不同腭部形态下上颌骨性扩弓器放置位置对微种植钉稳定性及位移影响的三维有限元分析

Effects of MSE position on stability and displacement of miniscrew under different palatal morphologies:a 3D finite element study

目的:利用三维有限元建立颅上颌复合体模型,探讨上颌骨性扩弓器放置位置对微种植钉稳定性及位移的影响。方法:在已建立的腭盖正常颅上颌复合体模型(腭盖正常组)上利用软件模拟腭盖高拱颅上颌复合体模型(腭盖高拱组),在两组模型上分别将骨性扩弓器放置在第二前磨牙与第一磨牙间、第一磨牙间、第一磨牙与第二磨牙间3个不同位置,建立6个三维有限元模型。每组扩弓器分别加载0.25 mm横向位移,比较6个模型颅上颌复合体及微种植钉的应力分布及位移趋势。结果:腭盖正常组和腭盖高拱组扩弓器放置在第一磨牙与第二磨牙间时上颌复合体的最小主应力最大。腭盖正常组前后部微种植钉比值在第一磨牙间最小;腭盖高拱组在第一磨牙与第二磨牙间最小。腭盖正常组和腭盖高拱组扩弓器放置于第一磨牙间扩弓后上颌骨横向位移最大。腭中缝横向位移前部大后部小,随着扩弓器位置后移,腭中缝前后向的位移差逐渐减小,更趋于平行移动。两种腭部形态下微种植钉均出现移位,前部位移均大于后部。结论:两种腭部形态下上颌骨性扩弓器放置于第一磨牙间扩弓效果较好。腭中缝呈前大后小的楔形扩展,扩弓器位置后移更有利于其平行开展。

Aim:To construct a cranio-maxillary complex model using three-dimensional(3D)finite element analysis and observe the effects of maxillary skeletal expander on stability and displacement of miniscrew.Methods:Based on the normal palatal vault cranio-maxillary complex model(normal palate group),a high-arched palatal cranio-maxillary complex model was simulated(high-arched palate group).In both groups,the skeletal expander was placed at three different positions:between the second premolar and first molar,between the first molars,and between the first molar and second molar.Six 3D finite element models were created.A 0.25 mm transverse displacement was applied to each group′s expanders,and the stress distribution and displacement trends of the cranio-maxillary complex and miniscrew were compared.Results:The maximum of minimum principal stress in the maxillary complex was observed when the expander was placed between the first molar and the second molar in both the normal palate and high-arched palate groups.In the normal palatal group,the anterior to posterior miniscrew stress ratio were the lowest between the first molars.In the high-arched palate group,the minimum values were observed between the first and second molars.The maximum transverse displacement of the maxilla after expansion was observed when the expander was placed between the first molars in both groups.The transverse displacement of the midpalatal suture was greater in the anterior region than in the posterior region.As the expander position moved posteriorly,the difference in anterior-posterior displacement gradually decreased,approaching parallel movement.Both palatal morphologies exhibited displacement of the miniscrew,with greater displacement in the anterior region.Conclusion:Placing the maxillary skeletal expander between the first molars may result in better expansion.Moving the maxillary skeletal expander posteriorly could result in a more parallel expansion of the midpalatal suture.