巻号一覧
55 巻, 5 号
May
選択された号の論文の14件中1～14を表示しています
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研究
研究
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高橋 清造, 高橋 卓, 勝田 基嗣, 山田 正2008 年 55 巻 5 号 p. 295-300
発行日: 2008年
公開日: 2008/11/06
ジャーナル オープンアクセスAlumina granule admixed with liquid paraffin was formed by flow compaction to square columnar-shaped green compact with eccentric and concentric spherical surfaces. The maximum sintered density was 96.6% on relative density by addition of liquid paraffin 2.5 mass% and compacting pressure of 98 MPa. Outer diameter of sintered compact was shrunk from green compact to 18%. The height from center of concentric spherical surface of sintered compact was shrunk from green compact to 18.7%. The height from center of eccentric spherical surface on sintered compact was shrunk from green compact to 18.5%. The difference of the shape precision of eccentric spherical surfaces at thin side on sintered compact by liquid paraffin content of 2.5 mass% and 5.0 mass% was not recognized. The difference of the shape precision between thin side and thick side of eccentric spherical surface on sintered compact by liquid paraffin content of 2.5 mass% was not recognized, it appeared the effect of flow compaction. However, in case of liquid paraffin content of 5.0 mass% exceeded the optimum value, the shape of thick side of eccentric spherical surface on sintered compact was smaller diameter than the shape of thin side.抄録全体を表示PDF形式でダウンロード (601K)
特集：傾斜機能・生体材料
総報
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後藤 孝2008 年 55 巻 5 号 p. 302
発行日: 2008年
公開日: 2008/11/06
ジャーナル オープンアクセスPDF形式でダウンロード (100K)
総説
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新家 光雄2008 年 55 巻 5 号 p. 303-311
発行日: 2008年
公開日: 2008/11/06
ジャーナル オープンアクセスβ-type titanium alloys composed of non-toxic and allergy-free elements with low modulus are getting much attention for biomedical applications. The author has developed Ti-29Nb-13Ta-4.6Zr (TNTZ) where Nb, Ta, and Zr are non-toxic and allergy-free are elements showing low Young's modulus. Focusing on TNTZ, biological and mechanical biocompatibility including fatigue characteristics, fretting fatigue characteristics, and wear characteristics, functionalities such as super elastic and shape memory effect, and bioactive surface modification of low modulus titanium alloys with high biological and mechanical biocompatibility for biomedical applications are described.抄録全体を表示PDF形式でダウンロード (1514K)
研究
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仲井 正昭, 新家 光雄, 赤堀 俊和, 山野井 秀明, 伊津野 真一, 原口 直樹, 伊藤 芳典, 小笠原 忠司, 大西 隆2008 年 55 巻 5 号 p. 312-317
発行日: 2008年
公開日: 2008/11/06
ジャーナル オープンアクセスHigh Young's modulus of metallic biomaterials in comparison with that of bone affects harmfully on bone healing and remodeling. Therefore, it is important to decrease Young's modulus of the metallic biomaterials. In that case, porous materials are advantageous from the viewpoint of obtaining a lower Young's modulus, because Young's modulus decreases with increasing porosity of the porous materials. However, with an increase in porosity, the other mechanical properties start deteriorating simultaneously. This deterioration of the mechanical properties is probably derived from the stress concentration at the pores of the porous materials. In comparison with metallic biomaterials, polymers exhibit lower Young's moduli; thus a polymer filling is a likely option to improve the mechanical properties of porous materials by preventing the stress concentration at the pores without increasing the Young's modulus. Furthermore, certain polymers exhibit intrinsic biofunctionalities. Thus, polymer filling is expected to improve the mechanical properties and impart biofunctionalities to porous materials without an increase in its Young's modulus. In this study, the pores of porous pure titanium (pTi) with the porosity of 22-50% were filled with a medical polymer (polymethylmethacrylate: PMMA). The effects of PMMA filling on the tensile strength and Young's modulus of pTi were then investigated. As a result, it is found that the PMMA filling improves the tensile strength of pTi with the porosity over 40%, although not significantly affecting the Young's modulus of pTi.抄録全体を表示PDF形式でダウンロード (1474K) -
