Assessment of change in mean area of nasopharynx, hyoid triangle and position of hyoid bone after functional appliance therapy

Introduction: The present study was conducted to understand changes in mean area of nasopharynx, hyoid triangle and position of hyoid bone in patients with retrognathic mandible after functional appliance therapy. Methods: Fourteen Class II malocclusion subjects in growing age with mandibular retrusion were selected. Mandibular retrusion in subjects was corrected by functional appliance therapy. Effect of functional appliances on nasopharynx and hyoid bone dimensions were evaluated from lateral cephalograms recorded before and after appliance therapy. Paired t- test was used for statistical analysis. Results: Mean area of nasopharynx and hyoid triangle was evaluated. It was found that there was increase in mean area of nasopharynx which is statistically significant with a P value of 0.004 in post cephalograms of treated subjects .It was also found that there was decrease in mean value of hyoid triangle in post cephalogram of treated subjects which was found statistically not significant with a P value of 0.773. There was mean decrease inhyoid distance from third cervical vertebrae which shows an upward movement of hyoid bone. Conclusion: Forward mandible displacement occurs with functional appliance therapy and, there were significant changes in the mean area of nasopharynx, and there is decrease in the mean area of hyoid triangle with upward movement of hyoid bone after functional appliance therapy.