The evaluation of blood compatibility of biomaterials is crucial for ensuring the clinical safety of implantable medical devices. To address the limitations of traditional testing methods in real-time monitoring and electrical property analysis, this study developed a portable electrical impedance tomography (EIT) system. The system uses a 16-electrode design, operates within a frequency range of 1 to 500 kHz, achieves a signal to noise ratio (SNR) of 69.54 dB at 50 kHz, and has a data collection speed of 20 frames per second. Experimental results show that the EIT system developed in this study is highly consistent with a microplate reader ( R ²=0.97) in detecting the hemolytic behavior of industrial-grade titanium (TA3) and titanium alloy-titanium 6 aluminum 4 vanadium (TC4) in anticoagulated bovine blood. Additionally, with the support of a multimodal image fusion Gauss-Newton one-step iterative algorithm, the system can accurately locate and monitor in real-time the dynamic changes in blood permeation and coagulation caused by TC4 in vivo. In conclusion, the EIT system developed in this study provides a new and effective method for evaluating the blood compatibility of biomaterials.
Electric Impedance ; Animals ; Tomography/instrumentation* ; Biocompatible Materials ; Materials Testing/instrumentation* ; Cattle ; Titanium ; Alloys ; Prostheses and Implants

OBJECTIVE: To evaluate the effect of biodegradable magnesium alloy materials in promoting tendon-bone healing during rotator cuff tear repair and to investigate their potential underlying biological mechanisms. METHODS: Forty-eight 8-week-old Sprague Dawley rats were taken and randomly divided into groups A, B, and C. Rotator cuff tear models were created and repaired using magnesium alloy sutures in group A and Vicryl Plus 4-0 absorbable sutures in group B, while only subcutaneous incisions and sutures were performed in group C. Organ samples of groups A and B were taken for HE staining at 1 and 2 weeks after operation to evaluate the safety of magnesium alloy, and specimens from the supraspinatus tendon and proximal humerus were harvested at 2, 4, 8, and 12 weeks after operation. The specimens were observed macroscopically at 4 and 12 weeks after operation. Biomechanical tests were performed at 4, 8, and 12 weeks to test the ultimate load and stiffness of the healing sites in groups A and B. At 2, 4, and 12 weeks, the specimens were subjected to the following tests: Micro-CT to evaluate the formation of bone tunnels in groups A and B, HE staining and Masson staining to observe the regeneration of fibrocartilage at the tendon-bone interface after decalcification and sectioning, and Goldner trichrome staining to evaluate the calcification. Immunohistochemical staining was performed to detect the expressions of angiogenic factors, including vascular endothelial growth factor (VEGF) and bone morphogenetic protein 2 (BMP-2), as well as osteogenic factors at the tendon-bone interface. Additionally, immunofluorescence staining was used to examine the expressions of Arginase 1 and Integrin beta-2 to assess M1 and M2 macrophage polarization at the tendon-bone interface. The role of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway in tendon-bone healing was further analyzed using real-time fluorescence quantitative PCR. RESULTS: Analysis of visceral sections revealed that magnesium ions released during the degradation of magnesium alloys did not cause significant toxic effects on organs such as the heart, liver, spleen, lungs, and kidneys, indicating good biosafety. Histological analysis further demonstrated that fibrocartilage regeneration at the tendon-bone interface in group A occurred earlier, and the amount of fibrocartilage was significantly greater compared to group B, suggesting a positive effect of magnesium alloy material on tendon-bone interface repair. Additionally, Micro-CT analysis results revealed that bone tunnel formation occurred more rapidly in group A compared to group B, further supporting the beneficial effect of magnesium alloy on bone healing. Biomechanical testing showed that the ultimate load in group A was consistently higher than in group B, and the stiffness of group A was also greater than that of group B at 4 weeks, indicating stronger tissue-carrying capacity following tendon-bone interface repair and highlighting the potential of magnesium alloy in enhancing tendon-bone healing. Immunohistochemical staining results indicated that the expressions of VEGF and BMP-2 were significantly upregulated during the early stages of healing, suggesting that magnesium alloy effectively promoted angiogenesis and bone formation, thereby accelerating the tendon-bone healing process. Immunofluorescence staining further revealed that magnesium ions exerted significant anti-inflammatory effects by regulating macrophage polarization, promoting their shift toward the M2 phenotype. Real-time fluorescence quantitative PCR results demonstrated that magnesium ions could facilitate tendon-bone healing by modulating the PI3K/AKT signaling pathway. CONCLUSION Biodegradable magnesium alloy material accelerated fibrocartilage regeneration and calcification at the tendon-bone interface in rat rotator cuff tear repair by regulating the PI3K/AKT signaling pathway, thereby significantly enhancing tendon-bone healing.
Animals ; Rotator Cuff Injuries/metabolism* ; Rats, Sprague-Dawley ; Signal Transduction ; Wound Healing/drug effects* ; Alloys/pharmacology* ; Rats ; Proto-Oncogene Proteins c-akt/metabolism* ; Rotator Cuff/metabolism* ; Macrophages/metabolism* ; Magnesium/pharmacology* ; Phosphatidylinositol 3-Kinases/metabolism* ; Vascular Endothelial Growth Factor A/metabolism* ; Male ; Biocompatible Materials ; Bone Morphogenetic Protein 2/metabolism*

