What is a Crown, or cap? A crown serves to protect our teeth from further or future damage. The process usually requires two appointments and involves shaping the tooth to certain dimensions to fit a crown. There are three different materials: gold, all porcelain, and porcelain fused to metal. Your dentist will recommend which material would be best on a case by case basis. Factors he or she will consider with you include but are not limited to esthetics, the amount of natural tooth left, your bite (occlusion), and parafunctional habits like clenching or grinding. Sometimes, your dentist may recommend a procedure called "crown lengthening". A specific height of natural tooth must be available for the crown to grasp to and to prevent the crown from causing inflammation of your gums and bone. Crown lengthening serves to provide that specific height of natural tooth structure. Ask your dentist for more details.
Why might I need a crown? The main purpose of crowns is to prevent tooth fracture. Our teeth are prone to fracture after root canal treatment and large cavities. Crowns may also serve to replace missing teeth via dental implants or for other esthetic reasons such as internal tooth discolorations when veneers are not an alternative.
I need a new crown??? After a crown or filling is placed we can still get tooth decay, especially around the margins which is where the crown or filling meets natural tooth structure. Without proper oral hygiene, plaque can buildup in these areas and cause decay again, a process called "recurrent decay". This process is especially tricky with crowns, because the bacteria often sneak up under the crown and cause decay where we can't see, even on xrays because the crown may hide the decay underneath. Your dentist will determine whether he or she will be able to place a filling with or without removing the old crown. In the majority of cases, the crown will need to be removed, a filling placed, and a new crown made.
On the xray, all we can see is a small defect on the back (left) side of the tooth with the crown. Clinically the crown looks fine. Upon removal of the crown, this is what the dentist found.
Dr. James Mahooti, DDS. http://mahooti.blogspot.com/
Post and Cores
Sometimes, there isn't enough natural tooth structure left to support a crown. In these cases, a post and core may be used to help provide enough structure for a crown to be placed. The post is placed and cemented into the tooth's canal (root canal treatment must be performed first). A core material which may be amalgam (silver filling material) or resin (tooth-colored filling material) based will then be built up on and around the post. The material used as the core buildup will be recommended by your dentist on a case by case basis considering the amount of natural tooth structure left, saliva control, and esthetics (amongst other considerations).
Courtesy of Curveed.com Dental Patient Education Software, for a video about post and cores, CLICK HERE