Root canaled 2nd upper molar still hurts & with previous chronic facial jaw pain. dentist said impossible as no root. considering extraction. wise?

You need a diagnosis: It is certainly very possible for a root canal treated tooth to be painful for a number of reasons. Depending on the time that has passed since the root canal procedure was completed and the clinical and radiographic evaluation of your tooth, a treatment plan should be possible. Extraction may be indicated if there is a root fracture or it may be something else altogether.

See an endodontist: If a tooth cannot be saved, it will need to be extracted and replaced with an artificial, tooth. You should get a second opinion with an endodontist about all of your options.