Liu D W, Li J, Guo L, Rong Q G, Zhou Y H
Department of Orthodontics,Peking University School and Hospital of Stomatology & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing 100081,China.
Department of Biomedical Engineering,College of Engineering,Peking University,Beijing 100871,China.
Beijing Da Xue Xue Bao Yi Xue Ban. 2018 Feb 18;50(1):141-147.
To analyze the stress distribution in the periodontal ligament (PDL) under different loading conditions at the stage of space closure by 3D finite element model of customized lingual appliances.
The 3D finite element model was used in ANSYS 11.0 to analyze the stress distribution in the PDL under the following loading conditions: (1) buccal sliding mechanics (0.75 N,1.00 N,1.50 N), (2) palatal sliding mechanics (0.75 N,1.00 N,1.50 N), (3) palatal-buccal combined sliding mechanics (buccal 1.00 N + palatal 0.50 N, buccal 0.75 N + palatal 0.75 N, buccal 0.50 N+ palatal 1.00 N). The maximum principal stress, minimum principal stress and von Mises stress were evaluated.
(1) buccal sliding mechanics(0.75 N,1.00 N,1.50 N): maximum principal stress: at the initial of loading, maximum principal stress, which was the compressed stress, distributed in labial PDL of cervix of lateral incisor, and palatal distal PDL of cervix of canine. With increasing loa-ding, the magnitude and range of the stress was increased. Minimum principal stress: at the initial of loading, minimum principal stress which was tonsil stress, distributed in palatal PDL of cervix of lateral incisor and mesial PDL of cervix of canine. With increasing loading, the magnitude and range of minimum principal stress was increased. The area of minimum principal stress appeared in distal and mesial PDL of cervix of central incisor. von Mises stress:it distributed in labial and palatal PDL of cervix of lateral incisor and distal PDL of cervix of canine initially. With increasing loading, the magnitude and range of stress was increased towards the direction of root. Finally, there was stress concentration area at mesial PDL of cervix of canine. (2) palatal sliding mechanics(0.75 N,1.00 N,1.50 N): maximum principal stress: at the initial of loading, maximum principal stress which was the compressed stress, distributed in palatal and distal PDL of cervix of canine, and distal-buccal and palatal PDL of cervix of lateral incisor. With increasing loading, the magnitude and range of the stress was increased. Minimum principal stress: at the initial of loading, minimum principal stress which was tonsil stress, distributed in distal-interproximal PDL of cervix of lateral incisor and mesial-interproximal PDL of cervix of canine. With increasing loading, the magnitude and range of the stress was increased.von Mises stress: von Mises stress distributed in palatal and interproximal PDL of cervix of canine. With increasing loading, the magnitude and range of stress was increased. Finally, von Mises stress distributing area appeared at distal-palatal PDL of cervix of canine. (3) palatal-buccal combined sliding mechanics: maximum principal stress: maximum principal stress still distributed in distal-palatal PDL of cervix of canine. Minimum principal stress: minimum principal stress distributed in palatal PDL of cervix of lateral incisor when buccal force was more than palatal force. As palatal force increased, the stress concentrating area transferred to mesial PDL of cervix of canine.von Mises stress: it was lower and more well-distributed in palatal-buccal combined sliding mechanics than palatal or buccal sliding mechanics.
Using buccal sliding mechanics,stress majorly distributed in PDL of lateral incisor and canine, and magnitude and range of stress increased with the increase of loading; Using palatal sliding mechanics, stress majorly distributed in PDL of canine, and magnitude and range of stress increased with the increase of loading; With palatal-buccal combined sliding mechanics, the maximum principal stress distributed in the distal PDL of canine. Minimum principal stress distributed in palatal PDL of cervix of lateral incisor when buccal force was more than palatal force. As palatal force was increasing, the minimum principal stress distributing area shifted to mesial PDL of cervix of canine. When using 1.00 N buccal force and 0.50 N palatal force, the von Mises stress distributed uniformly in PDL and minimal stress appeared.
通过定制舌侧矫治器的三维有限元模型，分析空间关闭阶段不同加载条件下牙周膜（PDL）的应力分布。
在ANSYS 11.0中使用三维有限元模型，分析以下加载条件下PDL中的应力分布：（1）颊向滑动力学（0.75 N、1.00 N、1.50 N），（2）腭向滑动力学（0.75 N、1.00 N、1.50 N），（3）腭 - 颊联合滑动力学（颊向1.00 N + 腭向0.50 N、颊向0.75 N + 腭向0.75 N、颊向0.50 N + 腭向1.00 N）。评估最大主应力、最小主应力和von Mises应力。
（1）颊向滑动力学（0.75 N、1.00 N、1.50 N）：最大主应力：加载初始时，最大主应力为压缩应力，分布于侧切牙颈部唇侧牙周膜和尖牙颈部腭侧远中牙周膜。随着加载增加，应力的大小和范围增大。最小主应力：加载初始时，最小主应力为拉应力，分布于侧切牙颈部腭侧牙周膜和尖牙颈部近中牙周膜。随着加载增加，最小主应力的大小和范围增大。最小主应力区域出现在中切牙颈部远中及近中牙周膜。von Mises应力：最初分布于侧切牙颈部唇侧和腭侧牙周膜以及尖牙颈部远中牙周膜。随着加载增加，应力大小和范围向牙根方向增大。最后，在尖牙颈部近中牙周膜出现应力集中区域。（2）腭向滑动力学（0.75 N、1.00 N、1.50 N）：最大主应力：加载初始时，最大主应力为压缩应力，分布于尖牙颈部腭侧和远中牙周膜以及侧切牙颈部远颊侧和腭侧牙周膜。随着加载增加，应力的大小和范围增大。最小主应力：加载初始时，最小主应力为拉应力，分布于侧切牙颈部远中邻间牙周膜和尖牙颈部近中邻间牙周膜。随着加载增加，应力的大小和范围增大。von Mises应力：分布于尖牙颈部腭侧和邻间牙周膜。随着加载增加，应力大小和范围增大。最后，在尖牙颈部远中腭侧牙周膜出现von Mises应力分布区域。（3）腭 - 颊联合滑动力学：最大主应力：最大主应力仍分布于尖牙颈部远中腭侧牙周膜。最小主应力：当颊向力大于腭向力时，最小主应力分布于侧切牙颈部腭侧牙周膜。随着腭向力增加，应力集中区域转移至尖牙颈部近中牙周膜。von Mises应力：与腭向或颊向滑动力学相比，其在腭 - 颊联合滑动力学中较低且分布更均匀。
采用颊向滑动力学时，应力主要分布在侧切牙和尖牙的牙周膜，应力大小和范围随加载增加而增大；采用腭向滑动力学时，应力主要分布在尖牙的牙周膜，应力大小和范围随加载增加而增大；采用腭 - 颊联合滑动力学时，最大主应力分布在尖牙远中牙周膜。当颊向力大于腭向力时，最小主应力分布在侧切牙颈部腭侧牙周膜。随着腭向力增加，最小主应力分布区域向尖牙颈部近中牙周膜转移。当采用颊向1.00 N力和腭向0.50 N力时，von Mises应力在牙周膜中分布均匀且应力最小。
