root canal is absolutely the worst medical procedure as far as maintaining physical health and well-being. I would not doubt if dental procedures in general are the causes of many preventable diseases.
Simply stated, rotting flesh inside the body eventually produces harmful and deadly toxins. These toxins create infections that eventually spread throughout the body. Although, you can remove a rotting appendix and tonsils etc. complete without incident. Meanwhile trying to remove the entire root is completely impossible. The situations are similar, the outcomes are ostensibly different.