Effect of halloysite nanotubes on poloxamer 407-containing calcium phosphate cement for bone repair applications


Effect of immersion in NaCl solution on the electrical conductivity and the reduction of the shear bond strength of resin-modifi ed glass-ionomer-cements after current application


Effects of water immersion on shear bond strength reduction after current application of resin-modified glass-ionomer-cements containing and not containing an ionic liquid.

The enhancement in the bonding strength of advanced dental cements has enabled long-lasting dental restorations. However, the high bonding strength can cause difficulty in removing these restorations. Therefore, "smart" dental cements with simultaneous strong bonding and easy on-demand debonding ability are required. A resin-modified glass-ionomer-cement (RMGIC) with an ionic liquid (IL) has demonstrated significant reduction in the bonding strength with current application (CA). This research investigates the effect of immersion in distilled water on the electric conductivity and bonding strength of RMGIC with and without an IL and CA. The RMGIC without the IL exhibited significant electric conductivity after immersion, and a significant decrease in bonding strength with CA. In comparison, the electric conductivity after immersion and the decrease in bonding strength with CA were greater for RMGIC with the IL. Thus, the feasibility of smart dental cements capable of electrically debonding-on-demand is indicated.


Electrical shear bonding strength reduction of resin-modified glass-ionomer-cement containing ionic-liquid concept and validation of a smart dental cement debonding-on-demand

With improvement of bonding strength of recent dental cement, it is difficult nowadays to remove restorations without excessive force or vibration to tooth, occasionally resulting in damage of dentin, enamel, and dental root. Therefore, "smart" dental cement indicating strong bonding and easy debonding-on-demand simultaneously is required. In this research, resin-modified glass-ionomer-cement containing an ionic-liquid, tris(2-hydroxyethyl)methylammonium methylsulfate was produced, and the shear bonding strength before and after direct current application were evaluated. The prototype cement containing 15 to 20 mass% ionic-liquid indicated simultaneously no significant reduction of shear bonding strength from that of the original cement not containing ionic-liquid, and significant reduction of bonding strength to approximately 20% of that of the original cement after direct current application of more than 2 mmC/mm. The prototype cement in this research demonstrated that the concept of smart dental cement electrically debonding-on-demand is feasible.


Effects of powder-to-liquid ratio on properties of β-tricalcium-phosphate cements modified using high-energy ball-milling

The authors have developed a β-tricalcium-phosphate (β-TCP) powder modified mechano-chemically through the application of a ball-milling process (mβ-TCP). The resulting powder can be used in a calcium-phosphate-cement (CPC). In this study, the effects of the powder-to-liquid ratio (P/L ratio) on the properties of the CPCs were investigated, and an appropriate P/L ratio that would simultaneously improve injectability and strength was clarified. The mβ-TCP cement mixed at a P/L ratio of 2.5 and set in air exhibited sufficient injectability until 20 min after mixing, and strength similar to or higher than that mixed at a P/L ratio of 2.0 and 2.78. Although the mβ-TCP cements set in vivo and in SBF were found to exhibit a lower strength than those set in air, it did have an appropriate setting time and strength for clinical applications. In conclusion, P/L ratio optimization successfully improved the strength of injectable mβ-TCP cement.


Volume magnetic susceptibility design and hardness of Au Ta alloys and Au Nb alloys for MRI-compatible biomedical applications

Biomedical Physics & Engineering Express


Bone Ingrowth to Ti Fibre Knit Block with High Deformability

Journal of Oral & Maxillofacial Research


Application of porous titanium in prosthesis production using a moldless process: Evaluation of physical and mechanical properties with various particle sizes, shapes, and mixing ratios

