Evaluation of Changes in Pharyngeal Space and Hyoid Bone Position in Skeletal Class II with Mandibular Advancement- A Prospective Clinical Study

Abstract

Introduction: Pharyngeal airway and hyoid position are highly influenced by its surrounding anatomical structures. Mandibular advancement appliances are one of the common options for an adult patient not willing to undergo mandibular advancement surgery. No prospective study with 3D imaging and pharyngeal airway volumetric analysis has been carried out in skeletal class II adult patients treated with mandibular advancement. Aim: To evaluate changes in pharyngeal airway space and hyoid bone position in adults with Skeletal Class II malocclusion with mandibular advancement.

Material and methodology: A prospective clinical trial was carried out in 20 adult patients. Sample consisted of adult patients with skeletal class II requiring mandibular advancement. Patients underwent mandibular advancement with either removable or fixed functional appliances. Pre treatment and post treatment full head CBCT scans were taken and change in the hyoid position and change in pharyngeal airway volume were recorded.

Results: Paired t- test was performed for evaluation of pre-treatment and post-treatment data using GraphPad Prism 10 for statistical analysis. Significant change was observed in airway parameters and hyoid bone position post treatment. There was significant improvement in nasopharynx, palatopharynx, glossopharynx and hypopharyngeal volume with (p < 0.001). There was significant decrease in H-HRP and H-RGn whereas increase in H-VRP and H-3vai indicating upward and forward movement of the hyoid bone.

Conclusion: Patients showed significant improvement in pharyngeal airway volume with upward and forward position of the hyoid bone.