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Objective To investigate the influence of different cell structures on the static and dynamic mechanical performance of porous titanium alloy scaffolds,and to provide a theoretical mechanical basis for the application of scaffolds in the repair of mandibular bone defects.Methods Porous titanium alloy scaffolds with diamond,cubic,and cross-sectional cubic cell structures were manufactured using three-dimensional printing technology.Uniaxial compression tests and ratcheting fatigue with compression load tests were conducted to analyze the static and dynamic mechanical performances of scaffolds with different cell structures.Results The elastic moduli of the diamond cell,cross-sectional cubic cell,and cubic cell scaffolds were 1.17,0.566,and 0.322 GPa,respectively,and the yield strengths were 71.8,65.1,and 31.8 MPa,respectively.After reaching the stable stage,the ratcheting strains of the cross-sectional cubic,diamond,and cubic cell scaffolds were 3.3%,4.0%,and 4.5%,respectively.The ratcheting strain increased with increasing average stress,stress amplitude,and peak holding time,and decreased with increasing loading rate.Conclusions The evaluation results of the static mechanical performance showed that the diamond cell scaffold was the best,followed by the cross-sectional cubic cell scaffold and the cubic cell scaffold.The evaluation results of the dynamic mechanical performance showed that the cross-sectional cubic cell scaffold performed the best,followed by the diamond cell scaffold,whereas the cubic cell scaffold performed the worst.The fatigue performance of the scaffold is affected by the loading conditions.These results provide new insights for scaffold construction for the repair of mandibular bone defects and provide an experimental basis for further clinical applications of this scaffold technology.
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Objective To study the mechanical properties of titanium mesh and three-dimensional(3D)-printed metal vertebral body substitutes(VBS)to provide guidance for the selection and structural optimization of artificial vertebral implants in clinical practice.Methods The equivalent elastic modulus,equivalent yield strength,and structural failure mode of titanium mesh and 3D-printed porous,truss,and topologically optimized VBS were systematically investigated using compression tests.Results The elastic modulus of the titanium mesh(2 908.73±287.39 MPa)was only lower than that of the topologically optimized VBS.However,their structural strengths and stabilities were inadequate.The yield strength of the titanium mesh(46.61±4.85 MPa)was only higher than that of the porous VBS and it was the first to yield during compression.The porous VBS was insufficient for use as the vertebral implant owing to its poor mechanical strength(18.14±0.17 MPa-25.79±0.40 MPa).The truss VBS had good elastic modulus(2 477.86±55.19 MPa-2 620.08±194.36 MPa)and strength(77.61±0.50 MPa-88.42±1.07 MPa).However,the structural stability of the truss VBS was insufficient,and instability occurred easily during compression.The topologically optimized VBS had the highest elastic modulus(3 746.28±183.80 MPa)and yield strength(177.43±3.82 MPa)among all the tested VBS types,which could provide improved security and stability for artificial vertebral implant in vivo services.Conclusions Topology optimization results in a high strength and high stability VBS design.Moreover,it provides a large design space and great safety margin to provide increased possibilities for lightweight and new material design of future artificial vertebral implants.
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Objective To study the corrosion-fatigue properties of a novel low modulus Ti-3Zr-2Sn-3Mo-25Nb(TLM)titanium alloy subjected to simulated body fluid(SBF).Methods Ti-6Al-4V(TC4)alloy was used as the control group.The electrochemical corrosion polarization curves of the two titanium alloys were measured in SBF.The pre-corroded TC4 and TLM titanium alloy samples were subjected to rotational bending fatigue tests.The loading stress amplitude and fatigue fracture cycle relationship was established using the experimental data,and the stress life curves were drawn.Subsequently,the fracture mechanism was analyzed by analyzing the corrosion fatigue micro-fracture morphology of the sample,and fatigue analysis on the titanium alloy sample was then conducted combined with the finite element software.Results The self-corrosion potential of the TC4 titanium alloy under stress annealing was lower than that of the TLM titanium alloy after heat treatment.The TLM titanium alloy was most sensitive to changes in cyclic stress.A comparison between the simulation and experimental results showed that the TC4 titanium alloy under stress annealing had a higher fatigue strength and stronger resistance to crack propagation than the TLM titanium alloy did after heat treatment,whereas its corrosion resistance was the opposite.Compared to the specimens without pre-corrosion treatment,the brittleness of the TLM titanium alloy increased,and its fatigue performance decreased after pre-immersion in SBF.Conclusions Through comparative analysis,the reliability of the test results proved to be high,and the COMSOL finite element software could effectively predict the fatigue life of titanium alloy materials.
