Fabrication of Shock Absorbing Photopolymer Composite Material for 3D Printing Sports Mouthguard

Sports mouthguards (MGs) can reduce the risks of sports-related oral injuries. The aim of this study was to fabricate a composite photopolymer with shock-absorbing properties suitable for use in 3D-printed MGs. By using a commercial, flexible, rubber-like photopolymer as matrix and a commercial rigid simulated polypropylene photopolymer as a reinforcement material, five composites with different Shore A hardness levels were fabricated. Furthermore, four laminated materials were prepared to assess the improvement effects associated with adding a rigid outer layer. The five composites and four laminated materials were evaluated in terms of their shock absorbing capabilities via a steel ball drop impact test along with two types of conventional mouthguard materials. The rubber-like photopolymer composite material compounded with the rigid photopolymer with a Shore A hardness of 50 showed excellent shock absorbing capabilities that were compatible with conventional mouthguard materials, suggesting that this shock absorbing photopolymer composite is a candidate material for 3D-printed sports MGs. If the commercial flexible rubber-like photopolymer is to be applied alone without reinforcement, laminating a rigid photopolymer on the outer surface may be an effective means of improving the shock absorption capabilities of such a MG. We succeeded in fabricating a prototype of a double-layered mouthguard with these composite materials using a 3D digital dental workflow.