An oral treatment device comprising: an intraoral mouthpiece comprising: a lamp support structure comprising a lamp support surface having a concave curvature and a front surface having a convex curvature, the lamp support structure formed of a first material; a lamp (300A-B) comprising: a flexible sheet body (301A-B) having a front surface (302A-B) and a rear surface (303A-B); and a plurality of light emitters (304A-B) embedded within the flexible sheet body (301A-B) that generate light which is emitted from the rear surface (303A-B) of the flexible sheet body (301A-B); the lamp (300A-B) mounted to the lamp support surface of the lamp support structure so that the rear surface (303A-B) of the flexible sheet body (301A-B) of the lamp (300A-B) assumes a concave curvature, thereby forming a lamp assembly, the lamp (300A-B) operably coupled to a control circuit having a power source; and a guard component overmolded to the lamp assembly, wherein: the guard component is formed of an elastomeric material having a hardness that is less than a hardness of the first material; and the guard component comprises a frame portion that seals a perimeter of the rear surface (303A-B) of the flexible sheet body (301A-B) of the lamp (300A-B), the frame portion of the guard component defining a window (714, 716) through which the rear surface of the flexible sheet body (301A-B) of the lamp (300A-B) remains exposed. an intraoral mouthpiece comprising: a lamp support structure comprising a lamp support surface having a concave curvature and a front surface having a convex curvature, the lamp support structure formed of a first material; a lamp (300A-B) comprising: a flexible sheet body (301A-B) having a front surface (302A-B) and a rear surface (303A-B); and a plurality of light emitters (304A-B) embedded within the flexible sheet body (301A-B) that generate light which is emitted from the rear surface (303A-B) of the flexible sheet body (301A-B); the lamp (300A-B) mounted to the lamp support surface of the lamp support structure so that the rear surface (303A-B) of the flexible sheet body (301A-B) of the lamp (300A-B) assumes a concave curvature, thereby forming a lamp assembly, the lamp (300A-B) operably coupled to a control circuit having a power source; and a lamp support structure comprising a lamp support surface having a concave curvature and a front surface having a convex curvature, the lamp support structure formed of a first material; a lamp (300A-B) comprising: a flexible sheet body (301A-B) having a front surface (302A-B) and a rear surface (303A-B); and a plurality of light emitters (304A-B) embedded within the flexible sheet body (301A-B) that generate light which is emitted from the rear surface (303A-B) of the flexible sheet body (301A-B); the lamp (300A-B) mounted to the lamp support surface of the lamp support structure so that the rear surface (303A-B) of the flexible sheet body (301A-B) of the lamp (300A-B) assumes a concave curvature, thereby forming a lamp assembly, the lamp (300A-B) operably coupled to a control circuit having a power source; and a guard component overmolded to the lamp assembly, wherein: the guard component is formed of an elastomeric material having a hardness that is less than a hardness of the first material; and the guard component comprises a frame portion that seals a perimeter of the rear surface (303A-B) of the flexible sheet body (301A-B) of the lamp (300A-B), the frame portion of the guard component defining a window (714, 716) through which the rear surface of the flexible sheet body (301A-B) of the lamp (300A-B) remains exposed.