| Project/Area Number |
18592248
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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 | Kagoshima University |
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Principal Investigator |
YAMASAKI Kounosuke Kagoshima University, Graduate School of Medical and Dental Sciences, Visiting Reseacher (40363650)
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| Co-Investigator(Kenkyū-buntansha) |
MIYAWAKI Siochi Kagoshima University, Graduate School of Medical and Dental Sciences, Professor (80295807)
HARADA Shuitsu Kagoshima University, Graduate School of Medical and Dental Sciences, Professor (60128452)
HIGUCHI Itsuro Kagoshima University, Medical and Dental Hospital, Senior Assistant Professor (80183573)
NAGATA Junko Kagoshima University, Graduate School of Medical and Dental Sciences, Assistant Professor (50264429)
YOSHIDA Reiko Kagoshima University, Medical and Dental Hospital, Assistant Professor (60244258)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,850,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥450,000)
Fiscal Year 2007: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
Fiscal Year 2006: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Keywords | muccla fatigue / muscle damage / spring appliance / masseter / adaption / electromvogram / 咀嚼筋 |
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| Research Abstract |
The purpose of this study was to define types of contraction of the rat masseter muscle which was fatigued and damaged with various overactivity. In 2006, to make rat masseter overactive, we created a new method using an spring appliance which exerted a force depending on the distance between upper and lower incisor. We set protection shields to all the rat except Sham to prevent the appliance from being removed by the rat. In 2007 and 2008, we conducted a study as described later. We used 14 male Wistar rats aged 7 weeks. First we checked the overactivity with electromyogram. We found the muscle activity increased while the appliance was fixed. Secondary, we performed histological examinations. The rats were divided into 5 groups : S24, S72, S168, Sham and P group. We set the appliance for 24 hours to S24 group, 72 hours to S72 group, 168hours to S168 group. Only the protection shield was set for 168hours to P group to check the effect of protection shield. All rats were killed, masse
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ter and gastrocnemius-soleus muscle group were extracted and then changed into frozen sections. Sections were stained with haematoxylin-eosin, acid-phosphatase, or immunohistochemically stained with monoclonal antibodies for dystrophin, dysferlin, heat shock protein (HSP) 27. The experimental masseter muscle fibers showed irregularity of size and shape with enlargement of interstitial space and infiltration of mononuclear cell into the fibers. Additionally, we could see the HSP27 expression around them However, no such histological changes were observed in P group and C group. The highly conserved Hsp accumulates in cells exposed to a variety of stressful stimuli. Hsp allows cells to adapt to gradual changes in their environment and to survive in otherwise lethal conditions, and this protective mechanism also might occur in the rat masseter which was damaged by overactivity.
Masseter muscle overactivity caused by spring appliances evokes muscle damage. And some protective mechanism also may occur at the same time. Less
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