回复：是牙医的责任吗？

Yes, he/she need take this responsibility.
Under the local anesthesia, the dentist may did a little "too" deep procedure to reach your dental nerve. After the anesthetics wean off, you feel uncomfortable due to the nerve exposing to the hot or cold water....before, you did not have that.
that is why 牙医说需要做根管治疗.
We know, most of dentists can do 根管治疗, but If I were you, I am looking for the specialist-dentist for 做根管治疗. the specialist have extra training for that.