Some strips uses hydrogen peroxide but only with 6% strength where normal concentration ranges from 10 to 20%. Since carbamide peroxide is only half the strength of hydrogen peroxide, the visible effect will take about two weeks of continued use, much longer than bleaching trays that contains hydrogen peroxide and in-office treatments but because it is, teeth whitening strips is gentle and comfortable to even those with very sensitive teeth and gums. Following that is the dentin. The dentin is very similar to the enamel except it is not as hard and as shiny and while the enamel is generally white in appearance, the dentin is not. Extrinsic tooth stains forms in the enamel while for the most part, intrinsic stains that show trough the enamel occur in the dentin. 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. Teeth that are more translucent tend to show more staining than those with more opaque teeth. Teeth transparency is the only known teeth condition today that could not benefit from teeth whitening and teeth bleaching. On the other hand, no amount of teeth bleaching will whiten teeth more than its natural color. Setting an appointment with the dentist aside from finding the time to sit in a dentist's chair and the follow up sessions that are required could be time constraining to other people. When it is just a simple teeth bleaching program, especially with those who have yellowed teeth only, other alternatives works just a fine. This means that you will not need another round of professional cleaning and whitening service for the next two years. When it comes to professional services, there are also those services that are referred to as more specialized, which means that there are added special services for you. For example there are specialize whitening centers that are present in major cities.