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Objective:To evaluate the curative effects of 3D printed microporous titanium (tantalum) prosthesis in reconstruction of large segmental bone defects caused by lower extremity osteomyelitis.Methods:A retrospective study was conducted to analyze the clinical data of 18 patients who had been treated for large segmental bone defects caused by lower extremity osteomyelitis between January 2020 to May 2022 at Department of Orthopaedics, The 920th Hospital of Joint Logistics Support Force. There were 10 males and 8 females with an age of (45.3±14.1) years. The defects were at the left side in 13 cases and at the right side in 5 cases, at the femur in 11 cases and at the tibia in 7 cases. The duration of osteomyelitis was 1.0 (1.0, 3.5) years. The length of bone defects was 8.35 (6.50, 9.84) cm. Their bone defects were repaired by an individually 3D printed microporous titanium (tantalum) prosthesis after operative removal of osteomyelitis lesions. The wound healing was observed after surgery. The clinical efficacy was comprehensively evaluated by the Paley grading for bone defect healing, visual analog scale (VAS), lower extremity functional scale (LEFS), and imaging examination.Results:The postoperative follow-up period for the 18 patients was (12.2±0.3) months. Wound infection occurred 2 months after surgery in one patient who was treated with Ilizarov bone transfer after removal of the microporous titanium prosthesis. The remaining 17 patients had good postoperative wound healing. At the last follow-up, the 18 patients had a VAS pain score of 2.0(1.0, 4.0) points, significantly lower than the preoperative one [(6.1±2.3) points], and a LEFS score of 54.00(34.50, 69.25) points, significantly higher than the preoperative one [18.50(9.00, 26.50) points] ( P<0.05). At the last follow-up, according to the Paley grading, the bone union was rated as excellent in 16 patients, as good in 1 patient and as poor in 1 patient. The integration of femoral fractures with 3D printed microporous titanium prostheses was fine. Conclusion:In reconstruction of large segmental bone defects caused by lower extremity osteomyelitis, implantation of a 3D printed microporous titanium (tantalum) prosthesis is feasible and effective, not only reducing pain but also restoring the limb function.
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The conversion of carbon dioxide into high value-added energy has become a research hotspot.In this study,by using Ti3AlC2 and CuCl2·2H2O as precursors,accordion-like two-dimensional Cu0/Cu2+-Ti3C2Tx catalysts modified with Cu0 nanoparticles and Cu2+ self-intercalation were successfully prepared for electrocatalytic reduction of CO2.The performance of the material was tested,and the results showed that in a CO2-saturated 0.5 mol/L KHCO3 electrolyte solution,compared with the original Ti3AlC2,the initial potential of the electrocatalytic conversion of CO2 to C2H4 over Cu0/Cu2+-Ti3C2Tx catalyst decreased from ?0.65 V(vs RHE)to?0.01 V(vs RHE).The maximum current density increased from 0.19 mA/cm2 to 2.5 mA/cm2,the double layer capacitance(Cdl)value increased from 2.61 mF/cm2 to 55.06 mF/cm2.The material showed higher catalytic activity and faster electron transfer rate(Charge transfer resistance(Rct)value was only 16.9 Ω).Moreover,the material showed high electrochemical active area and excellent stability.This research provided a promising method for designing and preparing elcetrocatalytic reduction(ECR)catalysts in the future.
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Background: Unstable sternal fixation following sternotomy is one of the risk factors that affects postoperative outcomes in cardio-thoracic surgery and is associated with increased risk of infection, bleeding and delayed rehabilitation due to pain associated with sternal movement. Sternal plate systems, which help stabilize fixation, has been limited in use due to patients' comorbidities, such as diabetes mellitus (DM) and obesity. The conventional wire sternal-fixation procedure, which depend on years of physician' experience, raise concerns such as unstable sternal fixation due to uncompleted wire twisting. Therefore, a novel sternal-fixation procedure using both titanium cable and a PLA mesh plate was investigated as a potential improvement for sternal closure. We compared the ability of this new sternum fixation procedure (group N) against the conventional sternal fixation procedure using only a wire (group O) to achieve more stable postoperative sternal fixation. Methods and Results: Among adult open-heart surgeries performed between August 2020 and April 2023, 155 patients who underwent postoperative CT were included, with group N being the combined group and group O being the group using conventional metal wires: group N (86 patients: M 65, F 21) and group O (69 patients: M 50, F 19). Preoperative factors included age at surgery (group N: group O)=68.4±10.6 : 69.6±11.5 years (p=0.25)), BMI (group N: group O=23.0±3.7 : 24.1±7.7 (p=0.16)) and HbA1c (group N: group O=6.3±1.1 : 8.0±10.3% (p=0.10), and no factors were significantly different between the two groups. The CT analysis at the point of hospital discharge after surgery measured postoperative sternal deviation in the third rib position. Transverse displacement was significantly reduced (group N: group O=0.22±0.73: 0.83±1.08 mm (p=0.005)), and longitudinal displacement also showed an improvement but the difference was not statistically significant (group N: group O=0.53±0.86: 0.72±1.14 mm (p=0.13). Conclusion: A novel sternum closing technique using a tension-anchored titanium cable and a PLA mesh plate demonstrated improved postoperative sternal fixation in a controlled study with 155 patients. This new procedure also enables standardized stable sternal closure with a constant force without relying on conventional empirical sensation and without suppressing sternal cutting, thus contributing to the improvement of postoperative quality of life and prevention of complications.
