There are lots of holistic doctors who believe W. A. Price's research about root canals and chronic health issues and have seen it in patients. In a nut shell, the tooth is dead but they fill up the nerve cavity with something and seal it off with a crown. But there are tiny spaces in there where bacteria flourish, often anaerobic bacteria. Dr. Price had so many patients with chronic health problems and root canals. He removed the tooth and surgically implanted it into a rabbit. The rabbit developed the same health issue that the person had, every single time. Removing the tooth and scraping out the nerve cavity improved the person's health.
So, there's that.
Secondly, it's just a scam. When I had a tooth that "needed" a root canal, I said I didn't want one. The dental assistant assumed I was afraid of the procedure and went on to tell me how nice and gentle their endo was when she had a root canal done. Her exact words, "I got three more years out of that tooth before it started hurting again and I needed to have it pulled."
. She was very surprised when I told her that was very helpful, pull the tooth.
Teeth with a root canal all need to be pulled eventually, they start hurting again. A root canal is thousands of dollars. Having a tooth pulled is a couple hundred.