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Crowns and bridges are fixed restorations, each of which have different purposes.
Crowns are used when:
there is a large cavity in the tooth and it can no longer be corrected with a filling.
a large filling or inlay in the tooth has to be removed and the natural crown of the tooth cannot be repaired with a filling
the tooth has severe congenital or acquired discoloration (e.g. enamel development defect, root-canal treated tooth).
restoring a tooth after root canal treatment.
Bridges are used when:
one tooth is missing and it is not necessary to use an implant.
more than one tooth is missing.
more than one tooth needs aesthetic correction.
splinting teeth which have become unstable
Crowns and bridges placements are made in a dental laboratory from an impression taken by the dentist from the prepared, trimmed tooth or teeth. Depending on how many intact teeth there are and whether they have had root canal treatment, trimming may be preceded by core build-up using a post or filler.
For a crown, only one tooth has to be trimmed, but for a bridge, the teeth on each side of the gap have to be prepared. The dentist applies a temporary replacement until the final one is ready. The final crown or bridge is fixed with special adhesive which cannot be removed later without damaging the crown.
Types of Crowns and Bridges
There are many different materials and techniques for making crowns and bridges.
The type most frequently is porcelain fused to metal. The metal core or cap of the crown or bridge is strong and flexible, to be capable of withstanding the biting force on molars. The dental technician then fuses several layers of porcelain on to the metal base. The porcelain has the same colour as the original tooth, resulting in a completely natural-looking tooth. Before adding the porcelain layer, the dentist tests whether the metal cap fits properly in the mouth, which means an extra visit. In our surgery, metal-containing tooth replacements are made from nickel-free cobalt-chromium alloy, which makes them appropriate even for people with nickel allergy.
For front teeth, crowns can be made from pure porcelain. These are known as jacket crowns. They have a very similar colour to the original tooth, but have the disadvantage of having to trim more from the surface of the front teeth, making them more vulnerable and less long-lasting. It is often also necessary to do root canal treatment on these teeth.
Zirconium oxide or zirconia is increasingly the material of choice for crowns. Zirconium is a metal, and its oxide is a ceramic material that has several advantages over the more familiar porcelain. It is as strong and hard as metal, and in fact it has better mechanical properties overall, but it is white in colour, giving it sufficiently good aesthetic properties to be used on its own. It is particularly suitable for people with metal allergies.
Zirconium oxide can only be worked using computer aided design/computer aided manufacturing (CAD/CAM) technology, which permits a very high degree of machining precision. The dentist takes an impression of the tooth in the usual way, but in the laboratory, the technician takes a laser 3D image of the impression and uses software to produce a “virtual crown”. The computer then directly controls the milling machine which carves the real crown from a block of zirconia. Crowns and bridges made with CAD/CAM technology are made with micron precision, unattainable without computer control.
Zirconium oxide is the material most commonly used with CAD/CAM systems, although metal and plastic can be worked in the same way.
Sometimes only the core of the crown is made of zirconium oxide, and the final aesthetic qualities are achieved by applying a layer of porcelain. We recommend this arrangement for restoring front teeth, where aesthetics are most important.
One of the most advanced CAD/CAM procedures is carving the whole crown from a block of zirconium oxide. This avoids the need for covering with a different material, and is mainly applicable for back teeth where function is more important than aesthetics. A pure zirconia crown or bridge – unlike one with a metal core – can cemented into place immediately, without the need for “test-fitting”.
Effective oral hygiene is essential to maximize the lifetime of a crown, bridge or veneer, and so we teach patients about proper cleaning technique after completing any fixed restoration.
Temporary Crowns and Bridges
After we prepare your teeth for a crown or bridge, we put a temporary restoration in place until the final one is ready.
Temporary crowns and bridges have several functions
They protect the prepared (reduced) tooth from mechanical action (chewing, hot and cold stimuli).
They are aesthetically acceptable, so that the patient does not leave the surgery without teeth.
They restore the chewing function.
They maintain the space between the neighbouring teeth and prevent them from moving together.
They allow the patient to get used to how the final restoration will feel.
If the neighboring teeth are prepared at the same time as a tooth is removed, a temporary restoration is needed until the gap has healed, a period of a month to six weeks. The final bridge can only be made after the gums have returned to normal.
There are two ways to make a temporary crown or bridge. One is for the dentist to make it immediately after preparing the teeth. We usually recommend this for short periods. The other is to have it made by a dental technician from an impression, which means that it can only be ready at the next visit. We use this for more protracted treatment procedures – waiting for the site of a removed tooth has to heal, or adjusting the bite.
Whether made in the surgery or the laboratory, a temporary restoration is made of tooth-coloured plastic. This is aesthetically acceptable, but not, of course, up to the standard of the final crown. It has an anatomic form, the same shape as the original tooth, but the surface is not as smooth. Its edges do not fit precisely, a situation which heightens the risk of decay, but it is not in the mouth long enough for this to be a concern.
The adhesive which holds the temporary restoration is easy to remove, and for that reason, a temporary crown or bridge can sometimes fall out or break when in use. If this happens, we will immediately put it back or make a new one.
Tooth brushing is just as important for temporary crowns and bridges!
Since my return to the UK I have received so many compliments on my new smile, it has given me new confidence. Thank you to all the team at Firstdent I will be back to see you soon"!
John from London
Dear Firstdent Team!
We both had a great time in Budapest and the dental work itself was simply first class, you carried out all of the work that we agreed in a most professional manner, using the highest quality materials, at a time to suit our holiday arrangements and all carried in your most modern luxurious surroundings.
Nobody could ask for anything more, I really do appreciate this level of service and I would not hesitate to recommend Firstdent to anybody.
Kind regards, Gordon