Page 178 - Clinical relevance of current materials for cranial implants
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Chapter 9
The effect of autoclave, EtO, and hydrogen peroxide (H2O2) sterilization, on the chemical structure and surface morphology of PMMA is previously described4. However, it is still unknown how these sterilization methods affect mechanical properties of cured PMMA. Therefore, the aim of this study is to investigate the effect of sterilization methods: EtO, HPGP, autoclavation, and γ-irradiation on the mechanical properties of PMMA-based personalized medical devices.
MATERIALS AND METHODS
The effects of sterilization with EtO, HPGP, autoclavation, and γ-irradiation on the mechanical properties of PMMA-based personalized medical devices were investigated (Table 1). Since the mechanical properties of the PMMA-based materials may vary depending on the application, three different types were investigated: Vertex Self-Curing, Palacos R+G and NextDent C&B MFH (Table 2).
For each material the flexural strength, flexural modulus, fracture toughness, and impact strength were determined after sterilization and compared to the unsterilized control. All test methods for determining the mechanical properties were taken from the appropriate standards, e.g. ISO 20795-1:2013 and ISO 179- 1:201014, 15.
Palacos R+G (Heraeus, Hanau, Germany) and Vertex Self-Curing (Vertex-Dental, Soesterberg, The Netherlands) were hand mixed and prepared according to the manufacturer’s instructions. These specimens were molded using a stainless-steel mold. Curing of Vertex Self-Curing followed in a water-filled pressure cooker for ten minutes at 55°C and 2.5 bar.
NextDent C&B MFH (NextDent, Soesterberg, The Netherlands) was 3D printed in a horizontal direction with a Rapidshape D30 (Rapidshape, Heimsheim, Germany) based on digital light processing (DLP). These specimens were washed in ethanol twice (three minutes and two minutes, respectively) under ultrasonic vibrations and dried for ten minutes prior to a 30 minutes post-cure in a LC3D-PrintBox (NextDent, Soesterberg, The Netherlands).
