Ebrahim A K, Yoshioka T, Kobayashi C, Suda H
Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, Japan.
Aust Dent J. 2006 Jun;51(2):153-7. doi: 10.1111/j.1834-7819.2006.tb00419.x.
The initial electronic apex locator (EAL) length measurement is generally established with a small-sized file. It is not known whether file size would be interfering with the reading accuracy of the EAL. This study aimed to evaluate the effect of file size on the accuracy of Root ZX apex locator using an agar model when sodium hypochlorite solution or blood was present during electronic measurements in enlarged root canals.
A total of 36 extracted lower premolars were used. In stage 1, the canals were instrumented using size 10-40 K-files with a size 40 K-file as the master apical file (MAF). The teeth were then divided randomly into two groups of 18 teeth each. In group A, the teeth were mounted in one per cent agar and irrigated with six per cent sodium hypochlorite solution (NaOCl), while in group B the teeth were mounted in agar and irrigated with human blood. In stage 2, the canals were enlarged using a size 60 K-file as the MAF. In stages 1 and 2, the apical portions of the canals were instrumented using the step-back sequence (up to a size 80 K-file). In stage 3, the canals were enlarged using a size 80 K-file as the MAF. In each stage, the length was measured with a Root ZX until the meter value reached 'APEX' using small and large size files.
Three-way ANOVA and Bonferroni test showed that file size, stage of preparation and type of irrigant all had a significant influence on the measurement error (P < 0.0001), with all the interactions between these three factors being significant (P < 0.0001).
As the diameter of the root canal increased, the measured length with the smaller size files became shorter. A file of a size close to the prepared canal diameter should be used for root length measurement in the presence of blood. In the presence of NaOCl, the Root ZX was highly accurate even when the file was much smaller than the diameter of the canal. The agar model was effective and suitable for testing EALs in vitro.
最初的电子根尖定位仪（EAL）长度测量通常使用小尺寸锉来确定。尚不清楚锉的尺寸是否会干扰EAL的读数准确性。本研究旨在评估在扩大的根管中进行电子测量时，当存在次氯酸钠溶液或血液时，锉的尺寸对Root ZX根尖定位仪准确性的影响，采用琼脂模型进行研究。
共使用36颗拔除的下颌前磨牙。在第1阶段，使用10-40号K锉对根管进行预备，以40号K锉作为主尖锉（MAF）。然后将牙齿随机分为两组，每组18颗。A组将牙齿固定在1%的琼脂中，并用6%的次氯酸钠溶液（NaOCl）冲洗，而B组将牙齿固定在琼脂中，并用人体血液冲洗。在第2阶段，以60号K锉作为MAF扩大根管。在第1和第2阶段，使用逐步后退法（至80号K锉）预备根管根尖部分。在第3阶段，以80号K锉作为MAF扩大根管。在每个阶段，使用Root ZX测量长度，直到测量值达到“根尖”，分别使用小尺寸和大尺寸锉。
三因素方差分析和Bonferroni检验表明，锉的尺寸、预备阶段和冲洗液类型均对测量误差有显著影响（P < 0.ooo1），这三个因素之间的所有交互作用均具有显著性（P < 0.0001）。
随着根管直径增加，使用较小尺寸锉测量的长度变短。在有血液存在的情况下，应使用尺寸接近预备后根管直径的锉进行根长测量。在有NaOCl存在的情况下，即使锉的尺寸远小于根管直径，Root ZX仍具有高度准确性。琼脂模型有效且适用于体外测试EAL。
