Comparison of Needle, Ultrasonic, and Laser Irrigation for the Removal of Calcium Hydroxide from Mandibular Molar Root Canals

Objective: This study aimed to compare the efficacy of conventional needle irrigation (CI), ultrasonically activated irrigation (UAI), photon-induced photoacoustic streaming (PIPS), and shock wave-enhanced emission photoacoustic streaming (SWEEPS) in removing calcium hydroxide [Ca(OH)(2)] from root canals of mandibular molars using microcomputed tomography. Background: Various adjunctive irrigation strategies have been recommended to improve the removal of Ca(OH)(2). No reports have evaluated the SWEEPS laser-activated method for the removal of Ca(OH)(2) from root canals of mandibular molars. Materials and Methods: Forty mandibular molars were instrumented and filled with Ca(OH)(2). Four irrigation groups (CI, UAI, PIPS, and SWEEPS) were established. The volume of root canals and Ca(OH)(2) and the Ca(OH)(2) volume reduction percentage (%Rd) were calculated. Data were analyzed by one-way analysis of variance and Kruskal-Wallis analysis of variance. Results: The residual Ca(OH)(2) in the apical third was higher than that in the cervical and middle thirds in all groups (p < 0.05). Comparison of the %Rd of Ca(OH)(2) in mesial canals revealed that PIPS and SWEEPS removed more Ca(OH)(2) than CI and UAI in the cervical third (p < 0.05). The middle third of the mesial canals and the cervical and middle thirds of the distal canals did not show significant differences among groups (p > 0.05). Significant differences in the %Rd of Ca(OH)(2) were noted between CI and other groups in the apical third of mesial and distal canals (p < 0.05). No group demonstrated complete removal of Ca(OH)(2). Conclusions: UAI and laser-activated irrigation significantly improved Ca(OH)(2) removal in the apical third of mesial and distal canals. No agitation technique could completely remove Ca(OH)(2).