Hemignathic surgery is a surgical operation to deal with jaw deformity problems caused by overdevelopment, underdevelopment, and childhood habits (always chewing food on one side as a child), correct abnormal jaw positions, and improve Teeth occlusion relationship.

Normally, in order to rebuild the relationship between teeth, pre- and post-operative orthodontic treatment (i.e. realignment of teeth) is required in the dental department. The main purpose of preoperative orthodontics is to promote the movement of the jaw during surgery by adjusting the relationship between the maxillary and mandibular dental arches, thereby laying a good foundation for surgical correction. The main purpose of postoperative orthodontics is to further improve the bite relationship, achieve dental and jaw balance, stabilize the surgical effect, and prevent recurrence.

During the above process, the upper and lower jaws will be operated on. Generally, the chin will not be moved. However, if the chin is severely crooked while the jaw is biased, the chin may need to be corrected simultaneously.

Of course, not everyone with a biased jaw can undergo surgery. If a minor has a biased jaw, surgery cannot be performed temporarily because the minor's skeletal development has not been finalized, so surgery is required. There will be certain unknown risks. More importantly, after the surgery, the bone tissue of minors will grow and develop again, which will not achieve the purpose of maintaining the surgical correction effect for life. Therefore, it is recommended to perform surgery after adulthood.