If a 4-year-old child has tooth decay, it is recommended to go to a dentist for treatment or pediatric dentistry in a timely manner. Usually, permanent teeth start to erupt around 6 years old, and the back teeth will be replaced one after another only when they are 9-12 years old, so they need to be used for a long time. Once a cavity appears, it should be repaired in time, and it can be filled with glass ionomer or composite resin after grinding out the decayed material. If the symptoms of gum abscess or pulpitis have appeared, root canal treatment or nerve killing treatment is needed. In addition, if children’s tooth decay is not treated in time, there is a possibility that the decayed area will become large and become tooth splitting or root stump, then the tooth may need to be extracted and lose the function of chewing, and the development of jaw bone will be affected, and it will affect the eruption of teeth, and the permanent teeth may also produce the phenomenon of enamel underdevelopment. Therefore, once tooth decay occurs, it is important to consult a doctor in time to avoid affecting the development of jawbone and the general health.