The Use of Micro-Computed Tomography to Determine the Accuracy of 2 Electronic Apex Locators and Anatomic Variations Affecting Their Precision.
BACKGROUND
The aim of this study was to compare the accuracy of 2 electronic apex locators (EALs), Apex ID (SybronEndo, Glendora, CA) and Root ZX (J. Morita, Tokyo, Japan), by means of micro-computed tomographic (micro-CT) imaging and to determine anatomic variations that may affect their accuracy.


METHODS
The root canal length (RCL) and working length (WL) of 33 single-rooted premolars were measured using a visual method, 3-dimensional micro-CT reconstructions, and 2 different EALs. Two different measurements were recorded for each EAL: at the "APEX/0.0" mark and at the "0.5" mark. The WL was determined using 2 different methods: method 1: at the "0.5 mark" of the apex locator and method 2: subtracting 0.5 mm from the "APEX/0.0" mark. The precision of measurements was compared with those recorded by micro-CT imaging. Apical foramen (AF) position and diameter, apical constriction (AC) diameter, distance between the AC and the AF, and the presence/absence of accessory canals were recorded from the micro-CT scans, and their correlation to the accuracy of EALs was determined.


RESULTS
There was no statistically significant difference in the RCL measurements by any of the different methods. There was a statistically significant difference in the WL recorded by micro-CT imaging compared with those by the visual method and at the "APEX/0.0 mark" - 0.5 mm (P = .031). There was no difference in the measurements acquired by any of the EALs. The "APEX/0.0 mark" - 0.5 mm was less accurate than the "0.5" mark. However, the results were not statistically significant (P > .05). The position of the AF and the AC-AF distance affected the accuracy of the RCL (P = .003) and the "0.5" mark (P = .013).


CONCLUSIONS
Root ZX and Apex ID are equally precise in determining the RCL and WL. The "0.5" mark can be used to determine the WL with high precision. Some anatomic variations may influence the accuracy of EALs.
Department of Periodontics and Endodontics, University at Buffalo School of Dental Medicine, Buffalo, New York; Department of Endodontics, Sapienza University, Rome, Italy. Electronic address: lucilapi@buffalo.edu.
Lucila
L
Piasecki
Department of Endodontics, Pontifical Catholic University of Paraná, Curitiba, Paraná, Brazil.
Everdan
E
Carneiro
Department of Endodontics, Pontifical Catholic University of Paraná, Curitiba, Paraná, Brazil.
Ulisses Xavier
UX
da Silva Neto
Department of Endodontics, Pontifical Catholic University of Paraná, Curitiba, Paraná, Brazil.
Vânia Portela Ditzel
VP
Westphalen
Department of Endodontics, State University of West Paraná, Cascavel, Paraná, Brazil.
Christian Giampietro
CG
Brandão
Department of Endodontics, Sapienza University, Rome, Italy.
Gianluca
G
Gambarini
Department of Periodontics and Endodontics, University at Buffalo School of Dental Medicine, Buffalo, New York. Electronic address: azim@buffalo.edu.
Adham A
AA
Azim
D001641:Bicuspid; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging / Q000601:surgery; D004582:Electronics, Medical; D006801:Humans; D066298:In Vitro Techniques; D009811:Odontometry / Q000295:instrumentation*; D018915:Root Canal Preparation / Q000295:instrumentation*; D019227:Tooth Apex / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D055114:X-Ray Microtomography
Apex ID; Root ZX; apical limit; electronic apex locator; micro–computed tomographic imaging; working length