Your dentist is correct. Over-the-counter whitening systems do work as well as many of the in-office systems, such as Zoom. In-office systems don't take as long to brighten your teeth. That's because the whitening solution is stronger. Zoom takes three, 20-minute sessions. Some laser whitening systems need only one, 1-hour session. Take-home whitening systems must be used every day (about 30 minutes a day) for weeks to achieve the same results. (Some dentists wonder whether this longer time frame increases the risk of tooth sensitivity.)

An in-office whitening also costs up to 10 times the cost of over-the-counter products. Often, even after an in-office whitening, a dentist will advise a patient to buy an over-the-counter system to have at home, just to keep the teeth white.