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BACKGROUND:Root canal preparation is a key step in root canal therapy.In recent years,with the rapid development of new nickel-titanium instruments,the results of root canal shaping ability have been significantly improved.However,the shaping abilities of different nickel-titanium instruments are also different.At present,there are few reports about the influence of the shaping ability of R-phase heat treatment NIC X-FILE and DENCO Pre-Shaper in simulated curved canals. OBJECTIVE:To compare the shaping effect of NIC X-FILE and DENCO Pre-Shaper nickel-titanium instruments in preparation for simulated curved canals. METHODS:Fifty simulated resin-curved canals were selected and randomly divided into two groups(n=25).NIC X-FILE and DENCO Pre-Shaper nickel-titanium files were used for root canal preparation.The root canal preparation time was recorded.Images of pre-and post-root canal preparation were taken.Image processing and analysis software were used to measure the amount of resin removed from the inner and outer walls of the root canal at each observation point.Statistical software was used to compare the root canal preparation time and centering ability of two kinds of mechanical nickel-titanium files. RESULTS AND CONCLUSION:(1)The average root canal preparation time was(1.58±0.02)minutes in the DENCO Pre-Shaper group and(2.22±0.03)minutes in the NIC X-FILE group.There was a significant difference between the two groups(P<0.05).(2)The amount of resin removed from the inner walls of the root canal of the DENCO Pre-Shaper group at 4,5,7,8,9,and 10 mm from the apical foramen was higher than that of the NIC X-FILE group(P<0.05).The amount of resin removed from the outer walls of the root canal of the DENCO Pre-Shaper group at 3,5,6,7,and 8 mm from the apical foramen was lower than that of the NIC X-FILE group(P<0.05).(3)At 2,4,5,6,7,8,and 9 mm away from apical foramen,the centering ability of the NIC X-FILE group was better than that of the DENCO Pre-Shaper group(P<0.05),and the centering ability of the NIC X-FILE group was the best at 4 mm away from apical foramen.(4)The results show that DENCO Pre-Shaper has higher mechanical efficiency than NIC X-FILE nickel-titanium root canal files.However,the centering ability of DENCO Pre-Shaper is inferior to NIC X-FILE nickel-titanium root canal files.
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BACKGROUND:At present,a large number of studies have found that Liuwei Dihuang Pill can be used to treat osteoporosis,but there are few related studies on the differentiation and mineralization of osteoblasts induced by wear particles using Liuwei Dihuang Pill. OBJECTIVE:To investigate the positive effect of different concentrations of Liuwei Dihuang Pill-containing serum on titanium particle-induced mouse MC3T3-E1 osteoblast in vitro osteolysis model. METHODS:Drug-containing serum was extracted after oral administration of Liuwei Dihuang Pill.The best concentration of Liuwei Dihuang Pill-containing serum and titanium particles on the viability of MC3T3-E1 cells was screened.MC3T3-E1 cells were divided into three groups.The blank group was given osteoblastic differentiation culture.The model group was given titanium particles(5 μg/mL)ossification culture.The drug-containing serum group was given titanium particles(5 μg/mL)+ Liuwei Dihuang Pill-containing serum(10%,15%and 20%doses).Osteoblast viability was detected by CCK-8 assay.Cell alkaline phosphatase activity was detected by alkaline phosphatase staining.Cell mineralization was detected by silver nitrate(Von Kossa)and alizarin red staining.Expression levels of bone differentiation-related genes Runx-2,Osterix,Ocn,Axin,Alp,and Opn were detected by qRT-PCR.Wnt/β-catenin signaling pathways β-catenin,p-GSK-3β,GSK-3β,Runx2 and Osterix protein expression levels were detected by western blot assay. RESULTS AND CONCLUSION:(1)Liuwei Dihuang Pill-containing serum culture reversed the decrease in alkaline phosphatase activity of MC3T3E-1 cells induced by titanium particles,increased the alizarin red staining and calcification of MC3T3E-1 cells,increased the expression of osteogenesis-related genes in MC3T3E-1 cells,and increased the expression of proteins related to the Wnt/β-catenin signaling pathway.(2)These findings indicate that Liuwei Dihuang Pill-containing serum can reverse the inhibitory effect of titanium particles on the differentiation and mineralization of osteoblasts,upregulate the expression of osteogenesis-related genes,and its mechanism is related to the regulation of Wnt/β-catenin signaling pathway,suggesting that Liuwei Dihuang Pill is expected to become an effective drug for preventing aseptic loosening of artificial joints.
