Influence of loops on the torsion stiffness of rectangular wire

Abstract

OBJECTIVE: To study the influence of loops on the torsion stiffness of rectangular wire. METHODS: The torsion moments and angles of 0.018 inch x 0.025 inch rectangular orthodontic arch wires in single 0.022 inch bracket of the first maxillary incisor were measured with a torsion measurement apparatus, and the measured values were analyzed by two-way ANOVA. The wires included straight stainless steel rectangular wires, and 3.5 mm, 7 mm, 10.5 mm, 14 mm high vertical loop wires, and 3 mm, 6 mm, 9 mm, 12 mm long horizontal loop wires. RESULTS: 1. The torsion stiffnesses of straight wire and vertical and horizontal loop wires were 4.909, 4.544, 4.137, 3.851, 3.454, 3.448, 3.024, 2.686, 2.378 N.mm/degree respectively. 2. The arch wires will be twisted 19.143 degrees, 19.377 degrees, 19.851 degrees, 20.949 degrees, 21.632 degrees, 21.812 degrees, 22.418 degrees, 23.254 degrees, 24.316 degrees respectively to obtain 20 N.mm force. CONCLUSION: The design of loop can reduce the torsion stiffness of rectangular wire. Compared with the length of loop, the shape of loop has more important effect on the reduction of torsion stiffness. The horizontal loop design as a factor for the control of the tongue is more effective than the vertical loop design.

目的 研究垂直曲、水平曲對方弓絲轉矩性能的影響規律。方法 采用轉矩測量儀 ,對 0 .4 6 m m×0 .6 3mm不銹鋼平直方絲 ,以及方絲彎制的 3.5 m m、7.0 m m、10 .5 mm、14 m m四種高度的垂直曲以及 3.0 m m、6 .0 mm、9.0 mm、12 .0 m m四種水平臂長度的 L形水平曲弓絲 ,在單個 0 .0 2 2英寸 (0 .5 6 mm )中切牙托槽內 ,測量與分析其轉矩力矩、轉矩角和抗扭剛度。結果 1帶曲弓絲抗扭剛度分別為平直弓絲抗扭剛度的 92 .6 %、84 .3%、78.4 %、70 .4 %、70 .2 %、6 1.6 %、5 4 .7%、4 8.4 % ;2轉矩力矩從 0 N· mm～ 2 0 N· mm ,以上弓絲將分別扭轉19.14 3°、19.377°、19.85 1°、2 0 .94 9°、2 1.6 32°、2 1.812°、2 2 .4 18°、2 3.2 5 4°、2 4 .316°。結論 曲可降低方弓絲的載荷撓曲率 ,對弓絲第三序列彎曲方向的影響規律不同于第一、二序列彎曲方向 ,曲的設計所用金屬絲的長度與附加金屬絲的構型相比 ,構型是更為重要的影響弓絲第三序列彎曲方向載荷撓曲率的因素。