scholarly journals Titanium Scaffolds by Direct Ink Writing: Fabrication and Functionalization to Guide Osteoblast Behavior

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1156
Author(s):  
Elia Vidal ◽  
Diego Torres ◽  
Jordi Guillem-Marti ◽  
Giuseppe Scionti ◽  
José María Manero ◽  
...  
Keyword(s):  
Stress Shielding ◽  
Total Porosity ◽  
Porous Titanium ◽  
Shielding Effect ◽  
Sintering Process ◽  
Thermosensitive Hydrogel ◽  
Recombinant Fragment ◽  
Direct Ink Writing ◽  
A Cell ◽  
Good Biocompatibility

Titanium (Ti) and Ti alloys have been used for decades for bone prostheses due to its mechanical reliability and good biocompatibility. However, the high stiffness of Ti implants and the lack of bioactivity are pending issues that should be improved to minimize implant failure. The stress shielding effect, a result of the stiffness mismatch between titanium and bone, can be reduced by introducing a tailored structural porosity in the implant. In this work, porous titanium structures were produced by direct ink writing (DIW), using a new Ti ink formulation containing a thermosensitive hydrogel. A thermal treatment was optimized to ensure the complete elimination of the binder before the sintering process, in order to avoid contamination of the titanium structures. The samples were sintered in argon atmosphere at 1200 °C, 1300 °C or 1400 °C, resulting in total porosities ranging between 72.3% and 77.7%. A correlation was found between the total porosity and the elastic modulus of the scaffolds. The stiffness and yield strength were similar to those of cancellous bone. The functionalization of the scaffold surface with a cell adhesion fibronectin recombinant fragment resulted in enhanced adhesion and spreading of osteoblastic-like cells, together with increased alkaline phosphatase expression and mineralization.

Porous Titanium Scaffolds for Biomedical Applications: Corrosion Resistance and Structure Investigation

2011 ◽  
Vol 674 ◽  
pp. 41-46 ◽  
Author(s):  
Bogdan Dabrowski ◽  
Janusz Kaminski ◽  
Wojciech Swieszkowski ◽  
Krzysztof J. Kurzydlowski
Keyword(s):  
Corrosion Resistance ◽  
Biomedical Applications ◽  
Electrochemical Impedance ◽  
Biomedical Application ◽  
Total Porosity ◽  
Porous Titanium ◽  
Porous Metals ◽  
Porous Ti ◽  
A Cell ◽  
Good Biocompatibility

Due to its suitable physical properties and good biocompatibility, the titanium (Ti) can be used for development of porous structures for biomedical applications. The state of art in the field of corrosion resistance showed problems with corrosion analysis of porous metals. Therefore, it is essential to understand the influence of porosity of metals on corrosion parameters. The aim of this study was to investigate the corrosion resistance of highly porous titanium scaffolds for biomedical application. The Ti scaffolds were fabricated by powder metallurgy technique. The total porosity of the scaffolds ranged from 45 to 75%. The cast Ti sample was also tested for comparison. The electrochemical behavior of the Ti samples was monitored by electrochemical impedance spectroscopy (EIS) and potentiodynamic method at the room temperature. All electrochemical experiments were performed by a three-electrode technique in a cell containing a 0.9% NaCl electrolyte solution. With use of AAF, the active area of porous Ti was estimated. The porous Ti with porosity of 75% shows a better resistance to corrosion than the other porous Ti scaffolds. However, the corrosion resistance of Ti scaffolds was lower than cast Ti.

scholarly journals Design and Performance Evaluation of Porous Titanium Alloy Structures for Bone Implantation

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Jianping Shi ◽  
Huixin Liang ◽  
Jie Jiang ◽  
Wenlai Tang ◽  
Jiquan Yang
Keyword(s):  
Elastic Modulus ◽  
Stress Shielding ◽  
Porous Titanium ◽  
Shielding Effect ◽  
Host Bone ◽  
Test Results ◽  
Porous Implant ◽  
Biomechanical Simulation ◽  
Design And Manufacturing ◽  
And Performance

