Mode of respiration and facial growth.

There is a substantial amount of evidence to support the theory that the spatial relationship of the mandible to the craniomaxillary complex is influenced, in part, by the function of the muscular elevators of the mandible. One factor acting on the elevators of the mandible is the rest position of the mandible, which may be influenced by the patient's mode of respiration. Obstruction of the nasal airway is followed by the lowering of the mandible to establish an oral airway. Allergic rhinitis is one cause of nasal airway obstruction. There are reports that avoidance of the ingestion of foreign airway. The orthodontist should recognize early signs of the development of the long face syndrome and make appropriate referrals to medical colleagues to promote nasopharyngeal health.