The prosthetic applications of titanium have been challenging because titanium does not possess suitable properties for the conventional casting method using the lost wax technique. We have developed a production method for biomedical application of porous titanium using a moldless process. This study aimed to evaluate the physical and mechanical properties of porous titanium using various particle sizes, shapes, and mixing ratio of titanium powder to wax binder for use in prosthesis production. CP Ti powders with different particle sizes, shapes, and mixing ratios were divided into five groups. A 90:10wt% mixture of titanium powder and wax binder was prepared manually at 70°C. After debinding at 380°C, the specimen was sintered in Ar at 1100°C without a mold for 1h. The linear shrinkage ratio of sintered specimens ranged from 2.5% to 14.2%. The linear shrinkage ratio increased with decreasing particle size. While the linear shrinkage ratio of Groups 3, 4, and 5 were approximately 2%, Group 1 showed the highest shrinkage of all. The bending strength ranged from 106 to 428MPa under the influence of porosity. Groups 1 and 2 presented low porosity followed by higher strength. The shear bond strength ranged from 32 to 100MPa. The shear bond strength was also particle-size dependent. The decrease in the porosity increased the linear shrinkage ratio and bending strength. Shrinkage and mechanical strength required for prostheses were dependent on the particle size and shape of titanium powders. These findings suggested that this production method can be applied to the prosthetic framework by selecting the material design.

Journal of the Mechanical Behavior of Biomedical Materials


Bone ingrowth of various porous titanium scaffolds produced by a moldless and space holder technique: An in vivo study in rabbits

Porous titanium has long been desired as a bone substitute material because of its ability to reduce the stress shielding in supporting bone. In order to achieve the various pore structures, we have evolved a moldless process combined with a space holder technique to fabricate porous titanium. This study aims to evaluate which pore size is most suitable for bone regeneration using our process. The mixture comprising Ti powder, wax binder and PMMA spacer was prepared manually at 70 °C which depended on the mixing ratio of each group. Group 1 had an average pore size of 60 μm, group 2 had a maximum pore size of 100 μm, group 3 had a maximum pore size of 200 μm and group 4 had a maximum pore size of 600 μm. These specimens were implanted into rabbit calvaria for three and 20 weeks. Thereafter, histomorphometrical evaluation was performed. In the histomorphometrical evaluation after three weeks, the group with a 600 μm pore size showed a tendency to greater bone ingrowth. However, after 20 weeks the group with a pore size of 100 μm showed significantly greater bone ingrowth than the other groups. This study suggested that bone regeneration into porous titanium scaffolds is pore size-dependent, while bone ingrowth was most prominent for the group with 100 μm-sized pores after 20 weeks in vivo.


Effects of high-energy ball-milling on injectability and strength of β-tricalcium-phosphate cement

Calcium phosphate cement (CPC) offers many advantages as a bone-substitution material. The objective of this study is to develop a new CPC that simultaneously exhibits fine injectability, a short setting time, and high strength. β-tricalcium phosphate (β-TCP, control) powder was ball-milled for 24h to produce a new cement powder. The modified β-TCP after 24h milling (mβ-TCP-24h) exhibited excellent injectability even 1h after mixing. The mechanical properties of the set cement (compact) were evaluated using compressive strength (CS) and diametral tensile strength (DTS) testing. The CS and DTS values of the mβ-TCP-24h compacts were 8.02MPa and 2.62MPa, respectively, at 5h after mixing, and were 49.6MPa and 7.9MPa, respectively, at 2 weeks after mixing. All the CS and DTS values of the mβ-TCP-24h compacts were significantly higher than those of the control for the same duration after mixing. These results suggest that the mechano-chemically modified β-TCP powder dissolves rapidly and accelerates hydroxyapatite precipitation, which successfully shortens the cement setting time and enhances the strength. This study supports that mβ-TCP-24h is a promising candidate for use in injectable CPCs with improved strength.


Pim-2 kinase is an important target of treatment for tumor progression and bone loss in myeloma.