Implant parts prepared by traditional design and manufacturing methods generally have problems of high stiffness and heavy self-weight, which may cause stress shielding effect between the implanted part and the host bone, and eventually cause loosening of the implanted part. Based on the implicit surface function equations, several porous implant models with controlled pore structure were designed. By adjusting the parameters, the apparent elastic modulus of the porous implant model can be regulated. The biomechanical simulation experiment was performed using CAE software to simulate the stress and elastic modulus of the designed models. The experimental results show that the apparent elastic modulus of the porous structure scaffold is close to that of the bone tissue, which can effectively reduce the stress shielding effect. In addition, the osseointegration status between the implant and the host bone was analyzed by implant experiment. The pushout test results show that the designed porous structures have a good osseointegration effect.

scholarly journals Additive Manufacturing of Porous Ti6Al4V Alloy: Geometry Analysis and Mechanical Properties Testing

2021 ◽  
Vol 11 (6) ◽  
pp. 2611
Author(s):  
Radovan Hudák ◽  
Marek Schnitzer ◽  
Zuzana Orságová Králová ◽  
Radka Gorejová ◽  
Lukáš Mitrík ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
Additive Manufacturing ◽  
Pore Size ◽  
Maximum Stress ◽  
Stress Shielding ◽  
Porous Titanium ◽  
Shielding Effect ◽  
High Porosity ◽  
Actual Weight

This work is devoted to the research of porous titanium alloy structures suitable for use in biomedical applications. Mechanical properties were examined on six series of samples with different structures and porosity via static compressive test to identify the type of structure suitable for elimination of the “stress shielding” effect. In addition, high porosity is desirable due to the overgrowth of bone tissue into the internal structure of the implant. The samples were made of titanium alloy Ti6Al4V by using selective laser melting (SLM) additive manufacturing. The series of samples differ from each other in pore size (200, 400, and 600 µm) and porous structure topology (cubic or trabecular). The actual weight of all samples, which plays an important role in identifying other characteristics, was determined. Compressive tests were focused on the detection of maximum stress. The highest porosity and thus the lowest weight were achieved in the samples with a trabecular structure and 600 µm pore size. All tested samples reached optimal values of maximum stress and tensile strength. The most appropriate mechanical properties were observed for samples with a 200 µm pore diameter and cubic structure.

scholarly journals Design of Customize Interbody Fusion Cages of Ti64ELI with Gradient Porosity by Selective Laser Melting Process

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 307
Author(s):  
Cheng-Tang Pan ◽  
Che-Hsin Lin ◽  
Ya-Kang Huang ◽  
Jason S. C. Jang ◽  
Hsuan-Kai Lin ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Selective Laser Melting ◽  
Stress Shielding ◽  
Simulation Software ◽  
Surrounding Tissue ◽  
Shielding Effect ◽  
Stress And Strain ◽  
Laser Melting ◽  
Flexion Extension ◽  
Intervertebral Cage

Intervertebral fusion surgery for spinal trauma, degeneration, and deformity correction is a major vertebral reconstruction operation. For most cages, the stiffness of the cage is high enough to cause stress concentration, leading to a stress shielding effect between the vertebral bones and the cages. The stress shielding effect affects the outcome after the reconstruction surgery, easily causing damage and leading to a higher risk of reoperation. A porous structure for the spinal fusion cage can effectively reduce the stiffness to obtain more comparative strength for the surrounding tissue. In this study, an intervertebral cage with a porous gradation structure was designed for Ti64ELI alloy powders bonded by the selective laser melting (SLM) process. The medical imaging software InVesalius and 3D surface reconstruction software Geomagic Studio 12 (Raindrop Geomagic Inc., Morrisville, NC, USA) were utilized to establish the vertebra model, and ANSYS Workbench 16 (Ansys Inc, Canonsburg, PA, USA) simulation software was used to simulate the stress and strain of the motions including vertical body-weighted compression, flexion, extension, lateral bending, and rotation. The intervertebral cage with a hollow cylinder had porosity values of 80–70–60–70–80% (from center to both top side and bottom side) and had porosity values of 60–70–80 (from outside to inside). In addition, according to the contact areas between the vertebras and cages, the shape of the cages can be custom-designed. The cages underwent fatigue tests by following ASTM F2077-17. Then, mechanical property simulations of the cages were conducted for a comparison with the commercially available cages from three companies: Zimmer (Zimmer Biomet Holdings, Inc., Warsaw, IN, USA), Ulrich (Germany), and B. Braun (Germany). The results show that the stress and strain distribution of the cages are consistent with the ones of human bone, and show a uniform stress distribution, which can reduce stress concentration.

