A power toothbrush (10) is disclosed having a handle (15) containing a rechargeable battery (12), an ultrasonic drive circuit (14), a sonic component (16) such as a motor, and a control unit (18). The handle is connected to a toothbrush head (20) preferably having a plurality of bristles (26) and an ultrasonic transducer (22) that is operatively connected to a waveguide (24) that extends from the toothbrush head generally adjacent the bristles. The waveguide facilitates the transmission of acoustic energy into the dental fluid. It is contemplated that the waveguide may be utilized in manual or power toothbrushes, and in a combination without the sonic component, or in a combination without the ultrasonic transducer. Toothbrushes disclosed herein achieve improved plaque and stain removal from the teeth as well as interproximal and subgingival regions, while enhancing the user experience, massaging the gums, and stimulating dental tissue.