When I was 10 years old I had a root canal done. I am 21 years old now, and after recently joining the army, I was required to go to the dentist. At the dentist, he was concerned my crown wasn't placed correctly so he decided to take it off and replace the crown. Before this, I NEVER had any pain in this tooth, but after the crown was replaced I get a tooth ache at least twice a day and the tooth seems to be very sensitive with hot and cold temperatures. I'm just very confused because I know the tooth is considered a "dead" tooth so why am I experiencing pain?