Page 443 - IJB-10-2

International Journal of Bioprinting 3D-printed silicon nitride-PEEK implants

Figure 2. Sample cages that were 3D-printed for mechanical testing. Solid (A, D), porous (B, E), and porous window (front and side views) (C, F) designs
for PEEK (A, B, C) and Si N -PEEK (D, E, F) materials.
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The data demonstrated a normal distribution for the There was no significant difference in stiffness
majority of the groups (four out of six). According to between PEEK and Si N -PEEK per design (Figure 3A).
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2 × 3 factorial ANOVA, design was significantly affecting The compression stiffness of PEEK porous and porous
the stiffness under compression (p < 0.001). The stiffness window designs was significantly higher than that of
of the porous design was significantly higher than the the solid design (mean difference = 5622 and 4277 N/
solid design (mean difference = 6185 N/mm, p < 0.001) mm respectively, p < 0.001 for both). Similarly, for Si N -
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and the porous window design (mean difference = 1606 PEEK, porous and porous window designs achieved higher
N/mm, p = 0.01). The stiffness of the porous window compression stiffness than solid design (mean difference
design was also significantly higher than the solid design = 6748 and 4881 N/mm respectively, p < 0.001 for both)
(mean difference = 4579 N/mm, p < 0.001). When stiffness (Figure 3B). In addition to surpassing the 5th percentile
was examined as a function of material, the main effect of ultimate strength loading, porous window designs for
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was not significant in stiffness of the cages as well as the both PEEK and Si N -PEEK materials were tested above
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interaction between material and design. 50th percentile of ultimate compression strength defined
In addition to the main effects, the group comparisons by Peck et al. (10,800 N) (Table S3 in Supplementary
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between PEEK and Si N -PEEK and the designs were File). Furthermore, solid and porous designs for both
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analyzed (Figure 3). PEEK and Si N -PEEK materials were tested above 75th
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Table 1. Mechanical testing metrics calculated for cages
PEEK solid PEEK porous PEEK porous Si N -PEEK solid Si N -PEEK Si N -PEEK porous
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window porous window
Compression stiffness 7886 ± 1771 13508 ± 918 12163 ± 388 6911 ± 1053 13659 ± 997 11791 ± 2032
(N/mm)
Shear stiffness 3171 ± 580 4052 ± 1291 3793 ± 1011 4482 ± 235 5501 ± 517 4587 ± 816
(N/mm)
Torsional stiffness 0.48 ± 0.08 0.36 ± 0.05 0.36 ± 0.04 0.60 ± 0.11 0.47 ± 0.09 0.45 ± 0.07
(Nm/deg)
Yield moment (N∙m) 8.27 ± 0.45 5.29 ± 0.52 4.77 ± 0.26 10.5 ± 0.60 6.90 ± 0.65 5.49 ± 1.07
Ultimate moment 8.86 ± 0.60 5.82 ± 0.28 5.45 ± 0.13 11.4 ± 0.37 7.76 ± 0.21 6.49 ± 1.05
(N∙m)

Volume 10 Issue 2 (2024) 435 doi: 10.36922/ijb.2124