Abstract: A tray for containing a tooth whitening gel such as hydrogen peroxide in various forms, similar active agents and agents of a proprietary nature is equipped with a single, external ultrasonic transducer. A parabolic reflector directs the ultrasound to the teeth. The ultrasound drives the whitening gel into the tooth enamel and thereby enhances the whitening action. The tray is attached to an adjustable ultrasonic frequency generator, which allows the practitioner to adjust the frequency of the ultrasound to obtain the optimum whitening. This ultrasonic system accelerates the tooth whitening process while simplifying, reducing the cost, and increasing the safety and patient comfort compared to current systems that employ ultraviolet light.