Overview
There are various methods of tooth whitening. These methods often result in success because they all use hydrogen peroxide to bleach the teeth. The peroxide lightens the the teeth from its previous shade.

Who Should Do It?
Tooth whitening is available to everyone. There are both over-the-counter methods as well as professional whitening available through dentists. Whitening is most likely to be successful for minor stains and yellowing, such as discoloring from things such as coffee, dark-colored soda and smoking. Whitening is rarely covered by insurance because it is purely aesthetic in purpose. It is up to the individual to decide if this process is worth the time and money spent on appearance.

How Often Should You Do It?
The effects of tooth whitening, depending on the method used, can last anywhere from a few months to one to three years. More official methods, such as professional whitening, are more likely to last for a few years. The informal methods, such as whitening strips and paint-on whiteners, do not have as permanent of effects. After a treatment is completed, it is best to wait for at least three months before beginning a new treatment. Continuous whitening attempts can actually damage the teeth as the peroxide strips the teeth of their enamel.

Methods
There are four common methods of tooth whitening, and each has their own advantages and disadvantages. These include:

1. Professional whitening. Done by a dentist, it can usually be done in one to three appointments. This method is more expensive because dentists charge separately for the bottom set of teeth and the top set of teeth. However, it is more convenient because it does not require a large time and effort commitment on the patients' end. This method's effects also last the longest.

2. Whitening strips. These strips are available over the counter in drugstores and grocery stores. The strips are put on the teeth twice a day for half an hour each time. They work by bleaching the teeth. It is recommended to continue use for two weeks for noticeable results.

3. Paint-on whiteners. Like the strips, this method has to be done regularly for two weeks twice a day and must be left on for half an hour each time. This method is trickier because the whitener may rub off if it has not completely dried before the mouth is closed.

4. Whitening trays. These can be worn for up to several hours a day, and continuously keep the whitening gel on the teeth. This is a very successful method, but not used as much as the others because it tends to interfere with daily life. The trays are not noticeable to everyone, but may cause speech difficulties.
All of the methods of tooth whitening have similar side effects. Most common are sensitivity to hot and cold foods and beverages as well as irritation of the gums. Less common are sore throats, headaches and tooth pain.

Success Rates
All methods of tooth whitening lighten the teeth by at least a shade. Most people who have been surveyed are satisfied with the products, and all have noticed at least a small difference in the color of their teeth. The main difference noted between customers was the duration of time for which they felt satisfied. Most remained content for over a year and then wanted another treatment; however, many people acknowledged that their teeth had still not returned to their pre-treatment state after seven years.