Passive ultrasonic irrigation (PUI) is irrigant agitation technique without simultaneous instrumentation of root canal. In present article the available literature on PUI is reviewed from a MEDLINE database search. This article presents an overview of ultrasonic irrigation and their debridement efficacy. The use of PUI for irrigant activation results in improved canal cleanliness; better irrigant penetration and flow in the canal system; necrotic tissue debridement; and removal of smear layer and bacterial biofilms. Most of the studies conducted till date have only evaluated the effect of using PUI on irrigant penetration, debris removal and microbial reduction. Whether these parameters translate into better clinical outcome or not, remains to be seen.
Keywords: ultrasonic irrigation, irrigant agitation, PUI.