The peroxides used in the past were watery and could only be used in an office setting. Some years ago, a new form of peroxide was developed called carbamide peroxide. It is most often used in the form of a gel, placed into a special tray that is custom-fitted to your teeth, and worn in the mouth for anywhere from one to four hours a day. When in contact with the teeth, the carbamide peroxide releases oxygen, and that is what releases the stain on your teeth. This safe and gentle process has proven to be very effective.
Teeth tend to change shades, usually yellow, with age.
This and other stains can be eliminated with the whitening processes. Whitening may not change the color of existing fillings, so whitening combined with tooth bonding is a popular choice. When the whitening is completed, new tooth-colored fillings are placed to match the whitened teeth. That depends on many factors such as product used, method, and intensity of the preexisting stains or discolorations you want to whiten. With so many options available, choosing the right tooth-whitening process can be confusing.