The “sixth-age teeth” are the teeth that erupt at the age of six, and are easily mistaken for milk teeth and not taken seriously. The position and relative stability of the “sixth-aged teeth” determine its position in the dental row, and is the key to maintain the normal occlusal relationship between the dental arches. When people do orthodontics, they always take the “six-year-old teeth” as the reference, which is the teeth that are constant and not easily misaligned. Its height also affects the height of the lower third of the face. “During this period, some good habits have not yet been fully developed, and there are more chances for caries to occur, and if not treated in time, they often lose their functions or fall off very early. The size of the child’s chewing power directly affects the child’s healthy development, premature loss of function or loss of “six-year-old teeth” will easily make the child anorexic, which is not conducive to the child’s development; in addition, it will also have an impact on the development of jawbone, when the jawbone lacks proper stimulation after missing teeth, the development will be slowed down, often causing malocclusion and bite disorder; Premature loss will cause the displacement of other teeth. It should be noted that a good set of “six-age teeth” depends on the health of the second molar, which plays an important role in maintaining the normal position of the “six-age teeth”. If the second molar is lost prematurely, the “six-year-old teeth” may be displaced forward, resulting in the misalignment of the eruption of the bicuspids later, which may also cause the disorder of the entire dental row. Therefore, it is very important to protect the “six-year-old teeth”. Parents should pay special attention to the eruption of teeth during the period of tooth replacement, and go to the dentistry department for regular checkups, and if caries is found in the “six-year-old teeth”, they should be treated in time, and should not be easily removed.