Both crowns and most bridges are what are termed fixed prosthetic devices. Unlike devices such as dentures, that must be removed and cleaned daily, crowns and bridges are cemented onto existing teeth or implants, and can only be removed by a dentist.
Dental crowns are used to fix problems such as badly decayed teeth, fractured teeth, as well as to protect and strengthen teeth. Because a dental crown covers the whole tooth in order to restore it to its original shape and size it is often called a cap.
The whole procedure is done in two visits and the process starts with removing and cleaning decay from the tooth. After that highly accurate impressions are made of the surface of the tooth. The impressions taken from the tooth are used to create a model of the tooth. The model is then sent to a laboratory where the crown will be made. After the crown is made it is then cemented onto the treated surface of the tooth.
If dental crowns are placed properly they should sit almost sit perfectly on the prepared surface of the tooth, which will reduce the size of the seam between the tooth and the crown. The reduced seam will help keep decay from eventually forming under the crown. Dental crowns should only be placed on a tooth that is not so decayed it may fracture and cause further damage. With good oral hygiene and regular dental exams your new dental crown can last you up to 15 years.
Dental bridges are used to fix problems such as a missing tooth or teeth, bite and jaw joint problems due to teeth shifting to fill a space, sunken face look associated with missing teeth, improve chewing ability, and as a more permanent solution than dentures.
A bridge is a single appliance usually attached to two teeth on each side of the space where a tooth is missing. The teeth on either side of the bridge are prepared for crowns (see crowns above) and an artificial tooth is placed in the middle of the bridge to cover the space where the missing tooth was. The bridge is cemented over the prepared surface of the teeth and gap, this effectively gives the appearance of a new tooth.