A method of whitening teeth. The method may include delivering a buffer solution from a reservoir of a toothbrush to one or more tooth cleaning elements of the toothbrush； applying a toothpaste containing a peroxide to the tooth cleaning elements, the toothpaste having a first pH； and brushing the teeth with the tooth cleaning elements, thereby mixing the buffer solution and the toothpaste to form, at surfaces of the teeth, a tooth whitening mixture having a second pH that is greater than the first pH.
