What to Expect When Whitening

Decided to have your teeth whitened? The first step is to be sure that your expectations are realistic.
It’s important not to expect a celebrity-bright smile, as everyone’s teeth react differently to the peroxide.
You may expect quicker whitening results if you opt for an in-office whitening procedure. These procedures are considered safe, though you can expect some sensitivity in your teeth and gums, which usually resolves after the whitening procedure is complete.  It is not uncommon for the tooth color to "rebound" a week or two following this type of treatment, so using an at-home product such as Crest Whitestrips may help maintain the results following the treatment.
When you undergo an in-office whitening procedure, your dentist will apply the bleaching solution directly to your teeth and may possibly use a laser or other specialized device to speed up the bleaching process. You can expect to see some results after one treatment, but you may choose to have more than one treatment to get the effect that you want. An in-office bleaching treatment usually takes 30 to 60 minutes and costs anywhere from $500 to $1000 for your entire mouth.
How long can you expect the benefits to last? That depends in part on your habits. If you smoke, or if you drink large amounts of coffee or tea, you may need another procedure after a few years.
Article taken from:  http://www.oralb.com/topics/what-to-expect-from-teeth-whitening.aspx