A comparative evaluation of position and orientation of hyoid bone in skeletal class i, class ii and class iii subjects: a cephalometric study

Aims & Objectives: 1.The purpose of this study was to compare and evaluate the positional changes of hyoid bone and its effect on the patency of airway in anteroposterior dimension of pharynx (C3 –Hy) compared with upper bony airway (AA’-PNS) in Class I, Class II and Class III malocclusions. 2. To evaluate the position of hyoid bone using hyoid triangle and its relation to mandibular position in Class I, Class II and Class III. Materials and methods: Cephalometric radiographs of 75 patients (25 each of skeletal Classes I, II and III respectively) were selected from the archives of the Department of orthodontics. Radiographs were manually traced on 0.003” acetate sheets. Descriptive statistics for 14 variables were calculated. Results: Linear and angular measurements showed positional alteration of hyoid bone in skeletal Class II and Class III subjects. In Class II group the hyoid bone was displaced posteriorly and angulated inferio-posteriorly. In Class III group it is positioned anteriorly and angulated superior-anteriorly. No statistically significant sexual dimorphism exists in linear and angular measurements of hyoid positioning. However, significant difference does exist in linear and angular measurements within same sex group related to skeletal Class I, Class II and Class III malocclusion.