Inlays and onlays are custom ceramic or composite pieces bonded to the tooth to repair bigger cavities, when a normal filling is not enough but a full crown is not yet required. They help save more natural tooth structure while adding strength.
Inlays and onlays are indirect restorations: they are crafted in a lab (or CAD‑CAM unit) and then bonded onto the tooth. Inlays sit within the grooves between the cusps, while onlays extend to cover one or more cusps as well as the chewing surface.