[An in vitro study of the antimicrobial effectiveness of ultrasonic instrumentation]

Successful endodontic therapy is based upon the classic triad of diagnosis, adequate canal preparation, and obturation. Preparation for a root canal has two major components--debridement and shaping. Debridement, or cleaning, consists of removal of necrotic intracanal dentin and organic debris, and reduction of the bacteria inside the root canal. According to the research, the endontic ultrasonic system plays a valuable and significant and synergistic role in aiding the bacteriocidal mechanisms based on the cavitation and acoustic streaming effect. The purpose of this study was to compare the antimicrobial effectiveness of two newly developed endodontic ultrasonic devices and the conventional hand-filing techniques. Eighty single root canal teeth with deep caries or apical lesions were selected and evenly divided into 4 groups. The root canals were prepared using conventional hand filing or one of two newly developed ultrasonic filing systems, ENAC and CAVI-ENDO. The contents of the root canals before and after debridement were cultured in a thioglycolate culture tube. The results showed that in the ultrasonically prepared specimens irrigated with a normal saline solution, the microbial culture numbers were significantly reduced and obviously different from those prepared by the hand instrumentation technique. The above mentioned differences were statistically significant at the level of p less than 0.05 by the McNemar test and Chi-square test.