A Comparative Study On The Mechanical Properties Of Three Different Kinds Of Arch Wires With Different Materials

Objective: Three different kinds of arch wires with different materials were measured and compared with each other.By comparing the mechanical properties of the three kinds of arch wires,to provide a reference for orthodontic clinical works.Methods:We selected low hysteresis nickel-titanium arch wires,copper nickel titanium(CuNiTi)arch wires and stainless steel arch wires from GRIMED Medical(Beijing)Co.,Ltd.Three commonly used sizes(0.016×0.022 inch,0.018×0.025 inch,0.019×0.025 inch)were selected for low hysteresis NiTi arch wires,four commonly used sizes(0.016 inch,0.018 inch,0.016×0.022 inch,0.019×0.025 inch)were selected for stainless steel arch wires and five commonly used sizes(0.016 inch,0.018 inch,0.016×0.022 inch,0.019×0.025 inch)were selected for CuNiTi and stainless steel arch wires.The classical three-point bending test was performed to each kinds of arch wire by material testing machine according to an ISO standard(ISO 15841:2014).The load displacement curve,stress hysteresis,super elasticity ratio(SER),plateau length,plateau slope,average plateau force and elastic modulus were assessed by three-point bending test.And the mechanical properties between types of arch wires were compared.Results:1.The stress hysteresis of low hysteresis nickel-titanium arch wires of 0.016×0.022 in,0.018×0.025 in,0.019×0.025 in were smaller than that of CuNiTi arch wires in the same size(P<0.05);there was statistical difference between the stress hysteresis of low hysteresis nickel-titanium arch wires 0.016×0.022in<0.018×0.025in<0.019×0.025 in,(P<0.05);there was statistical difference between the stress hysteresis of CuNiTi arch wires 0.016in<0.018in<0.016×0.022in<0.017×0.025 in,(P<0.05).2.The super elastic ratio for all of the sample of low hysteresis nickel-titanium arch wires and CuNiTi arch wires are higher than 8,and the plateau length for all of the sample of low hysteresis nickel-titanium arch wires and CuNiTi arch wires are longer than 0.5mm.3.The plateau slope of CuNiTi round wires are smaller than that of square wires(P<0.05).There are no statistical difference between the plateau slope of low hysteresis nickel-titanium arch wires of 0.016×0.022 in,0.018×0.025 in,0.019×0.025 in and that of CuNiTi arch wires.4.The average plateau force of low hysteresis nickel-titanium arch wires of 0.016×0.022 in,0.018×0.025 in,0.019×0.025 in were smaller than that of CuNiTi arch wires in the same size(P<0.05).There are no statistical difference between the average plateau force of low hysteresis nickel-titanium arch wires of 0.016×0.022 in and that of CuNiTi arch wires of 0.018in(P<0.05).6.All of the samples of low hysteresis nickel-titanium arch wires and CuNiTi arch wires which were tested in this experiment have lower elastic modulus than all kinds of stainless steel arch wires in this experiment,all parameters investigated were statistically different(P<0.05).Conclusions:1.All of the samples of low hysteresis nickel-titanium arch wires and CuNiTi arch wires which were tested in this experiment possess hyper-elasticity.The stress hysteresis and average plateau force of all kinds of low hysteresis nickel-titanium arch wires were smaller than that of CuNiTi arch wires in the same size.The stress hysteresis of low hysteresis nickel-titanium arch wires increased with the increase of arch wire size.2.The average plateau force of low hysteresis nickel-titanium arch wires and CuNiTi arch wires increased with the increase of arch wire size.And there are no statistical difference between the average plateau force of low hysteresis nickel-titanium arch wires of 0.016×0.022 in and that of CuNiTi arch wires of 0.018 in.Which means square low hysteresis nickel-titanium arch wires can be used in the early stage of orthodontic treatment.To realize three-dimensional control of the teeth while leveling and aligning.By using low hysteresis nickel-titanium arch wires,it can reduce the frequency and duration of patients’ return visit and the cost of treatment,so that we can shorten the course of treatment.3.The elastic modulus of low hysteresis nickel-titanium arch wires and CuNiTi arch wires were far less than that of stainless steel arch wires.These two kinds of NiTi arch wires can generate soft and sustainable orthodontic force,and are suitable in the leveling and aligning stage.