Abstract: A system and method for tooth whitening are disclosed wherein at least one peroxide-containing gel and at least one transition metal compound-containing gel, particularly at least one lower atomic number transition metal compound, more particularly at least a ferrous compound including gluconate, sulfate, nitrate, acetate or mixtures thereof, are applied to a patient's mouth. Gelling agent is also included. The activation of the peroxide whitens the patient's teeth. The system may be used with or without the application of light. The system further provides an additional gel including a sensitivity reduction compound including potassium nitrate, sodium nitrate or mixtures thereof for possible sensitivity treatment if needed.