Incisor torque control with fixed appliance

Abstract

OBJECTIVE: To evaluate the properties of orthodontic rectangular arch wires in torsion. METHODS: To measure and analyze the torsional moments and angles of 0.46 mm x 0.63 mm rectangular orthodontic arch wires in single 0.022 inch bracket of the maxillary central incisor with a torsion measurement apparatus. RESULTS: (1) The torsional stiffness of stainless steel arch wires, Chinese nitinol arch wires, 7.0 mm vertical loop arch wires, 3.0 mm and 6.0 mm horizontal loop arch wires is 4.909, 1.325, 4.137, 3.448 and 3.024 Nmm per degree, respectively. (2) The arch wires will be twisted 19.143, 36.832, 19.851, 21.812 and 22.418 degrees; respectively to obtain optimal force. (3) Vertical and horizontal loop decreased the torsional stiffness of the rectangular stainless steel arch wire. CONCLUSION: The straight rectangular stainless steel arch wire is not well suitable for the torque control of the incisor. Loop design in arch wire is capable of decreasing torsional stiffness. The horizontal loop is more effective than vertical loop.

目的: 探討切牙轉矩定量的控制規律。方法: 使用轉矩測量儀 ,對橫截面積為 0 4 6mm× 0 6 3mm的平直不銹鋼絲與鈦鎳絲 ,7 0mm高垂直曲不銹鋼絲 ,3 0mm長和 6 0mm長L形水平曲不銹鋼絲 ,在單個 0 5 6mm中切牙托槽內的轉矩力矩與扭轉角度進行測量與分析。結果: (1)這些弓絲的抗扭剛度分別為 4 90 9、1 32 5、4 137、3 4 4 8和 3 0 2 4N·mm/度 ;(2 )轉矩力矩達到2 0N·mm時 ,上述弓絲將分別扭轉 19 14 3、36 832、19 85 1、2 1 812和 2 2 4 18度 ;(3)不銹鋼絲和鈦鎳絲的轉矩余隙角分別為 15 0 7度和 2 1 73度 ;(4)曲能起到降低不銹鋼絲的抗扭剛度、增加弓絲彈性范圍的作用 ,其中以水平曲的效用更優。結論: 平直不銹鋼絲不是控制切牙轉矩的理想選擇。曲 ,特別是水平曲 ,能顯著降低弓絲的轉矩剛度、增加弓絲彈性范圍 。