Unlike most whitening methods, with easy periodic home maintenance, KoR whitening is entirely permanent. KoR Whitening whitens the teeth dramaticaly often lightening them by 16 shades or more, it even whitens tetracycline-stained teeth significantly. First, molds of your teeth will be made to fabricate your own unique, ultra comfortable KoR-Seal Whitening Trays. Then you and your dentist will decide which level of whitening is the best fit for you. KoR Whitening is different from normal whitening trays. There thin and ultra form fitting make them very comfortable in your mouth. Also wearing these only while you sleep makes them very convenient so that it doesnt interfere with your day. The KoR whitening system works by restoring your ability to absorb oxygen. The oxygen from KoR Whitening gel is absorbed deeply into the tooth, dissolving stain molecules. The KoR-Seal whitening tray seals the whitening gel inside the tray preventing the gel from quickly leaking into your mouth. However, the KoR Whitening does not does not whiten crowns, veneers or fillings, so if you have any on your front teeth you may need to replace them after the whitening.