Comparative study of sonic instrumentation on smear-layer-elimination in root-canal-preparation

Objectives: To compare the capability between sonic, ultrasonic and hand file instrumentation in root canal smear layer elimination. Methods: 40 extracted premolars with single root canal were prepared by means of sonic, ultrasonic, hand file and combination of sonic and hand file instrumentation, and evaluated by scanning electron microscope. According to the amount of smear layer and dentinal debris in root canal, the cleanliness of root canal was analyzed by Wilcoxon rank sum test. Results: In apical third, there was significant difference between sonic, ultrasonic, and combination of sonic and hand file instrumentation with hand file on smear layer and dentinal debris elimination,and no significant difference between sonic and combination of sonic and hand file instrumentation with ultrasonic instrumentation on dentinal debris elimination was found. In middle and coronal third, no statistical differences were observed among the four groups. Conclusions: In smear layer and dentinal debris elimination at root canal apical third, sonic instrumentation is better than hand file, especially in dentinal debris elimination, and similar to ultrasonic instrumentation.