Mouth breathing is a common condition in many children and can lead to poorly developed facial growth. As reported in “Dental Town,” June 2010, when air is not directed though the nose into the sinus cavities, but rather is sucked straight into the throat, the sinus cavities may not fully develop. Since the roof of the mouth is the “floor” of the sinus cavities, this can lead to a narrow palate and crowded teeth. Also the cheek bones are the side walls of the sinus cavities and mouth breathers can have a more sunken appearance when the sinus cavities are poorly developed. Bottom line: if your child is a mouth breather, see the ENT or allergist to learn what can be done to get them breathing through the nose. Also early orthodontics for mouth breathers can help to expand the roof of the mouth and avoid future dental problems.