記述言語：日本語   出版者・発行元：(一社)日本老年歯科医学会  

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記述言語：日本語   出版者・発行元：(公社)日本口腔インプラント学会  

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記述言語：日本語   出版者・発行元：日本歯科衛生学会  

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記述言語：日本語  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER IRELAND LTD  

Purpose: There are no entire maxillary finite element analysis models available, as a base of reference for the dimensions of conventional segment finite element analysis models. The objectives of this study were: (1) to construct a maxillary model derived from a human skull and to investigate the strain distribution around a posterior implant embedded in it; (2) to investigate the usability of conventional segment maxillary models.
Methods: CT DICOM data of a human dried skull maxilla was imported into the Mesh Generation Tools (ANSYS AI environment) and a computer-generated implant-abutment unit was bicortically embedded into it. In this Large model, Von Mises strains under axial and buccolingual loads were then calculated by a finite element program. Moreover, two simplified maxillary segments (Simplified models) were computer-generated and their Von Mises strains were similarly calculated.
Results: Although absolute values differed markedly, strain distribution patterns in the cortical bone were similar to those in the Simplified models: high Von Mises strains in the cortical bone concentrated in the sinus floor around the implant apex under axial load, and in the alveolar crest around the implant neck under buccolingual load.
Conclusions: The simplified and segmented three-dimensional finite element models of the human maxilla showed the same locations of the highest equivalent strains as the full maxilla model created from CT DICOM data. If absolute strain values are not of interest, the Simplified models could be used in strain analyses of simulated posterior maxilla for diagnostic suggestions in implant placement. (C) 2010 Japan Prosthodontic Society. Published by Elsevier Ireland. All rights reserved.

DOI： 10.1016/j.jpor.2010.07.002

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER IRELAND LTD  

Purpose: There is no clear evidence of the factors that could improve implant biomechanics in the posterior maxilla. Thus, a finite element analysis was performed to investigate the effect of maxillary cortical bone thickness, implant design and diameter on stress around implants.
Methods: A total of 12 models of the posterior maxilla with implant were computer-simulated by varying the thickness of the alveolar cortical bone (1.5, 1.0, 0.5 or 0 mm) and implant characteristics (cylindrical implant of 4.1-mm diameter, screw-type implants of 4.1-mm or 4.8-mm outer diameters). On top of each implant, forces were separately applied axially (100 N) and buccolingually (50 N), and the von Mises stresses were calculated.
Results: Regardless of load direction, implant design and diameter, cortical and cancellous bone stresses increased with the decrease of crestal cortical bone thickness. In the absence of crestal cortical bone, cancellous bone stresses were highest and, under axial load, were transferred to the sinus floor. Implant design and diameter influenced stress to a less extent, especially under buccolingual load and in the presence of crestal cortical bone.
Conclusions: From a biomechanical viewpoint, to improve implant success odds in the posterior maxilla, rather than implant selection, careful preoperative evaluation of the cortical bone at the planned implant site is recommended. If this cortical bone is very thin or even lacking, implant treatment should be carried on with caution by progressive loading in the range of functional loads. (C) 2010 Japan Prosthodontic Society. Published by Elsevier Ireland. All rights reserved.

DOI： 10.1016/j.jpor.2009.12.004

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   出版者・発行元：新潟歯学会  

Objectives : This study investigated the influence of post type and loading condition on the failure resistance and primary failure mode of flared canal roots. Materials and methods : Flared post holes were prepared in 40 sound human lower premolar roots. Twenty roots received glass fiber posts with resin core (fiber specimens) and 20 received cast post-and-core (cast specimens). After cementation with resin cement, in 10 fiber and 10 cast specimens, a quasi-static bending test was performed by an Instron-type testing machine. In the other specimens, before the bending test, a bucco-lingual load was applied for 900,000 cycles using a lever-type device. Failure resistance and primary failure mode in relation with post type and loading condition were statistically analyzed (significance level: 0.05). Results : After cyclic loading, all specimens were intact; therefore, they underwent the bending test. Failure resistance showed a significant difference only for the post type (p = 0.002) (two-way ANOVA). In the presence of cyclic loading, the post type significantly influenced failure resistance (p = 0.010), whereas in its absence, it showed only a tendency to influence failure resistance (p = 0.054) (Tukey test). In the cycled specimens, significantly fewer root fractures and more frequent debonding without root fracture were found in the fiber than in the cast specimens (p = 0.02) (Fisher's exact test). Conclusions : Rather than cast post-and-cores, the use of glass fiber-reinforced posts and resin core for the restoration of flared canal teeth may prevent root fracture, but debonding may occur under high loads.本研究は漏斗状に窩洞形成された歯根の修復物における破損強さと初期の破損様式に、ポストの種類と荷重条件が及ぼす影響を検討した。漏斗状に根管形成した抜去下顎小臼歯40歯を用い、20歯にはガラスファイバーポストとコンポジットレジンコア (ファイバーポスト群)、残りの20歯には鋳造ポストと鋳造コア (鋳造ポスト群) で支台築造を作製し、レジンセメントで被験歯に合着した。各ポスト群10歯に、インストロン型万能試験機を用いてポスト－歯根複合体が破損するまで準静的曲げ試験を行った。残りの被験歯には、曲げ試験の前に、てこ型試験機を用いて2-kgfの頬舌的荷重を90万回加えた。反復荷重では全ての試料が破損しなかったので、引き続き準静的曲げ試験を行った。破損強さの測定値には二元配置分散分析法で、ポストの種類に有意差が認められた (p = 0.002) ものの、荷重条件要因および二要因間の交互作用には有意差が認められなかった。Tukey法の多重比較検定結果から、ポストの種類は反復荷重があると破損強さに有意差を示した (p = 0.010) が、反復荷重がないと影響する傾向を示したものの有意には達しなかった (p = 0.054)。破損様式に関しては、反復荷重を行った試料ではFisher's の直接確率計算法で分析すると、ファイバーポスト群が鋳造ポスト群よりも有意に歯根破折が少なく、歯根破折を伴わないポスト脱離が多かった (p = 0.020)。90万回作用させた疲労試験とそれに続く準静的曲げ試験の結果から、漏斗状に窩洞形成された歯根の修復物には、鋳造ポストよりもガラスファイバーポストとコア築成材料を用いる方が歯根破折を防ぐ可能性が示された。しかし、このガラスファイバーポストを用いた修復物には、大きな頬舌的荷重が作用すると偶発症として、ポスト脱離が高頻度に生じる可能性がある。

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記述言語：日本語   出版者・発行元：新潟歯学会  

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記述言語：日本語  

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記述言語：日本語  

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記述言語：日本語  

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記述言語：日本語  

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記述言語：日本語   出版者・発行元：(一社)日本歯科理工学会  

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記述言語：日本語  

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記述言語：日本語   出版者・発行元：一般社団法人 日本小児歯科学会  

DOI： 10.11411/jspd1963.37.2_254

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その他リンク： http://search.jamas.or.jp/link/ui/1999189011

記述言語：日本語  

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記述言語：日本語  

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記述言語：日本語  

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