A tooth cleaning and whitening method applies a light transmitting oxidizing gel to the teeth, after which a hand-held LED light source with a light transmitting lens and a cup forming a chamber having an open end is moved over the teeth so that the cup distributes the gel while the teeth are exposed to light transmitted through the lens. This not only ensures intimate contact of the teeth with the gel, but also maintains a more or less constant spacing between the light source and the tooth surfaces for optimum results. A sealant is then applied to the gel-coated teeth, after which a dental prophylaxis is performed by cleaning and scaling the teeth at the gum line, gingival margins, and crevicular spaces while avoiding excessive disruption of the sealant composition. This simultaneous cleaning and whitening procedure reduces patient time at the dentist compared to separate cleaning and whitening procedures.