Crowns are full coverage indirect restorations and are made by a dental laboratory. There is a substructure of either ceramic or metal. To make the crown aesthetically pleasing, the outer layer is fabricated with porcelain. Crowns are bonded permanently to the tooth with cement. Crowns have good durability. Failures are usually due to cement failure (wash-out) over time or decay at the margin between the tooth and crown. Proper maintenance is required to maximize the longevity of a crown.