2007 Volume 50 Issue 5 Pages 596-600
In the previous reports on the removal of cemented postcores by means of ultrasonic vibration, we demonstrated that the best result was achieved when lateral vibration was simultaneously induced by two removal tips using two ultrasonic generators. In this study, in order to increase the efficiency of removing a cemented postcore attached to molar teeth, we measured the time taken to remove cast posts that had been divided into two parts and those that had not been divided into two parts. In this research, after removing a full veneer crown and applying ultrasonic vibration to the attached cast post, we measured the elapsed time until removing the cast post from the root canal by means of gripping the post with pliers. In addition, the cast posts were also divided into two for maxillary molar teeth in the mesiodistal direction and for mandibular molar teeth in the buccolingual direction. Ultrasonic vibration was applied to the cemented postcore, using two ultrasonic generators, by setting them at an angle of 90° between the tooth axis and the removal tip, setting the two sites for applying the tips in opposite directions, and with a power setting of 10. Consequently, the time taken to apply ultrasonic vibration and remove the cast post was 28.9±24.6 seconds for divided posts and 100.3±49.5 seconds (mean±SD) for undivided posts. As a result, such cast posts attached to molar teeth could be removed in a short time by dividing them into two and applying ultrasonic vibration from two different directions. However, a problem that remains for future consideration is to both evaluate and develop improved methods for dividing and removing the post safely without excessively cutting the pulp floor at the time of dividing the cast post.
