I get asked this question almost every time I tell a patient that they need a crown. The word crown actually has 2 meanings in dentistry. First, the crown of the tooth is that part of the tooth that is visible in the mouth and is covered by enamel. The second definition pertains to the type of restoration that covers this entire portion of the tooth to replace the enamel. It restores the anatomy, function, contours, contacts with other teeth, and the esthetics, or looks and color of the tooth. The procedure is done by basically removing the enamel of the tooth, taking and impression of the remaining tooth structure, sending it to a dental lab to construct the crown, and then cementing the crown in place.
There are 3 basic reasons to have a crown done on a tooth. They are: 1) to prevent the tooth from breaking after a root canal has been done on the tooth; 2) to repair a tooth once it has broken; and 3) to prevent the tooth from breaking when a large filling is present.
When a has had a root canal, the blood vessel and nerve tissue (pulp) is removed and the tooth becomes brittle and can break apart. The crown covers the tooth and strengthens it to prevent the tooth from cracking and breaking.
There are many different reasons for teeth to break, but once a tooth, and/or filling has broken, the tooth needs a crown done to strengthen it and rebuild it. Sometimes a restorative (filling) material is used to build the tooth up so it can have a crown prepared and placed on it. The main retention of the crown is dependent on the height of the remaining prepared tooth structure. The longer the prepared tooth structure is the better the retention of the crown is.
The third reason for having a crown done is when there is a large filling, involving more than 40% of the tooth, present. Fillings do not add any strength to the tooth and must be supported by the remaining tooth structure when the filling is placed. If a crown is not done on these teeth, they are likely to fracture and break apart.
Most insurances pay 50% of the fee for a crown and will pay to replace crowns after a 5 year period. The best way to protect the investment you have made in a crown is to maintain a good home base dental hygiene program followed up by regular check ups and cleanings.
