This study investigates how repeated steam sterilization affects the mechanical properties of 3D-printed surgical items made from methacrylate-based Surgical Guide Resin. Unlike single-use instruments, reusable 3D-printed instruments undergo multiple sterilization cycles, which may compromise their durability. Cuboids produced using Digital Light Processing (DLP) were exposed to up to ten steam sterilization cycles (121 °C, 110 kPa), followed by drying. Mechanical tests included three-point bending, Shore D hardness, and microscopic analysis to assess elasticity, hardness, and structural changes. Initial sterilization cycles increased hardness and stiffness due to further polymer cross-linking. However, continued exposure led to visible surface damage, microcracks, and signs of polymer degradation. While bending strength remained relatively stable, cumulative effects ultimately reduced material integrity. These results raise concerns about the long-term reliability of multi-use 3D-printed surgical instruments. The findings suggest that current sterilization practices should be re-evaluated, especially for items intended for repeated use. Future research should focus on improving material resistance to minimize thermal degradation. This work offers critical insights into the safety and performance of reusable 3D-printed surgical items in both veterinary and human medical applications.

Metal Injection Molding (MIM) enables complex orthodontic-bracket geometries but can introduce surface and geometric discontinuities that act as initiation sites for crevice and pitting corrosion. The effect of acidic, kombucha-like exposure on corrosion and repassivation was assessed for MIM-316L brackets relative to a commercial comparator, and the coupling between surface quality (roughness and wettability) and localized damage at scanning electron microscopy (SEM)-identified hot-spots was examined. Kombucha was characterized by pH and titratable acidity. Surfaces were characterized by SEM, areal roughness metrics (R_a, S_a, S_z, and A2), and wettability by sessile-drop goniometry. Electrochemical behavior in artificial saliva was measured using open-circuit potential and cyclic potentiodynamic polarization (ASTM F2129/G59), and a qualitative magnetic check was included as a pragmatic quality-assurance screen. Exposure in kombucha reduced breakdown and repassivation potentials and increased passive current density, with the strongest effects co-localizing geometric discontinuities. Commercial brackets exhibited markedly poorer surface quality (notably higher S_z), amplifying acidity-driven susceptibility. These findings indicate that, under acidic challenges, surface/geometry quality dominates corrosion behavior; non-magnetic-phase compliance and simple chairside screening (e.g., magnet test), alongside tighter manufacturing controls on roughness and edge finish, should be incorporated into clinical and industrial quality assurance (QA).

Co–Cr alloys are widely used in biomedical devices owing to their excellent mechanical properties and corrosion resistance; however, sustained metal-ion release in physiological environments remains an important materials concern. Low-temperature atomic layer deposition (ALD) enables the formation of conformal ceramic barriers that can restrict long-term metal-ion transport. In this study, nominally ~50 nm ALD-derived ZrO₂ coatings were deposited on Co–Cr substrates manufactured by investment casting (CAST), CAD/CAM milling (MILLED), and laser powder bed fusion (PRINTED). The coatings were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, transmission electron microscopy with selected-area electron diffraction (TEM/SAED), and X-ray photoelectron spectroscopy (XPS), while the electrochemical response was evaluated by open-circuit potential (OCP) and electrochemical impedance spectroscopy (EIS). Long-term barrier performance was quantified by inductively coupled plasma atomic emission spectroscopy (ICP-AES) as cumulative Co and Cr release for all manufacturing routes and Mo release for the Mo-containing CAST and PRINTED alloys after 28 days in artificial saliva at 37 °C. ZrO₂ deposition reduced cumulative Co and Cr release for all manufacturing routes. Mo release was also reduced in the Mo-containing alloys, with Mo remaining below the analytical detection limit (<0.005 µg cm⁻²) for the PRINTED + ZrO₂ system. Electrochemical measurements further demonstrated manufacturing-route-dependent differences in barrier response between the initial and 28-day exposure states. Overall, the findings establish a structure–barrier–release framework linking coating formation and electrochemical response with cumulative ion release, and identify 28-day cumulative ion release as a practical functional descriptor for comparing the long-term performance of ALD-derived ceramic barriers on Co–Cr alloys.