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BACKGROUND:At present,the traditional powder sintering method is easy to introduce impurities in the process of preparing porous titanium,and the manufacturing of porous titanium still faces two major problems:impurity pollution and difficult control of the material forming process. OBJECTIVE:To prepare pure porous titanium with certain porosity,and analyze the microstructure evolution and properties of the porous titanium. METHODS:Porous titanium was prepared at a low energy density by selective laser melting technology.The parameter range of porous titanium with large porosity was obtained by measuring the porosity of the formed specimen,and the evolution of the microstructure and mechanical properties of the specimen in the range were analyzed. RESULTS AND CONCLUSION:(1)With the increase in energy density,the porosity of the porous titanium specimen decreased gradually.When the energy density was between 10.61 and 27.78 J/mm3,porous titanium with a porosity of 11.23%-33.67%could be formed.When the energy density was between 27.78-37.88 J/mm3,the forming parts were relatively dense.(2)The phase composition of porous titanium formed was mainly α titanium.With the increase in energy density,the porosity gradually decreased,and the pore morphology changed from irregularly connected pores to closed nearly spherical pores.The powder particles changed from a slightly sintered neck to a continuous fuse.The CT scan results revealed that there were a large number of connected pores in the forming specimen with a large specific surface area and the pore radius was roughly distributed between 2-6 μm at the energy density of 10.61 J/mm3.Simultaneously,porous titanium with compressive strength of 188-1 000 MPa could be obtained at the energy density of 10.61-27.78 J/mm3,which could meet the requirements of biomedical applications.(3)These results have confirmed that the selective laser melting technology can overcome the problems of impurity pollution and long manufacturing cycle caused by the traditional preparation process,and provide an effective solution for the preparation of porous titanium with excellent mechanical properties.
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BACKGROUND:Anterior subtotal corpectomy,decompression and fusion is a conventional method to treat cervical degenerative diseases.A titanium cage is an important implant to maintain the stability of the cervical spine after subtotal corpectomy.In recent years,many patients have complications such as titanium cage sinking,which are highly controversial. OBJECTIVE:To investigate the internal biomechanical relationship between the tilt angle of the titanium cage and postoperative titanium cage subsidence after anterior subtotal cervical corpectomy,decompression and fusion. METHODS:A three-dimensional finite element model of the C4-C6 segment was established by CT images of a normal human cervical spine,in which the anterior subtotal resection,decompression and fusion of the C5 vertebral body were simulated,and titanium cages with different tilt angles(-6° to-1° negative angle,that is,the front edge of titanium cage is shorter than the rear edge of titanium cage;1° to 6° positive angle,that is,the front edge of titanium cage is longer than the rear edge of titanium cage)were placed.After setting the boundary conditions,preloads of 50,100 and 150 N were applied respectively on the C4 vertebral body.The stress value of each contact point between the titanium cage and C4 lower-end plate and C6 lower-end plate(seven stress contact points on the contact surface of titanium mesh)was recorded and statistical analysis was conducted. RESULTS AND CONCLUSION:(1)The tilt angles of the titanium cage of the positive angle group and negative angle group under 50,100 and 150 N stress respectively were found by Mann Whitn test,with P<0.05,which was statistically significant.The dispersion coefficients of the positive angle group were smaller than those of the negative angle group under 50,100 and 150 N stress conditions.(2)Under 50,100 and 150 N stress conditions,the Wilcoxon sign rank test in the positive angle group of titanium cage tilt angle found that when the angle was set to 1° to 5°,the difference was not statistically significant(P>0.05).However,when the tilt angle of the titanium cage was set to 6°,the difference was statistically significant(P<0.05).(3)Under 50,100 and 150 N stress conditions,the Wilcoxon sign rank test in the negative angle group of titanium cage tilt angle found that when the tilt angle was set to-1° to-6°,the difference was not statistically significant(P>0.05).(4)It is concluded that in the sagittal position,the titanium cage with a positive tilt angle is more stable than with a negative tilt angle,which is more suitable for clinical use.The tilt angle of the titanium cage is relatively stable in the range of 1° to 5°.When the tilt angle is 6°,the stability starts to decline,which is easy to cause complications of titanium cage sinking after surgery.It is more suitable to select the titanium cage with a tilt angle of 1° to 5° according to the clinical situation during surgery to improve the efficacy.