成島 尚之, 上田 恭介, 後藤 孝, 勝部 朝之, 川村 仁, 中川 浩伸, 平 雅之2008 年 55 巻 5 号 p. 318-324
発行日: 2008年
公開日: 2008/11/06
ジャーナル オープンアクセスCalcium phosphate coating films were fabricated on Ti-6Al-4V alloy plates and implants with a blast-treated surface using radiofrequency (RF) magnetron sputtering and were evaluated in vitro and in vivo. Amorphous calcium phosphate (ACP) and oxyapatite (OAp) films obtained in this study could cover the blast-treated Ti-6Al-4V substrate very efficiently, maintaining the surface roughness. For the in vitro evaluations of the calcium phosphate coating films, bonding strength and alkaline phosphatase (ALP) activity were examined. The bonding strength of the coating films to a blast-treated Ti-6Al-4V plate exceeded 60 MPa, independent of film phases. When compared with an uncoated Ti-6Al-4V plate, the increase in the ALP activity of osteoblastic SaOS-2 cells on a blast-treated Ti-6Al-4V plate coated with the ACP and OAp films was confirmed by a cell culture test. The removal torque of screw type Ti-6Al-4V implants with a blast-treated surface from the femur of a Japanese white rabbit increased with the duration of implantation and it was statistically improved by coating an ACP film two weeks after implantation. The in vitro and vivo studies suggested that the application of the sputtered ACP film as a coating on titanium implants was effective in improving their biocompatibility with the bones.抄録全体を表示PDF形式でダウンロード (1233K) -
佐藤 充孝, 塗 溶, 後藤 孝, 上田 恭介, 成島 尚之2008 年 55 巻 5 号 p. 325-330
発行日: 2008年
公開日: 2008/11/06
ジャーナル オープンアクセスCa-Ti-O and Ca-P-O films were prepared by MOCVD. The phases, composition and morphology of Ca-Ti-O and Ca-P-O films changed depending on the molar ratio of Ca to Ti (RCa/Ti) and Ca to P (RCa/P) precursors, total pressure (Ptot) and substrate temperature (Tsub). CaTiO3 films in a single phase were obtained at Tsub=973 and 1073 K. CaTiO3 films prepared at Tsub=873 K had a dense and smooth surface. CaTiO3 films prepared at Tsub=1073 K had complicated rough surface with a cauliflower-like texture. α-TCP and HAp films in a single phase were obtained at Tsub=973 and 1073 K, and both films had dense microstructure. Apatite formed after 3 days on the CaTiO3 film, while 14 days on the α-TCP film and 6 hours on the HAp film, respectively. Functionally graded Ca-Ti-O/Ca-P-O films were successfully prepared by MOCVD, and expected to have good bone conductivity and adherence to Ti substrate.抄録全体を表示PDF形式でダウンロード (1193K) -
丸森 亮太朗, 木村 禎一, 後藤 孝, 依田 正信, 木村 幸平2008 年 55 巻 5 号 p. 331-335
発行日: 2008年
公開日: 2008/11/06
ジャーナル オープンアクセスIn this study, TiO2 films were prepared on Ag-Pd alloys by Plasma-enhanced Chemical Vapor Deposition (PECVD) using Ti(O-i-Pr)2(dpm)2 precursor. Ag-Pd alloys are widely used as a substrate material of a resin-veneered dental crown. Since an adhesion of a dental resin to the Ag-Pd alloy substrate is poor, protuberances are usually formed on the substrate surface to sustain the mechanical retention. One of the weak points in the resin-veneered dental crown is that a mechanical retention should be indispensable to fix the resin onto the metal frame. Instead of mechanical retention, TiO2 films were prepared on the substrates.
