Influence of ultrasound application on the removal of posts

Objectives: The present study evaluated the influence of the direction of application of ultrasound on the removal of metallic posts using the traction test. Methods: Twenty-eight maxillary canines were sectioned at the cemento-enamel junction, the root canals were treated and the roots were embedded in acrylic resin. The canals were then prepared with a #6 largo bur using a delineator to pattern the preparation. Molding was performed by direct Duralay technique. After casting, the posts were cemented with Panavia F cement. The specimens were then divided into 4 groups: group I: no ultrasound; group II: ultrasound was applied perpendicularly to the long axis of the post; group III: ultrasound was applied parallel to the long axis of the post; group IV: ultrasound was applied in a cervical-incisal direction. The specimens were submitted to traction in an Instron 4444 universal testing machine at 1 mm/min. Results: The results were submitted to statistical analysis, which showed no statistically significant difference between groups I and IV and between groups II and III; however, groups I and IV were statistically different from groups II and III (p<0.01). Conclusions: We conclude that the direction of application of ultrasound can influence the removal of intraradicular posts and that perpendicular and parallel applications presented the best removal of posts.