| Project/Area Number |
15592181
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Orthodontic/Pediatric dentistry
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| Research Institution | Aichi-Gakuin University |
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Principal Investigator |
NEGORO Takefumi Aichi-Gakuin University, School of Dentistry, Assistant Professor(temporary), 歯学部, 非常勤講師 (30211460)
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| Co-Investigator(Kenkyū-buntansha) |
FUJIWARA Takuya Aichi-Gakuin University, School of Dentistry, Assistant Professor, 歯学部, 講師 (40340145)
MORITA Takumi Aichi-Gakuin University, School of Dentistry, Instructor, 歯学部, 助手 (60367612)
HIRABA Katsunari Aichi-Gakuin University, School of Dentistry, Professor, 歯学部, 教授 (60175560)
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| Project Period (FY) |
2003 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,900,000)
Fiscal Year 2006: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2005: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2004: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2003: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Keywords | Mandibular condyle / Mandibular disc / Occlusal vertical dimension / Analysis of electromyogram (EMG) / Analysis of Jaw tracking / Cortical masticatory area / Rabbits / CCD camera |
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| Research Abstract |
Temporomandibular joint disorder [Disturbance of jaw function] is often accompanied by pain of the temporomandibular joint and abnormal movements of the mandibular condyle. To record such a morbid condition and to elucidate the mechanisms of its development, we assume it necessary to investigate into movements of the mandibular condyle and activities of the lateral pterygoid muscle that directly exerts its influence to movements of the condyle. We recorded movements of the incisal point and the mandibular condyle during masticatory-like movements induced by electrical stimulation of the cortical masticatory area of urethane-anesthetized rabbits. There is a time lag between the onset of electromyogram (EMG) and the emergence of mechanical tension, and this time lag cannot be neglected in such a rapid movement as masticatory movements of rabbits. Accordingly we analyzed the relation between the EMG and the jaw movements taking this time lag quantitatively into consideration.
The trajector
… More
y of movements of the incisal point on the frontal plane showed a grinding-type movement, crossing the midline during the occlusal phase. During this movement, the movement of the mandibular condyle [incisal point] showed approximately the same trajectory on the working and balancing sides during the jaw-opening phase, while the trajectory of movements of the mandibular condyle in the jaw-closing and occlusal phases passed above the trajectory in the jaw opening phase on the working side, whereas it passed below the trajectory in the jaw-opening phase on the balancing side.
The lateral pterygoid muscle showed a biphasic activity coinciding with the middle occlusal phase and the jaw-opening phase. In addition to this finding, we took the delay time from the onset of EMG activity to the emergence of mechanical tension into consideration, and we assumed that these muscle activities evoked the lateral jaw movement across the midline at the late occlusal phase as well as the jaw-opening movement from the midline region in the jaw-opening phase. On the other hand, the lateral pterygoid muscle on the balancing side showed a continuous activity from the late occlusal phase to the jaw-opening phase. This activity was supposed to evoke the return of the jaw to the midline at the early jaw-opening phase and the following jaw-opening movement. Thus, by the study taking the delay time into consideration, we were able to elucidate the roles of the masseter and lateral pterygoid muscles in jaw movements. Less
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