Determination of the Accuracy of 5 Electronic Apex Locators in the Function of Different Employment Protocols

The aim of this study was to evaluate the accuracy of 5 electronic apex locators (EALs): Root ZX II (RZX; J Morita, Tokyo, Japan), Raypex 6 (RAY; VDW GmbH, Munich, Germany), Apex ID (AID; SybronEndo, Orange, CA), Propex II (PRO; Dentsply Maillefer, Ballaigues, Switzerland), and Propex Pixi (PIXI, Dentsply Maillefer) when used in the following protocols: (1) −1.0, insertion up to 1.0 mm below the apical foramen (AF); (2) 0.0/−1.0, insertion until the AF and withdrawn 1.0 mm short of the AF; (3) 0.0, insertion until the AF; and (4) over/0.0, insertion until “over” and withdrawal to AF. Thirty human lower premolars had coronary accesses and cervical and middle thirds preparations performed, allowing AF standardization (200 μm). Using an alginate experimental model, root canal length (RCL) measurements were performed sequentially with EALs following each of the protocols. Considering the suggested protocols, the lowest mean error values were observed in 0.0, 0.10 mm (RZX), 0.13 mm (RAY), 0.16 mm (AID), 0.23 mm (PRO), and 0.10 mm (PIXI), without a significant difference for over/0.0 (P > .05). Comparing the results obtained in 0.0 with those found in −1.0 and 0.0/−1.0, significant differences were observed for most EALs (P