Objective: To determine the variability in the distance between apical constriction determined by an apex locator and the radiographic apex on digital radiographs in a Moroccan population.
Methods: Once the apex locator indicated the position of the apical constriction marked by 0.5, an existing lime X-ray was taken and measurements were made using the Kodak Dental Imaging Software 220.127.116.11.
Results: The average distance between the tip of the instrument and the radiographic apex (DTIRA) was 0.792 mm + 0.61. The position of the apical constriction at 0.5 mm of the radiographic apex is in only 21% of selected teeth. Ninety eight out of 100 teeth had a DRLAAR of <2 mm. Considering these 98 teeth, 40.8% of them had a DTIRA in the range of 0–0.5 mm, 38.8% in the range of 0.5–1 mm, and 20.4% had DTIRA of >1 mm.
Conclusion: There is a great variability in the distance between the apical constriction determined by an apex locator and the radiographic apex on digital radiographs in this population. Indeed, the subtraction of 0.5 mm from the latter, as recommended by several authors, is in only 21% of selected teeth.