If a Prosthodontist decides that a patient is a good candidate for dental whitening, he or she can conduct the procedure in the dentist office. This procedure, called chairside bleaching, lasts between 30 minutes to an hour. Dental whitening performed by a dentist may require more than one office visit. During this process, the dentist applies a gel or rubber shield to protect the patient’s gums. The dentist then applies a special bleaching product to the teeth, using a light or laser to increase the effectiveness of the dental whitener.