The lower jaw teeth should be on the back side of the upper jaw teeth under normal circumstances. The best time for correction depends on what type of jaw protrusion, commonly including the following: 1, functional jaw protrusion: generally due to breastfeeding, the bottle or containing the nipple in the incorrect position and direction, causing functional jaw protrusion, can be corrected at about 4 years of age using functional orthodontic appliances, movable orthodontic appliances. 2, temporary or teeth alignment caused by jaw protrusion: generally at the age of about 12 years old can go to the Department of Orthodontics for correction, some patients can be corrected over. 3, hereditary mandibular protrusion: Generally, overdevelopment of the lower jaw or underdevelopment of the upper jaw causes osteogenic mandibular protrusion, which can be treated with orthodontic treatment around the age of 16 and orthognathic surgery around the age of 18. Patients or parents are advised to visit a regular hospital as soon as possible when they find their child with geodontia to avoid missing the best time for treatment, use the aligners as prescribed by the doctor, and follow up regularly to obtain satisfactory results. During the orthodontic period, it is necessary to protect the aligners carefully, avoid eating hard foods and pay attention to oral hygiene.