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1.
J Biomed Mater Res B Appl Biomater ; 112(1): e35335, 2024 01.
Article in English | MEDLINE | ID: mdl-37772460

ABSTRACT

Calcium phosphate cement (CPC) is generally used for bone repair and augmentation. Poloxamers are tri-block copolymers that are used as surfactants but have applications in drug and antibiotic delivery. However, their biological effects on bone regeneration systems remain unelucidated. Here, we aimed to understand how supplementing the prototype CPC with poloxamer would impact cellular activity and its function as a bone-grafting material. A novel CPC, modified beta-tricalcium phosphate (mß-TCP) powder, was developed through a planetary ball-milling process using a beta-tricalcium phosphate (ß-TCP). The mß-TCP dissolves rapidly and accelerates hydroxyapatite precipitation; successfully shortening the cement setting time and enhancing the strength. Furthermore, the addition of poloxamer 407 to mß-TCP could reduce the risk of leakage from bone defects and improve fracture toughness while maintaining mechanical properties. In this study, the poloxamer addition effects (0.05 and 0.1 g/mL) on the cellular activities of MC3T3-E1 cells cultured in vitro were investigated. The cell viability of mß-TCP containing poloxamer 407 was similar to that of mß-TCP. All specimens showed effective cell attachment and healthy polygonal extension of the cytoplasm firmly attached to hydroxyapatite (HA) crystals. Therefore, even with the addition of poloxamer to mß-TCP, it does not have a negative effect to osteoblast growth. These data demonstrated that the addition of poloxamer 407 to mß-TCP might be considered a potential therapeutic application for the repair and regeneration of bone defects.


Subject(s)
Calcium Phosphates , Poloxamer , Poloxamer/pharmacology , Calcium Phosphates/pharmacology , Calcium Phosphates/chemistry , Bone Cements/pharmacology , Bone Cements/chemistry , Hydroxyapatites
2.
J Prosthodont Res ; 67(3): 384-391, 2023 Jul 31.
Article in English | MEDLINE | ID: mdl-36288959

ABSTRACT

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.


Subject(s)
Acrylic Resins , Candida albicans , Acrylic Resins/chemistry , Polymers , Polymethyl Methacrylate/pharmacology , Polymethyl Methacrylate/chemistry , Surface Properties , Biofilms , Mucins
3.
J Biomed Mater Res B Appl Biomater ; 111(1): 184-193, 2023 01.
Article in English | MEDLINE | ID: mdl-36053744

ABSTRACT

Decellularized extracellular matrix (dECM) hydrogels have cytocompatibility, and are currently being investigated for application in soft tissues as a material that promotes native cell infiltration and tissue reconstruction. A dECM hydrogel has broad potential for application in organs with complex structures or various tissue injury models. In this study, we investigated the practical application of a dECM hydrogel by injecting a kidney-derived dECM hydrogel into a rat partial nephrectomy model. The prepared dECM hydrogel was adjustable in viscosity to allow holding at the excision site, and after gelation, had an elastic modulus similar to that of kidney tissue. In addition, the migration of renal epithelial cells and vascular endothelial cells embedded in dECM hydrogels was observed in vitro. Four weeks after injection of the dECM hydrogel to the partial excision site of the kidneys, infiltration of renal tubular constituent cells and native cells with high proliferative activity, as well as angiogenesis, were observed inside the injected areas. This study is the first to show that dECM hydrogels can be applied to the kidney, one of the most complex structural organs and that they can function as a scaffold to induce angiogenesis and infiltration of organ-specific renal tubular constituent cells, providing fundamental insights for further application of dECM hydrogels.


Subject(s)
Endothelial Cells , Hydrogels , Rats , Animals , Hydrogels/chemistry , Extracellular Matrix/chemistry , Injections , Nephrectomy , Tissue Engineering , Tissue Scaffolds/chemistry
4.
J Mech Behav Biomed Mater ; 130: 105182, 2022 06.
Article in English | MEDLINE | ID: mdl-35305410

ABSTRACT

A new CPC was developed in this study using a ß-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.


