Department of Mechanical Engineering, College of Engineering and Technology, SRM Institute of Science and Technology, Chengalpattu, Tamil Nadu, India.
Division of Orthodontics, Teeth "N" Jaws Centre, Chennai, Tamil Nadu, India.
Proc Inst Mech Eng H. 2021 Aug;235(8):940-946. doi: 10.1177/09544119211015086. Epub 2021 May 7.
In orthodontic fixed appliance therapy, the archwire torque used to refine the teeth position during the treatment imparts significant forces inside the bracket slot. The objective of this study was to measure the torque relevant bracket slot deformation in Stainless Steel (SS) brackets during various degree of archwire twist. Standard edgewise brackets 0.018-inch (in.)/0.022-in. each 20 no. and 0.016 × 0.022, 0.017 × 0.025, 0.019 × 0.025, and 0.021 × 0.025 in. archwires each 10 no. were used. A novel experimental setup consisting of loading fixture and torque key mounted on a Vision Measuring System (VMS) were used to measure the brackets slot deformation. The Top Slot and Middle Slot Deformations (TSD and MSD) of the brackets for 35° angle of twist in 0.016 × 0.022 in. archwire in 0.018-in. slot, 0.019 × 0.025 in. archwire in 0.022-in. slot and for 30° angle of twist in 0.017 × 0.025 in. archwire in 0.018-in. slot and 0.021 × 0.025 in. archwire in 0.022-in. slot were measured. Results showed that the mean TSD and MSD were higher when the archwire size, the slot size and the angle of twist were greater. In the evaluated bracket-archwire combinations, the TSD were higher than MSD and the bracket slots were elastically deformed within the clinically required 35° angle of twist in the archwire. Clinicians should be aware of this torque relevant bracket slot deformation which might be a factor for torque loss and suitably incorporate archwire angle of twist.
在正畸固定矫治器治疗中，矫治弓丝转矩用于在治疗过程中精细调整牙齿位置，会在托槽槽沟内产生显著的力。本研究的目的是测量不同弓丝扭转程度下不锈钢托槽槽沟相关的转矩变形。使用标准方丝弓 0.018 英寸/0.022 英寸托槽各 20 个，0.016×0.022、0.017×0.025、0.019×0.025 和 0.021×0.025 英寸弓丝各 10 根。一个由加载夹具和扭矩钥匙组成的新型实验装置，安装在视觉测量系统（VMS）上，用于测量托槽槽沟变形。测量了 35°扭转角下 0.016×0.022 英寸弓丝在 0.018 英寸槽沟、0.019×0.025 英寸弓丝在 0.022 英寸槽沟、30°扭转角下 0.017×0.025 英寸弓丝在 0.018 英寸槽沟和 0.021×0.025 英寸弓丝在 0.022 英寸槽沟的托槽的上槽沟变形（TSD）和中槽沟变形（MSD）。结果表明，当弓丝尺寸、槽尺寸和扭转角度较大时，平均 TSD 和 MSD 较高。在所评估的托槽-弓丝组合中，TSD 高于 MSD，并且在弓丝 35°的临床所需扭转角度范围内，托槽槽沟发生弹性变形。临床医生应该注意这种与转矩相关的托槽槽沟变形，这可能是转矩损失的一个因素，并适当纳入弓丝扭转角度。
