PDF(Pubmed)
Abstract：
BACKGROUND: Prefabricated myofunctional appliance can guide tooth eruption, improve dentition alignment, correct myofunctional disorders and harmful oral habits. However, its application to skeletal discrepancy may result in unsatisfactory tooth inclination. This study aimed to construct a novel appliance with overjet design to avoid this side effect and investigated its shape and mechanical changes under occlusion using three-dimensional finite element method.
METHODS: We established three samples of prefabricated myofunctional appliances. The first one was edge to edge without overjet, and the outer shield of both jaws were flattened. The second one was 3 mm overjet with stepped the outer shield. The last one was 3 mm overjet, and the outer shield of both jaws were flatted, which meant the front wall of lower jaw was strengthened with bumper, termed as lower bumper. A complete dentition model was applied to the study. 150 N occlusal force was applied to each type of appliance and the deformation displacement and the changes in stress was recorded.
RESULTS: The deformation was significant in the incisors regions, especially in the vertical and lateral dimensions. The maximum displacements of 3 mm overjet with step shield group were 7.08 mm (vertical), 3.99 mm (lateral), and 2.90 mm (sagittal), while it decreased to 3.92 mm(vertical), 1.94 mm (lateral), and 1.55 mm (sagittal) in overjet with bumper group. Moreover, the upper molar regions exhibited higher vertical and sagittal displacement in 3 mm overjet with step shield group, which were 3.03 mm (vertical) and 1.99 mm (sagittal), and the bumper design could decrease the maximum displacement to 1.72 mm (vertical) and 0.72 mm (sagittal). In addition, the Von Mises stress of appliances was analyzed, and results indicated that 3 mm overjet with step shield generated higher stress than other groups, with the maximum Von Mises stress was 0.9387 MP, which were 0.5858 and 0.5657 MP in edge to edge group and 3 mm overjet with lower bumper group, respectively.
CONCLUSIONS: The prefabricated myofunctional appliances may cause deformation during occlusion. Compared to step shield group, the application of lower bumper exhibited better resistance to occlusal force.
METHODS: We established three samples of prefabricated myofunctional appliances. The first one was edge to edge without overjet, and the outer shield of both jaws were flattened. The second one was 3 mm overjet with stepped the outer shield. The last one was 3 mm overjet, and the outer shield of both jaws were flatted, which meant the front wall of lower jaw was strengthened with bumper, termed as lower bumper. A complete dentition model was applied to the study. 150 N occlusal force was applied to each type of appliance and the deformation displacement and the changes in stress was recorded.
RESULTS: The deformation was significant in the incisors regions, especially in the vertical and lateral dimensions. The maximum displacements of 3 mm overjet with step shield group were 7.08 mm (vertical), 3.99 mm (lateral), and 2.90 mm (sagittal), while it decreased to 3.92 mm(vertical), 1.94 mm (lateral), and 1.55 mm (sagittal) in overjet with bumper group. Moreover, the upper molar regions exhibited higher vertical and sagittal displacement in 3 mm overjet with step shield group, which were 3.03 mm (vertical) and 1.99 mm (sagittal), and the bumper design could decrease the maximum displacement to 1.72 mm (vertical) and 0.72 mm (sagittal). In addition, the Von Mises stress of appliances was analyzed, and results indicated that 3 mm overjet with step shield generated higher stress than other groups, with the maximum Von Mises stress was 0.9387 MP, which were 0.5858 and 0.5657 MP in edge to edge group and 3 mm overjet with lower bumper group, respectively.
CONCLUSIONS: The prefabricated myofunctional appliances may cause deformation during occlusion. Compared to step shield group, the application of lower bumper exhibited better resistance to occlusal force.
摘要：
背景：预制肌功能矫治器可以引导牙齿萌出，改善牙列对齐，纠正肌功能障碍和有害的口腔习惯。然而,将其应用于骨骼差异可能会导致牙齿倾斜不令人满意。本研究旨在构建一种具有超喷射设计的新型矫治器，以避免这种副作用，并使用三维有限元方法研究其在闭塞下的形状和力学变化。
方法：我们建立了三个预制肌功能矫治器的样本。第一个是边缘到边缘没有过度喷射，两个钳口的外盾都变平了。第二个是3毫米外喷射机，外护罩呈阶梯状。最后一个是3毫米超喷，两个钳口的外部护罩都是平坦的，这意味着下颚的前壁被保险杠加固，称为下保险杠。将完整的牙列模型应用于研究。对每种类型的矫正器施加150N的咬合力，并记录变形位移和应力变化。
结果：切牙区域变形显著，特别是在垂直和横向尺寸。带阶梯屏蔽组的3mm超喷的最大位移为7.08mm(垂直),3.99mm(横向),和2.90毫米（矢状），虽然它减少到3.92毫米（垂直），1.94mm(横向),和1.55mm（矢状）在带保险杠组的超喷中。此外，上磨牙区域在3mm超喷中表现出更高的垂直和矢状位移，分别为3.03毫米（垂直）和1.99毫米（矢状），保险杠设计可以将最大位移减小到1.72mm（垂直）和0.72mm（矢状）。此外,分析了VonMises对电器的压力，结果表明，带阶梯屏蔽的3mm超喷比其他组产生更高的应力，最大VonMises应力为0.9387MP，边缘到边缘组的压力为0.5858和0.5657MP，下保险杠组的喷嘴为3mm，分别。
结论：预制的肌功能矫治器可能在闭塞过程中引起变形。与台阶屏蔽组相比，下保险杠的应用表现出更好的抗咬合力。
方法：我们建立了三个预制肌功能矫治器的样本。第一个是边缘到边缘没有过度喷射，两个钳口的外盾都变平了。第二个是3毫米外喷射机，外护罩呈阶梯状。最后一个是3毫米超喷，两个钳口的外部护罩都是平坦的，这意味着下颚的前壁被保险杠加固，称为下保险杠。将完整的牙列模型应用于研究。对每种类型的矫正器施加150N的咬合力，并记录变形位移和应力变化。
结果：切牙区域变形显著，特别是在垂直和横向尺寸。带阶梯屏蔽组的3mm超喷的最大位移为7.08mm(垂直),3.99mm(横向),和2.90毫米（矢状），虽然它减少到3.92毫米（垂直），1.94mm(横向),和1.55mm（矢状）在带保险杠组的超喷中。此外，上磨牙区域在3mm超喷中表现出更高的垂直和矢状位移，分别为3.03毫米（垂直）和1.99毫米（矢状），保险杠设计可以将最大位移减小到1.72mm（垂直）和0.72mm（矢状）。此外,分析了VonMises对电器的压力，结果表明，带阶梯屏蔽的3mm超喷比其他组产生更高的应力，最大VonMises应力为0.9387MP，边缘到边缘组的压力为0.5858和0.5657MP，下保险杠组的喷嘴为3mm，分别。
结论：预制的肌功能矫治器可能在闭塞过程中引起变形。与台阶屏蔽组相比，下保险杠的应用表现出更好的抗咬合力。
