In this procedure, 1st Dentist will apply either a protective gel to your gums or a rubber shield to protect your gums. Then your dentist will apply 15-35% hydrogen peroxide on the front surface of the upper and lower anterior teeth. Hydrogen peroxide can penetrate the porous outer layer of your teeth and breaks apart stains compounds using a chemical reaction called oxidation. Later on, after completing the cycle your dentist will wash off the material applied on the teeth and remove the protective shield of gums.