Inlays and Onlays are different to each other only due to the coverage of the tooth they are restoring. An Inlay fills in the spaces between the cusps of the tooth, or rounded edges at the centre of the tooth’s surface. An Onlay, covers one of more of the cusps of a tooth or the entire biting surfaces of the tooth. They can be built from different materials like crowns and bridges. Inlays and Onlays can be built from Gold, Porcelain, ceramic, composite and precious metal.