Inlays and onlays can be thought of as “internal crowns.” They are made from porcelain, and are designed to replace decayed tooth tissue, while preserving healthy tissue. They look natural, and are a strong restoration capable of withstanding the pressures of chewing and biting.
An inlay is essentially a custom made filling. It fills in hollows and cavities in areas between the cusps, encompassing mainly the chewing surface of your tooth. An inlay is often a preferred alternative to amalgam fillings, because less healthy tooth structure needs to be removed in the preparation. Inlays are also more conservative than crowns, highly durable, and can last many years if cared for properly. Porcelain is often the material of choice, but composite inlays are also available. The cost of a porcelain inlay can be a factor in deciding between the two. Porcelain inlays are made in a dental lab, and are permanently cemented into your tooth.
Onlays are more substantial reconstructions than inlays, and are used for larger restorations. They do more than just fill in cavities in areas of the chewing surface; they also extend out and cover one or more sides of the tooth. An onlay is also made of porcelain and fabricated in a dental lab. Both inlays and onlays can be matched to look like your natural teeth.