A CEPHALOMETRIC COMPARATIVE-STUDY OF THE SOFT-TISSUE AIRWAY DIMENSIONS IN PERSONS WITH HYPERDIVERGENT AND NORMODIVERGENT FACIAL PATTERNS

Purpose: This study was performed to compare the dimensions of the nas opharynx, oropharnynx, and hypopharynx of persons with hyperdivergent and normodivergent facial types, and to determine whether any variatio ns exist. Patients and Methods: Lateral cephalometric records of a pop ulation with a normodivergent facial pattern (n = 23) and a group with a hyperdivergent facial pattern (n = 27) as evidenced by increased ma ndibular plane angle were used to compare the soft tissue airway dimen sions. Statistical analysis consisted of Student's t-tests, Wilcoxon r ank sums, and chi(2). Statistical significance was set .05. Results: O verall the hyperdivergent group had a narrower anteroposterior pharyng eal dimension than the normodivergent control group. This narrowing wa s specifically noted in the nasopharynx at the level of the hard palat e and in the oropharynx at the level of the tip of the soft palate and the mandible. In addition, the posterior pharyngeal wall had a thinni ng at the level of the inferior border of the third cervical vertebrae , and there was a more obtuse palatal angle. The tongue was also posit ioned more inferiorly and posteriorly in the hyperdivergent group, as evidenced by the increased distance between the hyoid bone and the man dibular plane and the increased distance between the soft palate tip a nd the epiglottis. The hyperdivergent group had more retruded maxillar y and mandibular apical bases and a higher Class II skeletal discrepan cy. Conclusions: The narrower anteroposterior dimension of the airway in hyperdivergent patients may be attributable to skeletal features co mmon to such patients, that is, retrusion of the maxilla and the mandi ble and vertical maxillary excess. Other features, such as an obtuse s oft palate and low-set hyoid, also may be contributory factors. The re latively thin posterior pharyngeal wall observed in hyperdivergent pat ients might be a compensatory mechanism.