Forces transmitted through a laminated mouthguard material with a Sorbothane insert

Sorbothane is a visco-elastic polyurethane that has been used in sports and orthopaedic applications because of its shock-absorbing properties. The aim of this laboratory study was to evaluate the effect of an intermediate layer of Sorbothane on the peak force transmitted through two thermoplastic ethylene vinyl acetate (EVA) sheets as used in the construction of a custom-made sports mouthguard. The EVA sheets were tested at room temperature after thermal lamination under pressure, either without (control) or with a Sorbothane intermediate layer of 1.1 or 2.65 mm thickness. A piezo-electric transducer was used to measure the peak force transmitted through each sample from a free-falling steel ram. The peak force recorded was significantly less for laminated EVA samples with a Sorbothane intermediate layer than for controls of comparable thickness. We conclude that a Sorbothane intermediate layer between heat-cured laminated EVA sheets, as used in the fabrication of a custom-made sports mouthguard, may dissipate significantly the force of impact resulting from a blow to the teeth and jaws.