1992 Fiscal Year Final Research Report Summary

Study on the Muscle Function in Orthognathic Patients.

Research Project

Project/Area Number	03454478
Research Category	Grant-in-Aid for General Scientific Research (B)
Allocation Type	Single-year Grants
Research Field	小児・社会系歯学
Research Institution	Tokyo Medical and Dental University
Principal Investigator	KURODA Takayuki Tokyo Medical and Dental University, 2nd Department of Orthodontics, Professor., 歯学部, 教授 (10013939)
Co-Investigator(Kenkyū-buntansha)	KATO Yoshiyuki Tokyo Medical and Dental University, 2nd Department of Orthodontics, Instructor., 歯学部, 助手 (30224554) SUZUKI Syouichi Tokyo Medical and Dental University, 2nd Department of Orthodontics, Instructor., 歯学部, 助手 (90187732) SUSAMI Takafumi Tokyo Medical and Dental University, 2nd Department of Orthodontics, Instructor., 歯学部, 助手 (80179184) MIYASAKA Takahito Tokyo Medical and Dental University, 2nd Department of Orthodontics, Instructor., 歯学部, 助手 (80181999) MOTOHASHI Nobuyoshi Tokyo Medical and Dental University, 2nd Department of Orthodontics, Lecturer., 歯学部, 講師 (10134735)
Project Period (FY)	1991 – 1992
Keywords	congenital anomaly / facial deformity / orthognathics / muscle function / jaw movement / temporomandibular joint / temporomandibular disorder / laser
Research Abstract	The purpose of this series of studies was to clarify the adaptability of functional elements, such as muscle function, jaw movement and temporomandibular joint function, to the sudden change of facial morphology resulting from corrective orthognathic treatment. The comparative study on the attachments of human temporalis and masseter muscles to the facial bones revealed differences in of the bone structure and insertion pattern of Sharpey's fibers. In animal experiments, the denervation of masseteric nerve and experimentally induced masseter paralysis caused facial asymmetry and confirmed the usefulness of these experimental models for further cephalometric and histological examinations. Clinical studies were performed on facial morphology, muscle function and jaw movement of patients with facial deformities and congenital anomalies. On patients with mandibular prognathism, long term improvements in masticatory muscle functions were found after orthognathic surgery, and characteristic morphology of the temporomandibular joint was also evident. In one patient with mandibular retrognathism caused by condylar degeneration whose occlusion was corrected by orthodontic treatment the jaw movement was quite stable, although the positional difference between most retruded position and centric occlusion was notably large. This fact seemed valuable in evaluating the jaw position of treatment goal. On the cleft lip and palate patients with deep bite, large amount of rotation movement of the mandible was found in addition to characteristic facial morphologies such as mandibular anti-clockwise rotation. In one patient with hemifacial microsomia, asymmetric jaw movement and large mobility of the affected condyle were observed. Furthermore, a low power diode laser appeared to be effective in alleviating pain and mouth opening difficulties associated with temporomandibular disorders.