A comparison between two root end preparation techniques in human cadavers

The purpose of this study was to compare ultrasonic and bur root end cavity preparations with regard to retention, cleanliness, and root canal parallelism. Twenty anterior teeth from human cadavers were instrumented and obturated with gutta-percha and sealer. After raising a full-thickness flap, the apices of the roots were exposed and beveled at a 45-degree angle. Half of the apical cavities were prepared with an appropriate sized Carr alloy tip energized by an Amadent Ultrasonic unit. The other half was prepared with an inverted cone bur in a slow-speed handpiece. The teeth were then extracted, sectioned longitudinally, photographed, and scanning electron micrographs examined. The ultrasonic cavities produced more parallel walls and deeper depths for retention. In addition, the ultrasonic tips followed the direction of the canals more closely than those prepared by burs. Scanning electron microscopic examination of the cavity wall showed presence of cleaner surfaces of root end cavities prepared by ultrasonic tips than those made with burs.