When patients come in for a consultation for teeth whitening, a lot of times they are skeptical about whether teeth whitening really works. “Is it a paint that makes teeth white?” or “Is it a polishing agent that removes stain?”. Another common question patients ask is “How long does teeth bleaching last?” Hopefully, I can describe the teeth whitening process, or sometimes else called, teeth bleaching, in simple terms. 
There is no magic trick in dental bleaching. There is no paint that covers stain. Dental bleaching isn’t just about polishing teeth. In actual fact, there is a chemical process that goes on to whiten teeth. Most people tend to know that the common active agent in dental whitening is Hydrogen Peroxide. It is the same ingredient found in drug store bottles used for disinfecting cuts and wounds. Do you know what happens when you put that drug store hydrogen peroxide solution on a cut or a wound? You see the “bubbling” action going on? That’s what kills germs and bacteria and keeps the area clean so healing can take place. Now in the same way when you purchase a dental approved teeth bleaching product, such as “NiteWhite” for use at home, or “Zoom” for use in the dental office, hydrogen peroxide breaks down visibly dark organic stain molecules embedded in the enamel tooth layer, with that same “bubbling” effect, into smaller bits which are lighter in colour, hence the whitening effect. It is as simple as that. The more you use the dental bleaching product the more the deeper stains can be removed. Now it is also important to follow the instructions and control the use of the bleaching product and not to overuse it, as tooth sensitivity and tooth breakdown can occur. Please discuss the frequency of use with your dentist as he or she would be best to help you maximize the benefits of dental bleaching.
Dr. Andrew Lee