Pim-2 kinase is overexpressed in multiple myeloma (MM) cells to enhance their growth and survival, and regarded as a novel therapeutic target in MM. However, the impact of Pim-2 inhibition on bone disease in MM remains unknown. We demonstrated here that Pim-2 expression was also upregulated in bone marrow stromal cells and MC3T3-E1 preosteoblastic cells in the presence of cytokines known as the inhibitors of osteoblastogenesis in MM, including interleukin-3 (IL-3), IL-7, tumor necrosis factor-, transforming growth factor- (TGF-) and activin A, as well as MM cell conditioned media. The enforced expression of Pim-2 abrogated in vitro osteoblastogenesis by BMP-2, which suggested Pim-2 as a negative regulator for osteoblastogenesis. Treatment with Pim-2 short-interference RNA as well as the Pim inhibitor SMI-16a successfully restored osteoblastogenesis suppressed by all the above inhibitory factors and MM cells. The SMI-16a treatment potentiated BMP-2-mediated anabolic signaling while suppressing TGF- signaling. Furthermore, treatment with the newly synthesized thiazolidine-2,4-dione congener, 12a-OH, as well as its prototypic SMI-16a effectively prevented bone destruction while suppressing MM tumor growth in MM animal models. Thus, Pim-2 may have a pivotal role in tumor progression and bone loss in MM, and Pim-2 inhibition may become an important therapeutic strategy to target the MM cell-bone marrow interaction.Leukemia advance online publication, 30 May 2014; doi:10.1038/leu.2014.147.


Fabrications of zinc-releasing biocement combining zinc calcium phosphate to calcium phosphate cement.

Recently, zinc-releasing bioceramics have been the focus of much attention owing to their bone-forming ability. Thus, some types of zinc-containing calcium phosphate (e.g., zinc-doped tricalcium phosphate and zinc-substituted hydroxyapatite) are examined and their osteoblastic cell responses determined. In this investigation, we studied the effects of zinc calcium phosphate (ZCP) derived from zinc phosphate incorporated into calcium phosphate cement (CPC) in terms of its setting reaction and MC3T3-E1 osteoblast-like cell responses. Compositional analysis by powder X-ray diffraction analysis revealed that HAP crystals were precipitated in the CPC containing 10 or 30wt% ZCP after successfully hardening. However, the crystal growth observed by scanning electron microscopy was delayed in the presence of additional ZCP. These findings indicate that the additional zinc inhibits crystal growth and the conversion of CPC to the HAP crystals. The proliferation of the cells and alkaline phosphatase (ALP) activity were enhanced when 10wt% ZCP was added to CPC. Taken together, ZCP added CPC at an appropriate fraction has a potent promotional effect on bone substitute biomaterials.


MRI対応生体内金属の開発

MRI対応生体内金属の開発

The Journal of the Japanese Society of Magnetic Applications in Dentistry


Magnetic susceptibility and hardness of Au-xPt-yNb alloys for biomedical applications


Evaluation of strontium introduced apatite cement as the injectable bone substitute developments.

We have developed bone cement introducing Strontium (Sr) to promote early bone regeneration. To prolong the release duration of Sr, we applied inorganic Sr filler for containing into the cement powder. The purpose of this study is to evaluate the mechanical properties, crystallinic properties, and ion release activities, especially Sr anion, of this cement. Alpha-TCP powder was mixed with Sr filler, with 0.1wt%, 0.5wt%, 1.0wt%, and 5.0wt%. These were mixed with mixing liquid and formed for each test. They were incubated and crystalized in 95% moisture for 1 week. The mechanical properties were studied by the compression, the diametral tensile strength and 4-point vending. Tested specimens were evaluated by X-ray diffraction(XRD) and scanning electron microscopic(SEM) imaging. The ion release behaviors were measured by inductively coupled plasma mass spectrometry(ICP-MS). The mechanical properties were increased in consistency of filler, but decreased in some samples because of declining the apatite matrix. And the Sr release showed interesting results as the sequential resource of Sr. By adjusting the mixing ratio or considering the application of these Sr releasable cements, this material would show good performance by its strength and longer Sr release for bone regeneration.

Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society


Reinforcement of bond strength of self-etching orthodontic adhesive.