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BACKGROUND:Nanostructure modification of pure titanium surface is a hot research field of titanium implant surface treatment. OBJECTIVE:To evaluate the effect of nano-modified titanium surface treated with alkali heat treatment on early adhesion and growth of osteoblasts. METHODS:Four-grade pure titanium sheets with a diameter of 15 mm and a thickness of 1.5 mm were taken and processed in three groups:the smooth treatment group was polished step by step with 250 mesh,800 mesh,and 1 500 mesh silicon carbide sandpaper.In the sandblasting group,the smoothed titanium sheet was sandblasted with 100 μm Al2O3 particles at 0.45 MPa pressure,and then the acid etching was carried out.In the alkali heat treatment group,the smoothed titanium sheet was placed in the reactor,immersed in 10 mol/L NaOH solution,and heated in the oven at 100 ℃for 12 hours.The surface morphology,roughness,and hydrophilicity of three groups of titanium sheets were measured.MG63 osteoblasts were inoculated on the surface of three groups of titanium tablets,and the adhesion of the cells was observed by immunofluorescence staining. RESULTS AND CONCLUSION:(1)Scanning electron microscopy showed that the surface of titanium sheets in the smooth treatment group had uniform scratches;the surface of titanium sheets in the sandblasting group was uneven,and the surface of titanium sheets in the alkali heat treatment group had uniform nanoscale three-dimensional pore morphology.The roughness value of the titanium sheets in sandblasting and alkali heat treatment groups was higher than that in the smooth treatment group(P<0.05),and the water contact angle was lower than that in the smooth treatment group(P<0.05).(2)Immunofluorescence staining after 3 and 6 hours of inoculation of MG63 cells showed that the number of adhesion cells on the surface of the titanium sheet in the sandblasting group and alkali heat treatment group was higher than that in the smooth treatment group(P<0.05).Immunofluorescence staining 12 hours after inoculation showed that compared with the smooth treatment group,the actin skeleton of cells on the surface of titanium sheets in the sandblasting group and alkali heat treatment group was more extended,and most cells extended stronger pseudopodia,which was conducive to subsequent intercellular signal transduction and intercellular interaction.(3)The results showed that the nanostructures with certain biological activity could be prepared on the surface of a titanium sheet by alkali heat treatment,which was conducive to the early adhesion of osteoblasts.
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BACKGROUND:The combination of machine learning and medical metal materials can make up for the inefficiency and high cost of traditional experiments and computational simulations,and quickly and accurately predict the characteristics of metal materials by analyzing large amounts of data,optimize material design and performance,and improve the safety and efficiency of medical applications. OBJECTIVE:To summarize the research progress and shortcomings of machine learning in the characteristics of medical materials. METHODS:The first author searched CNKI,PubMed,X-MOL,and Web of Science databases by computer to search all relevant articles from January 2013 to April 2023.The Chinese search terms were"machine learning of medical metal materials,medical titanium alloy,medical magnesium alloy,medical metal material properties".The English search terms were"machine learning medical metal materials,medical stainless steel alloy,medical cobalt-chromium alloy,medical titanium alloy,medical magnesium alloy".Finally,70 relevant articles were included for a summary. RESULTS AND CONCLUSION:(1)The introduction of machine learning as a material design methodology has opened up new paradigms for material science research as the accessibility of large amounts of data generated by traditional experimental and computational simulation methods increases.(2)The machine learning workflow is divided into four main parts:data collection and preprocessing,feature engineering,model selection and training,and model evaluation,each of which is indispensable.(3)Medical metal materials are categorized into:stainless steel co-base alloys,cobalt-chromium alloys,titanium alloys,and magnesium alloys.For stainless steel co-base alloy,machine learning predicts its mechanical properties,to improve the generalization ability of machine learning.For cobalt-chromium alloy,machine learning predicts its mechanical properties,and it can conclude that cobalt-chromium alloy is the optimal material for hip implants.For titanium alloy,machine learning predicts its mechanical properties,and it can select the implant with the best mechanical properties.For magnesium alloy,machine learning predicts its corrosion resistance and mechanical properties;the ensemble model can accurately predict the mechanical properties of magnesium alloys,and the random forest model can predict the optimal elemental contents of magnesium alloys as vascular stents.(4)Machine learning has deficiencies in the field of medical materials.For example,the model is relatively lagging;the data failed to be standardized,and the generalization is low.To solve such problems,we should make full use of deep learning and segmentation algorithm technology,use unified standard data,and improve the model to increase the generalization ability.
