不同温度下正畸镍钛方丝超弹性及热弹性的对比研究

The Comparative Study of the Superelasticity and Thermoelasticity of Different Kinds of Rectangular Nickel-titanium Orthodontic Wires at Different Temperatue in Vitro

目的:在模拟口腔环境下,研究温度对不同的镍钛方丝力学性能的影响。方法:选取5种0.016×0.022英寸的镍钛方丝及1种0.016英寸镍钛圆丝,采用改良部分牙弓托槽弯曲实验装置,分别在不同温度(25℃、33℃、35.5℃、40℃)的人工唾液中进行力学性能检测。结果:随着温度升高,6种镍钛弓丝卸载至1.5mm时的应力值及卸载刚度随之增大,其中Copper Ni-Ti 40的应力值最小,镍钛圆丝的卸载刚度最小;滞后值最低的为镍钛圆丝,最大的为普通型中国镍钛牙弓丝。结论:6种镍钛弓丝均表现出了临床所需要的超弹性能,且L&H Titan,Copper Ni-Ti 35,Copper Ni-Ti 40同时具备热弹性;6种镍钛弓丝力学性能均表现出明显的温度敏感性;CopperNi-Ti 40能提供与镍钛圆丝相当的柔和的矫治力量,能胜任临床的早期使用。

Objective： To compare the mechanical properties of five different rectangular nickel-titanium（NiTi） archwires at different oral temperature which would provide reference for their clinical application.Methods： Five different kinds of rectangular NiTi orthodontic archwires with the same size（0.016×0.022 inch） and one group of round NiTi archwires（0.016 inch） were selected and tested in 25℃,33℃,35.5℃,40℃ artificial saliva using a modified partial dental arch bending system.Results： The stress value of 1.5mm unloading deflection point（UDP）,and the unloading stiffness had a significant tendency to be higher with increasing temperature for all six groups of NiTi archwires;the smallest stress of 1.5mm UDP among six group of wires tested was produced by COPPER Ni-Ti40 while Grikin Round NiTi had the smallest unloading stiffness.The smallest stress hysteresis was produced by Grikin round NiTi while Grikin Rectangular produced the largest one.Conclusion： Six different kinds of rectangular NiTi archwires exhibited superelasticity and LH Titan,COPPER Ni-Ti35,COPPER Ni-Ti40 demonstrated practical thermoelasticity.All six kinds of archwires displayed temperature sensitivity.Because COPPER Ni-Ti40 had the smallest stiffness and produced the smallest orthodontic force,it can be more suitable to be applied clinically during the early stage of the treatment.