Why does my jaw hurt after root canal therapy?

A lot of reasons: If you had a bad infection to start with, yes you may still have lingering effects. If the treatment was difficult or f the dentist could not for any reasons clean all the canals all the way. And in general it is normal to experience some mild pain for a few days or a week depending on your case and your pain tolerance. Pain killers should usually help good luck.

Call yor dentist: Some degree of discomfort may be normal immediately after root canal treatment completion or between visits, but other, serious dental problem may be occurring, so you need to call the treating dentist and have them make a proper determination as to the cause of your pain.

Depends: Your jaw joint may be sore from staying open for the entire time of the treatment. Or the jaw under the tooth may be sore just from the actual process of the root canal treatment. Take whatever it is you take for a headache (aspirin, advil, tylenol, (acetaminophen) etc.) for the soreness. If full blown pain or swelling develops, return to your dentist.

Time frame?: How long after the root canal? If more than a few days, you may have persistent disease not treated. Go back to dentist. If dentist not an endodontist, you may want another opinion from a board certifiec endocontist.