An oral treatment device that emits electromagnetic radiation onto surfaces of a user's teeth. The oral treatment device may include an intraoral mouthpiece and a handle extending therefrom, the handle containing the control circuitry required for operation of the device. The mouthpiece may include a lamp support structure, a lamp, a lens plate, and a guard component. The lamp may include an electromagnetic radiation source that includes a flexible sheet and a plurality of illumination elements located thereon. The illumination elements may be light emitting diodes printed with an electrically conductive. Additional electronic components such as a processor and a power source may also be included in the device.