There are several methods available for whitening the teeth: in-office, at-home whitening trays, or a White-Strip kit.
One session of in-office whitening can generally be done in about 45 minutes. If you wish to have whitening trays to use at home when necessary, impressions can be taken to make the trays.
Over-the-counter daily bleaching products are available, but it is important to use any whitening product only under the supervision of a dentist.
To achieve the whitening results you desire, the ADA recommends that you seek the professional advice of a dentist, including examination and diagnosis of the cause of tooth discoloration, before you begin any bleaching program.