Tooth whitening has become a wildly popular procedure, with many
over-the-counter toothpastes and mouthwashes claiming to have
whitening capability. While the efficacy of these products varies,
there are some tried-and-true methods that have been proven safe
and effective.

In-office bleaching, as the name implies, takes place in your
dentist’s office.  The dentist will use a shield to isolate
the teeth to be bleached and protect the gums. A bleaching compound is
applied to the teeth, and often activated using a special light.
After 30 minutes to an hour, the bleaching process is complete.

At-home bleaching is also commonly used to whiten teeth. 
A bleaching tray, which is worn over the teeth, is filled with a
bleaching gel, usually containing carbamide peroxide as the whitening agent.
Regular wearing of the bleaching trays produces a noticeable whitening
effect in just a couple of weeks.