Apex Locator
An electronic device used to determine the position of the apical foramen by measuring electrical impedance within the root canal.
Full Definition
An apex locator (also called an electronic apex locator, or EAL) is an instrument that measures the electrical resistance or impedance between a file inserted into the root canal and a lip-clip electrode to determine working length and locate the apical foramen. Modern units display a numerical or graphic readout corresponding to the file's proximity to the apex. In editorial contexts, 'apex locator' and 'electronic apex locator' are both acceptable; editors should ensure the device is not described as providing infallible measurements, as its accuracy depends on canal moisture conditions. The abbreviation 'EAL' should be expanded at first use.
Usage
Usage note: Do not confuse with the electric pulp tester (EPT), which assesses pulp vitality rather than canal length.
In Context
- "Working length was confirmed using an apex locator and corroborated with a periapical radiograph." — Operative note
- "The electronic apex locator indicated the file tip was at the apical constriction." — Procedure record