不同位置微种植支抗压入整个上牙列的三维有限元分析

Three-dimensional finite element analysis of intrusion the entire upper dentition by miniscrews with two different locations

目的通过有限元方法分析微种植支抗不同植入位置、不同大小牵引力作用下压入上颌全牙列时牙周膜的应力分布情况和牙齿位移趋势,为正畸临床提供参考。方法利用患者锥形束CT和临床矫治器数据,建立上牙列矫治系统的三维有限元模型。在上颌双侧侧切牙和尖牙之间颊侧、第一磨牙和第二磨牙之间腭侧植入微种植支抗后,将上颌后段颊侧微种植支抗分别置于两个不同的位置(第二前磨牙与第一磨牙之间或者第一磨牙与第二磨牙之间),并比较两者在上牙列的应力分布的差异。结果当微种植支抗植入在第一磨牙与第二磨牙之间时,牙周膜整体适宜应力面积占比为69.42%~78.19%;当微种植支抗植入在第二前磨牙与第一磨牙之间时,牙周膜整体适宜应力面积占比为85.83%~87.42%。在加载条件相同的情况下,微种植支抗植入在第二前磨牙与第一磨牙之间时牙周膜受力更加均匀,牙根吸收风险更低。两种方案的最佳加载模式为前牙段牵引力0.7~0.8 N,后牙段牵引力为1.3~1.2 N。结论两种方案均可实现上牙列的压入,但受微种植支抗位置和加载模式的影响,上牙列的应力分布及移动趋势不同。

Objective The finite element method was used to analyze the stress distribution of the periodontal ligament and the displacement trend of the teeth when the upper dentition was en-masse intruded under the influence of different miniscrew insertion positions and different traction forces,so as to provide reference for orthodontic clinics.Methods A three-dimensional finite element model of the upper dentition orthodontic system was established according to CBCT and clinical orthodontic data.Two strategies of miniscrews insertion places were considered.In both strategies,the miniscrews in the anterior were placed between maxillary lateral incisors and canines buccally,and the miniscrews in the palatal posterior region were placed between the first and second molar.In the buccal posterior region,the miniscrews were placed differently,by either between the first and second molar or between second premolar and first molar.Results The results showed that the effective stress area ranged from 69.42%to 78.19%in cases where the miniscrews were inserted between the first and second molar,while that varied from 85.83%to 87.42%where the insertion were between the second premolar and the first molar.Under the same loading conditions,when the miniscrews were implanted between the second premolar and the first molar,the periodontal ligament was more evenly stressed and the risk of root resorption was lower.The optimal loading modes of the two strategies were 0.7~0.8 N in the anterior segment and 1.3~1.2 N in the posterior segment.Conclusions Both of the two schemes can achieve the intrusion of the upper arch intrusion,but the stress distribution and movement trend are different due to the influence of the miniscrews position and the loading strategy.