Does vaporized hydrogen peroxide sterilization affect the geometrical properties of anatomic models and guides 3D printed from computed tomography images?

Background: Material extrusion is used to 3D print anatomic models and guides. Sterilization is required if a 3D printed part touches the patient during an intervention. Vaporized Hydrogen Peroxide (VHP) is one method of sterilization. There are four factors to consider when sterilizing an anatomic model or guide: sterility, biocompatibility, mechanical properties, and geometric fidelity. This project focuses on geometric fidelity for material extrusion of one polymer acrylonitrile butadiene styrene (ABS) using VHP.

Methods: De-identified computed tomography (CT) image data from 16 patients was segmented using Mimics Innovation Suite (Materialise NV, Leuven, Belgium). Eight patients had maxillary and mandibular defects depicted with the anatomic models, and eight had mandibular defects for the anatomic guides. Anatomic models and guides designed from the surfaces of CT scan reconstruction and segementation were 3D printed in medical-grade acrylonitrile butadiene styrene (ABS) material extrusion. The 16 parts underwent low-temperature sterilization with VHP. The dimensional error was estimated after sterilization by comparing scanned images of the 3D printed parts.

Results: The average of the estimated mean differences between the printed pieces before and after sterilization were - 0,011 ± 0,252 mm (95%CI - 0,011; - 0,010) for the models and 0,003 ± 0,057 mm (95%CI 0,002; 0,003) for the guides. Regarding the dimensional error of the sterilized parts compared to the original design, the estimated mean differences were - 0,082 ± 0,626 mm (95%CI - 0,083; - 0,081) for the models and 0,126 ± 0,205 mm (95%CI 0,126, 0,127) for the guides.

Conclusion: This project tested and verified dimensional stability, one of the four prerequisites for introducing vaporized hydrogen peroxide into 3D printing of anatomic models and guides; the 3D printed parts maintained dimensional stability after sterilization.