Fumi Mizuhashi1, Kaoru Koide1, Ryo Mizuhashi2. 1. Department of Removable Prosthodontics, The Nippon Dental University School of Life Dentistry at Niigata, Niigata, Japan. 2. Comprehensive Dental Care, The Nippon Dental University Niigata Hospital, Niigata, Japan.
Abstract
BACKGROUND/AIM: Ethylene vinyl acetate and polyolefin sheets have been used commonly for fabricating mouthguards. However, the change of the sheet temperature during heating of the polyolefin has not been clarified. The aim of this study was to examine the effects of changing the sheet temperature during heating, and to examine whether there were any differences between the sheet materials. MATERIALS AND METHODS: The mouthguard materials used were 4.0 mm sheets of ethylene vinyl acetate and polyolefin. The sheet temperature of the two materials was measured when the center of the sheet was displaced by 10, 15, and 20 mm from the baseline after heating. The sheets were pressure-formed when the heating temperatures reached 100°C. Mouthguard thickness and fit were measured at the central incisor and the first molar. Differences in the sheet temperature and the thickness between the sheet materials were analyzed by two-way analysis of variance. RESULTS: The sheet temperature of ethylene vinyl acetate and polyolefin sheets became higher as the hanging distance became larger (P < 0.01), and there were statistically significant differences between ethylene vinyl acetate and polyolefin sheets at the hanging distance of 10 and 15 mm (P < 0.01). The thicknesses of the pressure-formed mouthguard at the central incisor and the first molar were greater in the mouthguards formed by ethylene vinyl acetate sheets than those with polyolefin sheets (P < 0.01 and P < 0.05, respectively). The fit of the mouthguard was not different between mouthguards formed by ethylene vinyl acetate sheets and those formed by polyolefin sheets. CONCLUSIONS: The change of mouthguard sheet temperature during heating was different between ethylene vinyl acetate and polyolefin sheets. The ethylene vinyl acetate sheets maintained the mouthguard thickness in comparison with the polyolefin sheets at the same heating temperature.
BACKGROUND/AIM: Ethylene vinyl acetate and polyolefin sheets have been used commonly for fabricating mouthguards. However, the change of the sheet temperature during heating of the polyolefin has not been clarified. The aim of this study was to examine the effects of changing the sheet temperature during heating, and to examine whether there were any differences between the sheet materials. MATERIALS AND METHODS: The mouthguard materials used were 4.0 mm sheets of ethylene vinyl acetate and polyolefin. The sheet temperature of the two materials was measured when the center of the sheet was displaced by 10, 15, and 20 mm from the baseline after heating. The sheets were pressure-formed when the heating temperatures reached 100°C. Mouthguard thickness and fit were measured at the central incisor and the first molar. Differences in the sheet temperature and the thickness between the sheet materials were analyzed by two-way analysis of variance. RESULTS: The sheet temperature of ethylene vinyl acetate and polyolefin sheets became higher as the hanging distance became larger (P < 0.01), and there were statistically significant differences between ethylene vinyl acetate and polyolefin sheets at the hanging distance of 10 and 15 mm (P < 0.01). The thicknesses of the pressure-formed mouthguard at the central incisor and the first molar were greater in the mouthguards formed by ethylene vinyl acetate sheets than those with polyolefin sheets (P < 0.01 and P < 0.05, respectively). The fit of the mouthguard was not different between mouthguards formed by ethylene vinyl acetate sheets and those formed by polyolefin sheets. CONCLUSIONS: The change of mouthguard sheet temperature during heating was different between ethylene vinyl acetate and polyolefin sheets. The ethylene vinyl acetate sheets maintained the mouthguard thickness in comparison with the polyolefin sheets at the same heating temperature.