In adults, since the facial shape has basically been developed, the effect of mouth breathing on the facial shape is relatively small, affecting only dry mouth and reduced sense of smell. For children, because they are in the growth and development period, their facial shape is constantly changing, so if they keep using mouth breathing, it will indeed cause certain changes in their facial shape. Because the mouth is not the main organ of respiration, but the auxiliary organ of respiration, we should use the nasal cavity to carry out the main gas exchange, not the mouth. If the mouth is used for a long time during childhood, it can cause a series of problems. These include dental and maxillofacial malformations, which can include high arched palatal lids, elongated faces, outward protrusion of the maxillary anterior teeth, narrow maxillary arches and open lips and teeth, and a host of other problems.