root canals cause cavitations. when a root canal is done, the nerve is removed. 2/3 of the roots of a tooth is the dentine. it is inside the tooth and cannot b gotten to w/ a root canal. so, those roots decay and cause bateria. these bacteria r anerobic (they don't need oxygen; they feed off themselves). eventually, they eat at your jawbone and cause a cavitaion. that is a pocket of infection in your jaw that your body has to constantly fight. then, your immune system cannot fight off other conditions/diseases because it as to devoote time to the cavitations. if you keep this tooth, it will just continue to eat away at your jawbone. it was only some dentist who had some crazy idea that he could save a tooth by taking out the nerve, anyway; it isn't some scientific fact that we should have known forever.