| Project/Area Number |
04404006
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
人類学(含生理人類学)
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| Research Institution | The University of Tokyo |
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Principal Investigator |
ENDO Banri The University of Tokyo Graduate School of Science Professor, 大学院・理学系研究科, 教授 (20011504)
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| Co-Investigator(Kenkyū-buntansha) |
ADACHI Kazutaka The University of Tokyo Graduate School of Science Assistant, 大学院・理学系研究科, 助手 (70221041)
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥30,000,000 (Direct Cost: ¥30,000,000)
Fiscal Year 1993: ¥6,000,000 (Direct Cost: ¥6,000,000)
Fiscal Year 1992: ¥24,000,000 (Direct Cost: ¥24,000,000)
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| Keywords | Cranium / Stress Analysis / Biting Force / Mastication / バイオメカニクス / 顎運動 / 咀嚼筋 / 筋電図 / 骨ピエゾ電気 |
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| Research Abstract |
The purpose of this study is to clarify the relationship between the form and structure of the modern human skull in a viewpoint of dynamic function. We measured the jaw movement making use of the three-dimensional kinemetrical measuring system. We also measured the biting force with a custom-made apparatus, and at the same time we recorded the EMG of the temporal muscle and masseter in three subjects. The piezoelectricity was measured with high-impedance electrode at points of nasal and zygomatic bone, where the bones exist direct under the skin and the stress will increase remarkably during mastication. The mandible movement varies until a food comes between the upper and lower molar teeth. Then the mandible comes closer vertically to the maxilla. When just the upper and lower molar teeth have contact one another, the grinding movement begins. The result indicates that the integrated EMG is in proportion to the biting force greater than 4 kgf. When the biting force measuring apparatus was applied to the molar tooth in the left or right side, then the increasing ratio of the integrated EMG of the temporal muscle in the measured side would come would come remarkably greater than the ratio in the other side, in case that the biting force would go beyond 4 kgf. While the ratio in the masseter was almost the same in the both side. The piezoelectricity was observed in minus-voltage where the compression stress occurs, in the other hand it was observed in plus-voltage in the tensile stressed area. Then we measured the principle strain and its direction over the facial skeleton by the rosette type strain gages. For this experiment the artificial mandible, temporal muscle and masseter were attached to this subject skull. Every tooth was loaded by the force of 6 kgf. The result reveals that the stress is not so high in the forehead, and the amplitudes of the principle strain and its directions are almost the same in spite of the difference of the loaded point through the r
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