Crowns and Bridges
What is a crown?
Crowns are an ideal restoration for teeth which have been broken, or have been weakened by decay or a very large filling. The crown fits right over the remaining part of the tooth, making it strong and giving it the shape and contour of a natural tooth. Crowns are sometimes also known as caps.
Why would I need a crown?
There are a number of reasons:
- The tooth may have been weakened by having a very large filling
- You may have discolored fillings and would like to improve the appearance of the tooth.
- You may have had a root filling which will require a crown to protect it.
What are crowns made of?
Crowns are made of a variety of materials, and new materials are continually being introduced. Here are some of the options available at present:
- Porcelain Bonded to Precious Metal: This is what the majority of crowns are made from. A precious metal base is made and porcelain is then applied in layers over it.
- Ceramic ( Metal Free ): Advances in dental materials have allowed us to make ceramic crowns that look beautiful and are as strong as metal crowns. These new materials allow us to conserve tooth structure and eliminate the black lines seen on older porcelain metal crowns.
- Precious Metal (Gold and Palladium): These crowns are very strong and hard-wearing, but are usually used at the back of the mouth, where they are not visible.
How is a tooth prepared for a crown?
The dentist will prepare the tooth to the ideal shape for the crown. This will involve removing most of the outer surface, and leaving a strong inner 'core.' The amount of the tooth removed will be the same as the thickness of the crown to be fitted. Once the tooth is shaped, the dentist will take an impression of the prepared tooth, one of the opposite jaw and possibly another to mark the way you bite together. The impressions will be given to the technician, along with any other information needed to make the crown.
Who makes the crown?
The impression and shade information will be given to a dental technician who will be skilled in making crowns. Models will be made of your mouth and the crown will be constructed on these in order to ensure that the crown fits perfectly.
Will the crown be noticeable?
No. The crown will be made to match your other teeth exactly. The shade of the neighboring teeth will be recorded to make sure that the color looks natural and matches the surrounding teeth. A temporary crown, usually made in plastic, will be fitted at the end of the first appointment to last until the permanent one is ready. These temporary crowns may be more noticeable, but they are only a temporary measure.
How long does the treatment take?
Treatment usually takes two weeks. There is an initial appointment when the tooth is prepared for the crown and a final visit when the crown is cemented. During the time between appointents a provisional acrylic crown will be worn on the tooth.
Does it hurt to have a tooth prepared for a crown?
No. A local anesthetic is used and the preparation should feel no different to that of a filling. If the tooth does not have a nerve and a post crown is being prepared, then local anesthetic may not be needed.
What are posts?
Sometimes a tooth needs a crown but there is not enough tooth to support it. A tooth that has received root canal therapy can have a post placed inside the tooth to support a build-up. The build-up/ post combination replaces missing tooth structure to provide a sufficient platform for the new crown.
Are there any alternatives to post crowns for root-filled teeth?
If a root-filled tooth is not completely broken down, it may be possible to build it up again using filling material. This 'core' is then prepared in the same way as a natural tooth and the impressions are taken.
How long will a crown last?
The life of a crown will depend on how well it is looked after. The crown itself cannot decay, but decay can start where the edge of the crown joins the tooth. It is very important to keep this area as clean as your other teeth, or decay may occur which could endanger the crown. Properly cared for crowns will last for many years -- your dentist will be able to advise you how long.
How are crowns fixed to teeth?
Once the fit and appearance of the crown has been checked -- and approved by you -- it will be cemented in place with special dental cement. The cement also forms a seal to help hold it firmly in place.
Will the crown feel different?
Because the shape of the crown will be slightly different from the shape of the tooth before it was crowned, you may be somewhat aware of it in the beginning. Within a few days, it should feel fine and you will become unaware of it. The crown may need some adjustment if it feels like it crowds the surrounding teeth. If it is at all uncomfortable, you should ask your dentist to check and adjust it.
What is a dental bridge?
A dental bridge is a false tooth, known as a pontic. This is fused between two porcelain crowns to fill in the area left by a missing tooth. The two crowns holding it in place that are attached onto your teeth on each side of the false tooth. This is known as a fixed bridge. This procedure cab be used to replace one or more missing teeth. Fixed bridges cannot be taken out of your mouth as you might do with removable partial dentures.