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BACKGROUND:Titanium and its alloys are widely used in orthopedic implants due to their excellent biocompatibility,corrosion resistance,and mechanical properties.However,it has biological inertia itself,cannot provide a good growth environment for osteoblasts,and it is difficult to form good osseointegration. OBJECTIVE:To construct a composite hydrogel material of gelatin methacryloyl and polyacrylamide on the surface of titanium alloy scaffold,and analyze its osteogenic ability in vitro. METHODS:Gelatin methacryloyl was mixed with acrylamide.Crosslinking agent and catalyst were added to synthesize gelatin methacryloyl and acrylamide(Gelma-PAAM)composite hydrogel.The titanium alloy scaffold modified by affinity silane was mixed with the Gelma hydrogel and Gelma-PAAM composite hydrogel to complete the loading(recorded as Ti-Gelma and Ti-Gelma-PAAM,respectively).The swelling ratio and degradation rate of the two hydrogels on the surface of the scaffold were compared.The bonding state between hydrogels and titanium alloy was observed by scanning electron microscope.Rat bone marrow mesenchymal stem cells were inoculated into Ti,Ti-Gelma and Ti-Gelma-PAAM scaffolds,separately.Cell proliferation,adhesion,and osteogenic differentiation were detected. RESULTS AND CONCLUSION:(1)Compared with Gelma hydrogel,Gelma-PAAM hydrogel had higher swelling rate and lower degradation rate.(2)Scanning electron microscope showed that the surface of the two kinds of hydrogels was honeycomb structure.After being combined with porous titanium alloy scaffold,the film was wrapped on the surface of scaffold and filled with pores.Among them,the Gelma-PAAM composite hydrogel coated the scaffold more fully.(3)CCK-8 assay and live/dead fluorescence staining showed that bone marrow mesenchymal stem cells proliferated well after coculture with Ti-Gelma and Ti-Gelma-PAAM scaffolds and maintained high activity.After osteogenic induction culture,alkaline phosphatase activity,calcium deposition,and osteogenic gene expression of cells of titanium alloy scaffold group were the lowest,and alkaline phosphatase activity,calcium deposition,and osteogenic gene expression of cells of Ti-Gelma-PAAM scaffold group were the highest.(4)Phalloidin cytoskeletal staining exhibited that the cells of pure titanium alloy scaffold group and Ti-Gelma scaffold group were sparse and insufficiently extended,while the cells of Ti-Gelatin-PAAM group had the most adequate stretching and the densest filamentous actin.(5)The results show that Gelma-PAAM hydrogel has good biocompatibility and osteogenic ability,and is more suitable for osteogenic modification on the surface of titanium alloy than Gelma hydrogel.
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BACKGROUND:Calcium phosphate(CaP)coatings are widely used to improve the integration of titanium implants into bone but these coatings are associated with risks of infection.It is thus desirable to confer antibacterial properties to CaP coatings. OBJECTIVE:To prepare CaP-MgO composite coatings by impregnating magnesium oxide(MgO)sol into CaP coatings and assess the in vitro antibacterial activities and cytocompatibility. METHODS:An electrolyte was determined by titration and used for CaP coating electrodeposition on titanium(referred to as Ti-CaP).MgO was impregnated into the coating by immersing in an MgO sol with different mass fractions(15%,30%,50%)and subsequently calcined to form MgO-CaP composite coatings,which were recorded as Ti-CaP-15Mg,Ti-CaP-30Mg and Ti-CaP-50Mg,respectively.Microstructure,tensile properties,critical load,and Mg2+ release of coatings in vitro were characterized.Antibacterial activity was assayed using spread plate method by culturing S.aureus on the pure titanium sheet surface and Ti-CaP,Ti-Cap-15mg,Ti-Cap-30mg and Ti-Cap-50mg surfaces for 24 and 48 hours.Mouse osteoblast suspension was inoculated on pure titanium sheets and Ti-CaP,Ti-CaP-15Mg,Ti-CaP-30Mg and Ti-CaP-50Mg coated titanium sheets,respectively.Cell proliferation was detected by CCK-8 assay,and cell survival rate was calculated.The morphology of composite coating soaked in DMEM was also observed. RESULTS AND CONCLUSION:(1)Homogeneous,microporous CaP coatings consisting of octacaclium phosphate crystal flakes were prepared on titanium by electrodeposition.After sol impregnation-calcination,MgO aggregates were filled into the inter-flake voids.The extent of MgO filling and Mg concentration in the coating increased with the number of sol impregnation procedures.When immersed in phosphate buffered saline,all composite coatings actively released Mg2+ within 1 day;subsequently,the Mg2+ release slowed down on day 3.A small amount of Mg2+ release was still detected on day 7.The yield strength,tensile strength and fracture growth rate of Ti-CaP-30Mg coated titanium were not significantly different from those of pure titanium(P>0.05).There was no significant difference in the critical load of Ti-CaP,Ti-CaP-15Mg,Ti-CaP-30Mg and Ti-CaP-50Mg groups(P>0.05).(2)Except that pure titanium sheet and Ti-CaP had no antibacterial properties,the other samples had good antibacterial properties,and the antibacterial rate increased with the increase of MgO content in the coating.(3)After 1 and 3 days of co-culture,the cell survival rate of Ti-CaP-15Mg,Ti-CaP-30Mg and Ti-CaP-50Mg groups was lower than that of pure titanium group and Ti-CaP group(P<0.05).After 5 and 7 days of culture,there was no significant difference in cell survival rate among five groups(P>0.05).The content of MgO in the coating decreased gradually with the time of immersion in the medium.(4)The MgO sol impregnation added antibacterial properties to the CaP coatings while retained their biocompatibility.
