氟离子和酸对3M镍钛弓丝和Damon铜镍钛弓丝耐腐蚀性的影响

背景：在含氟的酸性环境中，Damon铜镍钛弓丝能否具有与传统镍钛弓丝相当的耐腐蚀性能，铜离子的加入会不会影响其耐腐蚀性？目的：观察氟离子和酸对3M镍钛弓丝和Damon铜镍钛弓丝耐腐蚀性的影响。方法：采用动电位极化曲线法测得3M镍钛弓丝和Damon铜镍钛弓丝分别在4种（pH=7、不含氟离子；pH=7、含氟离子浓度0.2%；pH=7、含氟离子浓度0.5%；pH=5、含氟离子浓度0.5%）不同人工唾液中的动电位极化曲线，得到自腐蚀电位、自腐蚀电流密度和极化电阻，并用扫描电镜观察其腐蚀后的形态。结果与结论：在中性（pH=7）人工唾液中加入0.2%氟离子，Damon铜镍钛弓丝试件极化曲线上移，自腐蚀电流密度增大，极化电阻减小（P 〈0.05），扫描电镜显示试件表面出现腐蚀；3M镍钛弓丝试件极化曲线没有偏移，自腐蚀电流密度、极化电阻基本不变（P〉0.05），腐蚀不明显；当氟离子浓度增大到0.5%时，两种试件极化曲线均上移，自腐蚀电流密度增大，极化电阻减小（P 〈0.05），试件表面均出现明显腐蚀；当加入酸之后（pH=5），腐蚀更加明显。提示低浓度氟不会影响3M镍钛弓丝的耐腐蚀性，但会降低Damon铜镍钛弓丝的耐腐蚀性；高浓度氟和酸均会降低他们的耐腐蚀性，Damon铜镍钛弓丝的耐腐蚀性不及3M镍钛弓丝。

Corrosion resistance of 3M nickel-titanium arch wires and Damon copper-nickel-titanium arch wires in different artificial saliva with different fluoride and pH

BACKGROUND：In the fluorine-containing acidic environment, it is unclear whether Damon copper- nickel-titanium arch wire can have a corrosion resistance similar to conventional nickel-titanium arch wire and whether copper ion wil affect its corrosion resistance. OBJECTIVE： To evaluate the corrosion resistance of 3M nickel-titanium arch wires and Damon copper-nickel-titanium arch wires in artificial saliva with different fluoride and pH. METHODS：Potentiodynamic polarization curves of 3M nickel-titanium arch wires and Damon copper-nickel-titanium arch wires were measured in four kinds of artificial saliva （pH=7; pH=7, 0.2% fluoride; pH=7, 0.5% fluoride; pH=5, 0.5% fluoride）. Then, the corrosion potential, corrosion current density and polarization resistance were acquired, and scanning electron microscope was used for morphological observation after corrosion. RESULTS AND CONCLUSION： In neutral （pH=7） artificial saliva, 0.2% fluoride ions added could shift up the Damon specimen polarization curve, increase the corrosion cerrent density and reduce the polarization resistance （P 〈 0.05）; under the scanning electron microscope, corrosion was observable on the specimen surface. But 3M specimen polarization curve did not move, corrosion current density and polarization resistance substantialy unchanged （P 〉 0.05）, and no significant corrosion was produced. When fluoride concentration was increased to 0.5%, the polarization curves of two kinds of the specimens moved, the corrosion cerrent density increased, the polarization resistance decreased （P 〈 0.05）, and there was significant presence of corrosion on the specimen surface. When pH=5, corrosion phenomenon was more pronounced. These findings suggest that low concentrations fluoride cannot affect corrosion resistance of 3M arch wire, but can reduce the corrosion resistance of Damon arch wire; high concentrations of fluoride and acid can both reduce their corrosion resistance. In addition, the corrosion resistance of 3M arch is stronger than that of Damon arch wire.