Background/Aims Mouthguards can reduce the risk of sports‐related injuries but the sheet material and thickness have a large effect on their efficacy and safety. The aim of this study was to investigate the effect of the thermoforming technique that moves the model position just before vacuum formation. Materials and Methods Ethylene vinyl acetate sheets of 4.0‐mm thickness and a vacuum forming machine were used. The working model was placed with its anterior rim positioned 40 mm from the front of the forming table. Three forming conditions were compared: (a) The sheet was formed when it sagged 15 mm at the top of the post under normal conditions (control); (b) the sheet frame was lowered to and heated at 50 mm from the level of ordinary use, and the sheet was formed when it sagged 15 mm (LH); and (c) the sheet frame at the top of the post was lowered and covered on the model when it sagged 15 mm. Subsequently, the rear side of the model was pushed to move it forward 20 mm, and it was then formed (MP). Sheet thickness after fabrication was determined for the incisal edge, labial surface, and buccal surface using a specialized caliper accurate to 0.1 mm. Thickness differences among forming conditions were analyzed by one‐way ANOVA and Bonferroni's multiple comparison tests. Results A significant difference was observed for all measurement points, and the thickness after formation increased in the order of control, LH, and MP. Particularly on the labial surface, MP was able to yield about 1.7 times the thickness (about 3.1 mm) of the control. Conclusion The forming method of moving the model forward just before vacuum formation was effective for suppressing the mouthguard thickness reduction, which is capable of securing the labial thickness at 3 mm or more with a single layer.

Background/Aim Wearing a mouthguard reduces the risk of sports‐related injuries, but the material and thickness of the mouthguard have 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. The aim of this study was to assess the effects of model height and model moving distance on mouthguard thickness. Materials and Methods Ethylene‐vinyl acetate sheets of 4.0 mm thick and a vacuum forming machine were used. Three hard plaster models were trimmed so that the height of the anterior teeth was 25 mm, 30 mm and 35 mm. Model position (MP) was 40 mm from the front of the forming unit. The sheet was softened until it sagged 15 mm, after which the sheet frame was lowered to cover the model. The model was then pushed from behind to move it forward, and the vacuum was switched on. The model was moved at distances of 20 mm, 25 mm or 30 mm whereas a control model was not moved. Thickness after formation was measured with a specialized caliper. Differences in mouthguard thickness due to model height and moving distance were analysed by two‐way ANOVA and Bonferroni's multiple comparison tests. Results Sheet thickness decreased as the model height increased. Each MP condition was significantly thicker than the control in each model. There was no significant difference among MP conditions except for the buccal surface. Conclusions Moving the model forward by 20 mm or more just before formation is useful to secure the labial thickness of the mouthguard. This thermoforming technique increased the thickness by 1.5 times or more compared with the normal forming method, regardless of model height.

Background/Aim: The safety and effectiveness of mouthguards depend on the sheet material and thickness. The aim of this study was to investigate the fabrication method for a mouthguard with appropriate thickness using a single sheet regardless of the model angle. Materials and methods: Mouthguards were thermoformed using 4.0 mm thick ethylene vinyl acetate sheets and a vacuum forming machine. The working models were three hard plaster models trimmed so that the angle of the anterior teeth to the model base was 90°, 100°, and 110°. The model position was 40 mm from the front of the forming unit. The sheet was softened until it sagged 15 mm, after which the sheet frame was lowered to cover the model. Next, the vacuum was turned on and held for 30 seconds for the control. Under the forming conditions in which the model position (MP) was moved, after the model was covered with the sheet, a scissors handle was positioned at the rear of the model and used to push it forward 20 mm, and then, the vacuum switch was turned on for 30 seconds. Six specimens were formed for each condition. Mouthguard thickness after formation was measured using a specialized caliper. The differences in mouthguard thickness due to forming conditions and model angle were analyzed. Results: The MP was significantly thicker than the control in each model (P < .01). The mouthguard thickness tended to decrease as the model angle increased. The average thickness of the labial surface in the MP was 3 mm or more and was not affected by the model angle. Conclusions: This study suggested that the fabrication method in which moving the model forward by 20 mm just before formation could produce a mouthguard with approximately 3 mm thickness on the labial side with a single sheet regardless of the model angle.

The thickness reduction of the mouthguard was not affected by the sheet material and thickness when the distance from the model to the frame was the same. However, when the distance between the model and the frame decreased, the thickness reduction of the adjacent portion of the model increased, such that the influence was larger in thin sheets.

