Inlays, Onlays, and Partial Crowns
Instead of directly placing a filling on a back tooth, an inlay can generally be used. An inlay is one solid structure with uniform properties that is precisely fabricated in a laboratory and can be made of composite, gold or porcelain. Because it is made of one solid piece, it is stronger to chewing forces than a direct filling. Additionally, it generally yields better contours, which affords better tissue health. Also, it is more uniform and finely polished which provides a better seal to the tooth at the margin and thereby makes it more resistant to getting a cavity at the inlay-tooth interface.
Because an inlay is fabricated by a laboratory and cemented into place, the treatment process is a two-part procedure, similar to that of a crown. The restoration is cared for just as a normal tooth would be by daily brushing and flossing.
An onlay is a restoration placed on back teeth when the involved tooth has a large cavity that weakens the cusps of a tooth or fractures are present on these cusps. In these cases, a filling or inlay is inadequate to protect the remaining tooth structure and a crown removes too much healthy tooth structure. An onlay is the perfect choice.
An onlay is designed similarly to an inlay, however, it incorporates a cusp or cusps into the onlay by covering or onlaying the missing cusps.
An onlay is made by a laboratory and cemented into place. It has all the same benefits and material choices as an inlay, and is cared for the same way.
A partial crown is used to restore compromised teeth that have lost enough tooth structure to where a crown is indicated, but still have a wall of healthy tooth structure. The partial crown is then designed to preserve this remaining healthy tooth structure.
Partial crowns are made in a laboratory like that of a crown and cemented into place. They have the same benefits and material choices as a crown and are cared for the same way.