A crown is a type of dental restoration, a tooth shaped 'cap' that is placed over a tooth.
Crowns can be made from various materials, such as stainless steel, all metal (such as gold or another alloy), resin, Porcelain-Fused-to-Metal or all ceramic. The most commonly used are the PFM and all ceramic.
Porcelain-fused-to-metal dental crowns(PFMs) have a metal shell which provides strong compression and strength, and a porcelain external part which gives the crown a white tooth-like appearance, suitable for front teeth restorations.
All-ceramic (all-porcelain) dental crowns provide better natural color match than any other crown type. They are not as strong as porcelain-fused-to-metal crowns, but they are a great choice for front teeth.
We recommend a crown after we restore a badly fractured tooth, when we want to protect a weak tooth from breaking, when we need to cover a discolored or poorly shaped tooth or when we attach a bridge and finally after any root canal treatment.
Preparing a tooth for a crown usually requires two visits to the dentist -- the first step involves examining and preparing the tooth, the second visit involves placement of the permanent crown.
Before a crown can be made, the tooth must be reduced in size so that the crown will fit over it properly. After reducing the tooth, an impression will be taken to provide an exact mould for the crown, and finally a suitable shade for the crown will be taken in order to match the color of the existing teeth.
Using this impression, a dental lab then constructs the crown in the material the dentist specifies. A temporary crown will be placed to cover the prepared tooth while the permanent crown is being fabricated. Once the permanent crown is ready, the temporary crown is removed, and the new crown is bonded to the tooth using a dental cement.
On average, dental crowns last between five and 15 years. The life span of a crown depends on the amount of "wear and tear" the crown is exposed to, oral hygiene practices, and personal mouth-related habits.
A bridge is a fixed dental restoration used to replace a missing tooth (or teeth) by joining an artificial tooth permanently to adjacent teeth. By definition, dental bridges literally bridge the gap created by one or more missing teeth. For example a bridge covering one missing tooth is made up of two crowns one on each anchoring tooth on either side of the gap and a false tooth in between.
There are three main types of dental bridges:
Traditional bridges are the most common type of bridges, which involve creating a crown on either side of the missing tooth, with a pontic in between.
Cantilever bridges are used when there are adjacent teeth on only one side of the missing tooth.
Maryland bridges, are made of porcelain or porcelain fused to metal and carry metal or porcelain wings on each side of the bridge, which are bonded to the existing teeth.