Toothache in children with tooth decay indicates that the infection in the cavity has reached the pulp of the tooth, causing pulpitis or even periapical inflammation of the baby tooth. In this case, parents must take the child to the doctor in time to carry out root canal treatment on the affected tooth, which requires 2-3 follow-up sessions. The root canal treatment method can completely remove the infection in the pulp cavity of the baby tooth, relieve and remove the pain, and also prevent the further spread of the tooth infection. If the infection in the pulp cavity spreads to the apical region, it will affect the development of permanent teeth and lead to abnormalities in the development of permanent teeth.