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Accuracy of working length determination with root ZX apex locator and radiography: An <i>in vivo</i> and <i>ex vivo</i> study

V Zand
H Mokhtari
M Lotfi
MF Reyhani
A Sohrab
P Tehranchi
HRM Zenouzi


The purpose of this study was to clinically compare working length (WL) determination with root ZX apex locator and radiography, and then compare them with direct visualization method ex vivo. A total of 75 maxillary central and lateral incisors were selected. Working length determination was carried out using radiographic and electronic apex locator methods. Subsequently, the tooth under study was extracted and actual working length was determined directly under a stereomicroscope. Data were analyzed by Wilcoxon signed-rank, Spearman’s correlation coefficient and intra-class correlation tests. All the statistical analyses were set with a significance level of α = 0.05. The absolute measurement errors of the two methods were compared using Wilcoxon signed test, exhibiting no statistically significant difference in measurement errors between the two methods. Descriptive evaluation revealed that in 72% (n = 54) of the specimens, both methods had errors in the same direction and in 28% (n = 21) of the specimens, the two methods had errors in opposite directions. Intra-class correlation coefficient test demonstrated a high degree of agreement between the two methods. In conclusion, this study did not show any difference between radiography, root ZX and direct visualization in WL determination.

Key words: Working length, electronic apex locator, root ZX, radiography.

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eISSN: 1684-5315