title: Movement of the lateral and medial poles of the working condyle during mastication in patients with unilateral posterior crossbite.
abstract: Patients with unilateral posterior crossbite often show reverse sequential jaw movement patterns on the frontal view during mastication on the crossbite side. Recent studies show that such patients are prone to suffer from temporomandibular joint (TMJ) disc displacement, particularly the lateral portion. The purpose of this study was to examine the movement of the lateral and medial poles of the working condyle during mastication in such patients. Subjects were 12 consecutive patients with unilateral posterior crossbites and without TMJ disc displacements and 12 normal subjects. An optoelectronic jaw-tracking system with 6 degrees of freedom was used to record the motion of the lateral and medial poles of the working condyle during mastication of standardized hard, gummy jelly. The data from the first 10 cycles were analyzed. The lateral and medial poles of the condyle on the crossbite side moved more in the medial direction and less in the lateral direction during mastication in the crossbite patients than the condyle in the normal subjects. The lateral pole of the working condyle moved more in the posterior and inferior directions and less in the anterior direction than the medial pole in all subjects. These results suggest that these condylar movements in patients with unilateral posterior crossbites might be related to the susceptibility to TMJ disc displacement, particularly the lateral portion.
authors.affiliation: Department of Orthodontics and Dentofacial Orthopedics, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan.
authors.forename: Shouichi
authors.initials: S
authors.lastname: Miyawaki
authors.forename: Yuko
authors.initials: Y
authors.lastname: Tanimoto
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Araki
authors.forename: Akira
authors.initials: A
authors.lastname: Katayama
authors.forename: Takuo
authors.initials: T
authors.lastname: Kuboki
authors.forename: Teruko
authors.initials: T
authors.lastname: Takano-Yamamoto
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002508:Cephalometry; D004198:Disease Susceptibility; D004581:Electronics / Q000295:instrumentation; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D004204:Joint Dislocations / Q000503:physiopathology; D008297:Male; D008310:Malocclusion / Q000503:physiopathology*; D008335:Mandibular Condyle / Q000503:physiopathology*; D008409:Mastication / Q000502:physiology*; D009068:Movement; D055095:Optics and Photonics / Q000295:instrumentation; D019224:Temporomandibular Joint Disc / Q000503:physiopathology