Subject(s)
Calcium Phosphates , Poloxamer , Bone Cements/chemistry , Calcium Phosphates/chemistry , Compressive Strength , Dental Materials , Glass Ionomer Cements , Humans
5.
Dent Mater J ; 41(3): 487-494, 2022 May 31.
Article in English | MEDLINE | ID: mdl-35264547

ABSTRACT

Advancements in dental cements have considerably improved their bond strengths. However, high bond strength often makes the removal of restorations difficult. Thus, smart dental cements that show controllable bond strength are required. A conventional resin-modified glass-ionomer-cement demonstrated a significant reduction in the bond strength after current application. However, for this system, the ions in the cement are released into the oral cavity, resulting in a reduction of the electrical conductivity and in losses of the expected on-demand debonding property. Herein, the effects of immersion in 0.9 and 15% NaCl solutions on the electrical conductivity and debonding properties were investigated. The cement immersed in 0.9% NaCl solution from 1 to 28 days maintained similar bond strength reductions after current application, whereas that in 15% NaCl solution initially showed no bond strength reduction after 1 day but exhibited an increase in the bond strength reduction after immersion for 28 days.


Subject(s)
Dental Bonding , Glass Ionomer Cements , Composite Resins/chemistry , Dental Materials/chemistry , Dental Stress Analysis , Electric Conductivity , Glass Ionomer Cements/chemistry , Immersion , Materials Testing , Resin Cements/chemistry , Shear Strength , Sodium Chloride , Surface Properties
6.
Materials (Basel) ; 14(17)2021 Aug 30.
Article in English | MEDLINE | ID: mdl-34501030

ABSTRACT

Short fiber reinforced plastics (SFRPs) have excellent moldability and productivity compared to continuous fiber composites. In this study, thermoelastic stress analysis (TSA) was applied to detect delamination defects in short carbon fiber reinforced plastics (SCFRPs). The thermoelastic temperature change ΔTE, phase of thermal signal θE, and second harmonic temperature component ΔTD were measured. In the fatigue test of SCFRP, it was confirmed that changes in ΔTE, θE, and ΔTD appeared in the damaged regions. A staircase-like stress level test for a SCFRP specimen was conducted to investigate the generation mechanism of the ΔTD. The distortion of the temperature change appeared at the maximum tension stress of the sinusoidal load-and when the stress level decreased, the temperature change returned to the original sinusoidal waveform. ΔTD changed according to the change in the maximum stress during the staircase-like stress level test, and a large value of ΔTD was observed in the final ruptured region. A distortion of the temperature change and ΔTD was considered to be caused by the change in stress sharing condition between the fiber and resin due to delamination damage. Therefore, ΔTD can be applied to the detection of delamination defects and the evaluation of damage propagation.

7.
Dent Mater J ; 40(5): 1270-1276, 2021 Sep 30.
Article in English | MEDLINE | ID: mdl-34193725

ABSTRACT

We aimed to elucidate stress distribution in miniscrews and the surrounding bone when miniscrews inserted at different depths were implanted vertically or obliquely. The distributions of the equivalent stress on the screw surface and the minimum principal stress in the surrounding bone were calculated using finite element models. When the miniscrews were inserted vertically and obliquely, screw head displacement, greatest equivalent stress on the miniscrew surface, and absolute value of minimum principal stresses in the surrounding bone decreased with increasing insertion depth. Stresses in the obliquely inserted miniscrew with upward traction were smaller than in other insertion conditions, irrespective of insertion depth. With the application of orthodontic force, stress distribution around the miniscrew and surrounding bone is closely related to the insertion depth and insertion angle, which mutually affect each other. In particular, the obliquely inserted miniscrew with upward traction might be the most secure against screw failure and fracture.


