Cephalometric norms of the upper airway of Chinese children and the association between airway dimensions and craniofacial structures

Abstract

AIM: To retrospectively establish cephalometric norms of the upper airway for Chinese children, and to determine association between airway dimensions and craniofacial features. SUBJECTS AND METHOD: A random sample of 224 male and 201 female 12-year-old southern Chinese children, for whom lateral cephalograms were available. Statistical analysis was performed to analyze 11 key cephalometric parameters for airway dimensions and 29 parameters for craniofacial features. Gender difference of airway dimensions was analyzed using two-sample t-test. The subjects were further divided into four subgroups according to ANB angle (Class I, mild Class II, severe Class II or Class III) and three subgroups according to the intermaxillary angle (low, normal or high angle), respectively. Association between airway parameters and ANB angle class and intermaxillary angle class was analyzed with analysis of variance. Pearson’s correlation analysis was computed to determine correlations between airway and craniofacial parameters. RESULTS: Significant differences were found in the high angle subgroup in the vertical position of the hyoid bone (P < 0.01), retroglossal pharyngeal depth (P < 0.05) and soft palatal angle (P < 0.001) compared with the other two intermaxillary angle class subgroups. A moderate correlation (r > 0.5) between airway dimensions and craniofacial features was evident in the severe Class II subgroups (ANB >7°). Of note there was a strong correlation (r > 0.7) between mandibular length (Cd-Gn) and the vertical position of hyoid bone and a moderate correlation (r > 0.6) between mandibular length and the sagittal position of hyoid bone. CONCLUSION: Cephalometric norms of the upper airway for Chinese children have been established with gender-specific standards. High angle subjects tend to have a lower positioned hyoid bone and a narrow retroglossal airway. In severe Class II subjects, mandibular length is correlated with the position of hyoid bone in both the vertical and sagittal dimensions.