How is a second root canal possible, if there is no root and no pain?

technically your tooth its death, has no nerve or blood support, so the normal way of the bone and body to react its to make a microscopical rejection, there is no root canal that seals 100 %, and all the root canals if you see them with a microscopic microscope,there is a halo, around the tooth, of the body rejecting that tooth, that has or either infection, or its a death tooth ,so no matter if any doctor makes or perform a root canal,there is always a chance of rejection always, this is more determined by the body acceptance,and tolarance,and just a few years ago root canals are performed, time before they used to extract teeth, now there is a an option,materials are organic,and 100 %compatible,but if the body reacts by making an infection,anaerobic microorganism are present, and once there is a communication with air, they will die,and antibiotics will help, and you will still be able to save that tooth,so re do that root cannal, and problem solved,try a dental vacation in sunny cancun,and for half you will pay ,you will find a solution,

A root canal removes the nerve not the root. Rather than lose the tooth, you should have the root canal redone. Antibiotics remove the symptoms but not the cause.