Abstract Objective: To determine the reinforcement of bond strength of a self-etching system by applying a pretreatment agent. Materials and Methods: Sixty extracted human premolars were used in this study. The enamel surfaces were treated with four pretreatment agents?phosphoric acid, polyacrylic acid, citric acid, and ammonium hexafluorosilicate (SiF)?and were examined under a scanning electron microscope. Afterward, orthodontic brackets were bonded with a self-etching adhesive system (n ?=? 10 for each agent), and shear bond strength was measured through a debonding process. The adhesive remnant index (ARI) was also assessed. Results: Enamel surfaces treated with polyacrylic acid seemed almost the same as intact enamel. Treatment with SiF induced slight shallow depressions compared with the intact enamel. On the other hand, enamel surfaces treated with citric acid and phosphoric acid showed severe etching patterns. All pretreatments increased the bond strength, but SiF-treated specimens revealed the greatest strength (12.201 ? 1.048?MPa), followed by polyacrylic acid (12.030 ? 2.103?MPa). The control group with no pretreatment showed the least strength (9.078 ? 1.678?MPa). All pretreatments increased ARI score compared with the control group. Conclusions: Surface conditioning before bracket adhesion could reinforce the bond strength of the self-etching adhesive system, resulting in a more reliable bonding system.


Antibacterial activity of composite resin with glass-ionomer filler particles

The purpose of this study was to examine the antibacterial activity of composite resin with glass-ionomer filler particles versus that of contemporary commercial composite resins. Three composite resins were used: Beautifil II (containing S-PRG filler), Clearfil AP-X, and Filtek Z250. Resin blocks were bonded to maxillary first molars, and plaque accumulation on the resin block surface was examined after 8 hours. For the antibacterial test, the number of Streptococcus mutans in contact with the composite resin blocks after incubation for 12 hours was determined, and adherence of radiolabeled bacteria was evaluated. Less dental plaque was formed on Beautifil II resin block as compared to the other two materials. Antibacterial test revealed that there were no significant differences in the number of Streptococcus mutans among the three composite resins. However, the adherence of radiolabeled bacteria to the saliva-treated resin surface was significantly (p>0.01) lower in Beautifil II than in the other two materials. These results suggested that Beautifil II could reduce dental plaque formation and bacterial adherence, leading to prevention of secondary caries


Enamel bonding of self-etching and phosphoric acid-etching orthodontic adhesives in simulated clinical conditions: Debonding force and enamel surface

This study aimed to evaluate the effectiveness of self-etching and phosphoric acid-etching orthodontic adhesives for enamel bonding in simulated clinical conditions. By using two self-etching (Transbond Plus, TP; Beauty Ortho Bond, BB) and two acid-etching (Transbond XT, TX; Superbond Orthomite, SB) adhesives, orthodontic brackets were bonded on human premolars (n=10 for each adhesive). Ten teeth without bracket bonding, i.e., intact enamel surfaces, were used as control for SEM observation. After 7-day storage in lactic acid solution, bracket debonding force by means of debonding pliers, adhesive remnant index (ARI), and enamel surface morphology were examined. All the tested adhesives exhibited sufficient bond strength for clinical use. The ARI scores were almost the same among the four adhesives. In terms of SEM observation, the enamel surfaces in the control and TP groups showed a slight change after immersion in lactic acid solution, while the BB group showed less change on the enamel surface compared with the TP group. Meanwhile, the two acid-etching adhesives caused considerable demineralization. Taken together, these findings indicated that the action of self-etching systems was evidently more conservative.


Effects of heat treatment on the bioactivity of surface-modified titanium in calcium solution

The purpose of this study was to determine the effects of heat treatment on the bioactivity of hydrothermal-modified titanium in CaO solution for improved bioactivity by immersion in simulated body fluid (SBF). The hydrothermal treatment of titanium in CaO solution was performed at 121 degrees C at 0.2 MPa for 1 h in an autoclave followed by 1 h heat treatments at 200, 400, 600 and 800 degrees C simultaneously. The bioactivity of titanium was evaluated by hydroxyapatite precipitation during immersion in SBF. Surface microstructure changes after the heat treatments and immersion in SBF were determined by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Heat treatments at high temperatures (600 and 800 degrees C) promoted the synthesis of anatase, increased the thickness of the titanium oxide layer on the modified titanium surface and promoted the synthesis of calcium titanate, which possibly promoted the precipitation of apatite in SBF. The extent of precipitations increased with the time of immersion in SBF and the temperature of the heat treatment. Island-like deposits of needle-like crystals were observed only on the surface of the 600 and 800 degrees C heat-treated specimens after two or four week immersions in SBF. The results suggested that treatments of the surface of hydrothermal-treated titanium specimens at high temperatures (600 and 800 degrees C) could be effective for the surface modification of titanium as an implant material offering better osseointegration.


