Comparative Impact Performance of Conventional and 3D-Printed Mouthguard Materials Across Varying Thicknesses

Mouthguards play a crucial role in preventing orofacial injuries in contact sports. Conventional thermoformed mouthguards made from ethylene vinyl acetate (EVA) are widely recognized for their effective shock absorption. However, advances in additive manufacturing have introduced potentially more efficient and sustainable alternatives, such as 3D-printed Ortho-Flex Resin (3D-OFR). Despite its promise, limited research has evaluated the mechanical performance of 3D-OFR, particularly the influence of thickness on impact resistance. This study aimed to (1) compare the impact energy absorption of conventional EVA and 3D-OFR at a standardized 4 mm thickness and (2) assess the effect of varying 3D-OFR thicknesses (3 mm, 4 mm, and 5 mm) on impact performance. Rectangular notched specimens (n = 10 per group) were prepared and tested using the Izod impact method in accordance with ASTM D256. Statistical analysis was performed using independent t-tests and one-way ANOVA. EVA demonstrated significantly higher impact resistance (7.27 ± 0.20 kJ/m2) compared to 3D-OFR (2.33 ± 0.30 kJ/m2) at 4 mm thickness (p < 0.05). Intriguingly, there was no significant improvement (p > 0.05) by increasing the thickness of 3D-OFR, with values recorded at 2.23 ± 0.35 kJ/m2 (3 mm), 2.33 ± 0.30 kJ/m2 (4 mm), and 2.38 ± 0.27 kJ/m2 (5 mm), respectively. These findings indicate that EVA remains superior in energy absorption compared to 3D-OFR, and increasing of 3D-OFR thickness does not enhance its protective capability. Exploration into the reinforcement of 3D-printed resins with high-performance polymers such as Polyetherketoneketone (PEKK) or Polyetherimide (PEI) is recommended for future research, as this may improve their mechanical performance for use in athletic protective devices.