It is the aim of this study to investigate a novel mouthguard design that incorporates the use of a nickel-titanium (Nitinol) layer and thin foam layer in addition to EVA layers. It is thought that the Nitinol layer can distribute the force of an impact and that the thin foam layer may absorb this distributed force better than a solid EVA mouthguard of the same thickness. Rectangular, flat coupons representative of several mouthguard configurations were constructed for testing using an instrumented drop-weight impact tower. The coupon configurations include a control made of laminated EVA, a group of laminated EVA and Nitinol, laminated EVA and foam, and a group of laminated EVA with foam and Nitinol. Several thicknesses of EVA were used in each configuration as well as three different Nitinol insert designs. The construction and subsequent testing of the coupons was performed in conjunction with the UNLV School of Dental Medicine.Two test methods were used to evaluate the coupons using the drop tower machine. The first test involved dropping a mass onto the coupon supported by a flat plate attached to a load cell. The second test involved dropping the mass onto the coupon resting on a simply supported beam attached to a load cell. The metric by which the coupons are evaluated are peak forces transmitted to the load cell, and strain (or deflection) experienced by the simply supported beam in the case of the second test. The energy absorbed by the coupon was calculated using the strain energy in the beam at the moment of peak force and deflection and performing an energy balance on the system. Measurements were normalized by thickness and compared to the control group.While there were some improvements in performance with the novel design, these were only modest, and the group of designs using only Nitinol (no foam) actually performed worse than the control.
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