If a tooth already has an extensive amount of decay or has been damaged to to injury, the dentist may suggest a crown. A crown is a dental restoration that replicates an entire tooth.
First, an impression is taken of your mouth, and the crown is created in a lab to be a perfect fit for you. Then, the remaining tooth will be reduced and shaped to create the optimal support structure for the restoration. If any decay is present, it will be removed.
The crown will then be bonded to the tooth structure, "capping" it and completing the process. This entire process will take several visits and possibly involve a temporary crown.
A crown is a long term restoration and with careful maintenance and proper oral hygiene can last for decades. It will look and feel just like a regular tooth.