摘要
目的建立下颌全牙列-直丝弓矫治器的生物力学模型,分析其在滑动法关闭间隙的载荷作用下牙根及牙周组织的应力和位移分布。方法根据志愿者颌面部CT扫描图像建立下颌骨(皮质骨和松质骨)和全牙列(牙釉质、牙本质、牙髓、牙周膜)的模型,并以Roth托槽的实际数据建立一套托槽模型,与牙齿间的空隙用粘结剂来填充;弓丝和每个托槽都考虑接触,并使用弹簧元连接托槽和弓丝,模拟扎丝的作用,施加滑动法关闭间隙的载荷。结果切牙出现牙冠向舌侧、牙根向唇侧的转矩移动,其牙周组织和牙根的应力较高,特别是中切牙,其牙周膜的最大应力为3.97 kPa;第1磨牙远中根也出现应力集中,牙周膜的最大应力达到5.75 kPa。结论为了避免切牙的牙根吸收,可考虑增加前牙托槽的转矩;第1磨牙远中根也容易发生牙根吸收,建议适当降低正畸力值或采用微植体作为支抗。
Objective To establish the model of dentulous mandible and straight wire appliance and investigate the stress and displacement distributions of the roots and periodontal tissues under en masse space closure with sliding mechanics.Methods The three-dimensional finite element model of mandible and teeth was developed from CT images,which consisted of the dentin,enamel,dental pulp,PDL（periodontal ligament）,cortical and cancellous bone.The models of Roth straight wire brackets with actual data were also constructed.The dental adhesives were used to stick the brackets on the corresponding teeth.Contact elements were used to simulate the interaction between the stainless steel arch wire and the brackets.Moreover,spring elements were used to connect the brackets and the arch wire.The load with the vale of 1 N was applied on the model to close the space.Results The lingual tipping of lateral and central incisors was found,corresponding with the clinical observation of en masse space closure with sliding mechanics.High stress in the teeth and periodontal tissue appeared at the incisors and the distal roots of the first molars.The maximum von Mises stresses in PDL of the central incisors and the distal roots of the first molars were 3.97 kPa and 5.75 kPa,respectively.Conclusions In order to avoid root resorption of incisors,the torque of the brackets could be increased.Less orthodontic forces or orthodontic implant could be used to avoid distal roots of first molars.
出处
《医用生物力学》
EI
CAS
CSCD
北大核心
2012年第5期556-561,共6页
Journal of Medical Biomechanics
基金
中央高校基本科研业务费重点基础研究专项资助项目(2010SCU21017)
国家自然科学基金项目(11202143)
关键词
牙周组织
直丝弓矫治器
有限元分析
CT扫描
应力分布
牙根吸收
Periodontal tissue
Straight wire appliance
Finite element analysis
CT scans
Stress distribution
Root resorption
作者简介
通讯作者：刘展，副教授，E-mail：bmeliuzhan@163．com；
樊瑜波，教授，E-mail：yubofan@buaa．edu．cn。
