To make the tooth tray, a dentist must first take a plaster cast impression of the teeth. Although this step is quick, the dentist must now create a custom tray of the patient's teeth using the plaster cast, which can take more than a week. The tooth tray should fit snugly over the teeth but stop short of irritating the gums. After the patient receives the teeth tray, he or she must be instructed in usage. This is generally a simple procedure, involving application of small amounts of teeth whitening agent to the tooth tray, and then wearing the teeth tray for an extended period of time.
