Thermoforming Technique for Suppressing Reduction in Mouthguard Thickness

Abstract

Wearing a mouthguard reduces the risk of sports-related injuries, but the material and thickness of the mouthguard has a substantial impact on its effectiveness and safety. The aim of this study was to establish a thermoforming technique in which the model position is moved just before formation to suppress the reduction in thickness. Mouthguards were vacuum formed using ethylene-vinyl-acetate sheets with a thickness of 2.0, 3.0, and 4.0 mm. The working model was trimmed to the height of 25-mm at the maxillary central incisor and 20-mm at first molar. The model was placed with its anterior rim positioned 40-mm from the front of the forming table. Two forming methods were compared: 1) the sheet was formed when it sagged 15-mm at the top of the post under normal conditions (control); and 2) the sheet frame at the top of the post was lowered and the model was covered when the sheet sagged 15-mm, the rear side of the model was pushed forward 20-mm, and the mouthguard was formed (MP; model position). Sheet thickness after fabrication was determined for the incisal edge, labial surface, and buccal surface using a specialized caliper accurate to 0.1-mm. The difference in the reduction in thickness depending on the forming methods and sheet thicknesses were analyzed by two-way ANOVA and Bonferroni’s multiple comparison tests. Reduction in thickness was greater for thicker sheets, and the reduction in thickness for the MP was less than that for the control. The reduction in labial for the MP was an exception; the reduction in thickness was only about half that of the control. The thermoforming technique of moving the model forward just before vacuum formation was effective for suppressing the mouthguard thickness reduction, which in thickness of the labial side can be reduced to about half of the normal forming method.