What Are Crowns?
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. For Instance:
- the tooth may have been weakened by having a very large filling
- you may have discoloured 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.
- you may have had an accident and damaged the tooth.
- it may hold a bridge or denture firmly in place.
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.
- Porcelain: These crowns are not as strong as bonded crowns but they can look very natural and are most often used for front teeth, especially for younger people.
- 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 tooth is prepared 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, an impression is taken 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 neighbouring teeth will be recorded, to make sure that the colour looks natural and matches the surrounding teeth. This is done using both a shade guide and digital photography. The technician will be able to match the characteristics of your own teeth with the help of the digital image. In some cases, the characterisation is so detailed, the only way to ensure a perfect match is to visit the laboratory and allow the technician to see your teeth himself. This can be arranged. A temporary crown, usually made in plastic, will be fitted at the end of the first appointment to last until the definitive one is ready. These temporary crowns may be more noticeable, but they are only a temporary measure.
How Long Does The Treatment Take?
At least two visits are needed, the first for the preparation, impression, shade taking and fitting the temporary crown, and the second to fit the permanent crown. The first appointment would normally be an hour.
Does It Hurt To Have A Tooth Prepared For A Crown?
No. A local anaesthetic is used and the preparation should feel no different to that of a filling.
Are Post Crowns Different?
Post crowns may be used when the tooth has been root filled or if there is no tooth remaining above the level of the gum. The weakened crown of the tooth is drilled off at the level of the gum. A double-ended ‘post’ is constructed to fit into the root canal. This can be either prefabricated Stainless Steel or custom made of gold. One end of the post is cemented into the root canal, and the other end holds the crown firmly in place.
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.