Subject(s)
Orthodontic Anchorage Procedures , Bone Screws , Dental Stress Analysis , Finite Element Analysis , Stress, Mechanical
8.
Ann Transl Med ; 9(4): 325, 2021 Feb.
Article in English | MEDLINE | ID: mdl-33708952

ABSTRACT

BACKGROUND: Sarcopenia characterized by skeletal muscle loss may influence postoperative outcomes through physical decline and weakened immunity. We aimed to investigate clinical significance of sarcopenia in resected early-stage non-small cell lung cancer (NSCLC). METHODS: We retrospectively reviewed 315 consecutive patients with pathologic stage I NSCLC who had undergone lobectomy with systematic nodal dissection. Sarcopenia was defined as the lowest quartile of psoas muscle area on the 3rd vertebra on the high-resolution computed tomography (HRCT) image. Clinicopathological variables were used to investigate the correlation to postoperative complications as well as overall and recurrence-free survival. RESULTS: Upon multivariable analysis, male sex [odds ratio (OR) =5.780, 95% confidence interval (CI): 2.681-12.500, P<0.001], and sarcopenia (OR =21.00, 95% CI: 10.30-42.80, P<0.001) were independently associated with postoperative complications. The sarcopenia group showed significantly lower 5-over all survival (84.4% vs. 69.1%, P<0.001) and recurrence-free survival (77.2% vs. 62.0%, P<0.001) comparing with the non-sarcopenia group. In a multivariable analysis, sarcopenia was an independent prognostic factor [hazard ratio (HR) =1.978, 95% CI: 1.177-3.326, P=0.010] together with age ≥70 years (HR =1.956, 95% CI: 1.141-3.351, P=0.015) and non-adenocarcinoma histology (HR =1.958, 95% CI: 1.159-3.301, P=0.016). CONCLUSIONS: This is the first study which demonstrates that preoperative sarcopenia is significantly associated with unfavorable postoperative complications as well as long-term survival in pathologic stage I NSCLC. This readily available factor on HRCT may provide valuable information to consider possible choice of surgical procedure and perioperative management.

9.
Dent Mater J ; 40(1): 35-43, 2021 Jan 31.
Article in English | MEDLINE | ID: mdl-32779608

ABSTRACT

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.


Subject(s)
Dental Bonding , Ionic Liquids , Composite Resins , Dental Stress Analysis , Glass Ionomer Cements , Immersion , Materials Testing , Resin Cements , Shear Strength , Water
10.
J Cardiol Cases ; 24(4): 149-152, 2021 Oct.
Article in English | MEDLINE | ID: mdl-35059046

ABSTRACT

Primary malignant pericardial mesothelioma is an extremely rare disease. Malignant disease of the pericardium is an infrequent cause of cardiac tamponade. Hence, cardiac tamponade in the context of primary malignant mesothelioma of the pericardium is an uncommon clinical scenario. A 67-year-old male patient, an ex-smoker, complaining of progressive lethargy was referred to a hospital for investigation of persistent pericardial effusion. The pericardial fluid cytology was categorized as class Ⅲ. Thereafter, he was referred to our hospital for further evaluation. Fluorodeoxyglucose (FDG) positron emission tomography (PET) revealed FDG accumulation in the pericardium and mediastinal lymph node. Surgical biopsy of the pericardium was performed through a subxiphoid approach for a definitive diagnosis. Histopathological examination revealed diffuse infiltration of the pericardium by a malignant tumor consisting of epithelioid cells with large round nuclei and prominent nucleoli, arranged in a tubular papillary pattern. Finally, the patient was diagnosed with primary malignant pericardial mesothelioma of epithelioid type. The patient died 6 weeks after admission. This diagnosis must be considered in patients having unexplained massive pericardial effusion. Furthermore, we should consider prompt cytological analysis and FDG PET to arrive rapidly at a definitive diagnosis to administer combination chemotherapy that may provide clinical benefit. .

