A crown is an artificial restoration that fits over the remaining part of a prepared tooth, making it strong and giving it the shape of a natural tooth. A crown is sometimes known as a ‘cap’.
Why would I need a crown?
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 will need a crown to protect it
· it may help hold a bridge or denture firmly in place.
What is a crown made of?
Crowns can be made of a variety of different materials and new materials are continually being introduced. Some of the most popular options are listed below.
Porcelain bonded to precious metal: this is what most crowns are made from. A precious metal base is made and then porcelain is applied in layers over it.
Porcelain crowns: these crowns are made entirely out of porcelain and are not as strong as bonded crowns, but they can look very natural and are most often used for front teeth.
All-ceramic crowns: this modern technique offers a metal-free alternative, which can give the strength of a bonded crown and the appearance of a porcelain crown. Therefore it is suitable for use in all areas of the mouth.
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.
Glass: these crowns look very natural and are used on both front and back teeth.
Gold alloy crowns: gold is one of the oldest filling materials. Today it is used with other metal alloys to increase its strength, which makes it a very hardwearing restoration. These crowns are white or gold in colour.
How is a crown prepared?
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.
Once the tooth is shaped, the dentist will take an impression (mould) of the prepared tooth, one of the opposite jaw and possibly another to mark the way you bite together.
The impressions will then be given to the dental technician, along with an appropriate shade and other information needed for the crown to be made.
How is the crown fitted?
When the dentist is 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.
How long does the treatment take?
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.
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.
How long will the crown last?
Properly cared for crowns should last for many years. Your dentist will be able to tell you how long the crown may be expected to last.
This depends on the number of teeth missing and on where they are in the mouth. The condition of the other teeth also affects the decision. There are two main ways to replace the missing teeth. The first is with a removable false tooth or teeth – a partial denture. The second is with a fixed bridge. A bridge is usually used where there are fewer teeth to replace, or when the missing teeth are only on one side of the mouth.
What is a partial denture?
This is a plate with a number of false teeth on it. It may be all plastic or a mixture of metal and plastic. Both types may have clips (clasps), to help keep the denture in place in the mouth. Depending on where they are, some of these clips may show when you smile or open your mouth.
What are the replacement teeth made of?
Usually plastic, and occasionally porcelain. Each replacement tooth is made specially, to get the right shape, colour and size for you.
What is the difference between a plastic partial denture and one that contains metal?
Plastic partial dentures are less expensive to make. But unless they are designed very carefully they can damage the teeth they fit against. Metal partial dentures are usually from an alloy of cobalt and chromium and they are much stronger. They are lighter to wear and can be supported by the remaining teeth. Although the base is metal, they have gum-coloured plastic and natural-looking teeth fixed to them. They are more expensive than the plastic ones.
How do I look after my denture?
You should remove the denture from your mouth for cleaning. You’ll be shown how to clean it by your dentist or hygienist, probably with a small toothbrush and toothpaste, or by soaking it in cleansing solution. If you have a metal-based denture you’ll need to choose a cleaning solution that’s suitable for metal.
What is the alternative to a partial denture?
The main alternative is a fixed bridge. This is made by putting crowns on the teeth at either side of the space, and then joining these two crowns together by placing a false tooth in the space. This is all made in the laboratory and then the pieces are cemented into place with special adhesives. The bridge can’t be removed
What are bridges made of?
Bridges usually made of a precious metal. If the bridge will show, porcelain is then bonded to the base. Sometimes, there are other non-precious metals used in the base for strength.
Are bridges expensive?
Although a bridge may seem expensive it will last many years. It will also improve your appearance and bite. A bridge uses the considerable skill of the dentist and technician, and in this way, it’s similar to ordering a piece of hand-made jewellery. The materials are also expensive so it’s fair to say a bridge will not be the cheapest treatment you have ever had.
How do I look after my bridge?
You need to clean your bridge every day, to prevent problems such as bad breath and gum disease. You also have to clean under the false tooth every day. Your dentist or hygienist will show you how to use a bridge needle or special floss, as a normal toothbrush cannot reach.
