Evaluation of ultimate tensile strength and surface roughness of NiTi and CuNiTi orthodontic archwires after recycling procedures

Abstract

Aim: The aim of this study is to evaluate and compare the influence of 2 types of sterilization/disinfection procedures on the tensile strength and surface topography of two orthodontic wires (Nickel-titanium (NiTi), and cupper Nickel-titanium (CuNiTi)). Materials and Methods: Sample comprised of 140 wires(100 new 0.017×0.025′′ Ovoid rectangular, and 40 used 0.017×0.025′′ Ovoid rectangular wires). They were randomly divided into 7 groups according to method and number of sterilization cycles,each group equally divided into 2 subgroups according to wire composition. Surface topography was examined with scanning electron microscope (SEM) and ultimate tensile strength (UTS) was tested using universal testing machine after sterilization and disinfection of the experimental groups. Result: SEM images revealed an increase in surface irregularities in CuNiTi and NiTi wires after sterilization. UTS of CuNiTi and NiTi wires after one cycle of autoclave sterilization procedure, or chemical sterilization for one or two cycles were not significantly different when compared with the control group. NiTi and CuNiTi archwires were affected after two cycles of autoclave sterilization.The mean UTS of clinically used and recycled archwires increased significantly when compared with the control group. Used and recycled archwires were affected considerably by autoclave sterilization Conclusion: Autoclave sterilization and chemical sterilization solution can be recommended for sterilization of orthodontic wires for one cycle.