镍钛再治疗器械去根管充填材料后的器械损伤评价

Evaluation of retreatment instrument damage after removal of root filling materials

目的:评价两种镍钛再治疗器械去根管内充填材料后的器械损伤情况。方法:使用ProTaper D和MtwoR去除充填完好的离体前牙根管,每通畅一个根管后在立体显微镜下观察并记录器械分离和螺纹松解情况。选取在立体显微镜下检测完好的D2、R25锉,在扫描电镜下观察其表面和切割刃的磨损情况。结果:经立体显微镜下观察:ProTaper D和MtwoR在使用6个根管后开始逐渐出现异常。在扫描电镜下观察:ProTaperD在使用5次后可见沟纹加深和少量微裂,MtwoR在使用5次后可见金属表面结构紊乱。两种再治疗器械在使用7次时扫描电镜下可见明显微裂纹。两组中最小尖端直径的D3锉和R15锉更易发生器械损伤和分离。结论:两组镍钛再治疗系统使用次数都不宜超过6次。

AIM： To evaluate the damage of two nickel-titanium retreatment instruments after removal of root filling materials. METHODS： 6 sets of ProTaper D and of MtwoR were used to remove the filling materials in extracted anterior teeth root canals. The instruments were examined under stereomicroscope after each removal of root filling material. D2 and R25 files without deformation under stereomicroscope observation were examined under scanning electron microscope（ SEM） for the observation of structure change. RESULTS： Deformation of ProTaper D and MtwoR was found after 6 times of filling material removal obsrved under stereomicroscope. Structural disorder or microcracks were found under SEM after 5 times of use and the microcracks were found to increase after 7 times of use. D3and R15 files were easier to deform and fracture than other files. CONCLUSION： It is recommended that the two Nickel-titanium retreatment instruments be used less than 6 times for removal of root canal filling materials.