Optimal heating conditions for forming a mouthguard using a circle tray: effect of different conditions on the thickness and fit of formed mouthguards.
OBJECTIVE
The aim of this study was to determine the optimal heating conditions for sheet forming using a circle tray by comparing the thickness and fit of mouthguards formed under different conditions.


METHODS
Mouthguards were fabricated using ethylene vinyl acetate sheets (4.0mm thick) and a vacuum forming machine. The working model was trimmed to a height of 20mm at the incisor and 15 mm at the first molar. Two forming conditions were compared: square sheets were pinched by the clamping frame attached to the forming machine; and round sheets were pinched at the top and bottom and stabilized by a circle tray. Each condition was defined when the sheet sagged by 10-mm or 15-mm below the level of the clamp. The thickness of the sheet was determined for the incisal and molar portion. Additionally, the difference in fit according to the forming conditions was measured by examining the cross section. Differences in the thickness or the fit due to forming conditions were analyzed using two-way analysis of variance (ANOVA) followed by Bonferroni's multiple comparison tests.


RESULTS
The thickness after formation was thicker at the 10-mm condition than that of 15-mm, and the fit at the 15-mm condition was better when that of 10-mm with square and round sheets.


CONCLUSIONS
Within the limitation of this study, it was suggested that when forming a mouthguard using a 4.0-mm EVA sheet and a circle tray on a vacuum forming machine, the sheet should be formed at a sagging distance of 10-mm.
Department of Removable Prosthodontics, The Nippon Dental University School of Life Dentistry at Niigata, Japan. Electronic address: mutsumit@ngt.ndu.ac.jp.
Mutsumi
M
Takahashi
Department of Removable Prosthodontics, The Nippon Dental University School of Life Dentistry at Niigata, Japan.
Kaoru
K
Koide
Department of Removable Prosthodontics, The Nippon Dental University School of Life Dentistry at Niigata, Japan.
Fumi
F
Mizuhashi
D000704:Analysis of Variance; D003764:Dental Materials; D004867:Equipment Design / Q000379:methods*; D006358:Hot Temperature; D003765:Models, Dental; D009064:Mouth Protectors; D011145:Polyvinyls; D014618:Vacuum
D003764:Dental Materials; D011145:Polyvinyls; C016438:ethylenevinylacetate copolymer
Circle tray; Fit; Heating condition; Mouthguard; Thickness