In most orthodontic cases, the range of tooth movement is forward and backward, so the appearance of facial profile changes the most. For example, in the case of sudden teething, the lips will become easier to close because the front teeth move backward, and the front teeth will not be easily exposed. Therefore, the face will look better from the side or from the front.

Because it involves future stability, general orthodontics does not change the width of dental arch much. Even in some adolescent cases, rapid maxillary expansion may be used to correct the narrow maxillary arch, but it should not have much impact on the width of the face.

Doctors can't control the facial changes of growing patients. The face change of adult patients may be caused by the change of lifestyle such as inconvenient diet, pain and psychological stress during orthodontic treatment, which makes the human body clumsy (because there are almost no thin faces of minors in clinic, because their psychological stress during orthodontic treatment is far less than that of adults). The fundamental reason is still unclear, which is one of the academic difficulties of orthodontics.