An orthodontic appliance includes a base with an outer surface, as well as at least one passageway extending through the base. An element is received in each passageway and is made of a material that transmits actinic radiation. The element serves as a window to facilitate the curing of light-curable orthodontic adhesive beneath the appliance base, while simultaneously preventing movement of the adhesive through the passageway. Optionally, one or more optical fibers are provided to facilitate curing of the adhesive.