A Comparative Study On Hyoid Position And Morphological In Skeletal Class Ⅲ Malocclusion With Different Vertical Facial Types Of Adults

ObjectiveThe aim of this study is to evaluate the changes on hyoid position and morphological in skeletal class III malocclusion with different vertical facial types of adults by using cone-beam computed tomography (CBCT),providing effective theoretical basis for orthodontic clinical diagnosis and treatment.Methods34normal occlusion individuals and75skeletal Class III malocclusion patients were select in Stomatological Hospital of Nan Kai University and were scanned by CBCT. The FMA angle was used to divide Class III malocclusion into25short face type,23normal face type, and27long face type patients.Mimics10.01was used to make three-dimensional reconstruction. Study by selecting the mark points of the8centers and13symmetric landmarks. The establishment of three-dimensional reference plane, to measure the signs point to the distance of the reference plane. comparing study on hyoid position and morphological in skeletal class Ⅲ malocclusion with different gender and vertical facial types.Independent samples t test was employed for comparison of the different gender. One-way ANOVA was used for analysis of different vertical facial types. P<0.05was considered the level of statistical significance.Results1There are statistically significant differences among G1-X, Gr-X, Hd-X, Hu-X, Hu-C3ME, plane1of hyoid-X, plane2of hyoid-X in females and males of normal occlusion individuals.The mean values in male was larger than that in female. In contrast, the value of plane1of hyoid-X-mandibular plane was larger in females. There was no statistical difference in Hu-Z, Hd-Z.2There is statistically significant difference of the vertical Position of hyoid bone of adults with different vertical skeletal Patterns.As FMA angle increases, the mean values of Hu-X, Hd-X, Hd-mandibular plane, Hu-mandibular plane are increasing gradually. Contrast to short and long facial type patients, the mean values of Hu-C3ME are larger in normal.In short facial type, The mean values of G1-X、Hd-X in male was larger than that in female. In contrast, the value of Hd-mandibular plane,Hu-mandibular plane was larger in females. In long facial type, the mean values of Hu-C3ME are lager in males.3In short facial type of males, Hu-Z, Hd-Z of the sagittal Position of hyoid bone are larger than that in the other two types. In long facial type of female, Hd-Z are smaller than in normal and short. Gl-Z、Gr-Z are no statistically significant differences among groups.4In long facial type of males, the axial inclination of the hyoid bone was larger than in normal and short. In contrast, women showed the opposite trend.5Gr-G1、H1-Hr、Hr-Gr、H1-G1of hyoid morphological in skeletal class Ⅲ malocclusion were larger in males. There were no statistically significant differences in height of hyoid body between different genders. Hyoid morphological were no statistically significant differences among different vertical skeletal Patterns.In long facial type of females, the height of hyoid bone was larger than in normal and short.Conclusions1The position of the hyoid bone of normal occlusion individuals was lower in males than in females. The axial inclinations of the hyoid bone were more downward and forward in males.2As FMA angle increases face, the vertical position of the hyoid bone was gradually reduced.3According to the order in the short, long and normal, the sagittal position of the hyoid bone was gradually forward.4In long facial type of males, the axial inclination of the hyoid bone was downward and forward than in normal and short. In contrast, women showed the opposite trend.5width the hyoid body and Greater horn were larger in males. In long facial type of females, the height of hyoid body was greater than others.