I am going through dental treatment since 10months approx. Both of my front teeth ars root canel trated due to tooth abscess. After final crown placed, there for no pain for 15days.now suddenly pain in started again in one of the tooth and it is swelling my upper lip. I have waited for a week but still pain exists. Please suggest what should I do. My dentist told me once that there may be crack in tooth root and it need extraction but he can't see crack in x-ray. I dnt want to loose my original tooth. Please suggest what should I do.