Abstract: Objective: To understand their resistance to corrosion of four kinds of nickel-titanium orthodontic arch wires in artificial saliva. Methods: We choose four common brands of clinical nickel-titanium arch wires, i.e. 3M (USA 3M company producing nickel-titanium orthodontic arch wire, abbreviated as 3M), SL (Super Hang Technology Co., Ltd. of Shenzhen City produced nickel-titanium orthodontic arch wire, abbreviated as SL), TP (Toboggan orthodontic Instruments Co., Ltd. produced nickel-titanium orthodontic arch wire, abbreviated as TP), and SMT (Beijing Science and Technology Co., Ltd. Saintmart produced nickel-titanium orthodontic arch wire, abbreviated SMT). Artificial saliva was prepared and the PH value of artificial saliva was adjurted to 4.0 and 6.75, respectively. We clipped arch wire ends relatively straight section (each 2cm) into the EP resin tube, and added 1 mL the adjusted good artificial saliva, saved electronic thermostat at 37 ℃, respectively. The amount of precipitation of titanium ions was tested and statistical analysed after 1 day, 7days, 28 days. Results: Four kinds of NiTi orthodontic arch wire titanium ion 7 days, 28 days after the average amount of precipitation, less than the arch wires have to be soaked first day of the amount of precipitation. Different brands of titanium ions in precipitation amount between the difference was not statistically significant. Conclusion: Four kinds of nickel-titanium orthodontic arch wires had good corrosion resistance. Acidic environment can accelerate nickel-titanium orthodontic arch wire the amount of precipitation of titanium ions and affect nickel-titanium orthodontic arch wire corrosion resistance.

Key words: Niti orthodontic wires, The resistance corrosion, The release amount of Ti ions