| Project/Area Number |
09672095
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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 |
矯正・小児・社会系歯学
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| Research Institution | Tokyo Medical and Dental University |
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Principal Investigator |
FUJITA Yukihiro Tokyo Medical and Dental University, Faculty of Dentistry, Lecturer, 歯学部, 講師 (50192729)
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| Co-Investigator(Kenkyū-buntansha) |
SOMA Kunimichi Tokyo Medical and Dental University, Faculty of Dentistry, Professor, 歯学部, 教授 (10014200)
HISANO Masataka Tokyo Medical and Dental University, Faculty of Dentistry, Assistant Professor, 歯学部, 助手 (80282763)
OHTSUBO Kunihuko Tokyo Medical and Dental University, Faculty of Dentistry, Assistant Professor, 歯学部, 助手 (20272601)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 1998: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1997: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Lip sensation / Orthodontic patients with interference of oral lip closure / Gum chewing / Orthodontic treatment / Changes of jaw movements / Changes of masticatory muscle activities / Microneurography method / positive-feedback mechanism / 口唇閉鎖不全 / 不正咬合者 / 最大開口距離 / 顎二腹筋筋電図 / 咬筋筋電図 |
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| Research Abstract |
To investigate the most effective inputs from human lips to control the mastication, from orthodontic point of view, we analysed the masticatory jaw movements in the orthodontic patients with interference of oral lip closure and the subjects without that and compared these data between both groups in 1997. After the severe maxillary protrusion or openbite cases were treated orthodontically, their lips can close easier and their positive feedback mechanism on mastication may be better because of increasing the sensory inputs from their lips. So we studied whether there are any changes in the path of jaw movements and masticatory muscle activities before and after the orthodontic treatment of the patients with interference of oral lip closure. In addition, we recorded mental nerve action potential innervating human lower lip by using microneurography method to investigate the input mechanism of jaw reflex on mastication in 1998. The following results were obtained.
The maximum jaw opening distances of mastication in the orthodontic patients with interference of oral lip closure were smaller than those of the control. On the other hand, after orthodontic treatment of a handycap patient, her maximum jaw opening distance was. increased, the time-lag between the start of closing phase and the onset of masseter muscle activity prolonged, the duration period of digastric muscle activity prolonged, and the time-lag between the start of occluding phase and the onset of digastric muscle activity shortened. Furthermore, it was identified that lip sensory information about the jaw position and velocity modulated masticatory action via positive feedback mechanism.
These results suggested strongly that the orthodontic cancellation of the skeretal discrepancies changes the conduction pattern of afferent inputs, and may regenerate masticatory movement.
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