Crowns and Bridgework
What Are Crowns and Bridges?
Both crowns and bridges are fixed prosthetic devices. Unlike removable devices such as dentures, which you can take out and clean daily, crowns and bridges are cemented onto existing teeth or implants, and can only be removed by a dentist.
Crowns can be used to rebuild badly broken teeth. 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.
What are crowns made of?
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 metal: A metal base is made and layers of porcelain are then applied over it.
• Porcelain: these crowns are not as strong as bonded crowns as they are naturally very brittle and can crack. They can look very natural and are most often used for front teeth.
• Newer reinforced porcelains can reduce the issue of porcelain fracturing. They cost a little more than standard porcelain but can last much longer
• Precious metal (gold and palladium): these crowns are very strong and hard-wearing, but are not usually used at the front of the mouth, where they are highly visible.
How is a tooth prepared for a crown?
The dentist will prepare the tooth to the ideal shape for the crown. This will mean removing some 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 they need to make the crown.
The technician then makes a custom made crown that fits the preparation perfectly. This resembles a tooth shaped thimble and can be slipped over the tooth core and cemented in place.
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 could endanger the crown. Properly cared for crowns will last for many years – your dentist will be able to tell you how long.
The following is a man who had avoided dental treatment for many years. After a program of prevention to halt the disease process, Claire was able to restore his teeth with minimal preparation crowns.
Bridges are an alternative to dentures and implants to replace missing teeth. When looking to replace missing teeth, dental bridges are a very good option. These false teeth are attached to neighbouring teeth with the purpose of filling the gap caused by the original missing teeth. Other options would be to leave the space or have a denture or implant fitted.
There are 2 basic styles of bridge. The first uses crown type preparations on neighbouring teeth to hold the false tooth in place.
The second style is a resin bonded bridge where metal wings are bonded onto the neighbouring teeth. These involve far less tooth loss than the traditional bridge but may not last as long.
The next photos show a girl who was missing 2 front teeth. Claire replaced these with resin bonded bridges.
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