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BACKGROUND:In recent years,additive manufacturing(also known as 3D printing)has gradually become the mainstream method for producing titanium alloy brackets for removable partial dentures.Heat treatment,as an important method to improve the mechanical properties of 3D printed titanium alloys,has become a current hot topic of attention.OBJECTIVE:To summarize the main heat treatment technologies currently applied to 3D printed titanium alloy specimens(including annealing,solution aging,hot isostatic pressing,and other heat treatments)and their effects on the mechanical properties and microstructure of 3D printed titanium alloy specimens,providing a theoretical basis for improving the heat treatment technology of removable partial denture titanium alloy supports.METHODS:A computer search was conducted on research materials related to 3D printed titanium alloy heat treatment in databases such as CNKI,PubMed,and ScienceDirect.The search period was from 2012 to 2023.A total of 61 articles were selected based on inclusion and exclusion criteria.RESULTS AND CONCLUSION:(1)Using conventional annealing techniques to treat 3D printed titanium alloy specimens,keeping them at 500-900 ℃ for 2-4 hours,can effectively increase the elongation of 3D printed titanium alloy specimens.(2)Compared to conventional annealing techniques,solid solution aging treatment is more complex,and the titanium alloy specimens after solid solution aging treatment exhibit outstanding yield strength and better corrosion resistance.However,the 3D printed titanium alloy specimens after solid solution aging treatment have no advantage in terms of ductility.(3)Hot isostatic pressing treatment can reduce the internal defects of 3D printed titanium alloy specimens,significantly increase the elongation of 3D printed titanium alloy specimens,and increase their fatigue life.(4)Rapid heat treatment can significantly improve the elongation of 3D printed titanium alloy specimens,and the speed is faster.In terms of elongation improvement and heat treatment efficiency,it has more advantages than conventional annealing in the past.(5)The improvement of elongation of 3D printed titanium alloy specimens by cyclic heat treatment exceeds that of conventional annealing.Cyclic heat treatment can significantly improve the grain structure of 3D printed titanium alloy specimens,but the heat treatment time is too long and the efficiency is low.
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BACKGROUND:The impact of anterior cervical surgery on the sagittal balance parameters of the cervical spine is gradually being paid attention to.Currently,there is a lack of clear and feasible clinical guidelines for the selection of surgical methods for two-level cervical spondylosis,aiming to find the most suitable fixation method that is more beneficial for this type of patient. OBJECTIVE:To compare the effects of different fusion devices for anterior cervical decompression on the changes of cervical sagittal parameters after surgery for adjacent two-level cervical spondylotic myelopathy. METHODS:A total of 44 patients with adjacent two-level cervical spondylotic myelopathy underwent anterior cervical discectomy and fusion from March 2018 to September 2020 in Liaocheng People's Hospital were retrospectively analyzed in the study,and they were divided into zero-p group(23 cases)and cage group(21 cases).All patients underwent anteroposterior X-ray,three-dimensional CT reconstruction and MRI examination before operation.At the last follow-up,the anteroposterior X-ray films of cervical spine were taken.The sagittal balance parameters of the cervical spine were measured before and after surgery,including cervical lordotic angle(C2-7 Cobb),C2-C7 sagittal vertical axis,segmented lordotic angle and T1 slope.The surgical time,intraoperative bleeding,last follow-up intervertebral fusion,and postoperative swallowing disorders were recorded,and Japanese Orthopaedic Association score on the patient was evaluated before and after surgery.The changes in cervical sagittal parameters before and after surgery were calculated and their differences were compared between the two groups. RESULTS AND CONCLUSION:(1)Both groups of patients successfully completed the surgery and received follow-up.The zero-p group had shorter surgical time and less intraoperative bleeding compared to the cage group,but the difference was not statistically significant(P>0.05).(2)The incidence rate of postoperative swallowing disorders in the cage group(7/21,33%)was higher than that in the zero-p group(3/23,13%),and the difference was statistically significant(P<0.05).(3)At the last follow-up,the clinical efficacy of the two groups was the same;all patients had bone fusion.Comparison within the group showed that the sagittal parameters of the cervical spine in both groups improved compared to before surgery(P<0.05).There was no statistically significant difference in sagittal parameters between groups(P>0.05),and there was no statistically significant difference in changes in C2-C7 sagittal vertical axis,C2-7 Cobb angle,and T1 slope between the two groups(P>0.05).However,the segmented lordotic angle changes in the zero-p group were smaller than those in the cage group,and the difference was statistically significant(P<0.05).(4)It is indicated that the use of zero-p and titanium plate combined with cage during anterior cervical discectomy and fusion surgery can effectively improve cervical sagittal balance.Titanium plate combined with cage intervertebral fusion can better reconstruct the patient's cervical lordosis and curvature.The selection of fusion devices should also comprehensively consider the occurrence of surgical complications.
