| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1998: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1997: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
A close relationship may be present between the masticatory muscle activities and the oral environment. The present study was carried out to evaluate the effect of the incrase in the vertical dimension, the change in occlusal area and region on masticatory muscle activity.
The subjects were 10 adult males with normal masticatory function.
1) Using a whole day EMG recording and analysis system, 24-hour masticatory electrornyograms were recorded with application of the plates to elevate the occlusal plane by 2,4, and 8mm as conditions 2,4, and 8, respectively, with the plate designed not to elevate the occlusal plane as condition 0, or without any plate as condition N.
2) The maximum occlusal force and occlusal contact area of each subject were tested by using Dental Prescale. The subjects were classified into two groups from the following two different criteria : the maximum occlusal force and the proportion of right-hand, and left-hand occlusal forces. On the basis of the data obtained fr
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om the above-mentioned occlusal forces, three biteplates were desined. Partial contact biteplate having a contact area on a tooth of lateral side, bilateral contact biteplate having two contact area on the respective teeth of bilateral side, and full contact biteplate contacting with whole teeth. Using a long-term EMG recording nocturnal EMG was recorded with application of the biteplate.
The following results were obtained.
1) The nocturnal masseter muscle activites are significantly reduced when the interarch distance is increased by applicaton of the plates to elevate the occlusal plane widely above the rest position of the mandible. The activites can also be reduced by the factors other than elevation of the occlusal plane.
2) The nocturnal masseter muscle activies are decreased when given occlusal contact on one side. IBut when given occlusal contact on bilateral side, the decrease of nocturnal masseter muscle activites are related to maximum occlusal force and the proportion of occlusion, but have no relation to the change of the occlusal area. Less
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