The short face phenotype is characterized by retrognathia, deep overbite, and frequently large overjet. Characteristic of the adult short face is a mandibular step plane of occlusion. The anterior six teeth are at a higher plane than the posterior eight. During a swallow the teeth are kept from touching in occlusion by the sides of the tongue. The lateral border of the tongue has a scalloped border indicative of dysphagia (lateral tongue thrust). In swallowing the lateral borders of the tongue extrude over the lower posterior teeth and against the lingual-incisal edges of the maxillary posterior teeth. This lateral resting posture of the tongue between the posterior teeth prevents the mandibular posteriors from erupting to their full potential. Centric occlusion is an adaptive retrognathic position. These patients generally have excessively large freeway spaces from rest position to centric occlusion. In centric occlusion however, there is reduced vertical dimension, lingually tipped posterior teeth, and reduced space for the tongue, which as a consequence encroaches downward and posteriorly, narrowing the oropharynx.
The long face is characterized by an open mouth resting posture, narrow maxilla, high palatal vault, anterior open bite, usually a unilateral or bilateral crossbite and an anterior tongue thrust dysphagia. These children are predominantly oral breathers and have some form of nasal obstruction to inhibit or prevent nasal breathing. A significant number of these patients are prognathic. The swallow is dysfunctional in that the tongue initially protrudes forward during deglutition to create the necessary seal to initiate propulsion of the bolus. In the resting posture the mouth is open and the tongue is in the floor of the mouth to facilitate a patent oral airway.
In mastication the long face child is only capable of occlusion on posterior teeth. Typically the first and/or second molars are the only teeth that touch in mastication. The anterior open bite causes noticeable muscular strain for these children to seal the lips. The open mouth resting posture and the narrow maxilla result in a narrow nose. This is readily noticeable in the frontal section view of panoramic radiographs.