AccScience Publishing / IJB / Online First / DOI: 10.36922/ijb.2124
RESEARCH ARTICLE

Exploring the mechanical strength, antimicrobial performance, and bioactivity of 3D-printed silicon nitride-PEEK composites in cervical spinal cages

Cemile Basgul1* Paul DeSantis1 Tabitha Derr1 Noreen J. Hickok2 Ryan M. Bock3 Steven M. Kurtz1
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1 Implant Research Core, School of Biomedical Science, Engineering, and Health Systems, Drexel University, Philadelphia, United States of America
2 Department of Orthopedics, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, United States of America
3 SINTX Technologies, Inc., Salt Lake City, Utah, United States of America
Submitted: 27 October 2023 | Accepted: 26 December 2023 | Published: 26 February 2024
© 2024 by the Author(s).. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International License ( https://creativecommons.org/licenses/by/4.0/ )
Abstract

 In this study, our goal was to assess the suitability of a polyether-ether-ketone (PEEK) and silicon nitride (Si3N4) polymer composite for antimicrobial three-dimensional (3D)-printed cervical cages. Generic cage designs (PEEK and 15 vol.% Si3N4-PEEK) were 3D-printed, including solid and porous cage designs. Cages were tested in static compression, compression shear, and torsion per ASTM F2077. For antibacterial testing, virgin and composite filament samples were inoculated with Staphylococcus epidermidis and Escherichia coli. In vitro cell testing was conducted using MC3T3-E1 mouse preosteoblasts, where cell proliferation, cumulative mineralization, and osteogenic activity were measured. The 3D-printed PEEK and Si3N4-PEEK cages exhibited adequate mechanical strength for all designs, exceeding 14.7 kN in compression and 6.9 kN in compression shear. Si3N4-PEEK exhibited significantly lower bacterial adhesion levels, with a 93.9% reduction (1.21 log), and enhanced cell proliferation when compared to PEEK. Si3N4-PEEK would allow for custom fabrication of 3D-printed spinal implants that reduce the risk of infection compared to unfilled PEEK or metallic alloys.

 

Keywords
Cervical fusion cage
Anti-infection
Polyether-ether-ketone
Silicon nitride
3D printing
ASTM F2077
Funding
This research was supported, in part, by the National Institute of General Medical Sciences of the National Institutes of Health under award number R41GM146268.
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Conflict of interest
Dr. Ryan M. Bock is currently employed by SINTX, a company specializing in the production of silicon nitride powder. As our research pertains to silicon nitride-based materials, there is a potential conflict of interest that arises due to Dr. Bock’s affiliation with SINTX. Dr. Noreen Hickok and Dr. Steven Kurtz are paid consultants for SINTX and also have a conflict of interest. However, we want to emphasize that the research presented in this paper has been conducted independently and without any undue influence from the company. Dr. Kurtz also reports that he is a member of Gyroid LLC, a scientific and technical consulting firm. Unrelated to the present work, Dr. Kurtz reports institutional funding from 3Spine; Celanese; Ceramtec; DJO Global; Invibio; Lima Corporate; Mitsubishi Chemical Advanced Materials; Orthoplastics; SINTX Technologies; Stryker; Wright Medical Technology; and Zimmer Biomet. Dr. Kurtz is a board member of Formae, Inc., and receives book royalties from Elsevier, Inc. We have taken necessary measures to ensure the integrity and objectivity of the present study, adhering to the highest standards of scientific rigor and ethics. We are committed to transparency and have disclosed Dr. Bock’s, Dr. Hickok’s, and Dr. Kurtz’s conflicts of interest to ensure that the journal’s readers can evaluate our work within this context.
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International Journal of Bioprinting, Electronic ISSN: 2424-8002 Print ISSN: 2424-7723, Published by AccScience Publishing