To repair damage to the tooth s biting surface, rather than using a simple filling, or a crown, a dentist will often use an inlay, or an onlay. Inlays and onlays can be made from porcelain, gold, or composite or ceramic resin, although porcelain is now becoming the material of choice because of its strength and potential to match the natural color of your tooth.
An inlay is similar to a filling and lies inside the cusp tips of the tooth. They are custom-made to fit the prepared cavity and are then cemented into place. An onlay is a more extensive reconstruction that covers one or more cusps of a tooth. Onlays are indicated in situations where a substantial reconstruction is required.
Inlays and onlays are applied in two dental visits. At the first visit, the old filling, or decay, is removed, and the tooth is prepared for the inlay/onlay. The dentist will then make an impression of the tooth, and send this impression to a dental laboratory. This impression will be used by the laboratory to construct a custom-made porcelain, or gold inlay/onlay. At this time the dentist will place a temporary sealant on your tooth and schedule a second appointment
At the second visit, the temporary sealant is removed. Your dentist will then ensure that the inlay/onlay fits properly in the tooth and does not interfere with your bite. The inlay/onlay is then bonded into the tooth with a strong bonding resin, and polished smooth.