Harsha Sarvajith B, Riyaz Khadeer, Manjappa Laxmikanth S, Talwar Ashita, Ravuru Divya, Narasimha Mogaveera Nandan K, Gupta Seema
Department of Orthodontics and Dentofacial Orthopedics, The Oxford Dental College, Bengaluru, IND.
Department of Orthodontics and Dentofacial Orthopedics, Kothiwal Dental College and Research Centre, Moradabad, IND.
Cureus. 2024 Oct 15;16(10):e71528. doi: 10.7759/cureus.71528. eCollection 2024 Oct.
This study aimed to perform a comparative analysis of stresses and displacements with incremental torque on the maxillary incisors and surrounding cortical bone using conventional metal brackets with rectangular slots and passive self-ligating brackets with square slots using finite element analysis (FEA).
An in vitro FEA study was conducted, in which a three-dimensional (3D) model of the maxilla was built using ANSYS software version 18 (ANSYS Inc., Canonsburg, PA). The conventional McLaughlin, Bennet, and Trevisi (MBT) bracket (3M Unitek, Monrovia, CA) of 0.022 × 0.028-inch slot with a 0.019 × 0.025-inch rectangular stainless steel (SS) archwire (model 1) was compared with the Pitts 21™ self-ligating bracket system (OC Orthodontics, McMinnville, OR) of 0.021 x 0.21-inch slot with a 0.020 × 0.020-inch square SS archwire (model 2) at incremental torques of 5°, 10°, 15°, and 20°. The von Mises stress was evaluated at the maxillary incisors and surrounding cortical bone. The torque moment, tipping angle, and displacement of the maxillary incisors were also measured and compared between the bracket systems.
The highest torque expression of 13.8 N-mm was observed in model 2, compared to a torque expression of 10.68 N-mm in model 1. The torque expression increased in both models from 0°to 20. There was a play of 6.2°at 20°torque in model 2, whereas it was 9.32°play in model 1. The torque expressions were better for the lateral incisors than for the central incisors. Increased incremental torque was associated with increased proclination of the incisors, and this movement was more pronounced for the central incisor and model 1. Furthermore, it was revealed that the stresses on the cortical bone and teeth were higher in model 2 than in model 1.
It was concluded that the Pitts 21™ passive self-ligating system produced better torque expression and less play with square SS archwire compared to conventional brackets with rectangular SS archwire.
本研究旨在使用有限元分析（FEA），对上颌切牙及周围皮质骨在施加递增扭矩时，采用带矩形槽的传统金属托槽和带方形槽的被动自结扎托槽，进行应力和位移的对比分析。
进行了一项体外有限元分析研究，其中使用ANSYS 18版软件（ANSYS公司，宾夕法尼亚州卡农斯堡）构建了上颌骨的三维（3D）模型。将0.022×0.028英寸槽的传统麦克劳林、贝内特和特雷维西（MBT）托槽（3M Unitek公司，加利福尼亚州蒙罗维亚）与0.019×0.025英寸矩形不锈钢（SS）弓丝（模型1），与0.021×0.21英寸槽的皮茨21™自结扎托槽系统（OC正畸公司，俄勒冈州麦克明维尔）和0.020×0.020英寸方形SS弓丝（模型2）在5°、10°、15°和20°的递增扭矩下进行比较。评估上颌切牙及周围皮质骨的冯·米塞斯应力。还测量并比较了两种托槽系统上颌切牙的扭矩、倾斜角和位移。
模型2中观察到的最高扭矩表达为13.8 N·mm，而模型1中的扭矩表达为10.68 N·mm。两种模型的扭矩表达均从0°增加到20°。模型2在20°扭矩时有6.2°的游隙，而模型1为9.32°的游隙。侧切牙的扭矩表达优于中切牙。递增扭矩增加与切牙前倾增加相关，且这种移动在中切牙和模型1中更为明显。此外，研究发现模型2中皮质骨和牙齿上的应力高于模型1。
得出的结论是，与带矩形SS弓丝的传统托槽相比，皮茨21™被动自结扎系统使用方形SS弓丝时产生了更好的扭矩表达且游隙更小。