OBJECTIVE: To compare the cyclic fatigue resistance of nickel-titanium files made by 3 new heat treatment in simulated S-shaped root canals at different temperatures. METHODS: Gold heat-treated nickel-titanium files TruNatomy (25 mm, tip size 26#/0.04) and ProTaper Gold (25 mm, tip size 25#/0.08) were selected as the experimental group, M wire technique nickel-titanium file ProTaper Next (25 mm, tip size 25#/0.06) was selected as the control group. It was speculated that the Gold technique used in TruNatomy nickel-titanium file was R phase separation technique, which included a complete intermediate R-phase, increasing its flexibility. ProTaper Gold was a CM wire nickel-titanium file and the increased phase transformation temperature by heat treatment introduced martensite at room temperature, while it underwent gold heat treatment on the surface, generating an intermediate R phase during phase transformation, providing hyperelastic. ProTaper Next used M wire technique, M wire included austenite at room temperature, where heat mechanical processing introduced hardened martensite, which was incapable of participating phase transformation. Because of the lower elastic modulus of hardened martensite than austenite, the flexibility of the file was increased. Twenty instruments of each nickel-titanium file were submitted to the cyclic fatigue test by using a simulated canal with double curvatures at room tem-perature (24 ℃) and 65 ℃, 10 instruments of each nickel-titanium file were selected at each temperature (n=10). At the same temperature, the number of cyclic fatigue (NCF) and fragment length were analyzed by using One-Way analysis of variance at a significance level of P < 0.05. NCF and fragment length of the same nickel-titanium file at room temperature and 65 ℃ were compared by paired sample t test and the significance level was α=0.05. Fractured surfaces were analyzed by using scanning electron microscope. RESULTS: In double-curved canals, all the failure of the files due to cyclic fatigue was first seen in the apical curvature before the coronal curvature. At room temperature, in the apical curvature, NCF of TruNatomy was 344.4±96.6, ProTaper Gold was 175.0±56.1, ProTaper Next was 133.3±39.7, NCF of Tru Natomy was the highest (P < 0.05). In the coronal curvature, NCF of TruNatomy was 618.3± 75.3, ProTaper Gold was 327.5±111.8, ProTaper Next was 376.6±67.9, NCF of TruNatomy was also the highest (P < 0.05). There was no significant difference among the apical and coronal fragment length of the 3 nickel-titanium files (P>0.05). At 65 ℃, in the apical curvature, NCF of TruNatomy was 289.6±65.8, ProTaper Gold was 187.5±75.4, ProTaper Next was 103.0±38.5, NCF of TruNatomy was the highest (P < 0.05). In the coronal curvature, NCF of TruNatomy was 454.2±45.4, ProTaper Gold was 268.3±31.4, ProTaper Next was 283.8±31.7, NCF of TruNatomy was also the highest (P < 0.05). The apical fragment length of ProTaper Next was the highest (P < 0.05), and there was no significant difference among coronal fragment length of the 3 nickel-titanium files (P>0.05). Compared with room temperature, at 65 ℃, in the coronal curvature, NCF of TruNatomy decreased significantly (P < 0.05). The fractured surfaces of the three nickel-titanium files demonstrated typical cyclic fatigue. CONCLUSION Gold heat-treated nickel-titanium file had better cyclic fatigue resistance than M wire nickel-titanium file in S-shaped root canals.
Nickel/chemistry* ; Titanium/chemistry* ; Hot Temperature ; Root Canal Preparation/methods* ; Humans ; Materials Testing ; Gold/chemistry* ; Dental Alloys/chemistry* ; Stress, Mechanical