Effects of ternary additions on martensitic transformation of TiAu


TiNi形状記憶合金ワイヤ強化Mg合金基複合材料の組織と機械的性質

TiNi形状記憶合金ワイヤ強化Mg合金基複合材料の組織と機械的性質


Processing of TiNi SMA fiber reinforced AZ31 Mg alloy matrix composite by pulsed current hot pressing


Shape recovery of shape memory alloy fiber embedded resin matrix smart composite after crack repair

Ni-Ti shape memory alloy fiber embedded resin matrix composites were produced for evaluation of "smart denture", a newly developing denture with the function to close its own crack. Their bending strength and shape recovery after instant crack repair was estimated. The embedded fibers did not decrease the bending strength of the composite after repair. The crack closure of the composites was performed well simply by heating at 80 degrees C. Nevertheless, they showed apparent deflection after crack repair. The following two phenomena were supposed to be the main cause of it: the polymerization shrinkage of matrix resin with heating, and the coefficient of the thermal expansion mismatch between the fiber and the matrix. The embedded fibers could close the crack of the matrix with enough high accuracy for specimen repair, but they turned out to change the specimen shape after repair.


Susceptability to delayed fracture of Ni-Ti superelastic alloy


Thermomechanical Behavior of Ti-25Pd-24Ni-1W Shape Memory Ally Reinforced Ti Matrix Smart Composites


Hydrothermal modification of titanium surface in calcium solutions

Hydrothermal modification of a titanium surface in calcium solutions was performed. The apatite precipitation on the modified surface in Hanks' solution, as a simulated body fluid, was evaluated and the surface microstructure changes after the modification were characterized by thin-film X-ray diffractometry (TF-XRD) and X-ray photoelectron spectroscopy (XPS). Hydrothermal modification in CaO solution enhanced the precipitation of apatite on the titanium surface. High pH, high pressure and high temperature of the CaO solution increased the thickness of the surface-modified layer and enhanced the synthesis of calcium titanate which possibly promoted the precipitation of apatite in Hanks' solution. Hydrothermal modification in CaCl2 solution, on the other hand, showed reverse effects. The modification of titanium in CaO solution with hydrothermal treatment is expected to result in excellent osteointegration and can be easily performed by using an autoclave, a clinical apparatus widely used.


Degradation and fracture of Ni-Ti superelastic wire in an oral cavity


Fracture analysis of hydrogen-charged nickel-titanium super alloy


Acoustic emission and thermal expansion measurements for gypsum-bonded investment in casting flask during thermal processing

本論文は，石膏結合された埋没材および鋳型リングで拘束された同じ埋没材を用いて，加熱/冷却中のAEが計測され，AE活動度は250°Cと300°Cで高くなり，鋳型リングで拘束されれば更に活発になることが明らかになり，計算された熱応力の発生と鋳型リング拘束されたときの熱膨張率の変化とを比較した結果，AEの発生源は石膏の局部割れによるものであり，検出されたこれらの破壊は鋳型の精度を損ない歪みの原因になることを明らかにした．


Acoustic Emission and Thermal Expansion Measurements for Gypsum-bonded Investment in Casting Flask during Thermal Processing


Thermomechanical Behavior of NiTi Shape Memory Alloy Fiber Reinforced 6061 Aluminum Matrix Composite

Metallurgical and Materials Transactions A


Effects of Neutron Irradiation on Microstructure and Mechanical Properties of Carbon/Carbon Composites


Effect of Neutron Irradiation on Impact Properties of Metal Matrix Composites


An Automated Tensile Machine for Small Specimens Heavily Neutron Irradiated in FFTF/MOTA

Small Specimen Test Techniques and their Application to Nuclear Reactor Vessel Thermal Annealing and Plant Life Extension, ASTM-STP


