A mouth breathers’ maxillas and mandibles are more retrognathic. Palatal height is higher, over- jet is more pronounced in mouth breathers. Overall, mouth breathers had longer faces, with narrower maxil- lae and retrognathic jaws. 

 Reference: Mouth Breathing in Allergic Children: It’s Relationship to Dentofacial Development Bresolin, Shapiro E.T. Al. American Journal of Orthodontics 1983.

Orofacial Myofunctional Therapy is very effective, allowing a child or adult to learn or relearn to establish a tongue to palate resting posture and lip seal. In the absence of a nasal obstruction, primary nasal breathing is one of the most important health benefit one can have.  Reference: The importance of Nasal Breathing.