If there is a cavity in the decayed tooth and there is a smell of decay, there is usually a large amount of accumulated food inside, so it is recommended to take an examination and diagnosis first to see how far the decayed tooth has reached. If the cavity does not involve the pulp corner or pulp cavity, the decayed material can be removed and filled directly, if it is a large area of decay, inlay restoration or full crown restoration can be carried out to preserve the tooth body and pulp. If it has reached the pulp cavity and involves the nerve, then root canal treatment is needed, after sealing the medicine in the root canal, the tooth is observed and then disinfected, and the tooth can be filled with hot-pressure adhesive, and the whole surface of the tooth is sealed. After sealing the crown, inlay restoration and porcelain crown restoration can be done to ensure a good adjacent relationship, and to ensure the hardness and pressure resistance of the tooth, to ensure that the tooth remains for a longer period of time, and to ensure the alignment of the tooth.