The main causes of facial size asymmetry are as follows: 1, congenital factors: for example, congenital facial mandibular hypoplasia, zygomatic bone imperfect development, which can cause asymmetry on both sides. In addition, dental dentition problems, such as dental asymmetry can also lead to facial asymmetry; 2, secondary factors: more common, such as red gums, gum swelling and other acute episodes of disease, as well as lymph node enlargement, parotid gland disease, will appear in the face size asymmetry. This outside neuritis can cause facial nerve paralysis, muscle atrophy, facial muscle spasm, etc. All of the above are triggering factors for facial size asymmetry. All of these are triggering factors for facial size asymmetry.