Comparison of Shock Absorption Capacities of 3D-Printed Custom-Made Mouthguards: A Comparative In Vitro Study

New resins for the additive manufacturing of mouthguards for contact sports are now available on the market. However, no study has evaluated the impact performance of these resins. The aim of this in vitro study was to compare the shock absorption capacities of custom-made mouthguards produced by additive manufacturing with those of thermoformed mouthguards.

Three types of custom-made mouthguards were fabricated: 3D-printed Keyguard and Dima resin mouthguards and thermoformed triple-layer mouthguards. For each type of mouthguard, eight samples were produced. Each mouthguard was subjected to an impact performance test defined by the NF S72-427 standard for industrial mouthguards. Mean transmitted deceleration must not exceed 230 g (g = 9.81 m/s²) and no individual impact should exceed 250 g. Mechanical performance was evaluated by a series of five consecutive impacts with a drop-mass impact test on the inter-incisal area. Peak force transmission and deceleration were measured. Thickness decrease was assessed by 3D scanning.

None of the mouthguards met the impact absorption standard. Thermoformed mouthguards exhibited major structural failure after the first impact. For 3D-printed mouthguards, average peak deceleration ranged from 255 to 278 g for Dima and 292 to 299 g for Keyguard. Corresponding transmitted forces ranged from 2753 to 3106 N (Dima) and 3192 to 3292 N (Keyguard), with no significant difference between the two 3D-printed mouthguards (p > 0.05). Mean thickness decrease at the impact site was 0.2 mm for Dima mouthguards, 0.1 mm for Keyguard mouthguards, and 0.3 mm for thermoformed mouthguards.

Although none of the tested mouthguards met the NF S72-427 standard, 3D-printed custom devices demonstrated promising shock absorption performance after repeated impacts. These results highlight the potential of additive manufacturing as a cost-effective alternative to conventional thermoformed mouthguards, particularly for younger athletes requiring frequent replacements.