Indirect composite curing units are light or heat-curing chambers used to fully polymerize composite restorations fabricated in the laboratory, outside the patient's mouth, before bonding or seating. Unlike handheld curing lights used chairside, these units apply higher-intensity or multi-directional light exposure, sometimes combined with heat or vacuum, achieving a more complete cure and superior physical properties than intraoral light-curing alone could provide. This extra-oral curing step is a defining stage in fabricating indirect composite crowns, inlays, onlays, and veneers, and directly affects the wear resistance and longevity of the finished restoration.