title: Ipsilateral Molar Clenching Induces Less Pain and Discomfort than Contralateral Molar Clenching in Patients with Unilateral Anterior Disc Displacement of the Temporomandibular Joint.
abstract: OBJECTIVE
  To assess the influence of clenching side and location (ie, tooth) on the bite force necessary to induce pain or discomfort in patients with unilateral anterior disc displacement (ADD) of the temporomandibular joint (TMJ).
  
  
  METHODS
  A total of 17 patients with unilateral ADD diagnosed clinically and with magnetic resonance imaging were included. A bite force meter was positioned at each of four experimental positions: the mandibular first premolars and first molars, bilaterally. Subjects were instructed to clench on the bite force meter until they felt pain or discomfort in the orofacial area and to report the location of the pain. Differences in pain location (ADD side versus contralateral side) and in the bite force thresholds for eliciting pain or discomfort were assessed by means of the paired t test and Wilcoxon signed-rank test.
  
  
  RESULTS
  Only 18% of subjects (3 out of 17) reported pain in the TMJ with ADD during clenching at the ipsilateral molar, whereas 65% (11 out of 17) reported joint pain during clenching on the contralateral molar (P = .005). At the molars, the mean ± standard deviation bite force necessary to induce pain was 241.2 ± 135.5 N on the side with ADD and 160.9 ± 78.0 N on the contralateral side. The mean molar bite force necessary to induce pain on the side with ADD was significantly higher than that on the contralateral side (P = .002).
  
  
  CONCLUSIONS
  Patients with unilateral ADD had fewer reports of TMJ pain and discomfort when they were molar clenching on the ipsilateral side compared to molar clenching on the contralateral side.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Kumazaki
authors.forename: Shigehisa
authors.initials: S
authors.lastname: Kawakami
authors.forename: Atsutoshi
authors.initials: A
authors.lastname: Hirata
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Oki
authors.forename: Shogo
authors.initials: S
authors.lastname: Minagi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D018771:Arthralgia / Q000503:physiopathology*; D001641:Bicuspid / Q000502:physiology; D001732:Bite Force; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000503:physiopathology*; D008297:Male; D008334:Mandible; D008410:Masticatory Muscles / Q000503:physiopathology; D008875:Middle Aged; D008963:Molar / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D009334:Neck Muscles / Q000503:physiopathology; D017288:Pain Threshold / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology; D019224:Temporomandibular Joint Disc / Q000503:physiopathology*; D013705:Temporomandibular Joint Disorders / Q000503:physiopathology*; D055815:Young Adult