Clinical study on the variability in the distance between apical constriction determined by an apex locator and the radiographic apex

D uring root canal treatment, canal preparation and obturation should stop at the cementodentinal junction.However, the stop location is detectable only histologically.[1] Determining the endodontic apical stop is a crucial step in canal treatment, and the success or failure of the treatment depends on correctly identifying the stop location.[2] Several methods for determining the length are now available, and the best known approach was reported by Kuttler.[1] The method recommends a canal preparation at 0.5 mm from the radiographic apex, and the apical constriction is, on average, located at this distance from the anatomical apex.However, the anatomy of this area is by definition different for each individual, and stopping the preparation to an estimated level does not allow for the evaluation of the remaining channel length.For a long time, X-rays remained essential for determining endodontic apical stops.However, estimates obtained from X-rays are considered approximate and biased.[3] X-ray images alone cannot precisely determine the 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 6.10.8.3. 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.