Abstract: An illuminating lip and cheek expanding device comprising a lip expander including a pair of lip engaging members to engage opposite corners of the mouth. At least one of the lip engaging members includes a fiber optic bundle having a light outlet end located at the periphery of the mouth and facing inwardly toward the teeth of the mouth to be illuminated. The fiber optic bundle also has a light inlet end connected to the light outlet end and adapted to be connected to a light source, so that light from said source may be conveyed through said fiber optic bundle and onto the teeth.