Recently I've seen several references to a documentary named "The Root Cause" and just this week someone at the office asked me about it I have not seen this personally since it appears to have been pulled from the online libraries of most sites where I have a subscription.
"The Root Cause" does appear to be based on the experience of a single person and that person's viewpoints and beliefs. Though he does have "experts" comment on this, I'm sure he chose "experts" to feature in his documentary that agreed with his beliefs. As Americans, we have the right to free speech. We can say almost anything we want--but that doesn't always make it true, just like reading something on the internet doesn't always mean it is true.
I would hate to see someone totally discount a valid dental treatment, such as root canals, based solely on this documentary. To be honest, it seems like these same claims pop up every so many years. Much seems to be based on the work of Dr. Weston Price, whose theory was proven false many years ago.
In fact, very little scientific evidence exists to support most of the claims made in this documentary. So I invite you to take whatever claim you are interested in from this documentary and to do a thorough search of the scientific literature on your own and see what the majority of it says.
If you're not the type to do your own scientific research then here are two reviews that you can read--one by a dentist and one by a dental hygienist:
P.S. In case you're wondering, I do have root canals on my teeth--on multiple teeth in fact--and I would not hesitate to get another one if I had a tooth that needed it. (I also have a dental implant that replaces a tooth that couldn't be saved with a root canal. Since I only have one dental implant surrounded by other teeth, I don't feel I can speak to how well it replaces a tooth and whether it feels different than having my own teeth.)