title: Postero-inferior condylar movement induced by artificial occlusal interference on the balancing side during fictive mastication in rabbits.
abstract: OBJECTIVE
  Tooth contact does not occur on the balancing side during mastication. Hence, it is possible that the presence of occlusal interference on the balancing side causes mandibular rotation followed by atypical condylar movement because the jaw-closing muscle activity on the working side is greater than on the balancing side. The aim of the present study was to investigate the relationship between occlusal contact on the balancing side and condylar movement during mastication.
  
  
  METHODS
  EMG activity of the masseter (MS), lateral pterygoid (LP) and digastric (DG) muscles and jaw movements were recorded. Condylar movements in the sagittal plane were recorded using a high speed charge-coupled device (CCD) camera. Incisal point movements were recorded using a magnet on the mentum and a magnetometric sensor on the nasal bone. A removable biting plate was used to introduce an artificial occlusal interference on the balancing side.
  
  
  RESULTS
  Nine of the 10 rabbits showed large postero-inferior condylar movement (Pi-Cm) when a biting plate was applied on the balancing side. Five rabbits showed very small Pi-Cm when a biting plate was applied on the balancing side. In the small Pi-Cm group, MS activity decreased markedly and LP and DG transient activity appeared in the early occlusal phase in the presence of the biting plate.
  
  
  CONCLUSIONS
  Interference on the balancing side always caused Pi-Cm on the ipsilateral side during mastication. However, the degree of Pi-Cm was often decreased by a jaw opening reflex response.
authors.affiliation: Department of Physiology, School of Dentistry, Aichi-Gakuin University, Kusumoto-cho 1-100, Chikusa-ku, Nagoya 464-8650, Japan. Electronic address: takumi@dpc.agu.ac.jp.
authors.forename: Takumi
authors.initials: T
authors.lastname: Morita
authors.affiliation: Department of Physiology, School of Dentistry, Aichi-Gakuin University, Kusumoto-cho 1-100, Chikusa-ku, Nagoya 464-8650, Japan.
authors.forename: Katsunari
authors.initials: K
authors.lastname: Hiraba
authors.affiliation: Department of Physiology, School of Dentistry, Aichi-Gakuin University, Kusumoto-cho 1-100, Chikusa-ku, Nagoya 464-8650, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Matsunaga
authors.affiliation: Department of Oral and Maxillofacial Surgery, School of Dentistry, Aichi-Gakuin University, Suemori-dohri 2-11, Chikusa-ku, Nagoya 464-8651, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Ito
authors.affiliation: Department of Oral and Maxillofacial Surgery, School of Dentistry, Aichi-Gakuin University, Suemori-dohri 2-11, Chikusa-ku, Nagoya 464-8651, Japan.
authors.forename: Hisanobu
authors.initials: H
authors.lastname: Maruo
authors.affiliation: Department of Oral and Maxillofacial Surgery, School of Dentistry, Aichi-Gakuin University, Suemori-dohri 2-11, Chikusa-ku, Nagoya 464-8651, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Kurita
mesh_terms: D000818:Animals; D001732:Bite Force; D003766:Dental Occlusion; D004558:Electric Stimulation; D004576:Electromyography / Q000379:methods; D008297:Male; D008334:Mandible / Q000502:physiology; D008335:Mandibular Condyle / Q000503:physiopathology*; D008406:Masseter Muscle / Q000503:physiopathology; D008409:Mastication / Q000502:physiology*; D008410:Masticatory Muscles / Q000502:physiology; D019736:Prostheses and Implants; D011626:Pterygoid Muscles / Q000503:physiopathology; D011817:Rabbits; D013704:Temporomandibular Joint / Q000503:physiopathology; D013705:Temporomandibular Joint Disorders / Q000503:physiopathology
keywords: Anterior dislocation of the disc; Fictive mastication; Occlusal contact on the balancing side; Postero-inferior condylar movements; Rabbits; TMJ disorder