What is a crown?
A crown is a tooth-shaped cover made of either metal, porcelain or ceramic, placed over the top of a tooth which has been badly damaged by trauma or by decay. Crowns are also sometimes called caps.
Crowns are placed on teeth for a variety of reasons:
- Because the tooth has been broken or severely damaged.
- Because the tooth has deteriorated due to decay to the extent that it cannot be save by a simple filling.
- A crown can be used to hold together the parts of a cracked tooth.
- A crown can be used to hold a bridge in place.
- Crowns are also used for cosmetic purposes to improve appearance by covering misshapen or discolored teeth.
Crowns are made in a dental laboratory, and can be made of metal, porcelain fused to metal (PFM), or of ceramic material. Metals include gold alloy, other alloys such as palladium, or of a base-metal alloy such as nickel or chromium. Metal and PFM crowns are the strongest and are better choices for back teeth than ceramic crowns which are more often used for front teeth. Metal crowns, of course, look like metal, but PFM and all-ceramic crowns are the same color as your natural teeth, and look just like your natural teeth.
Crowns usually last at least seven years, but in many cases they last a lifetime. Dental offices and dental labs, however, typically only guarantee a crown for a year because the life of a crown depends a great deal on the patient.
Preparing the Tooth
If you need a crown, there is the possibility that you may also need root canal treatment on the tooth. Excessive decay increases the risk of infection or injury to the pulp of the tooth, which necessitates root canal treatment. The dentist will have to decide.
If the tooth has excessive decay, or parts of it are broken off, a foundation will have to be built up before the crown can be installed. This is called a “build-up.” If you are receiving a crown after a root canal, you dentist may insert a “post-and-core” foundation. These are all separate treatments requiring extra charges.
Getting a crown requires at least two visits to the dentist. During the first visit, the dentist will file the tooth down to make room for the crown. He will then take an impression (copy) of the tooth using a rubber-like material. The impression material sets up in around 5 minutes, after which it is removed. An impression will also be taken of the teeth above or below the tooth being crowned in order to insure that the crown will fit your normal bite. After filing down the tooth during the first visit, you will receive a “temporary crown”, which you will wear while your permanent crown is being made at a dental lab. The permanent crown will be installed during the second visit.
After the Crown
You should not feel any sensitivity or discomfort after the crown is installed. However, if you did not have a root canal on the crowned tooth, the tooth will still contain the nerve, so there may be temporary sensitivity to heat and cold. But this should go away in time. If you have pain or sensitivity when you bite down, this usually means that the crown is too high. This can be adjusted easily. If you have any difficulty with your crown, contact your dentist for a follow up appointment.