Effect of pre-flaring and file size on the accuracy of two electronic apex locators

Abstract

ObjectiveThis ex vivo study evaluated the effect of pre-flaring and file size on the accuracy of the Root ZX and Novapex electronic apex locators (EALs). Material and methodsThe actual working length (WL) was set 1 mm short of the apical foramen in the palatal root canals of 24 extracted maxillary molars. The teeth were embedded in an alginate mold, and two examiners performed the electronic measurements using #10, #15, and #20 K-files. The files were inserted into the root canals until the "0.0" or ''APEX'' signals were observed on the LED or display screens for the Novapex and Root ZX, respectively, retracting to the 1.0 mark. The measurements were repeated after the pre-flaring using the S1 and SX Pro-Taper instruments. Two measurements were performed for each condition and the means were used. Intra-class correlation coefficients (ICCs) were calculated to verify the intra- and inter-examiner agreement. The mean differences between the WL and electronic length values were analyzed by the three-way ANOVA test (p<0.05). ResultsICCs were high (>0.8) and the results demonstrated a similar accuracy for both EALs (p>0.05). Statistically significant accurate measurements were verified in the pre-flared canals, except for the Novapex using a #20 K-file. ConclusionsThe tested EALs showed acceptable accuracy, whereas the pre-flaring procedure revealed a more significant effect than the used file size.

Influence of the instrument used for cervical preflaring on the precision of 2 Eletronic Apex Locators

“…This increase is similar to those found in previous studies that used other EALs 15,[20][21] . This result can be due to a better adjustment of the file to the apical third 26 , promoting less exposure of metallic surface to the surrounding electrolyte and allowing the impedance reading in that region to be more effective 10 .…”

“…According to the results obtained in this study, and also according to other similar studies, the tolerance range was adopted and allowed to observe that after cervical preparation the devices used were highly effective 21,27 . In addition, no cases of over extension were observed, which was similar to the results found by Brito Junior et al 21 .…”

“…The experimental models used in ex vivo research aimed at evaluating the accuracy of EALs must simulate clinical situations to reproduce the impedance values in human tissue 21 . For this reason, the material that is commonly used is 1% agar, saline solution, alginate, gelatin or sponge soaked in saline solution 10,24 .…”

“…Studies have shown that when the determination of WL was performed without prior cervical enlargement, there was a higher incidence of cases where the file stopped short of or beyond the apical limit of the root canal 14,16 . To date, few studies that evaluated the influence of cervical preparation on measurements by EALs suggest that the accuracy of some devices was increased after cervical preparation 15,[20][21] .…”

Accuracy of Four Electronic Apex Locators During Root Canal Length Determination

“…The effect of pre-flaring or widening prior to determination of the WL has been studied, for example in the study of Brito-Júnior et al (2012), who assessed the performance of the Root ZX and the Novapex. This study found greater accuracy in the electronic measurements taken by the devices, both of which presented acceptable results in the palatine canals of upper molars.…”