If you have a cavity or injury to the root of one of your teeth, it will usually cause the root in that tooth to become infected, which causes redness, swelling, and pain. To fix this problem, the dentist will have to perform a root canal procedure. This includes removing the infected area, cleaning the root canal, and filling it with a material to prevent further infection.
After the procedure, the dentist will rebuild your tooth by filling what is left of the tooth with a filling and crown. The crown can be made of many different substances like ceramic, resin, gold, stainless steel, or porcelain.