3种镍钛器械预备重度弯曲根管后牙本质微裂纹的观察

Comparison of dentinal microcracks formation in severely curved root canal with different Ni-Ti instruments

目的 :研究3种镍钛器械预备重度弯曲根管后牙本质微裂的发生情况。方法 :收集临床上拔除的近中根牙根弯曲度在25°~40°的磨牙240颗,按弯曲度25°~30°(不包括25°)、30°~35°、35°~40°随机分为A、B、C 3组,每组80个标本,均用K锉预备到15#。将3组随机分为4个亚组,每个亚组20颗,1组为对照组,另外3组为实验组。对照组不进行镍钛预备,将实验组中的牙根分别用WaveOne、ProTaper Next、M3-Pro 3种镍钛器械进行预备,并浸泡于1%亚甲蓝24 h。然后分别取牙根最弯处以及距最弯处上、下2 mm的截断面,在体视显微镜下观察各断面牙本质微裂纹的情况。采用SPSS 20.0软件包对数据进行统计学分析。结果:WaveOne、ProTaper Next、M3-Pro 3组均使牙本质产生微裂,WaveOne组发生比例最高,ProTaper Next组最低,WaveOne组与其他2组的差异有统计学意义(P<0.05),ProTaper Next组与M3-Pro组无显著差异(P>0.05)。随着牙根弯曲角度的增大,WaveOne、ProTaper Next、M3-Pro 3组牙本质微裂的数量增加,除Waveone组在A(25°~30°)与C(35°~40°)2组中牙本质微裂发生比例的差异有统计学意义(P<0.05)外,其余均无统计学差异(P>0.05)。结论:ProTaper Next与M3-Pro更有利于中重度弯曲根管的预备。

PURPOSE: This study was aimed to compare the incidence of dentinal microcracks produced by 3 kinds of Ni-Ti instruments during root canal procedures in severely curved canals. METHODS: Two hundred and forty extracted human molars with mesial roots of 25° to 40° curvatures were selected and divided into A, B, C group, with 80 teeth in each group according to root curvature of 25°-30° (excluding 25°), 30°-35°,35°-40°. Each of them was prepared with K file to 15#. Then, each group was divided into 4 sub-groups(n=20), one was as control, the others were prepared with WaveOne, ProTaper Next and M3-Pro, respectively. After preparation, all roots were stained with 1% methylene blue for24 hours. The roots were then sectioned at the most curved plane and 2 mm below and above the most curved plane with alow-speed saw under cold water. Stereomicroscope was used to inspect dentinal microcracks and differences between each group were analyzed using Chi-square test with SPSS 20.0 software package. RESULTS: Microcracks were observed in the group of WaveOne, ProTaper Next and M3-Pro. WaveOne system induced more dentinal microcracks compared with ProTaper Next and M3-Pro system(P<0.05), and there was no significant difference between ProTaper Next and M3-Pro system(P>0.05). The number of dentinal microcracks in WaveOne, ProTaper Next and M3-Pro group increased with the increase of root curvature. Except Waveone in group A(25°-30°) and group C(35°-40°), the occurrence of dentinal microcracks in two groups had significant difference(P<0.05), there was no significant difference among other groups(P>0.05). CONCLUSIONS: Compared to WaveOne, ProTaper Next and M3-Pro are more suitable for severely curved canal preparation.