关键词: 锥形束CT, 舌体形态, 舌体位置, 舌骨形态, 舌骨位置, 肌功能训练

Abstract: Objective　Cone-beam CT（CBCT）was used to study the position and morphological characteristics of  tongue and hyoid in patients with skeletal class Ⅱ malocclusion. Methods　From January 2016 to December 2018，35 patients with skeletal class Ⅱ malocclusion（group Ⅱ）and 35 patients with skeletal class Ⅰ malocclusion（groupⅠ）were treated in the Department of Orthodontics，the Ninth People′s Hospital Affiliated to Shanghai Jiao Tong University. Each group was further subdivided into three groups based on the cephalometric analysis of FMA. Compare the position and morphology of the tongue and hyoid among the groups and among types of patients by CBCT images. Results　（1）The measurement results of the tongue position of the two groups of patients were compared，and the differences were statistically significant（both P < 0.05），the measured values of group Ⅱ being greater than those of group Ⅰ；the tongue length of the two groups of patients was compared，and the difference was of no statistical significance（P > 0.05），while the sagittal cross-sectional area of the tongue in group Ⅰ was larger than that in group Ⅱ，the difference being statistically significant（both P < 0.05）.（2）Comparison of the measurement results of the hyoid position between the two groups of patients found that the H-H′ （vertical distance from the vertex of the hyoid bone to the line between cervical vertebral point and the submental point）and H-Y（the vertical distance from vertex of hyoid bone to the PS plane）in group Ⅱ were greater than those in group Ⅰ，and the difference was statistically significant（both P < 0.05）. The comparison of hyoid bone morphology between the two groups showed no significant difference（both P > 0.05）.（3）The measurement results of tongue length and H-Me（distance from hyoid bone to submental point）in group Ⅰ patients with low angle were larger than those in patients with average angle and high angle，and the differences were statistically significant（both P < 0.05）；the comparison of the measurement results of tongue body，hyoid position and morphology of patients with different vertical bone types in group Ⅱ showed no significant difference（all P > 0.05）. Conclusion　Class Ⅱ patients have the following characteristics compared to class Ⅰ：lower tongue posture and smaller tongue body，and the hyoid bone is usually placed in lower and posterior position. Among the patients with skeletal class Ⅰ malocclusion，the tongue and mandibular body are longer in patients with low angle than those with average angle and high angle.

Key words: cone-beam CT, CBCT；tongue morphology；tongue position；hyoid bone morphology；hyoid bone position；myofunctional training