【作者】 吕海燕；

【导师】 葛红珊；

【作者基本信息】 南昌大学 ， 口腔临床医学， 2010， 硕士

【摘要】 目的:本实验采用CT扫描结合各种图形处理软件,建立的上颌前牙段三维有限元模型。在中切牙之间组装镍钛合金正畸矫治弓丝与不锈钢正畸矫治弓丝,研究两者的减震特性,为正畸临床提供理论指导。方法:1、三维有限元模型的建立对一年轻女性自愿者进行头颅CT断层扫描获得断层影像,综合应用MIMICS、Rapidform及ABAQUS软件建立三维有限元模型,最后得到本实验的三组模型:无弓丝的上颌有限元模型(Wireless Model,WL模型);带不锈钢弓丝的上颌有限元模型(StainlessSteel Model, SLS模型);及带镍钛合金弓丝的上颌有限元模型(TiNiAlloy Model, TNA模型)。2、加载、计算本实验建立的三组模型边界条件及载荷相同。上颌远中方向及上端边界采用固定约束;载荷采用梯形脉冲方波曲线的形式加载,载荷大小为50N,加载时长0.1ms,随后撤消载荷,使模型呈自由振动。计算并绘制出载荷条件下的牙根、牙周膜的应力分布图和应力一时间曲线。结果:1、同等载荷作用下三组模型中,加载侧中切牙的位移均呈现随时间逐渐衰减的规律,最大振幅均发生在第一个振动周期。且装配正畸矫治弓丝将降低矫治系统的响应频率,即增加中切牙的振动周期。将SLS模型与TNA模型相比较,SLS的响应频率略低,周期略长。而非加载侧中切牙的位移均呈现先随时间逐渐增加,然后随时间逐渐衰减的规律。SLS模型衰减所需时间最长,TNA模型与WL模型衰减所用时间较接近。SLS模型、TNA模型与WL模型的非加载侧中切牙的时间位移曲线最大振幅相比,前者增加了3.03倍,而后者增加了48.7%。2、同等载荷作用下三组模型中,加载侧中切牙牙周膜的最大Von Mises应力出现时间TNA模型与WL模型相似(t=0.13*10-3s,最大应力发生在近中颊侧颈部),SLS模型出现最晚(t=0.39*10-3s,最大应力发生在中切牙远中颈部)。非加载侧中切牙牙周膜的最大Von Mises应力出现时间依次为WL<SLS<TNA,最大应力大小依次SLS>TNA>WL。3、同等载荷作用下三组模型中,加载侧牙根的最大Von Mises应力大小、出现时间及发生位置基本相似。加载侧牙根的最大Von Mises应力出现时间依次为WL<SLS<TNA,最大应力大小依次SLS>TNA>WL。结论:镍钛合金弓丝比不锈钢弓丝有更好的减震性能,对咬合力的传导起更好缓冲作用。更多还原

【Abstract】 Objective:This study was designed using CT scanning with a variety of graphics software, to build three-dimensional finite element model, and to assembled nickel titanium orthodontic archwire and stainless-steel orthodontic archwire between central incisors. The purpose of the study was to clarify the difference between the both archwires on occlusal force transmission during orthodontic treatment.and to provide theoretical guidance.Methods:1、The three-dimensional finite element model.By spiral CT scanning , a young female volunteers to get head CT images , integrated application Mimics, Rapidform, and Abaqus software to build three-dimensional finite element model,Finally, three groups was divide: no arch wires finite element model of maxillary (Wireless Model, WL model); with stainless steel wire of the maxillary arch finite element model (StainlessSteel Model, SLS model); and with nickel titanium arch wire finite element model of maxillary (TiNiAlloy Model, TNA model).2、Loads and calculation.The boundary condition was set as fixed constraint on the basal portion of maxillary ; the loading condition of force was applied on the occlusal surfaces of the teeth supposedly as an occlusal force,load curve was a trapezoidal form of square wave pulse load, load size 50N, load duration 0.1ms.Calculated and plotted out the load condition of the root, periodontal ligament of the stress distribution and stress-time curve.Results:1、Three groups under the same load model, the load side of tooth movement showed a gradual decay over time, the law, the maximum amplitude of vibration occurred in the first period. Orthodontic archwire and the assembly will reduce the frequency response correction system, an increase in the vibration cycle incisors. SLS model will be compared with the TNA model, SLS’s response frequency is slightly lower, slightly longer period. Not loaded side of tooth movement were gradually increased over time first and then gradually decay over time the law. SLS model the longest decay time, TNA model and WL model for time spent close to decay. SLS models, TNA model and WL model for non-load side of the central incisors of the time compared to the maximum amplitude displacement curve, the former increased by 3.03 times, while the latter increased by 48.7%.2、Three groups under the same load model, the load side of the incisor periodontal ligament in the maximum Von Mises stress appears time TNA model similar to WL model (t = 0.13*10-3s, the maximum stress occurs in the neck near the buccal side), SLS model appeared at the latest (t = 0.39*10-3s, the maximum stress occurred in the central incisor distal neck). Non-load side of the incisor periodontal ligament in the maximum Von Mises stress appears time were WL <SLS <TNA, The order of the maximum stress:SLS> TNA> WL.3、Three groups under the same load model, the load side of the root of the maximum Von Mises stress of size, time of occurrence and the occurrence of similar position. Load side of the root of the maximum Von Mises stress appears time were WL <SLS <TNA, The order of the maximum stress:SLS> TNA> WL.Conclusion:The results showed that high damping capacity of nickel titanium arch wire had an obvious ability to buffer the transmission of occlusal force to the PDL than stainless steel arch wires.更多还原