Comparison of Popular Mouthguard Materials to a Photocured Thiol-Ene Thermoset

Abstract

PURPOSE: The purpose of this investigation was to compare the material properties of a novel photocured thiol-ene thermoset to popular contemporary materials used in sport dental applications. METHODS: We measured the Shore A hardness values and energy dissipated upon impact for the thiol-ene-acry late based photocured materials as well as 3 popular contemporary dental materials (Glidewell Erkonex™(EVA), Proform™ (EVA), and Volara™ EO Foam). The Shore A hardness of each photocured thiol-ene acry late was measured at room temperature according to ASTM guidelines (D2240-97). Materials were fabricated into 6 mm test specimens at least 12 mm in length and width. For testing, the specimen was placed on a surface that was hard and horizontal. The hardness indenter was introduced to the test specimen from the vertical position as quickly as possible without shock and held for one second. The results from multiple sites were used to obtain an average hardness. The capacity of the material to dissipate energy upon impact was measured using the Charpy tup impact head mounted on a Tinius Olsen Model 92T pendulum impacter at room temperature. The Charpy tup that was affixed to the pendulum device was raised to a height where 1.13 joules of energy would be imparted to the specimen. Multiple samples were run and the mean value determined. RESULTS: As anticipated, the foam showed the lowest hardness (6 durometer). The hardness of EVA based elastomers was found to be in the range of 80–90 durometer and in agreement with the literature. The hardness of the thiol-ene acry late material was comparable to EVA based elastomers and was in compliance with the range of hardness of traditional materials used for mouthguard applications. Commercial EVA based mouthguard elastomers absorbed 40–50 % of the impact energy. The foam absorbed slightly larger energy, 60 %. The thiol-ene acrylate system showed promising impact energy dissipation, 86%. CONCLUSIONS: Our results suggest that the novel thiol-ene acrylate thermoset material can dissipate shock forces better than currently recommended materials while maintaining similar Shore A hardness values. Such materials have tremendous potential to exceed the current standards (Academy for Sports Dentistry, American Society for Testing and Materials, and Standards Australia International) for athletic mouthguard materials. Unlike current materials, our photocured thiol-ene acrylate material is environmentally friendly. Further investigation into the complete mechanical properties of this thiol-ene acrylate thermoset system and its potential application for use as protective materials is warranted.