: Department of Fixed Prosthodontics, Okayama University Dental School, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Takenami
authors.forename: T
authors.initials: T
authors.lastname: Kuboki
authors.forename: C O
authors.initials: CO
authors.lastname: Acero
authors.forename: K
authors.initials: K
authors.lastname: Maekawa
authors.forename: A
authors.initials: A
authors.lastname: Yamashita
authors.forename: Y
authors.initials: Y
authors.lastname: Azuma
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001732:Bite Force; D002012:Bruxism / Q000150:complications / Q000000981:diagnostic imaging*; D003799:Dental Stress Analysis; D005260:Female; D006801:Humans; D008297:Male; D008335:Mandibular Condyle / Q000000981:diagnostic imaging / Q000503:physiopathology; D009119:Muscle Contraction; D015203:Reproducibility of Results; D013704:Temporomandibular Joint / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology; D013706:Temporomandibular Joint Dysfunction Syndrome / Q000000981:diagnostic imaging* / Q000209:etiology; D014057:Tomography, X-Ray Computed; D014159:Transducers