摘要
目的:运用三维有限元法模拟研究下颌拔牙病例分步内收前牙时牙齿移动趋势和牙周膜应力分布,并与整体内收对比以探究分步内收设计的特点和优劣。方法:通过软件分析和模拟,构建出符合解剖规律的下颌牙列、牙周膜、牙槽骨联合模型,再根据具体整体内收和分步内收的设计分别构建共6副无托槽隐形矫治器模型。通过三维有限元运算,模拟矫治器加力下各结构的受力情况,对比分析得出结论。结果:(1)膜片厚度的影响:膜片厚度对无托槽隐形矫治器治疗下的牙齿牙周膜受力有明显的影响,较厚的无托槽隐形矫治器矫治下的牙齿牙周膜受力明显增大。(2)牙周膜应力分布:下颌单根牙牙周膜Von Mises等效应力集中在牙颈部及根尖区,最大等效应力出现在牙颈部;对于下颌多根牙,牙周膜Von Mises等效应力集中在牙颈部、根尖区、根分叉区,最大等效应力出现在牙颈部。(3)支抗保护:相较于整体内收前牙而言,分步内收前牙可以减轻后牙区段牙周膜所受应力大小,并使得后牙具有更小的初始位移趋势。结论:无托槽隐形矫治器治疗下颌拔牙病例,设计分步内收前牙可以降低后牙牙周膜应力,并减少后牙的初始位移量,或有保护后牙支抗的作用。
Objective:Using the 3-D finite element method,we aim to simulate the initial displacement of teeth and stress distribution in the periodontal ligaments under the treatment of clear aligners in mandibular extraction cases,in order to clarify the features and advantages of individual retractions of canines and incisors.Methods:First,the precise virtual model of lower teeth,periodontal ligament and jaw were created and refined using a series of software.The model was originated from the CT data obtained from a healthy male volunteer with satisfactory occlusion.Furthermore,a total of 6 sets of aligner models were fabricated,each one represents a distinct working condition specifically.Via simulation in the finite element software,we were able to simulate the stress and displacement of every structure of the system,and thus reveal the patterns and features of both mass retraction and individual retraction.Results:(1)Thicker aligners would cause significantly more stress in the periodontal ligament.(2)Von Mises stress concentration was discovered at cervical and apical areas of periodontal ligaments on incisors,canines,and premolars,and also at cervical,apical and furcation areas of molars.(3)Under simulation,individual retraction of incisors and canines would cause significantly lower initial displacement and Von Mises stress in their periodontal ligaments.Conclusion:On extraction cases treated by clear aligners,individual retraction of incisors and canines may be able to protect molar and premolar anchorage,causing less amount of initial displacement and periodontal stresses.
作者
曹世陶
杨宜靓
徐宝华
CAO Shi-tao;YANG Yi-liang;XU Bao-hua Peking(University School of Stomatology,National Center for Stomatology,National Re-search Center for Oral Diseases,National Engineering Laboratory for Dental Digital Medical Technology and Materials,Beijing 100081,China)
出处
《中日友好医院学报》
CAS
2022年第4期207-210,共4页
Journal of China-Japan Friendship Hospital
