First, the doctor will check the health of the patient’s teeth and repair any damage if any, after that impressions are taken. From the impressions, plastic trays are created which the patient will use at home with special whitening gels. The patient will place a small number of whitening gels on the front surface of the trays and place them over their teeth. Depending on what the doctor believes is best, the patient has to wear the trays for an hour a day or overnight for two weeks.