How can mouth breathing cause changes to the structure of the mouth & face?

Keeping an open mouth posture can cause: dry and chapped lips, short and fast breathing; diminished strength of the muscles of the lips, cheeks, jaw, and tongue; a lowered and more anterior rest posture of the tongue, leading to changes in the position of teeth; elongated face, retruded mandible or small chin, and palate (“roof of the mouth”) becoming more narrow and /or deep.