Similar to crowns, inlays and onlays protect teeth by returning strength, structure and function to a tooth that has been damaged by decay. They are engineered to fit into a tooth like a filling and to match the natural color of your existing teeth. Inlays fit in between the "cusps," or bumps on a tooth, while onlays fit over one or more cusps. But unlike crowns, inlays and onlays allow for more of the existing tooth structure to remain and are used for tooth restoration when the damage isn't as severe.