Di Fiore P M, Genov K I, Komaroff E, Dasanayake A P, Lin L
Department of Endodontics, College of Dentistry, New York University, New York, NY 10010, USA.
Int Endod J. 2006 Jun;39(6):502-9. doi: 10.1111/j.1365-2591.2006.01123.x.
To determine the incidence of ProFile nickel-titanium rotary instrument fracture in an endodontic laboratory simulation.
Three hundred and sixty dental students used 2880 ProFile nickel-titanium rotary instruments to prepare 1440 simulated root canals in 720 plastic teeth, and another 2880 ProFile nickel-titanium rotary instruments to prepare 1440 natural root canals in 720 extracted teeth. A standardized crown-down rotary instrumentation technique was used, which included measures to prevent fracture. Rotary instrument fracture was monitored during and after completion of the laboratory simulation exercises to determine the incidence of fracture. When fracture occurred, data were collected concerning the size of the instrument, the length of the instrument fragment, the location of the fragment in the canal and the curvature of the canal in which the instrument fractured.
The incidence of instrument fracture was 0.41% in plastic simulated canals and 0.31% in natural root canals. The overall incidence of instrument fracture was 0.36%. Of the instruments that fractured 67% were size 25, 0.04 taper; and 81% of the fragments were located in the apical third of the canal. The mean, median and mode of the fragment lengths were all 3 mm.
The low overall incidence of fracture in this study suggests that ProFile rotary instruments are safe for use by dental students in laboratory simulations and that if preventive measures are taken the incidence of instrument fracture can be minimized.
在牙髓病实验室模拟中确定Profile镍钛旋转器械折断的发生率。
360名牙科学生使用2880支Profile镍钛旋转器械在720颗塑料牙中预备1440个模拟根管，另外使用2880支Profile镍钛旋转器械在720颗离体牙中预备1440个天然根管。采用标准化的冠向下旋转预备技术，其中包括预防折断的措施。在实验室模拟操作过程中和操作完成后监测旋转器械折断情况，以确定折断发生率。当发生折断时，收集有关器械尺寸、器械折断片段长度、片段在根管内的位置以及器械折断所在根管弯曲度的数据。
在塑料模拟根管中器械折断发生率为0.41%，在天然根管中为0.31%。器械折断的总体发生率为0.36%。折断的器械中67%为25号、0.04锥度；81%的折断片段位于根管的根尖三分之一处。折断片段长度的均值、中位数和众数均为3mm。
本研究中较低的总体折断发生率表明Profile旋转器械在实验室模拟中供牙科学生使用是安全的，并且如果采取预防措施，器械折断发生率可以降至最低。
