2004 Fiscal Year Final Research Report Summary
A study on new types of retainers
| Project/Area Number |
15592040
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
補綴理工系歯学
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| Research Institution | Hokkaido University |
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Principal Investigator |
SAITO Masayasu Hokkaido Univ., Graduate School of Dental Medicine, Lecturer, 大学院・歯学研究科, 講師 (00133752)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAYAMA Yoshiyuki Hokkaido Univ., Graduate School of Dental Medicine, Research Assistant, 大学院・歯学研究科, 助手 (30236369)
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| Project Period (FY) |
2003 – 2004
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| Keywords | partial denture / clasp / rest / rigid / indirect retainer / displacement / stress distribution |
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| Research Abstract |
A mandibular simulation model of unilateral free-end missing teeth was used in this study. Three types of R-clasp (distal, mesial and distal, mesial rest) were designed as direct retainers. R-clasp included a proximal plate and a lingual enlarged bracing arm in order to get a rigid connection between the abutment tooth and the retainer. Double Akers clasps as indirect retainer were placed at from the first premolar to the second molar. When the load was applied, the stress distribution of the direct abutment tooth and the displacement of the denture base and the lingual bar were measured.
The followings were obtained. When only the rest position of R-clasps was changed in this study, there was not a significant difference among the types of R-clasps. The position of the indirect retainer influenced the stress distribution and the displacement. The more posterior the indirect retainer was, the smaller the stress distribution on the apical of the abutment tooth and the denture base displacement were. When the indirect retainer was placed at more posterior teeth, the distal stress of abutment root decreased and the buccal stress of that increased. The median part of the lingual bar rose in all designs. The more posterior the indirect retainer was, the larger the ascension of lingual bar was. It was indicated that the double Akers clasp as indirect retainer placed between 1^<st> premolar and 2^<nd> premolar or between 2^<nd> premolar and 1^<st> molar when R-clasp was used as direct retainer.
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