title: Masticatory performance and chewing cycle kinematics-are they related?
abstract: OBJECTIVE
  To compare chewing cycle kinematics of subjects with better and poorer masticatory performance.
  
  
  METHODS
  A cross-sectional study compared masticatory performance, based on the breakdown of the artificial test food Cuttersil, in 30 subjects with Class I occlusion. Individuals with median particle sizes greater and lesser than the median value for the entire sample were categorized as poorer (15) and better (15) performers, respectively. While chewing Cuttersil, three-dimensional jaw movements of subjects were tracked with an optoelectric computer system. Multilevel linear modeling was used to evaluate differences in estimated cycle shape, cycle duration, and maximum excursions, as well as within-subject variation between the two groups.
  
  
  RESULTS
  Poorer performers had a significantly longer opening duration (0.274 +/- 0.225 sec vs 0.325 +/- 0.270 sec) than better performers. Poorer and better performers also showed significant differences in cycle shape, including a less horizontal path of closure and more posterior jaw movement in the poorer performers. In addition, poorer performers exhibited significantly more cycle-to-cycle (within-subject) variability in chewing cycle duration, excursive movements, and lateral velocity than did better performers.
  
  
  CONCLUSIONS
  Poorer performers lacked consistency in their chewing cycles, and their cycle shape differs from that of better performers.
authors.affiliation: Department of Cell Biology, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA.
authors.forename: Casey
authors.initials: C
authors.lastname: Lepley
authors.forename: Gaylord
authors.initials: G
authors.lastname: Throckmorton
authors.forename: Sarah
authors.initials: S
authors.lastname: Parker
authors.forename: Peter H
authors.initials: PH
authors.lastname: Buschang
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology; D001732:Bite Force; D003430:Cross-Sectional Studies; D003799:Dental Stress Analysis; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D016014:Linear Models; D008297:Male; D008334:Mandible / Q000502:physiology*; D008409:Mastication / Q000502:physiology*; D009068:Movement; D055361:Multilevel Analysis; D010316:Particle Size; D012737:Sex Factors; D013997:Time Factors; D055815:Young Adult