1989 Fiscal Year Final Research Report Summary
A Study on the Reproducibility of the Crown's Height.
| Project/Area Number |
63480434
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
補綴理工系歯学
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| Research Institution | Showa University |
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Principal Investigator |
KAWAWA Tadaharu Showa Univ. School of Dentistry, Professor, 歯学部, 教授 (30014103)
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| Co-Investigator(Kenkyū-buntansha) |
FUKUNAGA Hideki Showa Univ. School of Dentistry, Assistant, 歯学部, 助手 (50199254)
TAKAHASHI Hidekazu Showa Univ. School of Dentistry, Lecturer, 歯学部, 講師 (90175430)
WARITA Kenji Showa Univ. School of Dentistry, Lecturer, 歯学部, 講師 (10119290)
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| Project Period (FY) |
1988 – 1989
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| Keywords | three-dimensional measurement / rubber base impression material / stone cast / master impression / full arch impression / intercuspal position / articulator / 咬合器 |
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| Research Abstract |
Crowns and bridges using a conventional indirect method become 100-300mum high at the first intercuspation. In order to solve this problem , a metallic model of a simplified maxillary dentition was prepared and we investigated the influence of tray designs and rubber impressions using a three-dimensional measurement system.
The results were as follows:
1.Distortion of rubber impressions was small so that the reproducibility of impressions was Superior three-dimensionally.
2. Stone casts made from a custom tray were more accurate than the cast made from an occlusal tray.
Taking into consideration the results of our initial study, we then mounted the Upper and lower metallic model of dentition on a articulator and took the upper and lower impressions respectively using a custom tray and rubber impression material and made the stone casts. On the articulated casts,the core was taken as a record of the occlusal relation between the abutment and the opposite tooth. The two distances of the reference points of the abutment tooth and the opposite tooth were measured with the IP-checker. The difference of the two measurements was obtained as the occlusal height of the cast.
As a result, the Upper and lower stone casts made from the custom tray, the rubber impression material (especially, the silicone rubber) and the improved stone were only 30mum higher than the original model.
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