title: Immediate effect of occlusal contact pattern in lateral jaw position on the EMG activity in jaw-elevator muscles in humans.
abstract: OBJECTIVE
  The aim of this study was to investigate the effect of experimental alterations of nonworking-side occlusal contacts on jaw-elevator muscle activity.
  
  
  METHODS
  Individual devices were fabricated to simulate various lateral occlusal relationships. Twelve human subjects were asked to carry out submaximal lateral clenching, and electromyographic (EMG) activity of the masseter and anterior and posterior temporalis muscles was measured.
  
  
  RESULTS
  Clenching in a lateral mandibular position under natural conditions induced an activity pattern with a clear dominance of the anterior and posterior temporalis muscles on the working side. Working-side dominance in the anterior temporalis was reduced moderately when an experimental nonworking-side occlusal contact was added. Dominance decreased dramatically when an experimental nonworking-side interference was added. The working-side activity in the posterior temporalis was also reduced dramatically by an experimental nonworking-side interference, but not by a nonworking-side occlusal contact. None of the experimental contact patterns had a significant effect on the masseter activity.
  
  
  CONCLUSIONS
  These results suggest that the nonworking-side occlusal contacts have a significant effect on clenching-induced temporalis muscle activity.
authors.affiliation: Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549 Japan. k.baba.pro1@dent.tmd.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Baba
authors.forename: K
authors.initials: K
authors.lastname: Yugami
authors.forename: S
authors.initials: S
authors.lastname: Akishige
authors.forename: M
authors.initials: M
authors.lastname: Ai
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001732:Bite Force; D003481:Cuspid; D003766:Dental Occlusion; D003769:Dental Occlusion, Traumatic / Q000503:physiopathology; D004576:Electromyography; D006801:Humans; D008297:Male; D008406:Masseter Muscle / Q000502:physiology*; D008963:Molar; D009119:Muscle Contraction; D012815:Signal Processing, Computer-Assisted; D018709:Statistics, Nonparametric; D013703:Temporal Muscle / Q000502:physiology*; D014716:Vertical Dimension