I had a cavity in one of my molars that was filled a year ago. After it was filled, I had a lot a problem with the tooth and I ended up with a root canal treatment. After the procedure, I got a temporary crown which also gave me problems. I had pressure pain and heat sensitivity. I went back to the dentist who saw no problems on X-rays. He decided to put the permanent crown on to see if it would solve the problem but unfortunately, it didn't. I still have extreme sensitivity to heat. Cold does not hurt, though.
How can I have this extreme sensitivity to heat after a root canal and a crown? Please help!

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