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J Endod. 2015 Sep;41(9):1551-4. doi: 10.1016/j.joen.2015.06.009. Epub 2015 Jul 23.

Ex Vivo Evaluation of the Accuracy of Electronic Foramen Locators in Root Canals with an Obstructed Apical Foramen.

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School of Dentistry of Sobral, Federal University of Ceará, Campus Sobral, Sobral, Ceará, Brazil. Electronic address:
School of Dentistry of Ceará, São Leopoldo Mandic University, Campus Fortaleza, Fortaleza, Ceará, Brazil.
Brazilian Dental Association, Taguatinga, Federal District, Brazil.
Department of Dentistry, Endodontics and Dental Materials Bauru Dental School, University de São Paulo, Bauru, São Paulo, Brazil.



The objective of the present study was to evaluate the accuracy of electronic foramen locators (EFLs), Root ZX II (RZX; J. Morita, Tokyo, Japan), Propex II (Dentsply Maillefer, Ballaigues, Switzerland), and Apex ID (AID; SybronEndo, Glendora, CA), in root canals with an obstructed apical foramen (OAF) and to compare them with those 1.0 mm short of the apical foramen (AF; -1.0) and at the AF (0.0).


Thirty human mandibular molars had their coronal and cervical preparations accessed. Then, the AFs were standardized (250 μm). Electronic root canal measurements were performed for the -1.0 and 0.0 working lengths, and the canals were obstructed with dentinal debris. The distance to the AF displayed by the EFLs was then recorded. The last instrument used was fixed with a cyanoacrylate-based adhesive; the apical portions of the roots were scraped, allowing for the determination of the distance between the tips of the instruments and the AFs.


The precision rates at 0.0, -1.0, and the OAF were 94.7%, 43.9%, and 1.8% (RZX); 93.0%, 54.4%, and 54.4% (Propex II); and 93.0%, 68.5%, and 75.4% (AID), respectively (±0.5 mm). No significant differences were found between the devices at 0.0; however, for the measurements at -1.0 and the OAF, the AID offered significantly better results than RZX (P < .05).


The absence of foraminal patency caused by dentin debris obstruction affects the accuracy of the EFLs differently, suggesting distinctive interactions with their operating mechanisms.


Apical patency; electronic foramen locators; working length

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