A surgical system having an ultrasonic handpiece having a handpiece shell, aplurality of piezoelectric elements connected to an ultrasound horn iscontrolled by acontroller. The piezoelectric elements and the horn held within the shell, andanaspiration line. The controller subjects the piezoelectric elements to a drivesignalhaving a first frequency where the first frequency produces torsional movementin thehorn. A vacuum in the aspiration line is sensed and the piezoelectric elementsaresubjected to a drive signal having a second frequency when the sensed vacuumin theaspiration line exceeds a predetermined threshold. The second frequencyproduceslongitudinal movement in the horn sufficient to clear an occlusion.
