Purpose: To evaluate the effects of retrograde preparation between ultrasonic retrotips and traditional slow-speed handpiece.
Methods: 27 maxillary second bicuspid teeth with two canals and one isthmus were divided randomly into 3 groups with 9 in each. The root-end preparations were made respectively using ultrasonic diamond tip Berutti and NiTi tip RE2, ultrasonic #40K file and slow-speed handpiece with NO.2 round bur. The postoperative epoxy resin replicas were examined under scanning electron microscope for further evaluating the number and type of the micro-cracks, the quality of cavity margin. SPSS13.0 software package was used for Kruskal-Wallis test.
Results: The number of micro-crack of ultrasonic instruments were significantly less than that of slow-speed handpiece(P=0.002).The type of micro-cracks has no significant difference between the two techniques(P=0.657). On the quality of cavity margin, the slow-speed handpiece group had significant inferior to the ultrasonic #40K file group(P=0.039); there was no significantly difference between the ultrasonic Berutti and RE2 group and the slow-speed handpiece group (P=0.136); there was no significant difference between the two ultrasonic groups (P=0.637).
Conclusion: Ultrasonic instrument is feasible in the root-end preparation.