The effects of the deposition conditions on the crystalline phases, microstructures, and color of the deposited films were investigated. As a result, at a substrate pre-heating temperature Tdep=500°C, microwave power PM=2 kW, deposition pressure Ptot=0.4 or 0.7 kPa, the film color changed from black to white, and crystalline phase was anatase. And the microstructure of the film was granular. The grain size was a diameter of about 100 nm. These are optimum deposition conditions.抄録全体を表示PDF形式でダウンロード (1328K)
解説
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東藤 貢, 馬渡 正明, 佛淵 孝夫2008 年 55 巻 5 号 p. 336-340
発行日: 2008年
公開日: 2008/11/06
ジャーナル オープンアクセスKyocera ABS system, a ceramics-on-ceramics type hip prosthesis, has been prohibited due to consecutive accidents such as the dissociation of the UHMWPE liner and the fracture of the alumina inlay. It has been presumed that loosening of the locking system connecting the metal shell and the liner is the primary mechanism of the liner dissociation. In this study, the finite element analysis (FEA) of the ABS system was conducted to assess the loosening mechanism qualitatively and quantitatively. The FEA results showed that very high stress concentration was generated at the locking grooves of the liner, indicating severe damage was likely formed under high stress condition. The FEA including a damage model was also performed to simulate such damage formation at the locking grooves. The FEA result exhibited that the four grooves were severely damaged under tensile and compression loadings, resulting in the loosening of the locking system. It was thus confirmed that the dissociation of the liner was initiated by those damage formation at the grooves.抄録全体を表示PDF形式でダウンロード (1353K)
研究
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加川 尊, 東藤 貢, 竹之下 康治, 名井 陽2008 年 55 巻 5 号 p. 341-346
発行日: 2008年
公開日: 2008/11/06
ジャーナル オープンアクセスThe effect of press process on the mechanical properties of PLLA and HA/PLLA was investigated. Bending modulus and bending strength were effectively improved by press process. The improvement was more effective in the uniaxial press than in the biaxial press due to higher level of molecular orientation. Mode I fracture energy was evaluated for the materials. FE-SEM observation of the fracture surfaces was also performed to characterize the effects of press process on microscopic deformation and failure behavior. Mode I fracture energy was dramatically improved due to the press process. The primary mechanisms of the improvement are thought to be crevasse-like failure at the interlayers of the layered structure created by press process and improved adhesion between HA particles and PLLA matrix.抄録全体を表示PDF形式でダウンロード (1161K) -
入江 皓平, 東藤 貢, 松下 恭之, 古谷野 潔2008 年 55 巻 5 号 p. 347-352
発行日: 2008年
公開日: 2008/11/06
ジャーナル オープンアクセスThe purpose of this study is to develop a detailed 3-Dimension mandibular model with dental implants on the basis of CT data and to conduct stress analysis to characterize the effects of the material type of prosthesis on stress/strain distribution in the mandibular bone. Three types of materials, a polymer and two metals, with different elastic properties were chosen as the prosthesis materials. The analytical results showed that the Mises equivalent stress and equivalent elastic strain along the circumference of the implant at distal side were much higher than in the anterior region. It was also shown that the stress/strain concentration at the bone increased with decreasing the prosthesis stiffness. The stress/strain concentration observed in the circumference of the implants could be the driving force for loosening and fracture of the implants.抄録全体を表示PDF形式でダウンロード (1050K) -
森田 康之, 内野 正和, 東藤 貢, 松下 恭之, 新川 和夫, 古谷野 潔2008 年 55 巻 5 号 p. 353-358
発行日: 2008年
公開日: 2008/11/06
