Calcium hydroxide has been commonly applied in the endodontic treatment due to its favorable biological property and antimicrobial activity. The removal of the Ca(OH)2 from the root canal system is essential for successful endodontic treatment. The ultrasonic irrigation is a technique proven effective for the removal of the Ca(OH)2, while its performance is influenced by various factors. This article proposes a review of the factors impacting on the removal efficiency of the Ca(OH)2 from the root canals by ultrasonic irrigation.
