Oral Biol Res.  2022 Mar;46(1):36-41. 10.21851/obr.46.01.202203.36.

Effect of file size in measuring electronic working length of teeth with open apex

• Jin R
• Jeong JH
• Cho AR
• Jo HH

• KMID: 2527539
• DOI: http://doi.org/10.21851/obr.46.01.202203.36

Abstract

This study aimed to evaluate the effect of file size in measuring the electronic working length of teeth with open apex. Twenty teeth were prepared to make the open apex models. A bur was used to cut a 2-mm apical end; the point where #10K file’s tip was reflected on the cut root surface was set to the actual root canal length (AL). A divergent open apex was prepared by retrograde apical preparation. The teeth that were covered with a gauze soaked with saline were inserted in a plastic mold, and an electronic apex locator was connected with it. In each tooth, #10, #20, #30, #40, #50, #60, #70, and #80 files were inserted into the root canal, and the electronic working length (EL) was measured at the “Apex” signal. Then, the mean difference (∆L) between the AL and EL was evaluated for each file size. EL measurements with all file sizes were short of the apical foramen, and there was a significant difference when the file size increased from #10 to #20 and #40 to #50. Within this study’s limitations, the file size showed an impact in measuring the teeth’s EL with open apex. When the size of the apical foramen is 1.14 mm, it is more accurate to use a file of #50 size or larger when measuring the working length with an electronic apex locator.

Keyword

Electronic apex locator; Open apex; Working length