There are many different types of whitening formulas that contain a variety of solutions and technologies. Hydrogen peroxide is not my first choice because it can cause sensitivity. Hydrogen peroxide forms radical intermediates -- extremely unstable and destructive molecules -- that break down into water and oxygen. The freeradical intermediates react with the pigments that stain your teeth and destroy and can also damage your gums and nerves.If you havegum disease, receding gums or allergies, you should avoid bleaching untilyour condition has been properly treated. You will want to consider the different formulas and make an informed andconscious choice with your doctor. You can avoid potentially serious toxicity and injuries to your teeth andgums if you follow these guidelines.Given all the possible dangerous effects of tooth bleaching, itis probably not your best choice. There are, however, other methods that can be used on stained teeth.Tooth veneers are one alternative option to bleaching. Veneers are thin coverings made of porcelain that are bonded to your teeth. Though they won't stain, they are not as long-lasting as real teeth.