Objective: To compare the application of ultrasound with the use of an engine-driven trephine bur to remove parallel-sided root canal posts. Method and materials: Single-rooted human canine teeth were decoronated and prepared to receive preformed titanium posts. The posts were cemented with Panavia F resin cement. Ten teeth acted as controls, 10 had a 4-mm-deep gutter cut around the post using a Masserann trephining bur, and 10 were subjected to 10 minutes of ultrasound. The forces required to dislodge the posts were determined using a universal testing machine, and the data were analyzed using analysis of variance. Results: The only significant difference was between the trephined and ultrasonically energized groups, with the ultrasonic group requiring greater forces for dislodgement. Conclusion: Resin composite cement could be removed from around the posts with the trephine bur but with considerable difficulty, and neither method of dislodging the posts was effective.