BACKGROUND: Physiologic Anchorage Spee's-wire System (PASS) is a new appliance for orthodontic treatment in recent years. It has its superiority in support control, torque domination and friction control, and it is also unique in opening bite. OBJECTIVE: To build a three-dimensional finite element model of PASS with intrusion arch, and to analyze its effects on intrusion of the anterior teeth and on enhancing anchorage of the molars.METHODS: The CT scan data were imported into software of Mimicsl7.0 to obtain a three-dimensional model of the teeth and jaw bone. A series of modeling software such as Geomagic Studio, NX, ANSYSl5.0 were used to obtain the three-dimensional model of the maxillary dentition with PASS and intrusion arch. The overall force of the dentition and movement of the anterior teeth were analyzed when the intrusion arch was located at the mesial side of the central incisor and lateral incisor as well as the distal side of the lateral incisor.RESULTS AND CONCLUSION: It was efficient to accomplish the intrusion of the anterior teeth when the arch was located between central incisors. Labial inclination of the anterior teeth was achieved when the arch was ligated at the mesial side of the lateral incisor. Lingual inclination and intrusion of the anterior teeth was found when the arch was located at the distal side of the lateral incisor. Under these three kinds of conditions, the trend of molar retrodisplacement became remarkable. The maximum movement trend of the incisors was achieved, when the arch was ligated at the mesial side of the central incisor, mainly due to the intrusion of the incisors. The molar retrodisplacement was improved under the three conditions. This experiment simulated the stress distribution and displacement trend of the teeth, which is beneficial to the clinical understanding and application of the PASS technology with intrusion arch.%背景:生理性支抗控制矫治器是近几年来应用于正畸临床治疗的一种新型矫治器.其在支抗控制、力矩主导及摩擦力控制等方面均有其优越性.生理性支抗控制矫治器矫治技术在打开咬合方面也有其独特性.目的:通过建立包含压低辅弓的PASS矫治器三维有限元模型,分析压低辅弓在PASS矫治技术中对前牙的压低作用以及对磨牙增强支抗的作用.方法:将CT扫描数据输入Mimicsl7.0软件获得牙齿及颌骨的三维模型.利用Geomagic Studio、NX、ANSYSl5.0等一系列建模软件获得包含压低辅弓和生理性支抗控制矫治器的上颌牙列三维有限元模型.分析主辅弓结扎位点分别置于中切牙近中、侧切牙近中、侧切牙远中时牙列的整体受力情况及前牙的运动趋势.结果与结论:①结扎位点在中切牙间时,前牙压低效果明显;侧切牙近中结扎时前牙唇倾效果明显;侧切牙远中结扎时,前牙出现舌倾伴压低的趋势.3种工况下磨牙后倾的位移趋势均较大;②结果表明,结扎在中切牙近中时,切牙运动趋势最大,主要作用是压低切牙,3种工况对磨牙均产生较大后倾力.实验模拟了临床牙齿受力情况和位移趋势,有利于临床对该项技术的理解和应用.
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