The properties of different orthodontic rectangular arch wires in torsion

Abstract

OBJECTIVE: To study the properties of orthodontic rectangular arch wires in torsion. METHODS: By using the torsion measurement apparatus, torsion moments and angles of four kinds of orthodontic wires (0.46 mm x 0.63 mm and 0.48 mm x 0.63 mm stainless steel wires, and the same size nickel-titanium wires) were tested respectively in a 0.56 mm-slot first maxillary incisor bracket. According to the torsion moments and angles, scatter graphs were drawn to fit the load-deflection curves of four kinds of wires and their linear equations were calculated. According to the equations, the torsion stiffness and the play angles of the wires at 20 N mm correspondingly were calculated. RESULTS: The torsion stiffness of four kinds of wires were 4.909, 6.417, 1.325 and 1.363 N mn/degrees, the torsion angles of different wires were 19.14 degrees, 15.33 degrees, 36.83 degrees and 35.07 degrees at 20 N mm respectively. CONCLUSION: The torsion stiffness of stainless steel wires was bigger than that of the same cross-section dimensional nickel-titanium wires. The difference of torsion stiffness between two dimensional nickel-titanium wires is smaller, while the difference of torsion stiffness between two stainless steel wires is larger.

目的研究正畸方絲的轉矩力。方法運用自行研制的轉矩測量儀測量0.46mm×0.63mm、0.48mm×0.63mm不銹鋼方絲和相同截面尺寸的鎳鈦方絲在單個0.56mm槽溝的中切牙托槽內的轉矩力矩與轉矩角度;根據轉矩力矩與轉矩角度,使用SPSS11.0軟件制作散點圖,擬合出4種弓絲的負荷形變曲線,并據此建立直線回歸方程;根據方程得出弓絲的抗扭剛度及轉矩力矩為20N·mm時的轉矩角度。結果以上4種弓絲抗扭剛度分別為4.909、6.417、1.325、1.363N·mm/°,達到20N·mm轉矩力矩時的轉矩角度分別為19.14°、15.33°、36.83°、35.07°。結論相同截面尺寸不銹鋼方絲的抗扭剛度明顯大于鎳鈦方絲;兩種截面尺寸鎳鈦方絲的抗扭剛度相差很小,而不銹鋼方絲則相差較大。