CROWNS AND BRIDGES
There are several different types of crowns and bridges and the type you may require will depend on multiple factors.
A crown is a covering usually made from porcelain/ceramic with or without some metal. This goes over the top of the natural tooth structure (which might have been built up with some filling material) to either strengthen it, protect it or to change the appearance of the tooth.
Depending on the material used to make the crown, the tooth will be prepared to some extent. Some of the tooth tissue is usually removed to create space for the crown to fit on top. This can range from 0.3mm to around 2mm. There is a small risk when the tooth is prepared that an alive pulp/nerve inside the tooth may die, meaning that a root canal treatment is also required. Therefore this procedure is not risk free and if being done for cosmetic purposes particularly, these are things which should be carefully considered.
The choice of material can affect how the crown is going to look, and the decision partly depends on how much tooth tissue there is, the health of the tooth and tissues around it and the amount of space for the crown.
Most root canal treated teeth benefit from having a crown placed, to hold the tooth structure together and provide support. Research has shown that the seal/restoration of the tooth after root canal treatment is a key factor in determining success of the treatment.
Some crowns are entirely made of metal. These can be very strong and usually require less natural tooth tissue to be removed, however you may prefer to have a white crown so it isn't noticeable amongst your other teeth.
A bridge is a false tooth to replace a missing tooth, with part of it attached onto a natural tooth. The artificial part is called the pontic and the natural tooth which holds the false tooth is known as the abutment. Some bridges have a wing to attach them to the adjacent tooth and this can mean that no preparation of the healthy tooth is required. Other times the false tooth is attached to a full 'crown', like those described above. Depending on the clinical situation, a different design may be appropriate and in some cases the false tooth is attached to more than one adjacent tooth. This is a decision to be made between yourself and the dentist.
Crowns are used to restore implants and sometimes crowns and bridges can replace multiple teeth in a row, but not all patients can have this treatment. If you are going to have a crown or bridge, it is likely this will be done across more than one appointment. As a minimum, most dentists will prepare the tooth, take an impression/mould of the tooth, and place a temporary crown. The crown can then be made in the laboratory and you return for a second appointment where the new crown can be placed. Sometimes further measurements and planning are required, but this varies between cases.