微种植体复合力作用下竖直倾斜磨牙牙周膜的应力分析

背景：微螺钉种植体虽然能提供强支抗,但控制牙齿的三维移动存在不足。Tomas微种植钉的顶部设计成十字形,可固定方形弓丝,从而利用方丝控制牙齿的三维移动,目前对于研究Tomas微种植钉此方面的研究尚未见报道。目的：观察Tomas微种植体复合矫治力系统对竖直倾斜磨牙的影响。方法：对上颌第二恒磨牙向近中、颊侧倾斜的干燥头颅骨进行多层螺旋CT扫描,利用有限元软件建立上颌第二恒磨牙及其牙周支持组织的三维有限元模型,观察计算机模拟微种植体位于不同位置、施加不同的远中向力值和根颊向力偶矩值作用下磨牙牙周膜VonMises应力。结果与结论：牙周膜的最大应力均出现在上颌第二恒磨牙颈部,沿着根尖的方向应力逐渐减小,在2个牙根的根尖处未出现应力集中。提示实验所建立的有限元模型达到了几何相似性和生物力学相似性,可用于精确的生物力学分析;Tomas微种植体可控制牙齿的移动方式。

Stress distribution of molar uprighting periodontal ligament under combined force with micro-implant anchorage system

BACKGROUND：Although mini-screws anchorage implant can provide strong anchorage,it cannot control the three-dimensional movement of the tooth.Tomas-pin can be fixed in a square archwire and designed into a cross,in order to control the three-dimensional movement of the tooth.And this research has not been reported.OBJECTIVE：To investigate the effects of combined force for maxillary second molar uprighting with micro-implant anchorage system.METHODS：Maxillary second molar and tipped mesiobuccally were selected to be the tooth sample,and maxillary which corresponds with sample tooth was also selected to be the alveolar bone sample.Multi-slice spiral CT scanning was taken for both of samples to get legible and accurate image information.A three-dimensional model of maxillary second molar with periodontal tissues was established by finite element software.Effects of embedding position of micro-implant,orientation of the loading force and loading force on the Von Mises stress of the periodontal tissue were investigated.RESULTS AND CONCLUSION：The maximum stress of the periodontal ligament was detected in the cervix of the maxillary second molar,and the stress was gradually decreased along with the apical.However,stress concentration could not be found in the apex of each root.The finite element model could be exhibited similarity in geometry and biomechanics,and could be used for the precisely biomechanics analysis.The bodily movement or tipping movement can be achieved with Tomas-pin.