title: Differences in masticatory function of subjects with different closing path.
abstract: OBJECTIVE
  The purpose of this study was to clarify whether there was a difference in the masticatory function between two masticatory path patterns: a convex closing path and a concave closing path.
  
  
  METHODS
  For 80 healthy subjects, the masticatory function (masticatory muscular activity, mandibular movement, and masticatory performance) when chewing a gummy jelly was recorded. Out of the 160 chewing cases (80 subjects chewing on either side), 65 cases (Group I) in which the incisal point opened in a linear or concave manner toward the working side and closed in a convex manner, and 15 cases (Group II) in which the opening path was the same as that in Group I, but the closing followed a concave path, were selected. For the masticatory function, the integral values per unit time of masseter and temporal muscular activities, the gape and masticatory width, the indicators representing the stability of movement path, and the glucose extraction from chewing gummy jelly were measured and compared between the two groups.
  
  
  RESULTS
  The integral values of muscular activities and the amount of glucose extraction were significantly greater in Group I. The gape and masticatory width were not significantly different between the groups. The values of the indicators representing the stability of path were smaller in Group I than in Group II.
  
  
  CONCLUSIONS
  From these results, it was suggested that there was a functional difference between Group I (with a convex closing path) and Group II (with a concave closing path), and that Group I had a superior masticatory function to Group II.
authors.affiliation: Department of Partial and Complete Denture, School of Life Dentistry at Tokyo, The Nippon Dental University, Chiyoda-ku, Tokyo, Japan. y-kobaya@ndu.ac.jp
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shiga
authors.forename: Masaoki
authors.initials: M
authors.lastname: Yokoyama
authors.forename: Ichiro
authors.initials: I
authors.lastname: Arakawa
authors.forename: Kunihisa
authors.initials: K
authors.lastname: Nakajima
mesh_terms: D000328:Adult; D006801:Humans; D008406:Masseter Muscle / Q000502:physiology; D008409:Mastication / Q000502:physiology*; D008410:Masticatory Muscles / Q000502:physiology*; D009068:Movement; D013284:Stomatognathic System / Q000502:physiology*; D013703:Temporal Muscle / Q000502:physiology; D055815:Young Adult