Whitening is an effective way to "lighten" your teeth without "bonding" material or removing any sound tooth structure. In this respect, it is one of the most conservative procedures that we have.
The amount of whitening and duration will vary between patients. Understand that porcelain and "white" fillings will be unaffected by the material.
While using this method of whitening, we can expect some sensitivity on your gums and teeth, but it is usually at a minimum. At the end of your whitening, the problem should be eliminated.