OBJECTIVE: To investigate the biocompatibility of porous WE43 magnesium alloy scaffolds manufactured by 3D printing technology and to observe its effect in treating femoral defects in New Zealand white rabbits. METHODS: In vitro cytotoxicity test was performed using bone marrow mesenchymal stem cells from Sprague Dawley (S-D) rats. According to the different culture media, the cells were divided into 100% extract group, 50% extract group, 10% extract group and control group. After culturing for 1, 3 and 7 days, the cell activity of each group was determined by cell counting kit-8 (CCK-8). In the in vivo experiment, 3.0-3.5 kg New Zealand white rabbits were randomly divided into three groups: Experimental group, bone cement group and blank group, with 9 rabbits in each group. Each rabbit underwent surgery on the left lateral femoral condyle, and a bone defect with a diameter of 5 mm and a depth of 6 mm was created using a bone drill. The experimental group was implanted with WE43 magnesium alloy scaffolds, the bone cement group was implanted with calcium sulfate bone cement, and the blank group was not implanted. Then 4, 8 and 12 weeks after surgery, 3 rabbits in each group were euthanized by carbon dioxide anesthesia, and the femur and important internal organs were sampled. Micro-computed tomography (Micro-CT) scanning was performed on the left lateral femoral condyle. Sections of important internal organs were prepared and stained with hematoxylin-eosin (HE). Hard tissue sections were made from the left lateral femoral condyle and stained with methylene blue acid fuchsin and observed under a microscope. RESULTS: In the cytotoxicity test, the cell survival rate in the 100% extract group was higher than that in the control group (140.56% vs. 100.00%, P < 0.05) on 1 day of culture; there was no statistically significant difference (P>0.05) in cell survival rate among the groups on 3 days of culture; the cell survival rate in the 100% extract group was lower than that in the control group (68.64% vs. 100.00%, P < 0.05) on 7 days of culture. Micro-CT scanning in the in vivo experiment found that most of the scaffolds in the experimental group had been degraded in 4 weeks, with very few high-density scaffolds remaining. In 12 weeks, there was no obvious stent outline. In 4 weeks, a certain amount of gas was generated around the WE43 magnesium alloy scaffold, and the gas was significantly reduced from 8 to 12 weeks. Hard tissue sections showed that a certain amount of extracellular matrix and osteoid were generated around the scaffolds in the experimental group in 4 weeks. In the bone cement group, most of the calcium sulfate bone cement had been degraded. In 8 weeks, the osteoid around the scaffold and its degradation products in the experimental group increased significantly. In 12 weeks, new bone was in contact with the scaffold around the scaffold in the experimental group. There was less new bone in the bone cement group and the blank group. CONCLUSION The porous WE43 magnesium alloy scaffold fabricated by 3D printing process has good biocompatibility and good osteogenic properties, and has the potential to become a new material for repairing bone defects.
Animals ; Rabbits ; Printing, Three-Dimensional ; Alloys/chemistry* ; Tissue Scaffolds/chemistry* ; Magnesium/chemistry* ; Rats, Sprague-Dawley ; Biocompatible Materials ; Mesenchymal Stem Cells/cytology* ; Femur/surgery* ; Rats ; Absorbable Implants ; Male ; Bone Regeneration ; Tissue Engineering/methods* ; Cells, Cultured

