Objective: To certify that the Vector™ device, a recently introduced piezo-driven ultrasonic device, has an efficacy comparable to conventional instrumentation and leads to a smoother root surface after debridement. Methods: Forty periodontally extracted human teeth were randomly divided into four groups and each group of 10 teeth were treated by one of the following methods in an artificial periodontal pocket for a total of 10 min: hand instrument debridement (HD); conventional ultrasonic system with an 'IS' tip (Satelec); Vector system with abrasive fluid and metal curette (VA); and Vector system with polishing fluid and metal curette (VP). The efficiencies of these four different debridements were assessed using a root calculus figure analysing system with an accuracy of 0.01 mm2. Root smoothness was observed at 7× magnification under a stereomicroscope after root debridement. Results: The calculus removal efficiency of VA did not differ from those of the HD and Satelec groups, while the calculus removal efficiency of the VP group was significantly lower than those of HD and Satelec groups (P 0.05). The root surfaces in the VA and VP groups were smoother than those in other groups, while the scratches were obvious on the root treated by HD or the Satelec ultrasonic system. Conclusion: This study indicates that the Vector system as a novel means is a promising alternative for initial and maintenance therapy of periodontitis. Schlagwörter: hand instrumentation, root smoothness, ultrasonic instrumentation, artificial periodontal pocket, debridement