When a tooth is rotten and painful, the first thing to do is to go to a professional dentist to have the tooth examined and treated. First of all, you should check the reason and the degree of tooth decay, in most cases, the tooth decay and pain are caused by tooth decay. At this time, we should check the degree of decay, if the degree of decay is mild, it is still in the stage of deep decay, and it does not cause the symptoms of pulpitis, then we can consider applying the direct repair method to fill the cavity after decay removal. If the decay has penetrated deep into the pulp of the tooth, then it is necessary to perform root canal treatment for the tooth, and after the root treatment, it is generally recommended to restore the crown of the tooth to protect the crown, so that the tooth can serve the chewing function for a longer time. However, if the tooth is so badly decayed that it has reached the roots and sometimes the tooth cannot be retained, then the tooth needs to be extracted directly and then restored by means of implant restoration or movable restoration, etc., to treat the missing tooth area.