Effects of adding poloxamer, collagen, and citric acid on mechanical strength, injectability, shape stability, and biocompatibility of mechanochemically modified beta-tricalcium phosphate cement using ball milling.

This study focuses on enhancing the mechanical properties and biocompatibility of calcium phosphate cement (CPC), a widely used bone replacement material. CPCs are limited by low mechanical strength and susceptibility to washout in body fluids. Four approaches were employed to improve CPC performance: 1. mechanochemical modification of CPC powder by ball milling to produce modified β-tricalcium phosphate (mβ-TCP) for better strength and injectability; 2. incorporation of poloxamer, a reverse thermosensitive gel, to enhance shape stability at body temperature; 3. addition of type I collagen to promote the cell viability and alkaline phosphatase (ALP) activity of osteoblast-like cells; 4. citric acid inclusion to restore compressive strength and injectability compromised by collagen. The resulting high-performance CPC demonstrated a compressive strength of 50.1 MPa, with significant improvements in injectability, shape stability, cell viability, and ALP activity of osteoblast-like cells.


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


Evaluation of torque moment in self-ligation lingual brackets.

This study investigates the moments generated when applying third-order bends to lingual brackets with different slot shapes and wires made of different materials. Three types of lingual brackets with different slot shapes: 0.018×0.018-inch square slot self-ligation bracket (AL-bracket); 0.018×0.025-inch slot self-ligation bracket (CL-bracket:); 0.018×0.025-inch slot self-ligation bracket (ST-bracket). Wires of three different materials were measured. The torque value generated during torque application was measured using a torque gauge. The AL-bracket had a significantly larger torque moment than the CL- and ST-brackets at the same angles. The CL-bracket had the smallest torque moment of the three for the square wire; however, the CL-bracket revealed a larger torque moment than the ST-bracket for the rectangular wire. The torque moment of Ti-Ni wires was observed the smallest. In lingual orthodontic treatment, the results suggested the shape of the lingual bracket slot and the wire material should be considered when adjusting and applying third-order bends.


2-methacryloyloxyethyl phosphorylcholine polymer treatment prevents Candida albicans biofilm formation on acrylic resin

We aimed to evaluate the effectiveness of photoreactive 2-methacryloyloxyethyl phosphorylcholine (MPC) in inhibiting Candida albicans biofilm formation on polymethyl methacrylate (PMMA) and assess its mechanism and need for re-application by evaluating its interaction with salivary mucin and durability during temperature changes. PMMA discs were used as specimens. The MPC coating was applied using the spray and cure technique for the treatment groups, whereas no coating was applied to the control. The MPC treatment (MT) groups were further differentiated based on the number of thermal cycles involved (0, 1000, 2500, and 5000). The optical density was measured to assess mucin adsorption (MA). Contact angle (CA) was calculated to evaluate surface hydrophilicity. The presence of MPC components on the PMMA surface was assessed using X-ray photoelectron spectroscopy (XPS). C. albicans biofilms were evaluated qualitatively (scanning electron microscope images) and quantitatively (colony-forming units (CFUs)). Statistical analysis was conducted using two-way analysis of variance and Tukey's multiple comparison test. MA rate and CA increased significantly in the MT groups, which exhibited significantly fewer CFUs and thinner biofilms than those of the control group. Based on the XPS, MA, and CFU evaluations, the durability and efficacy of the MPC coating were considered stable up to 2500 thermal cycles. Additionally, a significant interaction was observed between mucin concentration and MPC efficacy. The photoreactive MPC coating, which was resistant to temperature changes for approximately 3 months, effectively prevented C. albicans biofilm formation by modifying surface hydrophilicity and increasing mucin adsorption.


