In-office bleaching provides the quickest way to whiten teeth. With in-office bleaching, the whitening product is applied directly to the teeth. These products can be used in combination with heat, a special light, and/or a laser. Results are seen in only one, 30- to 60-minute treatment. But to achieve dramatic results, several appointments are usually needed. However, with in-office bleaching, dramatic results can be seen after the first treatment.