All of these terms refer to porcelain restorations that fix teeth with significant damage. A “crown” and a “cap” are the same thing. These are used when there is enough damage to the tooth that it has to be covered completely in order to restore its health and function. Inlays and onlays are very similar to crowns, but are used for teeth that still have some healthy tooth structure and don’t require a full crown. An inlay fits inside the cusps, or bumps, of a tooth. An onlay is larger and covers one or more tooth cusps. These porcelain fillings are extremely durable, match existing tooth color, and protect teeth for years to come.