Nasopharyngeal Airway Dimensions in Different Dentofacial Skeletal Patterns

Dentofacial growth and development is noticeably affected by the various oropharyngeal and nasopharyngeal structures. It is also presumed that airway adequacy is related to the size and position of the mandible rather than maxillary variables. The purpose of this study was to compare the dimensions of nasopharynx in subjects with Class I and Class II malocclusions with normodivergent and hyperdivergent facial patterns. Methodology: Pretreatment cephalometric radiographs of 80 subjects in age group of 14 to 25 years were taken and divided into four groups according to A point, nasion, B point ( ANB) and Frankfort to mandibular plane angle (FMA) with 20 subjects in each group. The measurements of the dimensions of the nasopharynx, in all the subjects were taken. Results: The anteroposterior dimensions of nasopharynx is narrower in subjects with Class I skeletal malocclusion with vertical growth pattern as compared to subjects with Class II skeletal malocclusion with vertical growth pattern as suggested by dimensions at posterior pharyngeal wall 1 and posterior pharyngeal wall 2 (PPW1 and PPW-2). The anteroposterior dimensions of nasopharynx was narrower in subjects with Class II skeletal malocclusion with vertical growth pattern as compared to subjects with Class II skeletal malocclusion with average growth pattern as suggested by dimensions Ptm-adl and Nphl. Conclusion: The nasopharyngeal airway dimensions are narrower in subjects with vertical growth patterns and compared to the subjects with average or horizontal growth patterns. The narrower anteroposterior dimension of the airway in hyperdivergent patients may be attributable to skeletal features common to such patients, that is, retrusion of the maxilla and the mandible and vertical maxillary excess and the relatively thin posterior pharyngeal wall observed in hyperdivergent patients might be a compensatory mechanism. INTRODUCTION From the late 1800s till now, the relationship between pharyngeal structures and dentofacial patterns have been intensively researched.' As was suggested by the functional matrix hypothesis, soft tissue units guided hard tissues to an extent. With regard to this dentofacial growth and development is noticeably affected by the various oropharyngeal and nasopharyngeal structures. Also it has been seen that the nasal obstruction and its inseperable counterpart "mouth breathing" also affect the dentofacial growth. Thus several studies tried to correlate patients with normal nasorespiratory functions with different malocclusions and airway dimensions The size of the nasopharyngeal airway space is of importance in its relationship to the morphology of the face because with reduction of the nasopharyngeal airway space, nasal breathing becomes difficult or impossible, and mouth breathing becomes necessary. It is with chronic mouth breathing that the normal balance of oral and paraoral structures is upset and changes of both structures can be expected. It has been noted that Class II patients have a tendency for a narrower anteroposterior pharyngeal dimension, specifically in the nasopharynx at the level of the hard palate and in the oropharynx at the level of the tip of the soft palate and the mandible.' The midsagittal