Page 446 - IJB-10-2

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

Figure 5. Comparison between PEEK and Si N -PEEK designs: torsional stiffness (A, B), yield moment (C, D), and ultimate torque (E, F). (A, C, E)
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Comparison based on the material. (B, D, F) Comparison based on the designs across the same material. Dotted line indicates the 5th percentile as per
Peck et al. 28
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torque compared to porous design for Si N -PEEK cages starting inocula of 10 , 10 , and 10 CFU/mL, respectively,
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(mean difference = 1.26 Nm, p = 0.01) (Figure 5F). as compared to PEEK samples. For E. coli, mean log
reductions were 1.10, 1.45, and 1.66. When all groups
3.3. Antibacterial testing were pooled, the average mean log reduction for Si N -
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Because Si N has been reported to possess antibacterial PEEK compared to PEEK was 1.28. Representative SEM
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activity, we tested the ability of the different materials to micrographs of S. epidermidis and E. coli on Si N -PEEK

inhibit bacterial adhesion, expressed as colony-forming units samples are shown in Figure 6C and D. 3 4
per milliliter (CFU/mL). For each level of inoculum and for
both S. epidermidis and E. coli, AFSN samples consistently 3.4. Osteogenic activity of cells cultured on
had the lowest numbers of adherent bacteria, indicating the different substrates
greatest overall antimicrobial effect (Figure 6). Si N -PEEK MTT assay was used to quantify short-term cell
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consistently showed greater antibacterial activity than pure proliferation of the mouse preosteoblasts on each surface
PEEK samples (p < 0.05), but less antibacterial activity when (Figure 7). Absorbance results for each group were
compared to pure Si N (p < 0.05). normalized to a known number of cells to determine
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When incubated with S. epidermidis, Si N -PEEK the approximate number of cells on each surface. The
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samples showed a 1.02, 1.21, and 1.22 log reduction for number of cells for each group was significantly different
Volume 10 Issue 2 (2024) 438 doi: 10.36922/ijb.2124