Before treatment, the dentist examines the patient orally and ensures that the patient has a set of healthy and unrestored teeth before deciding whether the patient is a suitable for teeth bleaching. There are two main ways to bleach teeth; one, a small bleaching solution is placed in the trays worn over the teeth for 2 hours a day for 3 weeks and the second a safe bleaching solution is applied to the teeth and exposed to a small intense light that activates the bleach. This takes 40 minutes.
Attribution: Straight Talk Foundation