Determining the apical terminus of root-end resected teeth using three modern apex locators: A comparative ex vivo study

A. ElAyouti, I. Kimionis, A. L. Chu, C. Löst

Research output: Contribution to journalArticlepeer-review

54 Citations (Scopus)


Aim: To assess ex vivo the accuracy of various electronic apex locators in locating the apical terminus of root-end resected teeth. Methodology: Ninety extracted human posterior teeth (182 root canals) were prepared to a minimum size of 40 and filled with gutta-percha and sealer. After resection of the apical 3 mm of the root, the root canal filling was removed using HERO rotary instruments. The size of the root canal at the apical terminus after removal of the filling ranged from size 50 to 90. The root canal length to the apical terminus was determined using 3 apex locators (Root ZX, Raypex®4 and Apex Pointer). A new mounting model that utilized a micrometer was used to perform the measurements and to visually determine the actual position of the apical terminus. The frequency of locating the apical terminus and the corresponding 95% confidence interval (CI) were calculated. Additionally, the coefficient of repeatability of each apex locator and the limits of inter-operator agreement were determined. Results: All apex locators showed an acceptable repeatability (0.02-0.03 mm coefficient of repeatability) and narrow limits of inter-operator agreement (+0.07 and -0.07 mm). The accuracy of determining the apical terminus within 1 mm in the root canal was as follows: Root ZX 90% (164/182 root-canals) [95%CI: 86-94%], Raypex®4 74% (135/182 root-canals) [95%CI: 68-80%], and Apex Pointer 71% (129/182 root canals) [95%CI: 65-77%]. No over-instrumentation resulted when the Root ZX device was used. In contrast, using the Raypex®4 or the Apex Pointer device resulted in over-instrumentation in 8 of 182 root canals (4%). Conclusions: Under the conditions of this study all three apex locators were able to detect the apical terminus of root-end resected teeth with an acceptable range. The Root ZX device was the most accurate without over-instrumentation of the root canals.

Original languageEnglish
Pages (from-to)827-833
Number of pages7
JournalInternational Endodontic Journal
Issue number11
Publication statusPublished - Nov 2005
Externally publishedYes


  • Apicectomy
  • Electronic apex locators
  • Odontometry
  • Retreatment
  • Root canal treatment
  • Working length

ASJC Scopus subject areas

  • General Dentistry


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