How can you whiten your teeth with hydrogen peroxide?

 There are a number of ways to whiten your teeth. Many tooth- pastes contain sodium percarbonate or calcium peroxide. Both of these chemicals release hydrogen peroxide when they are mixed with water. In the toothpaste they are more stable than plain hydrogen peroxide would be, so the toothpaste won’t decompose before you have a chance to use it.

                                  Your teeth can be yellow for several reasons. Many of the foods you eat can stain teeth. Coffee, tea, and tobacco are famous for yel- lowing teeth, but many other foods also have this ability. Peroxide toothpastes, or a rinse of 3 percent hydrogen peroxide, can help remove most of the stains. Peroxide bleaches the yellow by oxidiz- ing the stain molecules so that they no longer absorb light.

                     Bacteria that live in your mouth make a protein film on the teeth called a biofilm. This is easily stained and may be slightly yel- low all by itself. Peroxide bleaches the stain molecules, but it also breaks up the protein film so you can brush it away. If you have been brushing your teeth for many years, the white enamel on the outside of the tooth may get thin enough that the yellow dentin inside the tooth shows through. Peroxide can pen- etrate into the dentin and bleach the yellow to a whiter color.