Evaluation of the Efficacy of Smear Layer Removal Using Different Irrigation Activation Methods during Root Canal Treatment: An In Vitro Study

Aim: The current investigation aimed to assess the effectiveness of smear layer removal during root canal therapy utilizing three different irrigation activation techniques. Materials and methods:The study included 60 human mandibular premolars that were recently extracted for orthodontic and periodontal reasons.The samples were decoronated with a diamond disc to provide a standard working length (WL) of 14 mm, and then the root canal preparation was completed.These samples were divided into three groups at random, each containing 20 samples (n = 20).Group I: Conventional needle irrigation; group II: Ultrasonic activation; and group III: EndoVac (EV) activation.The efficacy of smear layer removal in the coronal, middle, and apical thirds of all canals was assessed using a scanning electron microscope (SEM) with a magnification of 2,000×.Data were collected and analyzed statistically.Results: In the conventional needle irrigation group, the maximum smear layer removal was found in the middle third (0.72 ± 0.10), followed by the coronal third (0.80 ± 0.01) and the apical third (1.10 ± 0.14).No significant difference was found on intragroup comparison.In the irrigation with ultrasonic activation group, the maximum smear layer removal was found in the apical third (0.44 ± 0.02), followed by the middle third (0.48 ± 0.10) and the coronal third (0.64 ± 0.08).A significant difference was found on intragroup comparison.In the irrigation with EV activation group, the maximum smear layer removal was found in the apical third (0.20 ± 0.04), followed by the middle third (0.36 ± 0.18) and the coronal third (0.62 ± 0.04).A significant difference was found on intragroup comparison.Conclusion: The current investigation concluded that the EV system group removed more of the smear layer than the ultrasonic activation and conventional needle irrigation group.Clinical significance: The smear layer created during root canal instrumentation has a detrimental effect on root canal irrigation activity, which may have an impact on the endodontic treatment's prognosis.When an efficient irrigation delivery system is used, the irrigants can reach the WL.This kind of distribution method must have sufficient flow, be efficient in debriding the entire canal system, and supply an appropriate quantity of irrigants up to the WL.