Background

• Teeth whitening is a process that removes stains from teeth and makes them a whiter, brighter color. Stains accumulate both on the surface and inside the tooth. This discoloration can be caused by time and particular food and drinks like soda and coffee. There are many over the counter whitening kits that are simple to use, but others who want a more aggressive treatment go to a dentist's office to find it.
  
  

The Science

• The whitening technique is often performed using some sort of bleaching gel. This gel is made up of either hydrogen peroxide or carbamide peroxide, the more stable version. When the gel is applied to a person's teeth, the peroxide breaks down into oxygen molecules that work effectively to go inside the teeth and break down stains that sit inside the pores of tooth enamel. Tooth stains actually cause less light to shine through teeth, making them look dull. When the stains break apart, they create less of a blockage for the light. The result is that more light is able to shine through the teeth and they look whiter.
  
  

Procedures in the Dentist's Office

• Bleaching gel works best for stains that are yellow, or a mild brown color. These are usually caused by food, tobacco or coffee. Sometimes teeth will get dark brown or blue-gray stains that are the result of taking certain medications during tooth development, and these are harder to get rid of. The latter procedure can take six months of bleaching to achieve desired results. When teeth whitening is performed in the dentist's office, the dentist will cover the rest of the mouth aside from the teeth, put on the peroxide gel and use a laser or light that forces the peroxide to become oxygen molecules and attack the stains. The usual time for one visit is 1 to 2 hours.
  
  

At Home Procedures

• Whitening at home can be supervised by a dentist too. The dentist makes a mouthpiece to fit both top and bottom teeth of each patient. Patients will then squirt some of the peroxide gel into these mouthpiece molds and keep them in the mouth for a certain amount of time. Because this peroxide gel is taken home, it's not as strong as the kind in the dental office. This process can take up to three weeks for results.
  Over the counter tooth whitening kits are also available for those looking for a cheaper alternative. The kits work very similarly to the dental procedures, using a peroxide gel, and come in a generic tray or whitening strips that the consumer attaches to his teeth. Most of these over the counter methods are applied once or twice for 7 to 10 days.