What Are Crowns?
Crowns are used to rebuild teeth which have become damaged, have large fillings or have been weakened by caries (dental decay). Sometimes crowns are also used to improve aesthetics at the front of the mouth. The crown fits over the remaining tooth after it is prepared restoring its natural shape and contour.
What Is Involved In Having A Crown Made?
A crown is custom made to fit your tooth by skilled dental technicians working in a dental laboratory. In order for the technician to make the crown the tooth must first be prepared by the dentist in the following stages;
- Reduction & shaping of the tooth to create a ‘core’ with an even space for the crown.
- Taking of an impression of the prepared tooth and adjacent teeth
- Taking of an impression of the opposite arch to allow the laboratory to see how you bite together.
- The shade of teeth will be recorded to allow the technician to match the crown (in the case of a porcelain crown) to your existing teeth.
The impressions are then sent to the dental laboratory where the impressions are cast using a dental stone which produces an exact replica of your teeth, including the prepared tooth.
How Long Does It Take?
To prepare and fit a crown usually takes two visits;
One visit to prepare the tooth, make the impressions & record the shade and one visit to fit the permanent crown. Tooth preparation normally takes around 45 minutes.
What Are Crowns Made From?
Crowns can be made from a wide variety of materials, these include:
- Gold Crowns – Gold or precious metal crowns are very strong and hard wearing, they are usually used in back teeth where they less visible.
- Porcelain Bonded Crowns (PBC) – PBC’s have an inner layer of metal onto which tooth coloured porcelains are built up to produce a naturally coloured tooth.
- Porcelain Crowns – Porcelain crowns or porcelain jacket crowns (PJC’s) are constructed entirely from dental porcelain which is a type of glass. They are used mainly on front teeth where aesthetics is of particular importance but are not as strong as PBC’s.
- Zirconia Crowns – are tooth coloured crowns and much stronger than all porcelain crowns. They can be used on both front and back teeth.
Will The Crown Look Different To My Existing Teeth?
No – A crown is produced to restore the tooth’s natural shape, where your teeth can be seen such as those at the front of the mouth the crown will be made of porcelain or have a layer of porcelain to reproduce and match the shade of adjacent teeth.
Will It Feel Different?
The shape of the crown may differ slightly from the natural tooth and if the tooth was badly decayed or broken before the crown was made it may feel quite different. The new crown may feel strange for a few days but this feeling should soon go away. The crown should not feel high or uncomfortable, if you are in any doubt please ask one of the dentists.
How Long Will The Crown Last?
A crown should last for many years but this depends on how well the crown is looked after once it is fitted. Although the crown will not decay the area where the crown meets the tooth can begin to decay. Particular attention to this area must therefore be paid to this area when cleaning you teeth.
Crowns are an ideal restoration for teeth that have been broken, or have been weakened by decay or a very large filling. A crown could be used for a number of other reasons, for instance:
– You may have discoloured fillings and would like to improve the appearance of the tooth
– You may have had a root filling which may need a crown to protect what is left of the tooth
– It may help hold a bridge or denture firmly in place
In root-filled teeth it may be necessary to insert a post before placing a crown. A post provides support and helps the crown stay in place. The weakened crown of the tooth may be shortened to gum level.
A post can be made of prefabricated stainless steel which the dentist can fit directly into the root canal, or a custom-made post can be constructed by the dental technician to accurately fit the shape of the prepared root canal. The post is placed into the root canal and cemented in position, ready for the crown to be attached.
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.
A temporary crown or temporary filling will be p-laced so that you can use the tooth while you wait for the crown to be made. This crown may be more noticeable but is only a temporary measure.
When you and your dentist are happy with the fit and appearance of the new crown it will be fixed in place with special dental cement or adhesive. The cement forms a seal to hold the crown in place.
You will need to have at least two visits the first for the preparation, impression, shade taking and fitting the temporary crown and the second to fit the permanent crown. There will usually be about 1 to 2 weeks in between appointments.
No, you will have a local anaesthetic and the preparation should feel no different from a filling. If the tooth does not have a nerve, and a post crown is being prepared, then you may not need a local anaesthetic.
Costs wil vary according to the type of crown and material used. It is advisable to get a written estimate and treatment plan before beginning any dental treatment.
How long your crown lasts depends on how well you look after it. The crown itself cannot decay, but decay can start where the edge of the crown joins the tooth. Therefore, to prevent decay affecting the crown, it is important to keep this area just as clean as you would your natural teeth. Brush for two minutes twice a day with a fluoride toothpaste and clean in between your teeth with inter-dental brushes or floss.