In this paper, a preliminary stress/strain analysis of the design structure of a nickel-titanium alloy patent foramen ovale occluder is conducted with the finite element simulation analysis method. In the analysis, solid structure modeling is carried out on three different specifications of domestic patent foramen ovale occluders. Referring to the test method of fatigue performance in inspection standard YY/T 1553-2017, an initial installation deformation is applied to the model, and then the fatigue displacement of 2 mm is applied to the sample to make the model fatigue deformation. The fatigue safety factors of each type of occluder are obtained by strain simulation analysis. The results indicate that the minimum fatigue safety factors of the three specifications of domestic patent foramen ovale occluders are 2.09, 2.35 and 2.06 respectively, which all meet the design of fatigue safety factor greater than 1. Among them, 1818 and 3030 specifications of patent foramen ovale occluders have close values in minimum fatigue safety factors, and both are lower than that of 1825 model. Therefore, it is recommended to carry out physical fatigue tests on both 1818 and 3030 specifications to further verify the fatigue performance of the products.
Finite Element Analysis ; Titanium ; Nickel ; Alloys ; Foramen Ovale, Patent ; Materials Testing ; Septal Occluder Device ; Stress, Mechanical

Due to their good properties of elastic modulus, degradability and ability to promote bone repair, magnesium alloys have become a research hotspot in research of orthopedic implants. Nevertheless, most of the biomedical magnesium alloys currently available fail to meet the requirements in orthopedics because of their rapid degradation after implantation. Rare earth-magnesium alloys possess excellent corrosion resistance and are expected to become important materials as clinical orthopedic implants. This review summarizes the recent progress in studies of the physiological functions of rare earth elements, the effects of supplementation of rare earth elements on biomechanical properties and the in vitro and in vivo biocompatibility of magnesium alloys, and their contribution to tendon-bone healing, addressing also the current clinical orthopedic applications of different rare earth-magnesium alloys, challenges, and future strategies for improving these alloys.
Alloys/chemistry* ; Magnesium/chemistry* ; Metals, Rare Earth/chemistry* ; Humans ; Biocompatible Materials ; Prostheses and Implants

Vascular stents are an essential tool in cardiovascular interventional therapy, and their demand is growing with the increasing incidence of cardiovascular diseases. Compared with permanent stents, which are prone to in-stent restenosis, and drug-eluting stents, which may cause late stent thrombosis, biodegradable stents offer advantages. After providing early radial support to prevent elastic recoil, biodegradable stents gradually degrade, allowing the vessel to regain its natural physiological contractility and undergo positive remodeling. A review of the current mainstream biodegradable metal stents, magnesium-based, iron-based, and zinc-based alloys, shows promising findings in both preclinical and clinical research. Magnesium-based stents exhibit good operability and low thrombosis rates, but their limitations include rapid degradation, hydrogen evolution, and significant pH changes in the microenvironment. Iron-based stents demonstrate excellent mechanical strength, formability, biocompatibility, and hemocompatibility, but their slow corrosion rate hampers broader clinical application; accelerating degradation remains key. Zinc-based alloys have a moderate degradation rate but relatively low mechanical strength; enhancing stent strength by alloying with other elements is the main improvement direction for zinc-based stents.
Humans ; Absorbable Implants ; Stents ; Alloys/chemistry* ; Magnesium/chemistry* ; Biocompatible Materials/chemistry* ; Zinc/chemistry* ; Drug-Eluting Stents ; Iron/chemistry* ; Metals/chemistry*

The purpose of this study is to establish and apply a correction method for titanium alloy implant in spinal IMRT plan, a corrected CT-density table was revised from normal CT-density table to include the density of titanium alloy implant. Dose distribution after and before correction were calculated and compared to evaluate the dose deviation. Plans were also copied to a spinal cancer simulation phantom. A titanium alloy fixation system for spine was implanted in this phantom. Plans were recalculated and compared with the measurement result. The result of this study shows that the max dose of spinal cord showed significant difference after correction, and the deviation between calculation results and measurement results was reduced after correction. The method for expanding the range CT-density table, which means that the density of titanium alloy was included, can reduce the error in calculation.
Radiotherapy, Intensity-Modulated/methods* ; Titanium ; Radiotherapy Dosage ; Alloys ; Radiometry/methods* ; Radiotherapy Planning, Computer-Assisted/methods*

