There are two types of bleaching procedures: 

At-Home Bleaching Trays
Plastic trays are made from impressions taken of the patient's mouth. A bleaching substance is given to the patient which is placed by the patient in the trays every night for three days to a week. Significant whitening is usually seen. The whitening lasts at least a year. It is inexpensive to purchase bleach every year or two as it is needed. 

In-Office Bleaching
This is done with the new advanced "Zoom" Bleaching Light. It is a two hour procedure in the chair. It is quick and effective, but more expensive. The procedure lasts approximately two years and can be maintained thereafter with bleaching trays or further in-office treatment.