Background: The endodontic treatment enables cleaning and shaping the root canal to then obtain a three-dimensional shutter, thus preventing reinfection by microorganisms. Thus, irrigation-aspiration complement the mechanical instrumentation facilitating the removal of microorganisms, debris and necrotic debris, especially the areas where instruments do not reach for the preparation of root canals, as isthmus, accessory canals and flattening. Objective: The aim of this study was to evaluate, through a literature review, the importance of passive ultrasonic irrigation in the sanitization of root canals, thus increasing the chances of success of endodontic treatment. Literature Review: Based on the literature, the use of passive ultrasonic irrigation complements the mechanical instrumentation facilitating the removal of microorganisms, debris and necrotic debris, especially the areas where instruments do not reach for the preparation of root canals, as isthmus, accessory canals and flattening. Discussion: The Ca (OH) 2 is used as an intracanal medication, in order to supply the instrumentation which, together with the use of auxiliary chemicals and agents of the root canal irrigants, failed to meet during the chemical-mechanical preparation. However, after his drug action, Ca (OH) 2 should be completely removed from the root canal, since there is a correlation between the presence of Ca (OH) 2 remaining and marginal leakage, resulting in the failure of endodontic treatment. Conclusion: It was concluded that the passive ultrasonic irrigation is more effective than the conventional ultrasonic irrigation and irrigation in the removal of debris and smear layer from root canals.