11.
Carcinogenesis ; 42(2): 169-179, 2021 02 25.
Article in English | MEDLINE | ID: mdl-33152763

ABSTRACT

Although some previous studies have examined epigenomic alterations in lung adenocarcinomas, correlations between epigenomic events and genomic driver mutations have not been fully elucidated. Single-CpG resolution genome-wide DNA methylation analysis with the Infinium HumanMethylation27 BeadChip was performed using 162 paired samples of adjacent normal lung tissue (N) and the corresponding tumorous tissue (T) from patients with lung adenocarcinomas. Correlations between DNA methylation data on the one hand and clinicopathological parameters and genomic driver mutations, i.e. mutations of EGFR, KRAS, BRAF and HER2 and fusions involving ALK, RET and ROS1, were examined. DNA methylation levels in 12 629 probes from N samples were significantly correlated with recurrence-free survival. Principal component analysis revealed that distinct DNA methylation profiles at the precancerous N stage tended not to induce specific genomic driver aberrations. Most of the genes showing significant DNA methylation alterations during transition from N to T were shared by two or more driver aberration groups. After small interfering RNA knockdown of ZNF132, which showed DNA hypermethylation only in the pan-negative group and was correlated with vascular invasion, the proliferation, apoptosis and migration of cancer cell lines were examined. ZNF132 knockdown led to increased cell migration ability, rather than increased cell growth or reduced apoptosis. We concluded that DNA hypermethylation of the ZNF132 gene participates in the clinicopathological aggressiveness of 'pan-negative' lung adenocarcinomas. In addition, DNA methylation alterations at the precancerous stage may determine tumor aggressiveness, and such alterations that accumulate after driver mutation may additionally modify clinicopathological features through alterations of gene expression.


Subject(s)
Adenocarcinoma of Lung/genetics , DNA-Binding Proteins/genetics , Lung Neoplasms/genetics , Neoplasm Recurrence, Local/epidemiology , Precancerous Conditions/genetics , Transcription Factors/genetics , Adenocarcinoma of Lung/diagnosis , Adenocarcinoma of Lung/mortality , Adenocarcinoma of Lung/surgery , Adult , Aged , Apoptosis/genetics , Carcinogenesis/genetics , Cell Line, Tumor , Cell Movement/genetics , Cell Proliferation/genetics , DNA Methylation , Epigenesis, Genetic , Female , Follow-Up Studies , Gene Expression Regulation, Neoplastic , Gene Knockdown Techniques , Humans , Lung/pathology , Lung/surgery , Lung Neoplasms/diagnosis , Lung Neoplasms/mortality , Lung Neoplasms/surgery , Male , Middle Aged , Mutation , Neoplasm Recurrence, Local/genetics , Neoplasm Staging , Pneumonectomy , Precancerous Conditions/diagnosis , Precancerous Conditions/pathology
12.
Dent Mater J ; 37(5): 768-774, 2018 Sep 30.
Article in English | MEDLINE | ID: mdl-29848856

ABSTRACT

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/mm2. The prototype cement in this research demonstrated that the concept of smart dental cement electrically debonding-on-demand is feasible.


Subject(s)
Dental Debonding/methods , Glass Ionomer Cements/chemistry , Ionic Liquids/chemistry , Resin Cements/chemistry , Composite Resins , Electricity , Materials Testing , Methylamines/chemistry , Shear Strength , Sulfuric Acid Esters/chemistry , Surface Properties
13.
Sensors (Basel) ; 17(12)2017 Dec 06.
Article in English | MEDLINE | ID: mdl-29210985

ABSTRACT

Carbon fiber-reinforced plastic (CFRP) is widely used for structural members of transportation vehicles such as automobile, aircraft, or spacecraft, utilizing its excellent specific strength and specific rigidity in contrast with the metal. Short carbon fiber composite materials are receiving a lot of attentions because of their excellent moldability and productivity, however they show complicated behaviors in fatigue fracture due to the random fibers orientation. In this study, thermoelastic stress analysis (TSA) using an infrared thermography was applied to evaluate fatigue damage in short carbon fiber composites. The distribution of the thermoelastic temperature change was measured during the fatigue test, as well as the phase difference between the thermoelastic temperature change and applied loading signal. Evolution of fatigue damage was detected from the distribution of thermoelastic temperature change according to the thermoelastic damage analysis (TDA) procedure. It was also found that fatigue damage evolution was more clearly detected than before by the newly developed thermoelastic phase damage analysis (TPDA) in which damaged area was emphasized in the differential phase delay images utilizing the property that carbon fiber shows opposite phase thermoelastic temperature change.

14.
Dent Mater J ; 36(5): 590-599, 2017 Sep 26.
Article in English | MEDLINE | ID: mdl-28450674

ABSTRACT

The authors have developed a ß-tricalcium-phosphate (ß-TCP) powder modified mechano-chemically through the application of a ball-milling process (mß-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 mß-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 mß-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 mß-TCP cement.


