Just found out that I need a root canal after my permanent crown has been put in. My bottom left far back molar had cracked requiring a crown. The tooth which had a filling in it looked good with no decay when the dentist prepared the tooth for the crown. After two weeks with the new crown, pain started. I went back to the dentist. He took another x-ray which now shows infection in my jawbone right below one of the roots. I am being sent to a Endodontist for the RCT. My dentist says that they will drill through the top of my new crown do the RCT and put a temporary filling in. Then I'll go back to my dentist for a permanent filling. This is my first crown and will be my first ever root canal. I'm pretty scared about the whole thing. After spending 1G on a new crown, can't they take it off to do the root canal? Why are they going to drill into it then patch it with a filling? Won't that weaken my new porceline crown? Thanks for taking the time to answer my questions.