In dentistry, a crown most commonly refers to a dental cap, a type of dental restoration that completely caps or encircles a tooth or dental implant. A crown may be needed when a large dental cavity threatens the health of a tooth. A crown is typically bonded to the tooth by dental cement. 

They can be made from various materials, which are usually fabricated using indirect methods. Crowns are used to improve the strength or appearance of teeth and to halt deterioration. While beneficial to dental health, the procedure and materials can be costly.

The most common method of crowning a tooth involves taking a dental impression of a tooth prepared by a dentist, then fabricating the crown outside of the mouth. The crown can then be inserted at a subsequent dental appointment. 

Attaching dental crowns to implants

When it is time to attach the permanent implant crown, the dentist can use two methods to place it: By using a small screw to enter the top of the crown into the abutment (known as screw-retained dental crowns), or by using dental cement to attach the crown to the abutment (known as cemented crowns).

Screw-retained dental crowns: Screw-retained dental crowns allow for retention and retrievability — meaning that they keep abutments and crowns in place effectively while still allowing ease of removal, replacement and restoration without damaging other components. Dental crowns with screws are therefore more easily maintained. These crowns have a small hole in the top as a passageway for the screw to be placed through the artificial tooth and attach to the abutment. Because crowns do need to be replaced every once in a while, screw-retained crowns allow for easier replacement. However, due to this hole in the top of the tooth, these kinds of dental crowns are not recommended for teeth that are visible. These are best used for teeth in the back of the mouth where the hole will not be as apparent.

Cemented dental crowns: Cemented crowns use a special type of dental cement to attach to the abutment. Although cemented crowns are more aesthetically pleasing, they are slightly more difficult to replace and maintain. Where a screw-retained crown can be easily taken apart to allow for replacement, the same cannot be said for cemented crowns. The entire crown needs to be removed when cemented crowns fail.