A 5-year-old child’s tooth is corroded (clinically known as caries) depending on the severity of filling treatment, root canal treatment or tooth extraction. 1. If the tooth decay does not damage the pulp tissue, i.e., no obvious symptoms such as spontaneous pain, hot and cold pain, or night pain, etc.; it can be directly filled and repaired, and the decayed part can be cleaned up and directly filled with the filling material. 2. If caries causes pulp infection and symptoms of pulpitis, root canal treatment is necessary to clean up the infected and inflamed pulp tissue in order to effectively cure the above symptoms. 3. If the tooth is severely decayed and most of the tooth tissue is missing and cannot be preserved by filling treatment or root canal treatment, the tooth must be extracted in time to prevent symptoms such as tooth swelling and pain. It is recommended that a 5-year-old child with decayed teeth should seek prompt medical attention for a clear diagnosis and symptomatic treatment in order to avoid delaying the condition.