Not too knowledgeable about root canals, but there was much research done in the 20s by a Dr. Weston A. Price (do a google search, and you'll find an amazing interview with a Dr. Meinig that discusses Price's research, or check out this link:
mizar5.com/coverup.htm)
Apparently, biological or "holistic" dentists won't do root canals because of focal infections. They say that some bacteria or other toxin remains trapped under the dead tooth which leads to secondary health problems.
There is much info about this on the web. Go find yourself a good natural dentist!
Good luck!