Related Experiment Video
Updated: Mar 25, 2026
Studying Orthodontic Tooth Movement in Mice
Published on: August 2, 2024
Postero-inferior condylar movement induced by artificial occlusal interference on the balancing side during fictive
Takumi Morita1, Katsunari Hiraba1, Tomoko Matsunaga1
1Department of Physiology, School of Dentistry, Aichi-Gakuin University, Kusumoto-cho 1-100, Chikusa-ku, Nagoya 464-8650, Japan.
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.
Conclusion:
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.
