| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1994: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1993: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
We have collected 150 sets of the upper and lower jaw casts collected both during the prime of youth (in their twenties) and during the matured age (about 20 year later) of the identical individuals to get age changes in the shape of healthy persons.
As for dentition, alveolar part and palete, a CAT (computer aided testing) system was used to measure the three-dimensional shape of the dentition cast. Based on this measurement, we made an "AISOME picture" of the old and the new casts to investigate which parts major age changes and which parts minor ones. As a result, the investigation showed a tendency that the center part of the palete and alveoler part had major changes and that there were only minor changes in the shape seen near midway between the plate and alveoler part.
The occurence rate of mandibuler torus is 50% during the prime of youth and 65% during the matured age, respectively. In most of the case, it occurs bilaterally and almost symmetrically. It occures most often, during the prime of youth, on the canine, the first and the second premolars. It occurs quite often, during the matured age, on the canine, the first and the second premolars, as well as on the central incisor and the second molar.
As for occlusion, the contact rates during the prime of youth were found to be high on the working side of the canine, the premolar and the second molar. Those during the matured age showed a tendency to lead to a group functioned occlusion, where the entire working side is guiding according to progress of attrition.
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