Finite element analysis of torque induced orthodontic bracket slot deformation in various bracket-archwire contact assembly.,Computer Methods and Programs in Biomedicine

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Finite element analysis of torque induced orthodontic bracket slot deformation in various bracket-archwire contact assembly.
Computer Methods and Programs in Biomedicine ( IF 4.9 ) Pub Date : 2020-09-09 , DOI: 10.1016/j.cmpb.2020.105748
Pandurangan Harikrishnan ₁ , Varadaraju Magesh ₂ , Akhil Minu Ajayan ₃ , Devadhas Kingsly JebaSingh ₂

Affiliation

Background and Objectives

Orthodontic fixed appliance therapy involves alignment of teeth through the bracket and archwires. The archwire twist (torque) imparts significant forces inside the bracket slot in refining the teeth position at the end of treatment. The objective of this in- silico study was to evaluate the torque induced bracket slot deformation in the commonly used 0.018 inch (") and 0.022" conventional Stainless Steel (SS) brackets with clinically relevant archwires during various angles of twist.

Methods

SS maxillary central incisor brackets of 0.018" width × 0.022" depth (0.457 mm × 0.558 mm) and 0.022" width × 0.028" depth (0.558 mm × 0.711 mm) were used. The SS archwires of 0.016" width × 0.022" depth (0.406 mm × 0.558 mm), 0.017" width × 0.025" depth (0.431 mm × 0.635 mm), 0.019" width × 0.025" depth (0.482 mm × 0.635 mm) and 0.021" width × 0.025" depth (0.533 mm × 0.635 mm) were engaged in the respective bracket slots. The assembled bracket-archwire Finite Element (FE) models were constructed. The archwire torque, the top, middle and bottom slot deformations (TSD, MSD, BSD) were obtained for the bracket-archwire combinations for various angles of archwire twist using FE Analysis (FEA).

Results

The torque, TSD, MSD and BSD for 30^o twist of 0.016" × 0.022" archwire in 0.018" slot were 28.13 Nmm, 35.71 µm, 21.51 µm and 15.67 µm respectively, and for 0.017" × 0.025" archwire were 50.18 Nmm, 54.52 µm, 32.47 µm and 19.11 µm respectively. Similarly for 0.019" × 0.025" archwire in 0.022" slot and 0.021" × 0.025" archwire in 0.022" slot they were 38.82 Nmm, 50.78 µm, 31.47 µm and 16.82 µm, and 60.22 Nmm, 65.22 µm, 36.44 µm and 22.68 µm respectively.

Conclusions

The slot deformation was present in both 0.018" and 0.022" brackets which increased as the angle of twist increased. The TSD were higher than the MSD and BSD in all the bracket-archwire combinations. We conclude that there is only elastic deformation of bracket slots upto 30^o angle of twist and clinicians could maintain within this torque limits to avoid plastic deformation leading to improper teeth position.

中文翻译：

各种托槽-弓丝触点组件中扭矩引起的正畸托槽狭槽变形的有限元分析。

背景和目标

正畸固定矫治器治疗涉及通过支架和弓丝对齐牙齿。在治疗结束时，弓丝的扭转（扭矩）会在支架槽内施加很大的力，从而完善牙齿的位置。这项计算机模拟研究的目的是评估在各种扭曲角度下，带有临床相关弓丝的常用0.018英寸（“）和0.022”常规不锈钢（SS）支架中的扭矩引起的支架槽变形。

方法

使用的SS上颌中切牙支架的宽度为0.018英寸×深度0.022英寸（0.457毫米×0.558毫米），宽度为0.022英寸×0.028英寸（0.558毫米×0.711毫米）。SS弓丝的宽度为0.016英寸×深度0.022英寸（0.406毫米×0.558毫米），0.017英寸宽度×0.025英寸深度（0.431毫米×0.635毫米），0.019英寸宽度×0.025英寸深度（0.482毫米×0.635毫米）和0.021 “宽×0.025”深（0.533毫米×0.635毫米）分别插入相应的支架插槽中。构造了组装的支架－弓线有限元（FE）模型。使用有限元分析（FEA），针对不同弓丝扭转角度的支架-弓丝组合，获得弓丝扭矩，顶部，中间和底部缝隙变形（TSD，MSD，BSD）。

结果

0.018“槽中0.016”×0.022“弓丝30 ^o扭转的扭矩，TSD，MSD和BSD分别为28.13 Nmm，35.71 µm，21.51 µm和15.67 µm，0.017”×0.025“弓丝的50.18 Nmm，54.52 µm，32.47 µm和19.11 µm。类似地，对于0.022“槽中的0.019”×0.025“弓丝和0.022”槽中的0.021“×0.025”弓丝，它们分别为38.82 Nmm，50.78 µm，31.47 µm和16.82 µm，以及60.22 Nmm，分别为65.22 µm，36.44 µm和22.68 µm。