| Budget Amount *help |
¥2,119,000 (Direct Cost: ¥1,630,000、Indirect Cost: ¥489,000)
Fiscal Year 2010: ¥962,000 (Direct Cost: ¥740,000、Indirect Cost: ¥222,000)
Fiscal Year 2009: ¥1,157,000 (Direct Cost: ¥890,000、Indirect Cost: ¥267,000)
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| Research Abstract |
Osteoarthritis (OA) occurs on various joints. It is known that causes of knee OA are deformity of the joints, muscular weakness, and so on. They might correlate with OA of the temporomandibular joint (TMJ), but there is no research about them. In this study, to investigate the relationship between TMJ dysplasia and OA during growth, we made the animal study model (rat) which can recreate TMJ dysplasia, and evaluated changes under nonphysiological load induced by jaw excess opening. 3-week-old male Wistar rats were used for this study. In the experimental group, the masseter muscles were bilaterally resected. After 3 and 6 weeks from the beginning of it, we sacrificed rats, made morphometric assessment of condyle with micro CT, and performed histomorphometry with toluidine blue staining. In the experimental group, we detected smaller condylar head, lower bone density of subchondral bone, and thinner condylar cartilage compared with the control group. So, we were able to make the TMJ dys
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plasia model. Next, 3-week-old male Wistar rats were classified into four groups. The first group served as control; and in the second group, jaw opening was forced for 5 days; for 3 hours per day, when the rats were 9 weeks old. In the third and fourth groups, the masseter muscles were bilaterally resected at 3 weeks of age, and the rats in the fourth group were additionally forced to open their jaw at 9 weeks of age. At the end of the experiment, all rats were sacrificed to evaluate histological differences in four groups. The jaw-opening rats revealed inflammatory changes including synovial hyperplasia, dilated vasculature, and fibrin deposits. Especially, the masseter-resection (+) jaw-opening (+) group showed more significant changes compared with the masseter-resection (-) jaw-opening (+) group. While the groups with no jaw-opening showed noninflammatory changes. These results suggested that TMJ dysplasia caused by decreased masseter activity during growth might be correlated with onset and exacerbation of arthritis, and additionally OA following them. Less
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