Theoretically, toothache caused by tooth decay is in most cases an inflammation of the pulp, that is, a toothache caused by pulpitis. In this case, if the tooth is extracted, the pain is naturally relieved without the lesion of pulpitis. However, in actual clinical work, this is absolutely wrong because the treatment is inappropriate. The decayed tooth can be completely preserved and there is no need for extraction, which is like a fractured arm, the best way is to perform a cast or an incision for fixation instead of direct amputation. It may sound exaggerated, but it is also true for teeth. For decay that has progressed to a painful stage, the tooth can be completely treated by means of pulp drainage and root canal treatment to make it painless, and finally the tooth can be protected by crown restoration. The tooth will still be able to serve the chewing function of the mouth for a long time instead of having to be extracted because of the decay.