This will vary, depending on many factors such as the type of whitening system used, your eating habits, oral hygiene, the genetic characteristics of your teeth and so forth. Typically, you can expect the results to last from three months to two years. In general, professional whitening systems tend to produce longer lasting results as opposed to over-the-counter whitening solutions. Some people’s teeth remain white for over two years after receiving professional whitening treatment that uses a light-activated gel system. Unfortunately, no whitening system can whiten teeth permanently. But the good news is there are home maintenance products that you can buy at any drugstore or your dentist’s office. With proper eating habits, oral hygiene, and a good maintenance program, your teeth can stay white for many years.