It is an accepted fact that the over the counter medications and formulations will contain less concentration of the bleaching agent. In many products, the concentration will only reach up to 10 percent. For the formulation that are used by the professionals that conduct supervised teeth whitening procedures, the formulation for the peroxide may reach up to 43 percent and the strength of the bleaching agent will depend on the service provider. After this is done, the teeth will then be coated with the whitening formulation, and the coating will cover the surface of the teeth. And depending on the attending dentist, the formulation may contain the hydrogen peroxide or the carbamide peroxide. Either way, it can be expected that the whitening effect can be achieved. After the initial consultation, the process of getting an appointment, finding the time and actually sitting in the dentist's chair is not always convenient besides there are a lot of conditions where it is actually more practical to get a teeth whitening kit and apply it at home where the person could save enormously on fees and time. Not everyone though is a good candidate for teeth whitening. There are teeth conditions and stains that are resistant to bleaching. Examples of these are trauma to the tooth that caused the stain, blood that has leeched to the dentin, people with fillings, crowns and veneers. Crowns, veneers and fillings will always retain its default color while those that are deep in the dentin will need professional supervision. These products may contain special abrasives and these are the ingredients that work to remove the dirt on the teeth. And these products will always contain chemicals. And it is the role of these chemicals to break down the stains taken down by the abrasives. Half of the reason why this product works can be linked to the proper use and application. If you have brown or gray teeth, then bleaching will not be as effective as you will expect. When shopping for this product, do keep in mind that the crowns, the fillings and the veneers will not be affected by the whitening action of the paste. Complement the use of the whitening toothpaste with the services of professional teeth cleaner.