These are fixed prosthetic devices that are cemented onto teeth and implants and can only be removed by the dentist.
Crowns are used to cover an entire tooth that is either fractured, root canal treated or that has a large filling that could weaken the tooth. The tooth is first shaped and impressions taken after which once the crown is ready, it is then cemented onto the shaped tooth.
Bridges are used to replace missing teeth using existing teeth or implants as anchors. This can prevent shifting of teeth into the gaps left by missing teeth. Depending on the number of missing teeth, the teeth on either side of the gap are shaped to receive crowns and the missing teeth attached to the crowns to be cemented onto the existing teeth. They are made of different materials such as porcelain, metal or zirconium.