Page 185 - IJB-10-4

International Journal of Bioprinting Effects of structure on the interbody cage

and right, 12 mm at the top and bottom, and a bottom diameter of the porous cages was 461.44 ± 31.03 μm
length of 10 mm, with four corners rounded by arcs of when the filling rate was 60%, and the pore diameter of
radius 2 mm, and a thickness of 5 mm. the porous cages was 896.64 ± 41.94 μm when the filling
rate was 40%. The beam diameter of each cage was 514.67
3.2. Appearance structure and morphology ± 24.23 μm. However, as the filling rate decreased and the
examination of the cages aperture diameter increased, the gap between adjacent
Printing consumables have a significant impact on the beams widened. Moreover, due to slower cooling after
printing process and the quality and appearance of the final extrusion from the nozzle, the overhanging portion of the
product. In tissue-engineering research, to avoid increased upper beams experienced shrinkage and sagging when
brittleness and mechanical performance degradation the filling angle was altered. This phenomenon was most
caused by high concentrations of ceramics, the majority of pronounced when there was only one layer crossing. The
PCL/HA composite materials have an inorganic ceramic SEM morphology of the vertical segment of the cage is
content below 30 wt%. Among them, PCL with 10 wt% HA
exhibits the best printability, characterized by low surface illustrated in Figure 4M–R. In the vertical scale, the
roughness, high interlayer uniformity, and high stability internal holes are rectangular holes with different heights,
in scaffold dimensions. PCL scaffolds with 25 wt% HA and the holes become larger with the increase of the
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demonstrate the best overall performance. Therefore, number of crossing layers of the beams. The hole heights
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cages were built using composites with 25 wt% HA content of the fusion apparatus with 60% filling rate (group A) are
in this investigation. 119.11 ± 9.17 μm, 452.91 ± 8.04 μm, and 962.69 ± 16.57
μm, respectively, when the number of crossing layers is
The porous spinal interbody fusion cages with 1, 2, and 4. However, due to the sagging phenomenon of
various structural characteristics manufactured via melt the beams, the vertical pore heights of the fusers with a
differential 3D printing are depicted in Figure 4A–F. They 40% filling rate (group B) are reduced, measuring 85.06
are all horseshoe-shaped in appearance, with the radius of ± 26.39 μm, 305.75 ± 9.17 μm, and 906.73 ± 16.75 μm,
the upper arc of 12 mm, the maximum width of the left and respectively. The SEM morphology of the vertical profile
right of 14.45 ± 0.04 mm, the maximum width of the upper also demonstrated that the cages with a small number
and lower of 12 ± 0.05 mm, and the thickness of 5.1 ± 0.02 of crossing layers of the beams had fewer holes on the
mm. The size is almost consistent with that of computer- vertical scale. Natural bone has an interconnected porous
aided design (CAD) model size, and the printing error is structure with a porosity of around 65% and a pore size of
within 0.2 mm. roughly 200–800 μm. 22,39 It is commonly assumed that a
According to the SEM topography from the top of pore size of 100–500 μm is beneficial for the proliferation,
the cage, as illustrated in Figure 4G–L, all holes on the migration, and nutrient transfer of bone tissue cells.
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constructed porous cages are square in shape. The pore The pore size of the fusion apparatus of the AII structure

Figure 4. (A–F) 3D-printed cages with varied structural features. (G–L) Upper view and (M–R) vertical section of 3D-printed cages; observed with SEM
at 80× magnification.

Volume 10 Issue 4 (2024) 177 doi: 10.36922/ijb.1996