An experimental study of the removal of cemented dowel-retained cast cores by ultrasonic vibration

A technique for the removal of cemented post-cores by means of ultrasonic vibration was studied clinically and histologically. The removal time was measured for 80 extracted human teeth, including 40 single-rooted teeth and 40 multiple rooted ones and then statistically analyzed. The periapical tissue reaction to the ultrasonic vibration was also examined histologically in dogs. The best result was achieved when lateral vibration was simultaneously given by 2 removal tips using 2 ultrasonic generators. There was little harmful influence on the periodontal tissue, excluding a transient reversible reaction.