A RADIOGRAPHIC ASSESSMENT OF HYOID BONE POSITION AND PHARYNGEAL AIRWAY SPACE IN VARIED SKELETAL TYPE – A CROSS SECTIONAL STUDY

In orthodontics, it is important to evaluate associated hyoid bone structure, since it is inuential in maintaining the size of the upper airway. Changes in the position of hyoid bone is always accompanied by changes in position of mandible during physiological, surgical and also due to orthodontic treatment and may cause a predisposition for change in the volume of the pharynx. The purpose of this study was to determine the position of the hyoid bone and pharyngeal airway spaces among subjects with class I, class II, class III skeletal patterns and to determine a correlation between hyoid bone and pharyngeal airway spaces. Sixty lateral cephalograms with varying skeletal patterns (class I, II, and III) were chosen. Skeletal patterns were determined based on ANB angle. In males the hyoid bone was placed more inferiorly when compared to females in the three classes. Skeletal class II pattern showed the least distance between H point and third cervical vertebra(C3) , H point to retrognathion indicating that in skeletal class II pattern the hyoid bone is placed more posteriorly. A signicant variation was observed in 'upper airway' among the classes and a statically signicant moderate positive correlation between the 'H-RGn(mm)' and 'lower airway (mm)' variables was observed. . The hyoid bone is spatially related to the cranial base, mandible, and cervical vertebrae.