关键词: 口呼吸, 锥形束CT, 上气道, 舌骨位置

Abstract: Objective    To evaluate the difference in upper airway morphology and hyoid bone position between mouth-breathing children and nasal-breathing children by cone-beam CT（CBCT）. Methods    A total of 78 adolescents and children with normal-angle and skeletal classⅠmalocclusion were included according to the inclusion criteria in the Department of Orthodontics，the First Hospital of Shanxi Medical University，from 2018 to 2021，and the 78 cases were divided into mouth-breathing group（n = 39）and nasal- breathing group（n = 39） and CBCT was taken. The upper airway was reconstructed by Dolphin11.95 software. The volume，sagittal surface area，minimum cross-sectional area，three-dimensional structural surface area of the upper airway and the position of the hyoid bone were measured. The data were statistically analyzed. Results    The volume，sagittal surface area，minimum cross-sectional area and three-dimensional structural surface area of palato-pharyngeal segment and hyold-pharyngeal segment of upper airway in mouth-breathing group were significantly lower than those in nasal-breathing group（P < 0.05）. There was no significant difference in the measurement items of nasopharyngeal segment or laryngopharyngeal segment of upper airway between mouth-breathing group and nasal-breathing group（P > 0.05）. There was no significant difference in the vertical or horizontal distance between the hyoid and the anterior skull base plane between the two groups（P > 0.05）. Conclusion    The upper airway of mouth-breathing patients with normal-angle and skeletal classⅠmalocclusion is significantly narrower than that of nasal-breathing patients，but the effect on hyoid position is not significant.

Key words: mouth-breathing, cone-beam CT, CBCT, upper airway, hyoid bone position