Endodontic Department, School of Stomatology, Nanjing Medical University, Jiangsu, China.
J Endod. 2011 Jun;37(6):758-63. doi: 10.1016/j.joen.2011.02.021. Epub 2011 Apr 2.
The purpose of this study was to identify the influential factors responsible for clinical instrument separation of reused ProTaper Universal rotary instruments (Dentsply Maillefer, Ballaigues, Switzerland).
Six thousand one hundred fifty-four root canals in 2,654 teeth were prepared using ProTaper Universal files in endodontic clinics. Separation incidence was determined based on the number of treated teeth or canals. Data were collected including the size of fractured instrument, the length and location of a broken segment within the root canal, and the curvature of canal. The chi-square test and independent samples t test were used to determine the statistical significance.
The overall instrument separation incidences were 2.6% according to the number of teeth and 1.1% according to the canal number, respectively. Separation incidences according to the number of teeth or canals were significantly higher (P < .05) in molars than those in premolars or anterior teeth. Because of its largest diameter, F3 file presented the highest separation incidence according to the number of teeth (1.0%) or canals (0.4%); 47.5% instrument separation of mandibular molars and 61.5% instrument separation of maxillary molars happened in the mesiobuccal canals. Moreover, 91.4% fragments were located in the apical third of root canals, and 54.2% instrument separation occurred in severely curved canals. There was a significant difference (P < .05) in the mean fracture length between shaping (2.42 ± 0.73 mm) and finishing files (3.32 ± 0.73 mm).
Separation incidence according to the canal number is more reliable than that according to the number of teeth because of the variable canal number in different teeth. The tooth type, rotary file size, canal location, and anatomy were correlated with the instrument separation of reused ProTaper Universal files.
本研究旨在确定导致重复使用 ProTaper Universal 机用镍钛锉（Dentsply Maillefer，Ballaigues，瑞士）发生临床器械分离的影响因素。
在牙髓病学临床中，使用 ProTaper Universal 锉对 2654 颗牙齿的 6154 个根管进行预备。根据治疗牙或根管的数量确定分离发生率。收集的数据包括折断器械的大小、根管内断段的长度和位置以及根管的弯曲度。采用卡方检验和独立样本 t 检验来确定统计学意义。
根据牙齿数量，器械整体分离发生率为 2.6%，根据根管数量则为 1.1%。根据牙齿数量或根管数量，磨牙的分离发生率明显高于前磨牙或前牙（P <.05）。由于 F3 锉的直径最大，根据牙齿数量（1.0%）或根管数量（0.4%），其分离发生率最高；下颌磨牙的器械分离发生率为 47.5%，上颌磨牙的器械分离发生率为 61.5%，发生于近中颊侧根管；此外，91.4%的断片位于根管的根尖三分之一，54.2%的器械分离发生在严重弯曲的根管中。成形锉（2.42 ± 0.73 mm）和完成锉（3.32 ± 0.73 mm）的平均折断长度之间存在显著差异（P <.05）。
由于不同牙齿的根管数量不同，根据根管数量计算的分离发生率比根据牙齿数量计算的更可靠。牙型、旋转锉的尺寸、根管位置和解剖结构与重复使用的 ProTaper Universal 锉的器械分离有关。
