Crown, Veneers & Bridges

Crowns

Why Do We Crown Teeth?

The main reasons for restoring teeth with crowns are:

To strengthen a badly broken down or weakened tooth,
To improve the appearance of a badly broken down or heavily filled tooth,
To support one end of a bridge which is replacing other missing teeth.

Crowns come in many forms, the most common varieties are:

All Porcelain
Porcelain Bonded to Gold
All Gold

All Porcelain: These have the most natural appearance for some tooth types, but they are weaker than metal reinforced crowns. They are built up of many layers of tooth coloured porcelain and are translucent and very tooth-like indeed. Unfortunately the strength of this material usually limits its use to the front of the mouth.

Porcelain Bonded to Gold: This type of crown consists of a thin gold casting, which fits the tooth and reinforces a covering layer of porcelain, which gives the tooth a very natural appearance. The majority of crowns for back teeth are made in this way, however the combination of metal and porcelain is relatively thick. This can sometimes make using this type of crown difficult if there is not enough space available between the crowned teeth and the opposing teeth.

All Gold: These crowns are made of yellow or white dental golds. They are very strong and resistant to biting forces, and can be made very thin. The preparation for this type of crown is conservative, and full gold crowns can be useful where there are strong biting forces and there is little space in the bite.

Before a tooth can be restored with a crown a strong foundation must be built on what is left of the tooth. This foundation helps to strengthen the tooth and ensures that the crown is well retained. The foundation or "Core" may either take the form of a large filling retained by adhesive techniques, or a glass-fibre post or laboratory-made cast gold post that is cemented to the prepared tooth. Posts are usually used with root filled teeth, where very little tooth structure remains.

Teeth that need crowns are usually broken down and in a poor state of repair. Because of this, there may be pre-existing inflammation of the dental nerve. An infrequent problem, which you should be aware of, is that just occasionally this inflammation may be too advanced to respond. Under these circumstances further treatment such as root canal therapy may be required.

Veneers

A porcelain veneer is a thin layer of custom-made porcelain which fits over the front of the tooth. As with traditional porcelain and gold restorations it is made in the laboratory by the dental technician on models of the prepared teeth obtained by taking very accurate impressions in the mouth. A strong bond between the veneer and the tooth is achieved by etching the tooth, and using a special adhesive. The result is a strong 'sandwich' restoration.

Veneers will never completely replace crowns which will often still be required for structural reasons - some of the indications for veneers are:

Highly discoloured and stained teeth
Poorly positioned teeth can be built forward.
Worn or fractured teeth can be restored to their original contour.
Spaces can be filled and a more regular appearance restored or created.

Tooth shapes may be dramatically altered. The great advantage of a veneer is that usually only minimal tooth preparation is required making this is a relatively conservative procedure, with the potential for a dramatic improvement in appearance.

Sometimes the technique can also be used in side and back teeth.

Bridges

Bridges are used to replace missing teeth. The teeth on either side of the "gap" are usually prepared to receive the bridgework which extends from tooth to tooth.

Bridges used to be considered the best way to replace missing teeth using a fixed reconstruction. However, as dental implants are reliable and feel more natural, we tend not to use this type of bridgework on a permanent basis, unless there is a good reason not to use the implant alternative.