三种器械预备磨牙弯曲根管成形能力的比较

目的　研究手用ProTaper与不锈钢K锉、镍钛合金K锉预备磨牙弯曲根管对根管弯曲度和根尖偏移的影 响。方法　45个弯曲度为20°~40°的磨牙根管,按弯曲度大小排序后分成15个区组,每区组3个根管,再随机分配 至3个不同处理组,每组15个根管。A组采用手用ProTaper系统行冠根向深入法根管预备;B、C组分别采用不锈钢 K锉和镍钛合金K锉行改良逐步后退法预备根管。记录3组根管预备前后根管影像及器械尖端所在位置,测量并 比较3组间根管弯曲度的变化、根尖偏移指数(ATI)和操作时间。结果　A组的根管弯曲度在根管预备前后仅改变 0·28°,明显低于B、C组,ATI亦小于B、C组(P<0·05);B组根管弯曲度的变化和ATI均大于A、C组(P<0·05);A组 的操作时间最短。结论　与不锈钢K锉、镍钛合金K锉比较,采用手用ProTaper预备磨牙弯曲根管成形效果较好, 效率较高。

Comparison on the Shaping Ability of Three Different Instruments in Preparing Curved Molar Canals

Objective To study the changes of root canal curvatures and apical transportation index when the curved root canals were prepared by hand_use ProTaper,stainless steel K_files or nickel_titanium K_files.Methods Forty_five extracted molars,with the degree of root canal curvature from twenty to forty,were divided into fifteen sections in curvature sequence.After that,three canals of each section were randomly distributed to three different instrumentation groups.One group of them was prepared by hand_use ProTaper with crown_down technique.The other two groups were instrumented by stainless steel or nickel titanium K_files with modified step_back technique to working length.The standard digital radiographs were taken to record the profiles of root canals and the positions of the tips of the instruments.The change of curvature degree between pre_and post_instrumentation and the apical transportation indexes(ATI) among three groups were analyzed respectively using SAS statistical software.Results The change of curvature degree between pre_and post_instrumentation for stainless steel K_files group was largest,and the ATI of stainless steel K_files group was significantly greater than that for nickel titanium K_files group(PWTBZ]<0.05).The canals prepared by hand_use ProTaper was smallest in the change of curvature and ATI among the three groups(P<0.01).Conclusion When preparing curved molar canals,hand_use ProTaper with crown down technique can obtain better shaping effect and higher efficiency.