Znic (Zn) alloys with good cytocompatibility and suitable degradation rate have been a kind of biodegradable metal with great potential for clinical applications. This paper summarizes the biological role of degradable Zn alloy as bone implant materials, discusses the mechanical properties of different Zn alloys and their advantages and disadvantages as bone implant materials, and analyzes the influence of different processing strategies (such as alloying and additive manufacturing) on the mechanical properties of Zn alloys. This paper provides systematic design approaches for biodegradable Zn alloys as bone implant materials in terms of the material selection, product processing, structural topology optimization, and assesses their application prospects with a view to better serve the clinic.
Orthopedics ; Zinc ; Alloys ; Dental Materials ; Prostheses and Implants

OBJECTIVE: To compare the retentions of different designs of cobalt-chromium (Co-Cr), pure titanium (CP Ti), and titanium alloy (Ti-6Al-4V) removable partial denture (RPD) circumferential clasps manufactured by selective laser melting (SLM) and to analyze the stress distribution of these clasps during the removal from abutment teeth. METHODS: Clasps with clasp arm size A (1.9 mm width/1.1 mm thickness at the body and 0.8-taper) or B (1.2 times A) and 0.25 mm or 0.50 mm undercut engagement were modeled on a prepared first premolar die, named as designs A1, A2, A3, and A4, respectively. The density and elastic modulus of SLM-built Co-Cr, CP Ti, and Ti-6Al-4V were measured and given to different groups of clasps. The density, elastic modulus, and Poisson ' s ratio of enamel were given to the die. The control group was the cast Co-Cr clasp with design A1, to which the density and elastic modulus of cast Co-Cr alloy were given. The Poisson's ratio of all metals was 0.33. The initial 5 N dislodging force was applied, and the maximum displacement of the clasp along the insertion path was computed. The load was reapplied with an increment of 5 N than in the last simulation until the clasp was completely dislodged. The retentive force range of different groups of clasps was obtained. The retentive forces of the SLM-built Co-Cr, CP Ti, and Ti-6Al-4V clasps with equivalent computed retentive force range to the control group were validated through the insertion/removal experiment. The von Mises stress distributions of these three groups of SLM-built clasps under 15 N loads were analyzed. RESULTS: SLM-built Co-Cr, CP Ti, and Ti-6Al-4V clasps with designs B1 or B2, and Co-Cr clasps with design A2 had higher retentive forces than those of the control group. SLM-built CP Ti and Ti-6Al-4V clasps with design A1 had lower retentive forces than those of the control group. SLM-built Co-Cr clasp with design A1 and SLM-built CP Ti and Ti-6Al-4V clasps with design A2 had equivalent retentive forces to those of the control group. The insertion/removal experiment showed that the measured retentive forces of these three groups of SLM-built clasps were (21.57±5.41) N, (19.75±4.47) N, and (19.32±2.04) N, respectively. No statistically significant measured retentive force difference was found among these three groups of SLM-built clasps (P>0.05). The maximum von Mises stress of these three groups of SLM-built clasps exceeded their responding yield strength except for the Ti-6Al-4V one. CONCLUSION SLM-built Co-Cr circumferential clasps had higher retention than CP Ti and Ti-6Al-4V ones with the same clasp arm size and undercut engagement. The retention of SLM-built circumferential clasps could be adjusted by changing the undercut engagement and clasp arm size. If SLM-built circumferential clasps are used in clinical practice, the Ti-6Al-4V clasp with clasp arm size A and 0.50 mm undercut engagement is recommended considering the long-term use of RPD in the patient's mouth.
Chromium Alloys ; Dental Clasps ; Denture Retention ; Denture, Partial, Removable ; Finite Element Analysis ; Humans ; Lasers ; Titanium