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@#The sternum is the pivotal component of the thoracic cavity. It is connected with the clavicle and ribs on the upper part and both sides respectively, and plays an important role in protecting the stability of the chest wall. Sternal resection usually results in a large segmental chest wall defect that causes the chest wall to float and requires sternal reconstruction. This paper reports a 62 years male patient with thymic squamous cell carcinoma with sternal metastasis, who underwent thymotomy, sternal tumor resection and autologous lilum graft combined with sternal reconstruction by titanium plate after relevant examination was completed and surgical contraindications were eliminated. The patient was followed up for 6 months, the respiratory and motor functions were normal and the thoracic appearance was good.
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Objective@#To deposit degradable amino-hybrid mesoporous silica (AHMS) in situ on the surface of titanium nanotube (TNT) and explore its protective effect on nanomorphology and osteogenesis.@*Methods@#TNT and TNT@AHMS were sequentially prepared via an anodizing method: the oil-water two-phase method (experimental group) and the acid-etched titanium method [control group (Ti)]. The parameters for synthesis were explored by changing the silicon source dosage ratio (3∶1, 1∶1, 1∶3); the surface morphology was observed by scanning electron microscope(SEM), hydrophilicity was detected by Water Contact Angle Tester, elemental composition was detected by X-ray photoelectron spectroscopy (XPS); nanoindentation test and ultrasonic oscillator were used to observe the morphological holding effect as mechanical strength of TNT@AHMS in vitro; simulated immersion experiments in vitro was used to observe the degradation behavior of the material. the MC3T3-E1 cell line was used to observe the effect of cell adhesion, proliferation and differentiation on the material; and an SD rat femoral implant model and micro-CT were used to verify the protective effect and osseointegration effect of AHMS on TNT morphology.@*Results@#The morphologies of TNT and TNT@AHMS were successfully prepared, and the silicon source ratio was 1:3. SEM showed that the titanium nanotubes were uniformly covered with AHMS coating, and the mesoporous pore size was about 4 nm. After AHMS was incorporated, the surface of the material was hydrophilic (12.78°), the presence of amino groups (NH2-) was detected, the material was completely degraded within 12 h in vitro, and the active morphology of the TNT was re-exposed with a cumulative silicon release of 10 ppm. Nanoindentation test showed that TNT@AHMS exhibited more ideal surface mechanical strength. SEM revealed that TNT maintains its own morphology under the protection of AHMS, and the TNT group suffered severe exfoliation. In addition, the early adhesion and proliferation rates, ALP activity, and bone volume fraction of cells on the TNT@AHMS surface 4 weeks after implantation were significantly higher than those in the TNT group.@*Conclusion@#By depositing AHMS on the surface of TNT, the nanotopography can be protected. It not only prevents the active base topography from exerting subsequent biological effects but also further endows the material with the ability to promote bone regeneration, laying a foundation for the future development of nanotopography-modified titanium implants.
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Objective@#The purpose of this study was to investigate the differences in the anti cyclic fatigue performance of Woride KS (WKS), Proteper Gold (PTG), and Hyflex CM (HCM) nickel titanium instruments with different tip diameters in curved root canal models, and to provide reference for the targeted selection of suitable nickel titanium instruments in clinical preparation of curved root canals.
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ObjectivesTo compare the clinical efficacy and complications of anatomic locking titanium plate （hereinafter referred to as “titanium plate screw”） and intramedullary nail in the treatment of distal tibial fractures.Methods From September 2019 to September 2021， 32 patients diagnosed with AO-A fracture of distal tibia at Sun Yat-sen Memorial Hospital of Sun Yat-sen University were included in this study. Of these， 15 cases were treated with titanium plate screws and 17 cases were treated with intramedullary nails. General surgical indexes， fracture healing time and postoperative operation were compared between the two groups.ResultsAll patients were followed up for 10 to 20 months， with an average of 12 months. The operative time and intraoperative fluoroscopy times of intramedullary nail group were longer than those of titanium plate screw group， but the preoperative waiting time and hospitalization days was less or were fewer than those of titanium plate screw group， the difference was statistically significant （P < 0.05）. There was no significant difference in fracture healing time between the two groups （P> 0.05）. At 6 weeks after operation， VAS scores in both groups were lower than those before operation， with statistically significant difference （P<0.05）. There was no significant difference in VAS scores between the intramedullary nail group and the titanium plate screw group （P> 0.05）. AOFAS scores 6 months after surgery， ankle joint motion and complication rate 1 year after surgery in intramedullary screw group were better than those in titanium plate screw group， and the differences were statistically significant （P< 0.05）. There was no significant difference in AOFAS scores between the two groups at 1 year after operation （P> 0.05）.ConclusionTitanium plate screw and intramedullary nail are both effective methods for the treatment of distal tibial AO-A fracture， and there is no significant difference in long-term clinical efficacy. Intramedullary nail has fewer soft tissue complications， less impact on ankle motion， faster recovery and higher safety， while titanium plate screw has a higher probability of postoperative soft tissue infection. We suggest that in clinical work， preoperative evaluation of patients should be done well. Under the premise of grasping the indications， intramedullary nail has fewer complications and certain advantages.