What dilution of peroxide is safe on tooth enamal?

Peroxide: If you are trying to whiten your teeth, regular peroxide will not work. Some people mix it with baking soda, which will remove some surface stain. The only safe and effective way to whiten teeth is at the dentist office, or through the use of over-night whitening trays with whitening gel provided by your dentist.

Peroxide and teeth: Mixing 3% hydrogen peroxide equally with water is sometimes recommended in order to cleanse the mouth or improve the health of the gums. However, I do not personally recommend doing this other than on a limited short term basis. Carbamide peroxide of varying strengths is used in most tooth whitening techniques, but should only be used after consulting with and under the guidance of a dentist.