Ebrahim A K, Wadachi R, Suda H
Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, Japan.
Aust Dent J. 2006 Sep;51(3):258-62. doi: 10.1111/j.1834-7819.2006.tb00439.x.
The aim of this ex vivo study was to evaluate the accuracy of four electronic apex locators (EALs) to determine the working length in teeth with various foramen diameters. Our previous study revealed that electronically measured canal length was influenced by the root canal diameter. It is not known whether foramen size would interfere with the reading accuracy of an EAL.
A total of 36 extracted human lower single rooted premolar teeth were divided into four groups of nine teeth each. In groups A, B and C, the root canals were instrumented using #10-80, #10-100 and #10-120 K-files, and the tip of size #80, #100 and #120 K-files were permitted to pass through the apical foramen to a length of 1mm, respectively. In group D, the teeth were instrumented using #10-140 K-files and the tip of #140 K-file was permitted to pass through the apical foramen to a length of 5 mm. Thus, the average apical foramen diameters in groups A, B, C and D were approximately 0.82 mm, 1.02 mm, 1.22mm and 1.5 mm, respectively. The teeth were then mounted in 1% agar and four EALs were used: Root ZX, Foramatron D10, Apex NRG and Apit 7. For electronic measurement, sizes #10 and #80, #10 and #100, #10 and #120, and #10 and #140 K-files were used for groups A, B, C and D, respectively. During electronic measurement the canals were flushed with 6% sodium hypochlorite solution.
Three-way ANOVA and Bonferroni test showed that EAL, file size and foramen size 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).
The four EALs were unreliable to determine the working length of teeth with a wide apical foramen, when using a small size file. The Root ZX and Foramatron D10 showed significantly better scores than the other two EALs and may be more reliable to determine the working length of teeth with a wide apical foramen, if a tight-fit file is used.
本体外研究的目的是评估四种电子根尖定位仪（EAL）在确定不同根尖孔直径牙齿工作长度时的准确性。我们之前的研究表明，电子测量的根管长度受根管直径影响。尚不清楚根尖孔大小是否会干扰EAL的读数准确性。
总共36颗拔除的人类下颌单根前磨牙被分为四组，每组9颗牙齿。在A、B和C组中，使用#10 - 80、#10 - 100和#10 - 120 K锉对根管进行预备，#80、#100和#120 K锉的尖端分别允许穿过根尖孔1mm。在D组中，使用#10 - 140 K锉对牙齿进行预备，#140 K锉的尖端允许穿过根尖孔5mm。因此，A、B、C和D组的平均根尖孔直径分别约为0.82mm、1.02mm、1.22mm和1.5mm。然后将牙齿固定在1%的琼脂中，并使用四种EAL：Root ZX、Foramatron D10、Apex NRG和Apit 7。进行电子测量时，A、B、C和D组分别使用#10和#80、#10和#100、#10和#120以及#10和#140 K锉。在电子测量过程中，用6%的次氯酸钠溶液冲洗根管。
三因素方差分析和Bonferroni检验表明，EAL、锉的尺寸和根尖孔大小均对测量误差有显著影响（P<0.0001），这三个因素之间的所有交互作用均具有显著性（P<0.0001）。
当使用小尺寸锉时，这四种EAL在确定根尖孔宽大牙齿的工作长度时不可靠。Root ZX和Foramatron D10的得分显著高于其他两种EAL，如果使用紧密适配的锉，它们在确定根尖孔宽大牙齿的工作长度时可能更可靠。