Background/Aim Wearing a mouthguard during sports reduces the risk of dental injury via absorbing impact forces, and the effectiveness and safety of the mouthguard are closely linked to the mouthguard material and thickness. The aim of this study was to clarify the suppression effect of the thickness reduction of the mouthguard when changing the moving distance of the model forward in a stepwise manner. Materials and Methods Ethylene‐vinyl acetate sheets of 4.0 mm thick and a vacuum forming machine were used. The working model was placed at a position 40 mm from the front of the forming unit. The sheet was softened until it sagged 15 mm, and the sheet frame was lowered and covered the model. The model was then pushed from the back to move it forward, and the vacuum was switched on. The model was moved 10 (MP‐10), 20 (MP‐20), or 30 mm (MP‐30). The control model was not moved. The thickness after formation was measured with a specialized caliper. Differences in the mouthguard thickness caused by the forming conditions were analyzed by one‐way ANOVA and Bonferroni's multiple comparison tests. Results Significant differences were observed between the control and each MP condition (P < 0.01). Reduction rate of the thickness decreased as the moving distance of the model increased. In particular, the thickness difference depending on the forming conditions was greater at the labial site. The reduction rate of MP‐30 was 33.8 ± 0.8% smaller than that of the control. Conclusion The thickness reduction in mouthguards was mitigated by moving the model forward just before vacuum forming. The reduction was smaller as the moving distance of the model increased. This study suggested that moving the model 20 mm or more forward just before vacuum forming could secure the labial thickness of 3 mm or more.

Background/Aim: The effectiveness and safety of mouthguards are affected by their thickness. The aim of this study was to investigate the effect of an acute angle model on the mouthguard thickness with the thermoforming method in which the model position was moved just before fabrication. Materials and Methods: Mouthguards were thermoformed using 4.0 mm thick ethylene vinyl acetate sheets and a vacuum forming machine. Three hard plaster models were prepared: 1) the angle of the labial surface to the model base was 90°, and the anterior height was 25 mm (model A); 2) the angle was 90°, and the anterior height was 30 mm (model B); and 3) the angle was 80°, and the anterior height was 30 mm (model C). The sheet was softened until it sagged 15 mm, after which the sheet frame was lowered to cover the model. The model was then pushed from behind to move it forward, and the vacuum was switched on (MP). The model was moved 20 mm whereas a control model was not moved. Mouthguard thickness was measured using a specialized caliper. The differences in mouthguard thicknesses due to model forms and forming conditions were analyzed by two-way ANOVA and Bonferroni's multiple comparison tests. Results: The MP tended to be thicker than the control in all models. In the controls, model C was significantly thicker than models A and B at the labial and buccal surfaces. In MP, model A was significantly thicker than models B and C on the labial surface. On the labial and buccal surfaces in MP, model C was significantly thicker than model B. Conclusions: This study suggested that in the thermoforming method in which the model position was moved just before fabrication, reducing the height was more effective than changing the angle of the model to ensure the appropriate thickness.

Background/Aim Using mouthguards can reduce the risk of injury when playing sports, but the sheet material and thickness have a large effect on their efficacy and safety. The aim of this study was to investigate the effect of moving the model position just before formation in the pressure forming technique to maintain the thickness of a single‐layer mouthguard. Materials and Methods A 4.0‐mm‐thick ethylene vinyl acetate (EVA) mouthguard sheet (diameter: 125 mm) and a pressure forming machine were used. The working model was placed with its anterior rim positioned 40 mm from the front of the forming table. The sheets were placed in the forming table with the sheet extrusion direction either vertical (V) or parallel (P) to the model's centerline. Two molding methods were compared: (a) The sheet was formed when it sagged 15 mm (control) and (b) the sheet was covered on the model when it sagged 15 mm, next the model was pushed forward 20 mm, and the sheet was then formed (MP). Mouthguard thickness was measured for the labial surface, palatal surface, cusp, and buccal surface using a specialized caliper. Thickness differences according to molding methods and sheet extrusion directions were analyzed by two‐way ANOVA. Results The thicknesses of the labial surface, cusp, and buccal surface were significantly larger in MP than in the control (P < 0.01). In particular, the thickness differences caused by the molding method were large on the labial and buccal surfaces: For the control, the thicknesses were 1.9 ± 0.03 and 2.1 ± 0.02 mm, whereas for MP, they were 3.2 ± 0.03 and 2.9 ± 0.03 mm, respectively. Conclusion The molding method of moving the model forward just before formation was useful as a thermoforming technique for maintaining the thickness of single‐layer mouthguards during pressure forming with 4.0‐mm‐thick EVA sheet. This method produced labial and buccal thicknesses of 3.2 ± 0.03 and 2.9 ± 0.03 mm.

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