3 Tips & Tricks to Effectively Use an Apex Locator


Digital technology has become highly prevalent and crucial in Endodontics as a result of the rapid growth of digitalization in dentistry. One of the fastest and broad technological evolutions in dentistry has occurred in the last few decades. Endodontic technology has advanced dramatically throughout this time period.

Working length determination is one of the most critical aspects of root canal therapy (RCT). Canal preparation, which involves removing all soft tissues and germs from the root canal and can be performed by correctly determining the working length. This is where the electronic apex locators come into play, and their effective application decreases the number of radiographs necessary before or even during the failure of traditional handling techniques or radiographic techniques. They also aid in diagnosing the perforations or fractures in the root.

Why Electronic Apex Locators are Needed?

The working length determination sets the apical limit of biomechanical preparation as well as obturation that ensures minimal injury to the periapical tissues. The use of an apex locator in root canal therapy (RCT) helps in


·         Prevention of Over-instrumentation / Over-filling

·         Prevention of Under-instrumentation/ Under-filling

·         Helps detect perforation/ fractures/resorption

·         Improved Accuracy and efficiency

·         Less time consuming

·         Eliminates traditional methods



Tips & Tricks for accurate Working Length Determination:

Endodontic therapy has been modified thanks to the Electronic Apex Locator (EAL). While it hasn't replaced imaging approaches for estimating working length, it does provide a fairly accurate alternative for determining where the canal ends.

Many clinicians have been upset by the flawless readings in one minute but increased fluctuations the next minute, from the first resistance-based devices to today's most contemporary multi-frequency and impedance-based equipment.


Here are a few pointers on how to make the greatest and most efficient use of your EAL.

1.     Drying the canal for more accuracy

The apex locator performs admirably in a dry oral environment.  Irrigating and broaching the Canal should come first. Suction is used to remove the majority of the NaOCl, saliva, and water from the oral cavity. Proper isolation of the operated tooth is required with rubber dam kit or placing cotton rolls on the buccal and lingual side. Most issues with initial readings are caused by the electrolytic impact of NaOCl contacting metals and restorations of teeth. The file must have a clear path to the dentin with no restoration or metal contact.

2.     Right File Selection

The second most common mishap is selecting the wrong file. It's important to remember that apex locators rely on contact with canal walls to function. The reading will be improved if the file is better adapted to the canal walls. When a #10 file is used in a Maxillary central incisor, the results will be erroneous. The accuracy improves when the file size approaches that of the foramen's diameter. As a result, it's critical to strive to acquire a good fit in wider canals using a file.

3.     Properly using Electronic Apex Locator

Attach the file clip with the K file.

Then touch both file clip and lip hook to check whether the reading comes “-3”, then the apex locator is working properly. 

Place the lip hook on the patient’s mouth.



As you reach the apex, your apex locator readings should reflect a seamless transition. The apex locator's audio signal also aids in determining where the file is located inside the canal. 
As it gets closer to the apex, the beep grows faster, and when it reaches the apex, the sound becomes continuous (00). If the file is pushed any further, an alarm will ring and the display will indicate Over Apex with a red color warning.
Regardless of the sort of apex locator used, the most accurate reading is one in which the apex locator reads consistently as the file approaches the apex. Try switching to the next larger size file if the apex locator's display is "jumpy" or "fluctuates" more.
The initial reading is usually the most accurate when treating an upper molar with roots near the sinus, as the apex locator may read a file that is in the sinus.


Woodpecker DTE Dpex V Apex Locator:

Dpex V apex locator from DTE Woodpecker is a 6th generation apex locator. It is the most advanced apex locator with the ability to give accurate readings even in presence of saliva, blood, or pulp residues due to its multifrequency impedance technology. It gives an accuracy of 97.78% in measuring the working length.


In assessing endodontic working length, no single technique is completely satisfactory. The CDJ is a practical and anatomic end-point for root canal preparation and obturation that cannot be established radiographically. Modern electronic apex locators can estimate this point with higher than 90% accuracy, but they are not without flaws. The correct knowledge of electronic apex locator use along with the apical anatomy will facilitate practitioners obtaining predictable results.