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


Development and initial performance of a miniature axial flow blood pump using magnetic fluid shaft seal

In this study, we developed a new catheter-mounted micro-axial flow blood pump (MFBP) using a new miniature magnetic fluid shaft seal (MFSS). The prototype of the catheter-mounted MFBP had a maximum diameter of 8 mm and a length of 50 mm. The new MFSS composed a neodymium magnet ring, an iron ring, and a magnetic fluid particularly designed for the MFSS. The new MFSS had outer and inner diameters of 4.0 mm and 2.6 mm, respectively, and a length of 3.0 mm. The sealing pressure of the MFSS was calculated to be 432 mmHg using FEM (Finite Element Method) result; therefore, the MFSS had sufficient sealing pressure for the catheter-mounted MFBP. The friction loss of the MFSS included the friction owing to the viscosity of the magnetic fluid and the magnetic force between the iron ring and ring magnet. The total friction loss of the MFSS was 0.08-0.09 W in the pump operational speed range from 22,000 to 35,000 rpm. From the in vitro experimental results, the catheter-mounted MFBP using the MFSS had a pump output of 3 L/min. against a differential pressure of 60 mmHg, and the pump characteristics of the MFBP were almost the same as those of Impella 5.0.


Volume Magnetic Susceptibility Estimation of α- and β-Phases in Titanium Alloys for Biomedical Applications.

Metallic medical devices in the human body cause serious artifacts in magnetic resonance imaging owing to the volume magnetic susceptibility (χν) mismatch between the device and tissue around the device. To reduce artifacts, medical devices produced from alloys with χν values of approximately -9 × 10-6 are required. Controlling the phase constitution is a basic technique used to control the χν value of an alloy, and the χν value of each phase is a fundamental property. In this study, an α+β-type Ti alloy and two β-type Ti alloys were investigated. The estimated χν values of the α-phase of the alloys were similar to or smaller than that of pure Ti. In contrast, the estimated χν values of the β-phase of the alloys were larger than that of pure Ti. Since the χν value of pure Ti is much larger than -9 × 10-6, the χν values of the β-phases suggested that increasing the volume fraction of the β-phase was not appropriate for producing a Ti alloy with a lower χν value.


Dentin-pulp complex tissue regeneration via three-dimensional cell sheet layering

The dentin-pulp complex is a unique structure in teeth that contains both hard and soft tissues. Generally, deep caries and trauma cause damage to the dentin-pulp complex, and if left untreated, this damage will progress to irreversible pulpitis. The aim of this study was to fabricate a layered cell sheet composed of rat dental pulp (DP) cells and odontogenic differentiation of pulp (OD) cells and to investigate the ability to regenerate the dentin-pulp complex in a scaffold tooth. We fabricated two single cell sheets composed of DP cells (DP cell sheet) or OD cells (OD cell sheet) and a layered cell sheet made by layering both cells. The characteristics of the fabricated cell sheets were analyzed using light microscopy, scanning electron microscope (SEM), hematoxylin-eosin (HE) staining, and immunohistochemistry (IHC). Furthermore, the cell sheets were transplanted into the subrenal capsule of immunocompromised mice for 8 weeks. After this, the regenerative capacity to form dentin-like tissue was evaluated using micro-computed tomography (micro-CT), HE staining, and IHC. The findings of SEM and IHC confirmed that layered cell sheets fabricated by stacking OD cells and DP cells maintained their cytological characteristics. Micro-CT of layered cell sheet transplants revealed a mineralized capping of the access cavity in the crown area, similar to that of natural dentin. In contrast, the OD cell sheet group demonstrated the formation of irregular fragments of mineralized tissue in the pulp cavity, and the DP cell sheet did not develop any hard tissue. Moreover, bone volume/tissue volume (BV/TV) showed a significant increase in hard tissue formation in the layered cell sheet group compared with that in the single cell sheet group ( < 0.05). HE staining also showed a combination of soft and hard tissue formation in the layered cell sheet group. Furthermore, IHC confirmed that the dentin-like tissue generated from the layered cell sheet expressed characteristic markers of dentin but not bone equivalent to that of a natural tooth. In conclusion, this study demonstrates the feasibility of regenerating dentin-pulp complex using a bioengineered tissue designed to simulate the anatomical structure. Impact statement The dentin-pulp complex can be destroyed by deep caries and trauma, which may cause pulpitis and progress to irreversible pulpitis, apical periodontitis, and even tooth loss. Current treatments cannot maintain pulp health, and teeth can become brittle. We developed a three-dimensional (3D) layered cell sheet using dental pulp cells and odontogenic differentiation of pulp cells for dentin-pulp complex regeneration. Our layered cell sheet enables the regeneration of an organized 3D dentin-pulp-like structure comparable with that of natural teeth. This layered cell sheet technology may contribute to dentin-pulp complex regeneration and provide a novel method for complex tissue engineering.


