title: Chewing movements altered in the presence of temporomandibular joint internal derangements.
abstract: OBJECTIVE
  The objectives were to find specific factors that are mathematically distinct between the chewing timings, movement pattern shapes, variability, and movement velocities of: (1) normal asymptomatic subjects and (2) a group of subjects with verified temporomandibular joint (TMJ) internal derangements.
  
  
  METHODS
  Left- and right-sided chewing movement recordings of 28 subjects (34.5 ± 14.0 years) were randomly selected from a large database of patients exhibiting verified unilateral or bilateral TMJ internal derangements. The chewing movements of an age- and gender-matched control group of 20 asymptomatic subjects (32.5 ± 11.6 years, P>0.60) with verified normal TMJ function were also recorded. Means and standard deviations of the opening, closing, turning point, terminal chewing position, and velocity patterns were calculated. A two-tailed Student's t-test with unequal variances was used to compare the parameters between the two groups (alpha = 0.05).
  
  
  RESULTS
  The dysfunctional group functioned significantly slower and with greater variability than the control group. The vertical dimension was consistently smaller in the dysfunctional group (P<0.00001). The terminal chewing position was significantly less precise in the dysfunctional group (vertical: P<0.002 and lateral: P<0.037). The maximum lateral width was significantly less (P<0.0071), and the peak and the average velocities were significantly lower (P<0.00001 for both) in the dysfunctional group.
  
  
  CONCLUSIONS
  This group of dysfunctional subjects exhibited significantly slower, smaller, and more variable chewing patterns than the control group. The functional pattern of mastication appears to be significantly altered in the presence of an internal derangement of the TMJ.
authors.forename: John C
authors.initials: JC
authors.lastname: Radke
authors.forename: Robert S
authors.initials: RS
authors.lastname: Kull
authors.forename: Manminder S
authors.initials: MS
authors.lastname: Sethi
mesh_terms: D000328:Adult; D001699:Biometry; D016022:Case-Control Studies; D003768:Dental Occlusion, Centric; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D007180:Incisor / Q000503:physiopathology; D007574:Jaw Relation Record / Q000295:instrumentation; D008297:Male; D008409:Mastication / Q000502:physiology*; D009068:Movement; D016059:Range of Motion, Articular / Q000502:physiology*; D013704:Temporomandibular Joint / Q000502:physiology; D013705:Temporomandibular Joint Disorders / Q000503:physiopathology*; D013997:Time Factors; D014716:Vertical Dimension
keywords: Evaluation,; Human,; Jaw tracking,; TMJ dysfunction and mastication