Crowns are an ideal way to rebuild 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’.
There are a number of reasons why we need a crown, For instance:
- tooth may have been weakened by having a very large filling
- discoloured fillings and would like to improve the appearance of the tooth
- you may have had a root filling which will need a crown to protect it
- you may have had an accident and damaged the tooth
- It may help hold a bridge or denture firmly in place.
Crowns are made of a variety of materials and new materials are being introduced all the time. Here are some of the options available at present:
- Porcelain bonded to precious metal: A precious metal base is made and layers of porcelain are then applied over it.
- Porcelain: they can look very natural and are most often used for front teeth.
- Porcelain and composite: porcelain and composite resin materials can sometimes look the most natural. However, these crowns are not as strong as bonded metal crowns.
- Precious metal (gold and its alloys): these crowns are very strong and hard-wearing, but are not usually used at the front of the mouth, where they are highly visible.
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.
We will prepare the tooth to the ideal shape for the crown. This will mean 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. A local anaesthetic is used 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 local anaesthetic may not be needed. Once the tooth is shaped, we will take an impression of both upper and lower jaws. The impressions will be given to the technician, along with other information they need to make the crown.
The impressions and information about the shade (with a shade guide and photo of your tooth- The shade of the neighbouring teeth will be recorded, to make sure that the colour looks natural and matches the surrounding teeth) of your teeth will be given to a dental technician who will be skilled in making crowns. They will make the crown that fits perfectly.
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 in place for about two weeks.
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 could endanger the crown. Properly cared crowns last for many years.
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.
Because the shape of the crown will be slightly different from the shape of your tooth before it was crowned, you may be aware of it to begin with. Within a few days it should feel fine, and you will not notice it. The crown may need some adjustment if it feels higher than the surrounding teeth.
An Onlay crown is a conservative way to restore a decayed or broken down tooth. The special shape of an Onlay crown protects the tooth from further damage whilst leaving healthy un-weakened parts of the tooth intact.
- The tooth may have been weakened by having a very large filling or extensive decay extending under one of the cusps (points).
- You may have a root filling that will need a crown to protect it.
- You may have a large mercury amalgam filling which you would like removed in order to improve the appearance of the tooth.
They were originally made of gold but are nowadays mostly made of tooth coloured materials. Zirconium/Porcelain or pressed porcelain are the strongest and most natural materials. Composite resin based materials like Belle-Glass are a less expensive alternative but do not retain their appearance for so long.
To prepare the tooth, all decayed or weakened parts of the tooth are removed; we will then make an impression of the prepared tooth. This impression, along with a record of the shade of your tooth will be sent to the dental laboratory
While your Onlay crown will be made. A temporary filling will be placed in your tooth to protect it for two weeks which it takes for the technician to make your permanent onlay crown.
After we get the Onlay from the lab, the fit and appearance are checked. Onlay crown will then be cemented in place with a special dental cement.