It is not necessary to extract the nerve of the tooth to fill the tooth. There are two kinds of fillings: the first one is simply with caries, get rid of the decaying matter, and if there is no nerve problem involved, it can be filled with resin. If there are pulp symptoms, such as hot and cold stimulation pain is obvious. The second kind is that there is still delayed pain or spontaneous pain, biting pain and other symptoms after removing the stimulus, the problem cannot be solved by simple filling, and the root canal needs to be treated before filling or crown restoration. If there is nerve symptom, simple filling cannot solve the fundamental problem.