Page 230 - IJB-10-2

International Journal of Bioprinting Property of scaffolds with different lattices

demonstrated that titanium porous alloy scaffolds with a material, which better met the modulus requirements of
porosity of 60–70% and a pore diameter of 500–700 μm human cortical bone. However, the diamond scaffold has
have good mechanical and biological capabilities, although the lowest elastic modulus (calculated: 11.6 GPa, test: 5.360
the aforementioned research has given insufficient attention ± 1.057 GPa), which resembles to that of human cancellous
to pore shape. In light of this, computer-aided software bone, thus lending itself to better prevention of osteolysis
was utilized in this experiment to create porous scaffold caused by stress shielding of cancellous bone. Overall, the
models with 66% porosity, 600 μm pore size, and three diamond scaffold offers superior mechanical properties to
lattice geometries of CPL, diamond, and cuboctahedron, those of the CPL and cuboctahedron scaffolds.
which were then processed using SLM technology into On the premise of meeting the mechanical qualities of
Ti6Al4V scaffolds. The results of SEM and micro-CT scans human bones, how to create porous titanium alloy scaffolds
revealed that 3D-printed Ti6Al4V scaffolds had uniform that integrate more effectively with the surrounding bone
pore distribution, good internal connectivity, and no has always been a topic of intense research. Li et al.
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evident powder deposition or pore blockage. The actual conducted a hydrodynamic investigation on porous
porosity, pore diameter, and rod diameter of the three scaffolds with various pore sizes and discovered that the
scaffolds closely matched their designed values. It can be permeability of scaffolds increased with the porosity,
demonstrated that the SLM technique has good processing and the porous scaffolds with a pore size of 800 μm
precision and can produce the correct Ti6Al4V scaffolds experienced the highest shear stress. Li et al. simulated
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with varying pore types, which is consistent with previous the fluid characteristics of two shapes of unit cells (octet
results in the literature. 49,50 truss and rhombic dodecahedron) with different strut
Biomechanical adaptation is a prerequisite for the use sizes and discovered that the unit cell shape and strut size
of porous titanium alloy scaffolds in bone defect healing. significantly determined and influenced other physical
Not only must the yield strength match the load-bearing parameters and flow properties of porous scaffolds. Li
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criteria, but the elastic modulus must also be comparable et al. used CFD to analyze the fluid characteristics of five
to that of human bone (3–30 GPa for cortical bone and different unit cell types of porous scaffolds and discovered
0.02–3 GPa for cancellous bone), so as to avoid the stress that different unit cells could directly lead to diverse fluid
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shielding effect. The static simulation analysis revealed properties of porous implants. Porosity, pore size, and
that the yield strength of Ti6Al4V porous scaffolds with pore shape have a significant effect on the fluid dynamics
CPL, diamond, and cuboctahedron lattice elements is of porous scaffolds, and the fluid dynamics influence the
approximately 140 MPa, which is quite different from delivery of nutrients and the shear stress of the scaffold
the compression test result. The discrepancy can be wall. Relevant research has demonstrated that nutrition
justified by a fabrication error in SLM, which leads to a transport and shear stress are crucial for cell adhesion,
difference between the diameter of the connecting rod of proliferation, and differentiation 55-57 .
the porous structure and the theoretical designed value. In The present study investigated the fluid dynamics of
addition, simulation analysis is a theoretical calculation three pore forms (CPL, diamond, and cuboctahedron) with
of the mechanical properties of the scaffolds using the identical porosity and pore size. The results demonstrated
finite element analysis method, and the reliability of the that the diamond scaffold had superior permeability and
results is related to the type, number of grid units, and average flow rate compared to the cuboctahedron and CPL
material attribute assignment. Therefore, the simulation scaffolds. Therefore, diamond scaffold is comparatively
analysis results can only be used as a supplement to the better than others in nutrient transport, which is a crucial
research on the mechanical properties of the porous aspect of cell proliferation. In vitro investigations with
scaffolds, and the in vitro mechanical test data should mouse MC3T3-E1 cells revealed that the number of cells
still be used as the standard. According to the literature, proliferating on diamond scaffolds was much higher than
the yield strength of human cortical bone is 109.6 ± 4.7 that on CPL and cuboctahedron scaffolds after 3 days
MPa, and the yield strength of cancellous bone is 55.3±8.6 of culture, confirming the results of the fluid simulation
MPa, demonstrating that Ti6Al4V scaffolds with three analysis. Shear stress study revealed that the average shear
pore shapes can acquire the strength requirements of stress on the walls of the three types of scaffolds differed
the human body when the porosity is 66% and the pore significantly (P < 0.05), the diamond scaffold displaying
diameter is 600 μm. In addition, we evaluated the elastic the smallest average shear stress, while the cuboctahedron
modulus of the three types of porous scaffolds, and the scaffold the largest. Nevertheless, based on the proportion
results demonstrated that their calculated elastic modulus diagram of shear stress distribution, the diamond scaffold
decreased to 83.6–89.5% when compared to the elastic with a shear stress of 120–140 MPa accounted for the
modulus (110 GPa) of the dense solid titanium alloy biggest part, whereas the other two scaffolds had the

Volume 10 Issue 2 (2024) 222 doi: 10.36922/ijb.1698