Effect of Neutron Irradiation on Fracture Toughness of Metal Matrix Composites


R & D of an Automated Tensile Machine for Heavily Neutron Irradiated Materials


Effects of Neutron Radiation on Ceramic Fiber-Reinforced Composites

Effect of Radiation on Materials, ASTM-STP


The effect of supplementing the calcium phosphate cement containing poloxamer 407 on cellular activities

Journal of Biomedical Materials Research. Part B, Applied Biomaterials


Effects of fiber-resin interface property on shape recovery and mechanical properties of denture-base-resin matrix smart composite


Processing and Properties of NiTi Shape Memory Fiber Reinforced 6061 Aluminium Matrix Composite Made by Spark Plasma Sintering

Proceedings of 5th European Conference on Smart Structures and Materials


電解水を利用した義歯洗浄機 イオデント

電解水を利用した義歯洗浄機 イオデント


Thermomechanical behavior of TiPd-based SMA reinforced Ti matrix smart composites

The Japan institute of metals proceedings 12, solid-solid phase transformations


Processing of NiTi SMA Fiber/6061 Al Metal-Matrix Composite by Vacuum Hot Pressing

Proceedings of US-Japan Workshop on Smart Materials and Structures


Hierarchical Modeling of Shape Memory Alloys and Composites

Proceedings of the 18th Riso International Symposium on Materials Science


Mechanical Properties of Smart Metal Matrix Composites by Shape Memory Effects

Materials Research Society Symposium Proceedings


Microstructure and Mechanical Properties of Smart Aluminum-matrix Composite by Shape Memory Effects


Enhanced Mechanical Properties of Smart Polymer Matrix Composite by Shape Memory Effect


C/C複合材料のTEMによる3次元微細構造解析

C/C複合材料のTEMによる3次元微細構造解析

東京大学工学部総合試験所年報

東京大学工学部総合試験所年報


Effect of Heat Treatment Temperature on Interfacial Mechanical Properties of C/C Composites by means of Micro-Indentation Test

Proceedings of International Conference on Microstructures and Function of Materials


微少押し込み試験法によるC/C複合材料の界面特性評価

微少押し込み試験法によるC/C複合材料の界面特性評価

東京大学工学部総合試験所年報

東京大学工学部総合試験所年報


Interfacial Microstructure and Mechanical Properties of C/C Composites

Proceedings of the 10th International Conference of Composite Materials


C/C複合材料の熱処理による界面構造の変化

C/C複合材料の熱処理による界面構造の変化

東京大学工学部総合試験所年報

東京大学工学部総合試験所年報


Neutron Irradiation Effects on Correlations between Microstructure and Mechanical Properties of C/C Composites

Science Reports of the Research Institute, Tohoku University, Series A


C/C複合材料の黒鉛化過程による弾性率と強度特性

C/C複合材料の黒鉛化過程による弾性率と強度特性

東京大学工学部総合試験所年報

東京大学工学部総合試験所年報


C/C複合材料の熱処理による微細構造の変化

C/C複合材料の熱処理による微細構造の変化

東京大学工学部総合試験所年報

東京大学工学部総合試験所年報


Microstructural Changes of C/C Composites during Graphitization Process

Proceedings of Japan-Europe Symposium on Composite Materials


Effects of Heat Treatment Temperature on Mechanical Properties and Microstructure of C/C Composites

Proceedings of the 9th International Conference on Composite Maaterials


炭素繊維/炭素複合材料の微細構造解析

炭素繊維/炭素複合材料の微細構造解析

東京大学工学部総合試験所年報

東京大学工学部総合試験所年報


Radiation Effects on Metal Matrix Composites by Fission Neutrons from JMTR and JOYO

Science Report of the Research Institute Tohoku University, Series A


繊維強化型複合材料の弾性率と内部摩擦

繊維強化型複合材料の弾性率と内部摩擦

東京大学工学部総合試験所年報

東京大学工学部総合試験所年報


Effects of Radiation on Metal Matrix Composites

Proceedings of the 5th Japan-U.S. Conference on Composite Materials