Onlays are also laboratory fabricated and used for larger restorations. They restore inside the tooth and extend over one or more sides of the tooth. They can also be used as a crown or cap. Because of their size, onlays are made of strong material, usually porcelain or gold. Like inlays, they are conservative tooth restorations that require far less drilling than fillings and some crowns. An onlay can often be used to repair only the damaged portion of the tooth, leaving much more of the original tooth structure intact.
Both inlays and onlays are much more conservative and precise than traditional fillings and crowns. While traditional fillings can reduce tooth strength up to 50 percent, inlays and onlays made of high-strength materials can actually increase tooth strength by up to 75 percent, lasting sometimes up to 25 to 30 years.
Dr. Steven Hart received his degree from Tufts University School of Dental Medicine in Boston and has practiced full time in Chapel Hill since 1982. Dr. Hart teaches advanced courses to practicing dentists throughout the world who travel to the prestigious L.D. Pankey Dental Institute in Florida to continue their professional development. 
Dr. Mary Bennett Houston received her degree from the UNC School of Dentistry and completed a one-year Advanced General Dentistry Residency at UNC. She is a Fellow in the Academy of General Dentistry, an active member of the American Dental Association and continues her dental education through courses at the L.D. Pankey Institute and the Dawson Center for Advanced Dental Education. 
