A New Approach to the Design and Fabrication of Customized Multi-material Mouthguards to Maximize Athletes' Safety and Comfort

Mouthguards are primarily designed to attenuate the oral impacts and decrease the risk of dental damage. For this reason, they are recommended or obligatory in certain sports. However, only well-designed customized mouthguards could provide efficient protection and comfort. The high cost and long lead time for fabricating customized mouthguards with specific structural and material properties restrict their usage. Emerging digitalbased additive manufacturing technologies could overcome these difficulties. Accordingly, we propose an innovative strategy to create functional and custom-made mouthguards with 3D-printed interlockable components. The developed modular device comprises removable components with targeted properties for maximum performance. The protectiveness of the developed mouthguards was evaluated by direct impact tests on a 3Dprinted dental model using an impetus setup in different loading conditions. The impact tests revealed that significantly higher dental protection is achievable with thinner 3D-printed mouthguards than conventional multi-layered mouthguards such as the Playsafe (R) Heavypro type. In particular, the impact-induced strain on the incisors is reduced by >90 % with the protection of the 3D-printed modular mouthguards and only around 40 % with conventional Playsafe (R) Heavypro type in a mild testing condition compared to the situation without a mouthguard. We showed that both the material and the geometrical properties of the components of the modular mouthguards determine the level of protection. Based on our modular strategy, the developed mouthguard is adaptable to different sports, necessitating different levels of protection by swapping the removable components. Moreover, the developed mouthguard is durable as the hard insert can be replaced after an eventual damaging impact. Thanks to the developed design strategy, the selection of materials is no longer limited to chemically bondable compositions, offering a new flexibility to fine-tune the employed materials in specific jaw regions. Simultaneous maximal dental protection and athletes' comfort can be obtained.