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.


Effects of zirconia additives on β-tricalcium-phosphate cement for high strength and high injectability


Evaluation of the Cytotoxicity of Oil-Based Magnetic Fluid Based on Cell Proliferation Study

Medical applications of magnetic fluids (MFs) have attracted much interest due to the liquid's unique properties. Non-toxicity is important for clinical applications of MFs. Cytotoxicity of MFs has been studied, but previous studies on cytotoxicity of MFs were limited to water-based MFs. We have developed new oil-based MFs specialized for the MF seal in a blood pump. The cytotoxicity of newly developed oil-based MFs was evaluated by cell proliferation and LDH (lactate dehydrogenase) assays. The cell proliferation ratio against the negative control decreased on Day 2 of cell incubation, but increased to the negative control level on Day 6. LDH cytotoxicity was about 10% on Day 6. In conclusion the new oil-based magnetic fluids have low levels of cytotoxicity.

Journal of the Chinese Society of Mechanical Engineers, Transactions of the Chinese Institute of Engineers, Series C


Magnetic fluid seals working in liquid environments: Factors limiting their life and solution methods

Journal of Magnetism and Magnetic Materials


Development of structural and chemical enforcement of neointimal growth as the blood contacting surface for the vascular prosthesis

The International Journal of Artificial Organs


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.


Bone Ingrowth to Ti Fibre Knit Block with High Deformability

Journal of Oral & Maxillofacial Research


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.

Journal of the Mechanical Behavior of Biomedical Materials


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.


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


Evaluation of newly developed bone cement introducing Strontium consistencies for bone regenerative substitute

Transactions of the Japanese Society for Medical and Biological Engineering


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 poloxamer additives on strength, injectability, and shape stability of beta-tricalcium phospEffects of poloxamer additives on strength, injectability, and shape stability of beta-tricalcium phosphate cement modified using ball-millinghate cement modified using ball-milling

A new CPC was developed in this study using a β-TCP powder mechano-chemically modified by ball-milling. The prototype CPC exhibits excellent fluidity for easy injection into bone defects; however, there is a risk of leakage from the defects immediately after implantation due to its high fluidity. The addition of poloxamer, an inverse thermoresponsive gelling agent, into CPC optimizes the fluidity. At lower temperatures, it forms a sol and maintains good injectability, whereas at the human body temperature, it transforms to a gel, reducing the fluidity and risk of leakage. In this study, the effects of poloxamer addition of 3, 5, and 10 mass% on the injectability, shape stability, and strength of the prototype CPC were evaluated. The calculated injectability of the prototype CPC pastes containing three different poloxamer contents was higher than that of the CPC paste without poloxamer for 15 min at 37 °C. Furthermore, the shape stability immediately after injection of the three CPC pastes with poloxamer was higher than that of the CPC paste without poloxamer. After 1 week of storage at 37 °C, the compressive strength and diametral tensile strength of the CPC compacts containing 10 mass% poloxamer were similar to those of the CPC compact without poloxamer. Additionally, the CPC compacts containing 10 mass% poloxamer exhibited clear plastic deformation after fracture. These results indicate that the addition of poloxamer to the prototype CPC could reduce the risk of leakage from bone defects and improve the fracture toughness with maintaining the injectability and strength.


コイル状形状記憶合金を応用した機能代行型人工食道デバイスの開発

コイル状形状記憶合金を応用した機能代行型人工食道デバイスの開発


Proceedings of Japan-Taiwan International Conference on Magnetic Fluids 2018


金属粉末を用いた微細porous表面の作製によるオーダーメイド加工可能なbiolized血液接触表面の作製