Department of Conservative Dentistry, College of Dentistry, Yonsei University, Seoul, Korea.
J Endod. 2011 Jan;37(1):49-52. doi: 10.1016/j.joen.2010.08.048.
A measuring instrument must be both accurate and reliable. This study compared the reliability of the "0.5" and "APEX" mark measurements by using 2 impedance quotient-based electronic apex locators (EALs).
One hundred four extracted human premolars were used in this study. After access preparation, the teeth were embedded in an alginate model. By using 2 EALs (Root ZX and i-Root), the tooth length was measured at the "0.5" and "APEX" marks with K-files. The file was then cemented, and the apical 3-4 mm was trimmed for the photograph under an operating microscope. The distance between the tip of the file and major foramen (MF) was measured. The intraclass correlation coefficient, the Bland-Altman plot, and box plot were used to compare the reliability.
The intraclass correlation coefficient ranged from 0.976-0.994, indicating excellent agreement in both "0.5" and "APEX" marks. The Bland-Altman plots showed that the limits of agreement (mean ± 2 standard deviations) were small enough to confirm that both marks of the 2 EALs can be used for clinical purposes. The distribution of the measurements and outliers was analyzed by using box plots, and it was found that there was no significant difference between the 2 marks.
There was no significant difference in the reliability of the "0.5" and "APEX" marks for locating the MF in both devices. Accordingly, knowing where each mark indicates is more important for determining the working length than which mark to choose.
测量仪器必须既准确又可靠。本研究通过使用 2 种基于阻抗商的电子根尖定位仪（EAL）比较了“0.5”和“APEX”标记测量的可靠性。
本研究使用了 104 颗离体人前磨牙。在制备牙体入口后，将牙齿嵌入藻酸盐模型中。使用 2 种 EAL（Root ZX 和 i-Root），在“0.5”和“APEX”标记处用 K 锉测量牙长度。然后将锉针粘固，在手术显微镜下对根尖 3-4mm 进行拍照。测量锉针尖端与主根管（MF）之间的距离。使用组内相关系数、Bland-Altman 图和箱线图比较可靠性。
组内相关系数范围为 0.976-0.994，表明两种标记均具有极好的一致性。Bland-Altman 图显示，允许限（平均值±2 个标准差）足够小，可确认两种 EAL 的两种标记都可用于临床目的。使用箱线图分析了测量值和离群值的分布，发现两种标记之间无显著差异。
两种设备中“0.5”和“APEX”标记定位 MF 的可靠性无显著差异。因此，了解每个标记的位置对于确定工作长度比选择哪个标记更重要。