Subject(s)
Bone Cements , Calcium Phosphates , Compressive Strength , Dental Cementum , Humans , Materials Testing , Powders
15.
J Mech Behav Biomed Mater ; 61: 581-589, 2016 08.
Article in English | MEDLINE | ID: mdl-27148637

ABSTRACT

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.


Subject(s)
Prostheses and Implants , Titanium/chemistry , Materials Testing , Particle Size , Porosity
16.
Biomed Mater ; 11(1): 015012, 2016 Feb 02.
Article in English | MEDLINE | ID: mdl-26836201

ABSTRACT

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.


Subject(s)
Bone Substitutes/chemical synthesis , Osseointegration , Polymethyl Methacrylate/chemistry , Skull Fractures/pathology , Skull Fractures/therapy , Tissue Scaffolds , Animals , Bone Regeneration , Equipment Design , Equipment Failure Analysis , Materials Testing , Porosity , Rabbits , Skull Fractures/physiopathology , Treatment Outcome , Waxes/chemistry
17.
J Oral Maxillofac Res ; 7(4): e2, 2016.
Article in English | MEDLINE | ID: mdl-28154746

ABSTRACT

OBJECTIVES: The objective of this study is to develop a Ti fibre knit block without sintering, and to evaluate its deformability and new bone formation in vivo. MATERIAL AND METHODS: A Ti fibre with a diameter of 150 µm was knitted to fabricate a Ti mesh tube. The mesh tube was compressed in a metal mould to fabricate porous Ti fibre knit blocks with three different porosities of 88%, 69%, and 50%. The elastic modulus and deformability were evaluated using a compression test. The knit block was implanted into bone defects of a rabbit's hind limb, and new bone formation was evaluated using micro computed tomography (micro-CT) analysis and histological analysis. RESULTS: The knit blocks with 88% porosity showed excellent deformability, indicating potential appropriateness for bone defect filling. Although the porosities of the knit block were different, they indicated similar elastic modulus smaller than 1 GPa. The elastic modulus after deformation increased linearly as the applied compression stress increased. The micro-CT analysis indicated that in the block with 50% porosity new bone filled nearly all of the pore volume four weeks after implantation. In contrast, in the block with 88% porosity, new bone filled less than half of the pore volume even 12 weeks after implantation. The histological analysis also indicated new bone formation in the block. CONCLUSIONS: The titanium fibre knit block with high porosity is potentially appropriate for bone defect filling, indicating good bone ingrowth after porosity reduction with applied compression.

18.
J Mech Behav Biomed Mater ; 47: 77-86, 2015 Jul.
Article in English | MEDLINE | ID: mdl-25855467

ABSTRACT

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. ß-tricalcium phosphate (ß-TCP, control) powder was ball-milled for 24h to produce a new cement powder. The modified ß-TCP after 24h milling (mß-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 mß-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 mß-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 ß-TCP powder dissolves rapidly and accelerates hydroxyapatite precipitation, which successfully shortens the cement setting time and enhances the strength. This study supports that mß-TCP-24h is a promising candidate for use in injectable CPCs with improved strength.


Subject(s)
Bone Cements , Calcium Phosphates , Mechanical Phenomena , Compressive Strength , Injections , Tensile Strength , Time Factors
19.
J Mech Behav Biomed Mater ; 29: 151-60, 2014 Jan.
Article in English | MEDLINE | ID: mdl-24090874

ABSTRACT

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.


Subject(s)
Bone Cements/chemistry , Calcium Phosphates/chemistry , Phosphates/chemistry , Zinc Compounds/chemistry , Zinc/chemistry , Alkaline Phosphatase/metabolism , Bone Cements/pharmacology , Cell Line , Cell Proliferation/drug effects , Cell Survival/drug effects , Mechanical Phenomena , Osteoblasts/cytology , Osteoblasts/drug effects , Osteoblasts/enzymology , Time Factors
20.
Article in English | MEDLINE | ID: mdl-24109823

ABSTRACT

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.


Subject(s)
Apatites/pharmacology , Bone Cements/pharmacology , Bone Substitutes/pharmacology , Materials Testing , Strontium/pharmacology , Compressive Strength/drug effects , Crystallization , Injections , Microscopy, Electron, Scanning , Tensile Strength/drug effects , X-Ray Diffraction
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