scholarly journals Bioactivity of PEEK GRF30 and Ti6Al4V SLM in Simulated Body Fluid and Hank’s Balanced Salt Solution

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2059
Author(s):  
Piotr Prochor ◽  
Żaneta Anna Mierzejewska
Keyword(s):  
Simulated Body Fluid ◽  
Salt Solution ◽  
Body Fluid ◽  
Stress Shielding ◽  
Shielding Effect ◽  
Orthopedic Implant ◽  
New Materials ◽  
Optical Analysis ◽  
Calcium Phosphate Layer ◽  
Cylindrical Samples

In recent years, scientists have defined two main paths for orthopedic implant fabrication: searching for new materials with properties closest to natural bone in order to reduce the stress-shielding effect or creating individually adapted geometry of the implant with the use and Rapid Prototyping methods. Therefore, materials such as PEEK GRF30 and Ti6Al4V selective laser melting (SLM) are of interest. They are defined as materials suitable for implants, however, the knowledge of their bioactivity, a feature which is one of the most desirable properties of biomaterials, is still insufficient. Using Simulated Body Fluid and Hank’s Balanced Salt Solution, the bioactivity of PEEK GRF30 and Ti6Al4V SLM was assessed, as well as commercial Ti6Al4V as a reference material. Ten cylindrical samples of each material were prepared and immersed in solutions per period from 2 to 28 days at 37 °C. Optical analysis of the changes on the examined surfaces suggested that right after 2-day crystals with different morphologies were formed on each material. Further analysis of the chemical composition of the altered surfaces confirmed the formation of a calcium phosphate layer on them, however, the Ca/P ratio was slightly different from 1.67. On the basis of the obtained results, it can be concluded that both PEEK GRF30 and Ti6Al4V SLM are characterized by appropriate—comparable to Ti6Al4V—bioactivity.

scholarly journals Topology Optimization to Reduce the Stress Shielding Effect for Orthopedic Applications

Procedia CIRP ◽  
2017 ◽  
Vol 65 ◽  
pp. 202-206 ◽  
Author(s):  
Abdulsalam A. Al-Tamimi ◽  
Chris Peach ◽  
Paulo Rui Fernandes ◽  
Akos Cseke ◽  
Paulo J.D.S. Bartolo
Keyword(s):  
Topology Optimization ◽  
Stress Shielding ◽  
Shielding Effect ◽  
Orthopedic Applications

Development of computational Tibia model to investigate stress shielding effect at healing stages

2018 ◽  
Vol 5 (5) ◽  
pp. 13267-13275 ◽  
Author(s):  
Emon Barua ◽  
Saurav Das ◽  
Ashish B. Deoghare
Keyword(s):  
Stress Shielding ◽  
Shielding Effect

Direct Write Assembly of 3-Dimensional Structures with Aqueous-Based Piezoelectric Inks

2012 ◽  
Vol 512-515 ◽  
pp. 390-394 ◽  
Author(s):  
Ya Yun Li ◽  
Bo Li ◽  
Jing Bo Sun ◽  
Kun Peng Cai ◽  
Ji Zhou ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Xrd Analysis ◽  
Direct Write ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
3 Dimensional ◽  
Direct Ink Writing ◽  
Shaping Process ◽  
Piezoelectric Devices ◽  
Sintering Condition

A kind of aqueous based suspensions of lead lanthanum zirconnate titanate (PLZT) was developed for direct ink writing (DIW) assembly. Piezoelectric ceramic woodpile structures with diameter of 315-470μm were fabricated from these inks by using DIW. The preparation of aqueous based piezoelectric inks, the principle of DIW and the sintering process were systematically discussed. The ink with solids volume fraction over 70% by 1 day aging reveals shear-thinning behavior and proper viscoelastic properties, which ensures a feasible extrusion in the whole shaping process. The PLZT samples sintered at varying temperatures between 1150 oC and 1250 oC for 2h or 4 h in either air or a lead-rich atmosphere yielded various microstructures observed by scanning electron microscopy (SEM). Choosing the optimum sintering condition, the sintered products were densified with relative density exceed 98%. The test of X-ray diffraction (XRD) analysis reveals that the main phase of sintered samples is rhombohedral Pb0.93La0.07(Zr0.65Ti0.35)0.9825O3. The direct ink writing technique has advantages of good design ability and rapid forming capability, which opens up a potential route for the design and fabrication of piezoelectric devices.

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