The ultrasonic handpiece utilizes either magnetostrictive or piezo-electric technology. Magnetostrictive inserts operate at 25,000 to 30,000 cycles/second and, like the sonic scaler, have an elliptical motion. A low-voltage magnetic signal causes tip movement. Piezo-electric technology operates at 28,000 to 36,000 cycles/second. The tip moves in a back-and-forth motion and works along the side of the tooth, shaving off calculus and debris. The ultrasonic tip spray promotes elimination of dental plaque and can be more efficient at removing dental plaque and calculus.