Had a root canal by a endo,simply because my dentist attempt to do ,however failed this pass AUG,2016 DUE THE OLDER YOU GET SMALLER THE NERVE .MY PERSONAL insight is my canal work was done on upper RI tooth.I will get to my point.Personally the endo drilled tooDeep,THEREFORE I HAVE SERVE SINUS PROBLEM .MEDICARE HAS CONTACTED ME IN turn my ent,allergy docs primary phycian as simple to explain endo went to deep &trigger SERIOUS RESPOTORY along terrible past nasal drip.Hopefully no one else had these promblems.TAKE CARE.