Abstract: A flexible duplex dental tray such that the upper and the lower teeth can be placed in the upper and the lower dental troughs of the flexible duplex dental tray, respectively. The duplex dental tray is made of an elastic material and is has a radius of curvature less than the dentition of the patient such that the tension created by extending the duplex dental tray when it is worn provides additional support for holding the duplex dental tray in place, in addition to pressure for maintaining contact of tooth bleaching materials contained therein.