Root Cancel retreatment vs extraction

Posted by dory

I had a root canal done on tooth #3 over 20 years ago; now there is an infection in one of the canals.  Antibiotics have not helped so the options are retreatment or extraction.  I know the importance of keeping the original tooth, however I was told the success rate is only 50/50.  I have also had a lot of nose bleeds on the same side and everything smells and tastes the same.  Any advice is greatly appreciatied.