Morphometric growth changes of the nasopharyngeal space in subjects with different vertical craniofacial features.

Abstract

The purpose of this study was to morphometrically investigate the growth pattern of the adenoids in growing subjects with hyperdivergent and hypodivergent vertical craniofacial features. In this retrospective study, we used a longitudinal sample of lateral cephalometric radiographs of 28 hyperdivergent and 30 hypodivergent subjects from 4 to 13years of age. The radiographs were obtained from the American Association of Orthodontists Foundation Craniofacial Growth Legacy Collection. Measurements were made using digital tracings of the lateral cephalograms and point distribution models. Mixed-model analyses were used for statistical analysis. The mean distance between the sphenoid bone and the posterior nasal spine increased up to 5.3mm over a 9-year span (95% CI, 4.1-6.5mm; P<0.001). Furthermore, the mean distance between the sphenoid bone and the posterior nasal spine differed significantly (P=0.029) between facial types; it was consistently greater (1.8mm; 95% CI, 0.2-3.3mm) in the hyperdivergent group. The nasopharyngeal airway area showed a trend to increase with age up to 12-fold (P<0.001). A significant interaction (P=0.004) was found between age and facial type. Assessment of the adenoid shapes showed greater convexities in the hyperdivergent group, which were observable from an earlier age and for a longer duration. Clear differences in the morphometric growth pattern of the adenoids were found between facial types. Evaluation of adenoid shapes showed more prominent convexities that lasted longer in the long facial types than in the short facial types.