| Objective: Through the scanning electron microscopy (SEM) and tensile test toobserve the influence of surface structure and mechanical properties of super-elasticnickel-titanium(Ni-Ti)alloy wire in artificial saliva before and after test，and comparecorrosion resistance ability of five different commercial Super-elastic Ni-Ti AlloyWire.Methods: About3cm segments were obtained from two terminals of IMD, smart,YY,SL and OT super-elastic alloy arch wires respectively, maintained in EP resin tubecontaining artificial saliva(pH=4.0,pH=6.75,1mL),and cultured at37℃.Microstructure was observed under scanning electron microscopy and Tensilestrength was measured after1,7and28days.Results:1. More surface structure changes were observed on super-elastic Ni-Tialloy wires in pH=4.0group compared to pH=6.75group，except OT orthodontic archwires.2.Materials yield strength and fracture had obviously decreasing trend with pHvalue decreased and the time of immerse prolonged in artificial saliva（P<0.001）, andat the same immerse time, the yield strength and fracture decreased significantly atpH=4.0group (P<0.05).3.The same material yield strength decreased more serious thanfracture. When using the yield strength as parameters, corrosion resistance ability ofIMD was best, OT was worst; when using the fracture as parameters, corrosionresistance ability of IMD was best, OT was worst.Conclusion:1.After immerse by artificial saliva, due to production processingcraft difference, which caused the difference in corrosion resistance ability of fivedifferent commercial Super-elastic Ni-Ti Alloy Wire.2. The lower pH of artificialsaliva and the longer immerse days, the more serious of material corrosion degrees andtensile properties decreased.3. The immerse time more than7days, the super-elastic Ni-Ti Alloy Wire in artificial saliva achieve to corrosion limitation, and the lower pH,the more serious destruction of super-elastic Ni-Ti Alloy Wire at corrosion limitation. |
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