Abstract:

Objective    To electrochemically evaluate corrosion resistance and longevity of nickel-titanium endodontic instruments after modifided by surface coating. Methods    A total of eight sets of new Mtwo NiTi instruments（size 10，size 15，size 20，size 25 in each set）were randomly divided into four groups（A1，A2 and B1，B2）. The instruments of group B1 and B2 were exposed to multi-arc plating machine to create a coating of a TiZrNO layer，and the files of group A1 and A2 were not coated. Scanning electron microscopes（SEM）were used to examine surface morphology of NiTi instruments with and without coating. Moreover，X-ray energy dispersive spectroscopy analysis（EDX）was performed before and after coating to evaluate the effect on the chemical composition. The following irrigation solutions were used：in group A1 and B1 files 5.25% NaOCl was used. In groups A2 and B2 2.5% NaOCl was used. Files were used to prepare single-rooted extracted human teeth. The procedure was repeated to prepare10 canals. Files were used for a cycle of preparation and sent to autoclave. The instruments were sent for corrosion assessment. Results    Scanning electron microscopes showed that surface morphoology has been improved compared with uncoated NiTi instruments. Electrochemical measurements indicated that coated instruments were significantly higher in corrosion resistance  than uncoated instruments. Conclusion    Corrosion resistance and surface morphology of coated NiTi files are significantly higher than that in uncoated files.

Key words: nickel-titanium instrument, surface modification, corrosion resistance

摘要：

目的    探讨镍钛根管器械表面镀膜后是否能提高镍钛根管器械的抗腐蚀性，从而提高其使用寿命。方法       共选用8套Mtwo镍钛器械（每套型号为10号，0.04锥度；15号，0.05锥度；20号，0.06锥度；25号，0.06锥度），随机分为4组（A1、A2、B1、B2），每组2套器械，共8只。A1、A2组不做任何处理，B1、B2组进行镀膜。A1、B1组采用5.25%NaOCl作为根管预备过程中的冲洗液；A2、B2组用2.5%NaOCl作为根管预备过程中的冲洗液。通过多弧离子镀膜机将TiZrNO作为阴极电弧蒸发靶原，在B1、B2组Mtwo镍钛器械表面制备一层均匀的0.4 μm厚的膜层。选取2014年8月至2015年8月于中国医科大学附属口腔医院门诊就诊患者拔除的单根牙共80颗，均根尖发育完好、15号K锉到达根尖口且有摩擦感，截去牙冠，留取根尖至釉牙骨质界13 ~ 15 mm。每套器械分别进行根管预备，每次预备1个根管，每换一支锉用冲洗液冲洗根管，预备后放入超声荡洗机内荡洗，封袋高温高压消毒。每套器械预备10个根管。扫描电镜下观察镀膜器械和未镀膜器械，保留图片。最后将每只镍钛器械进行电化学实验，通过恒电位仪获得极化曲线。结果    扫描电镜结果，镀膜镍钛合金根管器械表面性状较未镀膜器械高，电化学测试镀膜镍钛合金根管器械腐蚀速率较未镀膜镍钛器械显著降低。结论    镀膜技术对镍钛合金根管器械进行表面改性可以改善器械表面性状，提高其耐腐蚀性。

关键词: 镍钛根管器械, 表面改性, 抗腐蚀性