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目的 :建立含微钛板支抗和牙支持式前牵引装置的唇腭裂颅上颌复合体三维有限元模型,探讨其前牵引生物力学效应。方法:选取1例恒牙早期唇腭裂男性志愿者,进行锥形束CT(cone beam CT,CBCT)扫描,构建模型,模拟加力,分析位移变化及应力分布。结果:建立了含微钛板支抗和牙支持式前牵引装置的单、双侧唇腭裂颅上颌复合体三维有限元模型。前牵引时,上牙弓内缩;微钛板支抗模型上颌中上部位移量大于牙支持式模型,后者上颌前部及上尖牙位移量大于前者。微钛板支抗模型应力集中于上颌骨中上部,牙支持式模型的应力集中在上颌尖牙点,且前者应力值及分布范围均大于后者。双侧唇腭裂模型上前牙牙槽嵴处位移小于单侧唇腭裂模型,后者患侧位移和应力分布范围均大于健侧。结论:本研究构建的模型生物力学仿真性好,为唇腭裂上颌骨前牵引治疗的生物力学研究提供了良好的实验载体。微钛板支抗上颌骨前牵引以骨性作用为主,牙支持式上颌骨前牵引以牙性作用为主,前者更有利于效果稳定和侧貌改善。
OBJECTIVE: To establish a three-dimensional finite element model of the cranial maxillary complex of the cleft lip and palate with a micro-titanium plate support and a tooth-supported front traction device to investigate the biomechanical effect of the pre-traction. Methods: One male patient with cleft lip and palate of permanent dentition was selected and scanned by cone beam CT (CBCT). The model was built to simulate the force, and the displacement and stress distribution were analyzed. Results: Three-dimensional finite element models of cranial maxillary complex of single and bilateral cleft lip and palate with micro-titanium plate support and orthodontic traction device were established. In the first traction, the maxillary arch was retracted. The displacement of the maxillary middle and upper part of the micro-titanium plate support model was greater than that of the dental support model, and the displacement of the maxillary anterior and maxillary canines was greater than the former. The stress of micro-titanium plate support model is concentrated in the middle and upper part of the maxilla. The stress in the tooth-support model is concentrated in the maxillary canine teeth, and the stress and distribution range of the former is greater than the latter. The displacement of the alveolar ridge of the anterior teeth in the bilateral cleft lip and palate model was smaller than that of the unilateral cleft lip and cleft palate model, and the affected side displacement and stress distribution range were greater than that in the unilateral cleft lip and palate model. Conclusion: The biomechanical simulation model constructed in this study is good, which provides a good experimental support for the biomechanical study of maxillary anterior traction in cleft lip and palate. Micro-titanium plate support the maxillary pre-traction to bone-based, tooth-supported maxillary pre-traction to the main role of the dentine, the former is more conducive to the effect of stability and lateral improvement.