A decayed tooth in a six year old can be treated with a direct filling or a root canal. Most of the teeth in a six year old child are milk teeth, and the large teeth in the back are not replaced until the age of 12 or 13 years old. After the tooth is decayed, a drill is used to remove the decayed portion of the tooth, and if the nerve is not exposed, the tooth is filled directly. If the tooth decay is deeper, or the tooth has pain from eating, cold, hot, sour or sweet stimulation pain, the nerve is exposed after removing the decayed tooth tissue, root canal treatment is needed. Therefore, six-year-old children with shallow tooth decay can be filled directly, and serious caries need root canal treatment, you can go to the stomatology department.