In Vivo-Ex Vivo Evaluation of the Root ZX3 for Working-Length Determination

Accuracy and Precision of the Root ZX3 Electronic Apex Locator for Working-Length Determination in Teeth With Different Pulpal and Periapical Conditions: A Mixed In Vivo-Ex Vivo Diagnostic Accuracy Study

This study evaluates the accuracy and repeatability of the Root ZX3 electronic apex locator for determining root canal working length in single-rooted permanent teeth requiring extraction. Before extraction, working length is measured clinically using the Root ZX3. Following extraction, cone-beam computed tomography (CBCT) measurements and microscopic actual working length are obtained, with the microscopic measurement serving as the reference standard. The study compares the diagnostic accuracy and agreement of the Root ZX3 with these reference measurements across different pulpal and periapical conditions.

Study Overview

• Status: Completed
• Conditions: Apical Periodontitis; Pulp Disease, Dental
• Intervention / Treatment: Device: Root ZX3 Electronic Apex Locator

Detailed Description

Accurate determination of root canal working length is essential for successful endodontic treatment because instrumentation and obturation should terminate at an appropriate apical endpoint. Electronic apex locators have become widely used to improve working-length determination and reduce reliance on radiographic methods. The Root ZX3 is a third-generation electronic apex locator that has demonstrated promising accuracy; however, limited evidence exists regarding its performance under different pulpal and periapical conditions using microscopic actual working length as the reference standard.

This prospective mixed in vivo-ex vivo diagnostic accuracy study evaluates the accuracy and repeatability of the Root ZX3 electronic apex locator in single-rooted permanent teeth indicated for extraction. Adult participants requiring extraction of teeth for prosthodontic, periodontal, orthodontic, or non-restorable reasons and requiring primary nonsurgical root canal treatment are enrolled after providing informed consent.

Before tooth extraction, electronic working length is determined using the Root ZX3 according to the manufacturer's instructions with a standardized coronal reference point. Pulpal and periapical diagnoses are recorded clinically. After extraction, limited field-of-view CBCT imaging is performed, and working length is measured using standardized imaging protocols. The actual working length is then determined microscopically by directly identifying the apical foramen and is used as the reference standard.

The primary outcome is the diagnostic accuracy of the Root ZX3 compared with the microscopic actual working length. Accuracy is evaluated as the proportion of measurements within ±0.5 mm and ±1.0 mm of the reference standard. Agreement between measurement methods is assessed using Bland-Altman analysis, Lin's concordance correlation coefficient, and the intraclass correlation coefficient. Repeatability of electronic measurements is also evaluated.

• Study Type: Interventional
• Enrollment (Actual): 41
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Saudi Arabia
  • Riyadh Region
    • Riyadh, Riyadh Region, Saudi Arabia, 12755
      • Abier alhekeir

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• * Adults (≥18 years) requiring extraction of a single-rooted permanent tooth for prosthodontic, periodontal, orthodontic, or non-restorable reasons.

  • Tooth requiring primary nonsurgical root canal treatment.
  • Fully formed root with a closed apex.
  • Ability to provide written informed consent.

Exclusion Criteria:

• Teeth with root resorption (internal or external).

  • Teeth with root perforation or previous endodontic treatment.
  • Teeth with immature (open) apices.
  • Teeth with root fractures.
  • Teeth in which apical patency could not be achieved.
  • Teeth with no electronic working-length measurement obtained using the Root ZX3.
  • Teeth that fractured during extraction, preventing microscopic determination of the actual working length.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Root ZX3 Working-Length Determination; Participants underwent electronic working-length determination using the Root ZX3 electronic apex locator during primary nonsurgical root canal treatment. Electronic working-length measurements were obtained before tooth extraction and subsequently compared with cone-beam computed tomography (CBCT) measurements and microscopic actual working length, with the microscopic measurement serving as the reference standard for evaluating diagnostic accuracy and precision.

Device: Root ZX3 Electronic Apex Locator; The Root ZX3 electronic apex locator was used to determine electronic working length in single-rooted permanent teeth during primary nonsurgical root canal treatment according to the manufacturer's instructions. A size 10 or 15 K-file was advanced within the root canal until the device indicated the apical foramen (red bar), and the working length was recorded using a standardized coronal reference point. Electronic measurements were compared with microscopic actual working length after tooth extraction, which served as the reference standard. Cone-beam computed tomography (CBCT) measurements were also obtained for comparison.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Diagnostic accuracy of the Root ZX3 electronic apex locator for working-length determination	The diagnostic accuracy of the Root ZX3 electronic apex locator was evaluated by comparing electronic working-length measurements with the microscopic actual working length, which served as the reference standard. Accuracy was assessed by the proportion of measurements within ±0.5 mm and ±1.0 mm of the reference standard. Agreement was further evaluated using mean differences and Bland-Altman analysis.	during endodontic treatment before tooth extraction

Secondary Outcome Measures

Outcome Measure	Time Frame
Repeatability of Root ZX3 measurements	before tooth extrac

Collaborators and Investigators

• Sponsor: Riyadh Elm University
• Investigators: Principal Investigator: Abier Fahad Alhekeir, Riyadh Elm University

Publications and helpful links

General Publications

• Dunlap CA, Remeikis NA, BeGole EA, Rauschenberger CR. An in vivo evaluation of an electronic apex locator that uses the ratio method in vital and necrotic canals. J Endod. 1998 Jan;24(1):48-50. doi: 10.1016/S0099-2399(98)80214-8.
• Izadi A, Golmakani F, Kazeminejad E, Mahdavi Asl A. Accuracy of Working Length Measurement Using Cone Beam Computed Tomography at Three Field of View Settings, Conventional Radiography, and Electronic Apex Locator: An Ex-vivo Study. Eur Endod J. 2024 Aug 22;9(3):266-272. doi: 10.14744/eej.2023.97769.

Study record dates

Study Major Dates

• Study Start (Actual): October 19, 2025
• Primary Completion (Actual): February 28, 2026
• Study Completion (Actual): June 30, 2026

Study Registration Dates

• First Submitted: July 1, 2026
• First Submitted That Met QC Criteria: July 1, 2026
• First Posted (Actual): July 8, 2026

Study Record Updates

• Last Update Posted (Actual): July 8, 2026
• Last Update Submitted That Met QC Criteria: July 1, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Cone-Beam Computed Tomography; Diagnostic Accuracy; Endodontics; Root Canal Therapy; Microscopy; Working Length; Dental Pulp Cavity
• Additional Relevant MeSH Terms: Periodontal Diseases; Mouth Diseases; Stomatognathic Diseases; Periapical Diseases; Jaw Diseases; Tooth Diseases; Tooth Demineralization; Periodontitis; Periapical Periodontitis; Dental Pulp Diseases; Dental Caries
• Other Study ID Numbers: HAP-01-R-14; 2529 (Other Identifier: Saudi food and drug authority)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: Yes