A dental illumination system includes an adjustable lamp head including a source of radiation, which may including IR, visible, and/or UV, is provided with an adjustable mounting device adapted for mounting in such a manner that offers freedom of movement for the patient undergoing the procedure, for example, whitening, so that radiation may be directed at the tooth or teeth. In some embodiments, the lamp head includes a housing and a spacer having formations that is adapted to removably mechanically couple the lamp head to a reference device, again having formations, for facilitating illumination of a tooth by a light source contained within the lamp head. The spacer and lamp head may be formed integrally. If formed separately, both the lamp head and the spacer may include formations.