Cephalometric studies on the upper airway space in normal Chinese.

A detailed cephalometric analysis of the soft and hard tissues of the upper airway was conducted with lateral cephalographs from 116 normal Chinese, aged between 18 and 25 years. Normal values and deviation range were preliminarily established for the size of the tongue, soft palate, nasopharynx, oropharynx, and hypopharynx, and for the relative position of the hyoid bone and vallecula in both sexes. Statistical findings showed that there were significant differences between the sexes. Significant relationships (P < 0.001) were observed 1) between the hypopharyngeal depth and the position of the hyoid bone and the vallecula, in which the horizontal position of vallecula appears to be the best predictor of the hypopharyngeal depth, as confirmed by the multiple regression equation; 2) between the upper airway depths at four different levels; and 3) between the naso-oropharyngeal area and tongue, soft palate, and oral area. The present data can be used to investigate further the upper airway in abnormal states.