Bleaching is a treatment that discolors teeth. There are two methods of bleaching teeth: at-home or in-office treatments. Under their dentist's supervision, the at-home treatment requires patients to place a bleaching agent in their custom fitted tooth tray. Patients are requried to wear the tray nightly for 2-3 weeks. However, the in-office treatments take approximately 1-1.5 hour. The results are immediate. The dentist will cover your gums and apply a bleaching solution to the teeth. Alight is then applied to the teeth in order toactivate the solution and discolor teeth.