A total of 100 maxillary molar canals were hand instrumented to a master apical file size #35 and flared to a size #60 file. The canals were randomly divided into 5 groups of 20 each. Group 1 received no further treatment. Groups 2 and 3 received passive sonic irrigation for 30 and 60 s, respectively. Groups 4 and 5 received passive ultrasonic irrigation for 30 and 60 s, respectively. The roots were split longitudinally and photographed with a digital camera. The apical portion of the root was magnified to 100x. A debris score was calculated for the apical 3 and 6 mm. The debris score was calculated as a percentage of the total area of the canal that contained debris as determined by pixels in Adobe Photoshop 5.0. Passive sonic or ultrasonic irrigation, for as little as 30 s, resulted in significantly cleaner canals than hand filing alone. Ultrasonic passive irrigation produced significantly cleaner canals than passive sonic irrigation, when sonic and ultrasonic passive irrigation were compared with only each other.