The 3 reasons for the placement of crowns (caps) and bridges:
The first reason is that a tooth has been so badly damaged by decay or so heavily restored
by fillings that it can only be saved with cast restoration.
The second reason is that a tooth has been treated endodontically (root canal treatment).
These teeth are almost always restored with a cast restoration because they have lost a great deal of tooth structure from fracture, decay, or the drilling process. These teeth are prone to fracture under normal and light chewing forces
The third reason a crown might need to be placed is that the tooth needs to be used as an
abutment (anchor) for a bridge to replace missing teeth.
Hope the above information is useful who needs it.
Thanks and your comments are welcome.