| Co-Investigator(Kenkyū-buntansha) |
NODA Koji Tsurumi University, Dentistry, assistant, 歯学部, 助手 (10148059)
NAKAMURA Yoshiki Tsurumi University, Dentistry, lecturer, 歯学部, 講師 (10097321)
田中 隆 鶴見大学, 歯学部, 助手 (50271367)
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| Budget Amount *help |
¥6,600,000 (Direct Cost: ¥6,600,000)
Fiscal Year 1996: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1995: ¥5,600,000 (Direct Cost: ¥5,600,000)
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| Research Abstract |
Cytochrome c oxidase activity, an indicator of ATP productivity, was examined in rat first upper molars that were moved by varied force magnitudes in order to assess the experimental tooth movement on the standing point of biomechanical activity. we focused histochemically on osteoclasts, odontoclasts, and multinucleated giant cells (MNGcell) resorbing degenerating tissues that appeared in the area of compressed periodontal ligaments in all experimental groups. In the present study, seven kinds of orthodontic forces consisting of five continuous force group (NT) of 0.8g, 1.6g, 4g, 8g, and 18g and two non-continuous force group (ST) of 8g and 18g were applied in experimental periods of 1d, 7d, 14d, 21d, and 28d. Following the experimental tooth movements, the enzymal activity was examined, and the reactive products of the enzyme was measured by a real time image analyzer. In NT-0.8g group, the degenerating tissue could not be seen in the compressed area where comparatively many osteoclasts with high enzymal activity appeared in all experimental periods. In addition, the enzymal activity of odontoclasts was low, and root resorption was rarely seen in this group. This result may indicate a presence of optimal force on rat experimental tooth movement, 6.8-8.3g in human premolar, but it was unreal to apply practical orthodontic treatment because of that only a slight tooth movement occur in this group. On the other hand, largest tooth movement could be seen in NT-8g group. The degenerating tissue could be seen obviously in this group, and osteoclasts, odontoclasts, and MNGcells showed high enzymal activity, indicating a dynamic reconstruction in the compressed periodontal ligament. The magnitude of 8g in rat upper first molar was applicable to 68-83g in human premolar. From these results, it was suggested that a more effective tooth movement is conducted by osteoclastic bone resorption that originated in high ATP productivity.
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