Department of Physiology, The Nippon Dental University School of Life Dentistry at Niigata, Niigata City, Japan.
Graduate School of Health and Sport Science, Nippon Sport Science University, Tokyo, Japan.
Dent Traumatol. 2020 Oct;36(5):543-550. doi: 10.1111/edt.12554. Epub 2020 Apr 1.
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.
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.
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.
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.
背景/目的：佩戴口腔防护器可降低运动相关损伤的风险，但防护器的材料和厚度对其有效性和安全性有重大影响。本研究旨在建立一种热成型技术，即在成型前移动模型位置以抑制厚度减小。本研究旨在评估模型高度和模型移动距离对口腔防护器厚度的影响。
使用 4.0 毫米厚的乙烯-醋酸乙烯酯片和真空成型机。将三个硬石膏模型修剪，使前牙高度为 25 毫米、30 毫米和 35 毫米。模型位置（MP）距离成型单元前端 40 毫米。将薄片软化，直至下垂 15 毫米，然后降低薄片框架以覆盖模型。然后从后面推动模型向前移动，并打开真空。模型移动距离为 20 毫米、25 毫米或 30 毫米，而对照模型不移动。使用专用卡尺测量成型后的厚度。通过双向方差分析和 Bonferroni 多重比较检验分析模型高度和移动距离对口腔防护器厚度的差异。
随着模型高度的增加，薄片厚度减小。每个 MP 条件下的厚度都明显大于对照条件下的厚度。除颊面外，MP 条件之间没有显著差异。
在成型前将模型向前移动 20 毫米或更多，可以有效地确保口腔防护器的唇侧厚度。与正常成型方法相比，无论模型高度如何，这种热成型技术都可使厚度增加 1.5 倍或更多。
