If a four-year-old child has a large gap between teeth, there is no need to do special treatment immediately, because the size of permanent teeth is obviously larger than the milk teeth with the advent of the period of tooth replacement, so it is possible that the gap of the milk teeth will be closed after the permanent teeth erupt. At the age of four, the most important thing is to observe that the food residue should not be kept in the tooth gap, because the food residue may cause the adjacent surface caries of the milk teeth, which may cause pain to the child or the teeth have heavy caries, causing the child to have poor chewing function and poor nutritional function. For four years old children, the large gap between teeth is not an abnormal problem, and there is no need for special treatment as long as they are not suffering from dental caries under close observation.