1.中南大学湘雅口腔医院;2.中南大学湘雅口腔医院 正畸科;3.湖南大学 汽车车身先进设计制造国家重点实验室
1.Xiangya Stomatological Hospital,Central South University Changsha;2.State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body,Hunan University Changsha
目的 用三维有限元方法,分析扩弓时上颌复合体应力蓄积至腭中缝完全断裂过程的力学特点,并验证模型有效性。方法 建立包含种植钉的上颌复合体有限元模型。并设定腭中缝屈服强度,以每5ms加载0.25mm水平横向位移为载荷,加载至腭中缝完全断裂,同时以临床1例种植钉辅助扩弓患者扩弓前后CT影像结果进行对比验证。结果：0-17ms腭中缝应力主要蓄积于腭骨水平板、种植钉周围、腭中缝中后方及颧颌缝，第18ms-60ms，腭中缝中后部出现裂纹并向前后扩展，61-71ms腭中缝中后部—前部—后部依次发生断裂。结论 建立了一个基于断裂力学的种植钉辅助扩弓的三维有限元模型有效,其计算的断裂过程结果更符合临床实际,为今后更有效的研究种植钉辅助扩弓提供了力学参考模型。
Objective Using the three-dimensional finite element method to analyze the mechanical characteristics of the stress accumulation of the maxillary complex during the expansion until the complete fracture process of the mid-palatal suture and verify the validity of the model. Methods A finite element of the maxillary complex model containing the microimplants was established.The yield strength of the mid-palatal suture was set. the transverse displacement of 0.25 mm was loaded every 5ms as the load until the suture was completely fracture. The CT images of 1 clinical patient before and after the expansion were compared and verified. Result ：0-17ms, the stress is mainly concentrated around the microimplants, the middle of the mid-palatal suture and the zygomatico-maxillary sutures. At the 18ms-60ms cracks began to occur in the mid-palatal suture, and expand forward and backward.. 61-71ms, The rupture path is followed by the posterior part of the mid-palatal suture-the front part-the back part. Conclusion The three-dimensional finite element model of microimplant-assisted expansion based on fracture mechanics was effective and the calculated fracture process results are more accord with clinical practice. A mechanical reference model is provided for more effective research on microimplant-assisted palatal expansion assisted expansion in the future.