A CBCT Comparative Study On Hyoid Position Of Skeletal Class â…¡ And Skeletal Class â…  Adolescent Patients

Objective: The aim of this study was to investigate the differences between Skeletalclass II and Skeletal class I adolescent patients’ hyoid positions by cone-beamcomputed tomography and InvivoDental5.1software.Methods:45malocclusion patients (Male23, Female22,average age16.78±1.19years old.)were chosen among the250patients（age15-19） in Dalian stomatologicalhospital complaining of malocclusion from January2012to December2013. Accordingto the measuring average of Chinese normal occlusion by Steiner analysis method,patients were divided into two groups: Class I (0.7°≤ANB≤4.7°) and Class II (ANB＞4.7°) by ANB angle. All the selected patients met the need of normal-angle range27.3°≤SN-MP≤37.7°. Patients were scanned by KaVo3DeXam cone-beam computedtomography system (CBCT) of America KaVo Company on the same scanningcondition and Craniomaxillary Facial3D images were reconstructed. InvivoDental5.1software was used to measure and analyze the pre-treatment CBCT image about thedifference in hyoid position horizontally and vertically. Obtained data was importedinto SPSS13.0software package so as to establish a database for statistical analysis oftwo independent sample t-test. Only P<0.05was considered statistically significant.Results: Horizontal measured items including distance from hyoid point to anteriorpoint of third cervical vertebra、distance from hyoid point to Z Plane and distance fromhyoid point to posterior point of chin showed statistically significant difference betweenskeletal Class I group and skeletal Class II group. Vertical measured items includingdistance from hyoid point to FH plane、distance from hyoid point to maxillary plane anddistance from hyoid point to mandibular plane showed statistically insignificantdifference between skeletal Class I group and skeletal Class II group.Conclusion: The hyoid position of Class II adolescence patients was comparatively behind compared Class I adolescence patients horizontally, but there was no obviousdifference vertically.