CROWNS & BRIDGES
Indirect restorations are fabricated in the dental laboratory from impressions taken once the tooth has been prepared. Typically these might be porcelain crowns. When the crown is returned from the laboratory it is cemented in place. Laboratory fabricated crowns are much harder and stronger than any filling materials which are placed directly in the mouth. There are many varieties of modern ceramics that range from extremely tough to those offering outstanding translucency and a vital appearance. They are often placed when a tooth already has extensive restorations especially if the tooth has undergone root canal therapy. Importantly the crown makes a collar around the underlying tooth structure and filling material and holds them together. Crowns may be fabricated when there is much wear on a tooth, or to restore its shape or colour. Often the appearance is dramatically improved when a tooth has multiple existing fillings. A temporary crown is used between the preparation and cementation appointments. Crowns are more expensive, but have a considerably longer life expectancy than large directly placed fillings.
A bridge may be suggested to replace an extracted tooth. This is achieved by preparing crowns on the adjacent teeth and cementing the combined crowns and connected bridge tooth (the pontic) when it is returned from the laboratory. This option is especially useful if the teeth adjacent the space have large restorations and so benefit from the protection of the crowns. Fixed bridges are much easier to keep clean than removable partial dentures. Partial dentures always pose a risk to the hygiene of the supporting natural teeth.