During endodontic treatment, the efficiency of irrigation depends on two criteria: the antimicrobial and dissolving properties of the irrigation solution and the delivery system used that dictates the flushing action of the irrigant and consequently enable it to reach complex areas. The purpose of this in-vitro study was to compare the cleaning efficiency of EDDY sonic activation with needle irrigation and passive ultrasonic activation regarding elimination of dentin debris. Forty single rooted extracted teeth were instrumented and then were split in bucco-lingual direction. A longitudinal groove was performed in the inner surface of one root half of each tooth. Grooves were filled with dentine debris mixed with 5.25 % NaOCl in order to simulate an uninstrumented canal extension. Root halves were reassembled and were randomly divided into three groups: G1 needle irrigation, G2 passive ultrasonic activation (Acteon Satelec, Merignac, France) and G3 sonic activation using EDDY system (VDW, Munich, Germany). Ten roots served as control. After irrigation protocols, root halves were disassembled and digital images of grooves were taken using a stereomicroscope (Olympus, Japan). Evaluation of the amount of the remaining dentin debris was performed using a scoring system. No statistically significant difference existed between negative control and passive ultrasonic activation and EDDY activation respectively. Both activation techniques performed equally in removing dentine debris and significantly better than needle irrigation. No significant difference was found between needle irrigation and positive control
