There are three main teeth whitening options. The first is over the counter products. These products are always weaker because they are sold OTC and the delivery method does not whiten all your teeth. A second option is the fast or quick chairside whitening. This is usually about an hour long visit and uses a high concentration whitening gel applied to your teeth and heated with a light. This process will give you an instant whitening effect but only to a certain degree. This is the most expensive option and the results vary from person to person. The third option is the most common and most reliable. Custom made whitening trays. These custom trays are made from molds of your teeth and given to you with a whitening gel that fits your treatment goals. The ability to whiten as much or as little as needed makes this option the best. Plus these custom trays are used for many years and so the only cost becomes the gel. IT is the most cost effective way to go.