Aalmohamed, EimanAhmed, FatemehAlfardan, LayalEl Abed, RashidHassan Khamis, AmarJamal, Mohamed2022-07-202022-07-202022‎204-2022.27‎https://repository.mbru.ac.ae/handle/1/989Introduction: The aim of this study was to compare the vibration/oscillation frequencies of WaterPik and ‎EndoActivator devices and their effectiveness in smear layer (SL) removal.‎ Materials and Methods: The root canal of 60 single‑rooted extracted human premolars were prepared until ProTaper Universal F2 ‎file, and randomly grouped according to the irrigation activation technique used: EndoActivator group; ‎WaterPik group; manual dynamic agitation (MDA) group; and control group (conventional irrigation with ‎no activation). The vibration/oscillation frequencies of EndoActivator and WaterPik devices were ‎measured using a digital tachometer. Electron microscopy images of all specimens were evaluated for ‎SL removal according to a modified Hülsmann scoring system. Data were statistically analyzed.‎ Results: The mean vibration frequency of the EndoActivator was significantly higher than that of WaterPik (200.6 ‎‎± 2.1 and 185.2 ± 2.744 Hz, respectively). A significant difference was detected in the SL removal along ‎the full length of the canal between the experimental and control groups (P ˂ 0.001). EndoActivator and ‎MDA groups had significantly more samples with no to minimum SL at the coronal and middle thirds ‎compared to the apical third, whereas there was no significant difference among the thirds in the ‎WaterPik group. At the apical third, the WaterPik group had significantly more samples with no to ‎minimum SL (60%) than WaterPik and MDA groups (20% and 26.7%, respectively).‎ Conclusion: WaterPik was as effective as MDA and EndoActivator in SL removal, with better performance at the ‎apical third, probably attributed to the lower vibration/oscillation frequency of WaterPik.‎enEndoActivatorIrrigation activationOscillation frequencySmear layerWaterPikArticle