Zhang Jian, Liu Caiyun, Dong Yan
College of Stomatology, Dalian Medical University, Dalian, Liaoning, China.
Affiliated Hospital of Stomatology, Dalian Medical University, Dalian, Liaoning, China.
Front Bioeng Biotechnol. 2023 Oct 26;11:1245764. doi: 10.3389/fbioe.2023.1245764. eCollection 2023.
The skeletal anterior crossbite is a common malocclusion in clinic. However, there have been no reports on the maxillary sagittal expansion to correct the premaxillary hypoplasia, which greatly influences the facial morphology and masticatory function, using finite element analysis. In the present study, a three-dimensional finite element model of craniomaxillofacial complex with maxillary sagittal hypoplasia is constructed and the treatment for premaxillary hypoplasia by the sagittal screw expander appliance is simulated. The hypoplasia of the left premaxilla is more serious than that of the right and thus the size of the left part of premaxillary expander baseplate is designed to be larger than that of the right part and the loading is applied at 10° leftward to the sagittal plane and 30° forward and downward to the maxillary occlusal plane. The displacements or equivalent stress distributions of the maxilla, teeth and their periodontal ligaments, are analyzed under the loads of 5.0 N, 10.0 N, 15.0 N, and 20.0 N. Consequently, as the load increases, the displacements or equivalent stresses of the maxilla, teeth and their periodontal ligaments all increase. Almost the whole premaxilla markedly move forward, downward, and leftward while other areas in the craniomaxillofacial complex remain almost static or have little displacement. The equivalent stress concentration zone of the maxilla mainly occurs around and in front of the incisive foramina. The displacements of left premaxilla are generally greater than those of the right under the loading forces. The maximum equivalent stress on the teeth and their periodontal ligaments are 2.34E-02 MPa and 2.98E-03 MPa, respectively. Taken together, the sagittal screw expander appliance can effectively open the premaxillary suture to promote the growth of the premaxilla. An asymmetrical design of sagittal screw expander appliance achieves the asymmetric expansion of the premaxilla to correct the uneven hypoplasia and obtains the more symmetrical aesthetic presentation. This study might provide a solid basis and theoretical guidance for the clinical application of sagittal screw expander appliance in the efficient, accurate, and personalized treatment of premaxillary hypoplasia.
骨性前牙反合是临床上常见的错牙合畸形。然而，尚未见有关于采用上颌矢状向扩展矫治前上颌骨发育不足（这极大地影响面部形态和咀嚼功能）的有限元分析报道。在本研究中，构建了具有上颌矢状向发育不足的颅颌面复合体三维有限元模型，并模拟了采用矢状螺旋扩弓器矫治前上颌骨发育不足的过程。左侧前上颌骨发育不足比右侧更严重，因此将前上颌骨扩弓基托左侧部分的尺寸设计得大于右侧部分，并在矢状面左侧10°、上颌牙合平面30°向前向下的方向施加加载力。分析了在5.0 N、10.0 N、15.0 N和20.0 N载荷下上颌骨、牙齿及其牙周膜的位移或等效应力分布。结果显示，随着载荷增加，上颌骨、牙齿及其牙周膜的位移或等效应力均增加。几乎整个前上颌骨明显向前、向下和向左移动，而颅颌面复合体的其他区域几乎保持静止或仅有微小位移。上颌骨的等效应力集中区域主要出现在切牙孔周围及前方。在加载力作用下，左侧前上颌骨的位移通常大于右侧。牙齿及其牙周膜上的最大等效应力分别为2.34E-02 MPa和2.98E-03 MPa。综上所述，矢状螺旋扩弓器可有效打开前上颌骨缝，促进前上颌骨生长。矢状螺旋扩弓器的不对称设计实现了前上颌骨的不对称扩展，以矫治不均匀的发育不足，并获得更对称的美观效果。本研究可能为矢状螺旋扩弓器在高效、精确和个性化矫治前上颌骨发育不足的临床应用提供坚实的基础和理论指导。
