I had a cavity in my tooth. Dentist first said I may need root canal. I was traveling so he cleaned it and put something to settle down. When I visited her he did cavity filling instead of root canal. Cavity filling is hurting now.I don't feel I have sensitivity to hot or cold. When I went to get the crown for cavity filling, I told it is hurting, he said he will continue with crown and then we will watch for few days and if it is still hurting then we may have to do root canal. It's been 8 days, I still take a advil a day (gone down from 2). Is this common that you may need root canal after cavity filling. Do I need to pay again for root canal(I already paid for crown and cavity filling and now the root canal) now that dentist's cavity filling did not work?