Doctor: Bone of the ground, that is, the inverse joint, especially hereditary is more difficult orthodontic treatment, generally divided into three cases, one is the upper jaw is underdeveloped, this case can be performed early orthopedic treatment (such as front traction), the effect is better; one is the lower jaw body is long, the lower jaw protrusion, this orthopedic treatment is not effective, serious to be performed after adult surgery; there is another is the upper jaw is underdeveloped and the lower jaw is overdeveloped This treatment depends on the specific situation. Early orthopedic treatment should be carried out during the pre-puberty growth spurt, about 8-10 years old, when treatment can be effectively carried out.