ジャーナル オープンアクセスStudy on displacement and deformation behaviors of periodontium under dental occlusion, in general, was concluded only from two information, which are a single-point displacement value from a strain gauge, applied force from a load cell, etc. Direct visualization of these behaviors has been actively conducted by various research groups in the world. However, these studies have relied on dried periodontia or photoelastic materials such as resin to simulate living tissue. Thus, their results may differ significantly from the displacement and deformation behaviors that occur under the dental occlusion of fresh periodontium. In this study, the visualization of displacement and deformation behaviors of fresh periodontium was attempted by using the skull of a pig killed in several days earlier for rendering to obtain fresh periodontia as close as possible to live tissues. The dental occlusion was simulated by applying a forced displacement using a material tester. In addition to the dental occlusion process, we observed the displacement behavior of the fresh and dried periodontium in the process of restoration. To clarify difference in these behaviors between both periodontia, similar experiments were also conducted to compare their displacement distributions. A digital image correlation method was applied to the analysis.抄録全体を表示PDF形式でダウンロード (1200K) -
汪 文学, 高雄 善裕, 松原 監壮, 右近 晋一2008 年 55 巻 5 号 p. 359-364
発行日: 2008年
公開日: 2008/11/06
ジャーナル オープンアクセスA hand made nano-whisker reinforced glass ceramics used for the artificial crown is developed. Commercially available white nano-whiskers 9Al2O32B2O3 and dental glass-ceramic powders of porcelain AAA are used as reinforcement and matrix, respectively. A wet mixing process is conducted to ensure a homogeneous distribution of whiskers in the whisker/powder mixture by the use of a mortar. The remaining hand made procedures and the heating process of nano-whisker reinforced glass ceramics are the same as those of glass ceramics without whiskers used by ordinary dental technicians. The hand made ceramics specimens are investigated by means of SEM, EPMA, hardness tester and testing machine for various whisker weight fractions. Slight increase in flexural stiffness and strength and moderate increase in fracture toughness are observed. The reinforcement does not give serious damage if the weight fraction of whiskers is less than 7%.抄録全体を表示PDF形式でダウンロード (1694K) -
— TiH2-(SHAp-100+β-TCP)系傾斜機能材料の作製 —渡辺 卓, 山本 昌平, 深瀬 康公, 松田 信之, 出井 裕, 岡野 道治2008 年 55 巻 5 号 p. 365-372
発行日: 2008年
公開日: 2008/11/06
ジャーナル オープンアクセスHydroxyapatite (HA)/β-tricalcium phosphate (β-TCP)/TiH2 FGMs were fabricated by spark plasma sintering (SPS). It aimed at the compatibility of strength and a good biocompatibility by fabricating the artifical tooth root as FGMs. This study focuses on the effects of composition of the layer on the bending strength, elastic modulus, thermal expansion coefficient and crack generation behavior. The measurement of the bending strength clarified that strength lowered in a specific composition. The residual stresses induced in the FGMs were calculated by FEM. By this analysis, it became clear that the layer on which stress concentrated. And the stress can be lowered by change the layer composition gradually. The generation of the crack became hard by controlling the composition of the layer and suppressing the stress below the bending strength. The crack-free FGMs with five concentric layers were successfully fabricated by SPS.抄録全体を表示PDF形式でダウンロード (1387K) -
堀田 幹則, 後藤 孝2008 年 55 巻 5 号 p. 373-377
発行日: 2008年
公開日: 2008/11/06
ジャーナル オープンアクセスAl2O3-cBN functionally graded material (FGM) was synthesized by spark plasma sintering (SPS) using powder compact with graded compositions containing 0 to 20 vol% cBN under a uniaxial pressure of 100 MPa. Densification, phase transformation of cBN, microstructure, hardness and fracture toughness of the FGM were investigated. Al2O3-cBN FGM with relative density of more than 99% was prepared at 1300°C for 600 s. No obvious interface between Al2O3 and cBN layers was observed, and cBN particles were uniformly dispersed in an Al2O3 matrix. Vickers hardness and fracture toughness continuously increased with cBN content, and reached to 28 GPa and 5 MPa·m1/2 respectively at the surface layer.抄録全体を表示PDF形式でダウンロード (971K)
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