A crown is a "cap" to place over a damaged tooth. If a tooth has a significant amount of decay on multiple sides, a filling may not be the best option for building the tooth back after removing the decay. A stronger option would be the use of a crown. Crowns are made in a dental lab after your tooth has been prepped and an impression has been taken of the tooth. The crown will come back from the lab and will be cemented onto the tooth.
Bridges are multiple crowns connected together to "cap" 2 teeth adjacent to a missing tooth in the middle, thus creating a "bridge". Bridges are a great option to replace a missing tooth when the teeth next to it also need a crown.
Sensitivity to cold, hot, and pressure
Presence of a deep and wide cavity that is too large for an ideal standard filling
Deep hole in tooth
Need of a permanent restoration over a root canal
Replace a missing tooth (bridge)
Crowns and bridges are both made in dental labs from impressions taken of the prepped tooth/teeth. The tooth is prepped by removing all decay around the tooth. Next the tooth will be shaped to the ideal measurements of height and thickness for a crown to optimally be placed over. Once shaping is done, an impression will be taken to send to the lab to fabricate the crown or bridge to proper dimensions. It is common for a temporary crown or bridge to be made in the office until the permanent restoration has returned from the lab.
After a permanent crown or bridge has been placed, it is advised to not eat on that side of the mouth for the first day. This will allow the cement to properly dry without interruption. Continue to keep up with a proper hygiene routine of brushing and flossing to help prevent decay from entering underneath the crown.