Inlays and onlays are custom-made restorations made from porcelain or composite resin. They are used to repair damaged teeth in cases where a filling would not be strong enough. Inlays are used to repair small cavities that are located inside the tooth, while onlays are used to repair larger cavities that involve the cusps (the bumps on the chewing surface of a tooth). Both inlays and onlays are bonded to the tooth, providing a strong and durable restoration that can last for many years.