Cross-sectional and retrospective study regarding the changes in the spatial position of the hyoid bone and upper airways before and after orthodontic therapy in developing patients with normocclusion.

Objective: The objective was to study the effect of orthodontic therapy regarding the position of the hyoid bone and upper airways in nighty-one 6-21 year-old Caucasian patients with normoclussion.

Methods: Nineteen variables were analyzed by teleradiography. The differences were analyzed with the ANOVA test of repeated measures with an intra-group factor for two occasions.

Results: The statistical analysis revealed a greater influence on the variables Hy-MP (12.3 vs 14.2), Hps-C3 (25.2 vs 28.1), Hpi-C3 (28.8 vs 35.5), H°-C3 (14.4 vs 12.7), Hps-Rg (36.0 vs 42.7), Hpi-Rg (34.1 vs 39.7), USP (16.2 vs 20.2), MPP (12.9 vs 14.8), C3P (10.6 vs 12.8), PNS-Ba (43.5 vs 66.5), PtV-Ad (12.0 vs 17.1) and PtM-Ba (33.9 vs 35.9), and Ad2-SO (24.16 vs 20.87).

Discussion: Significant differences were observed between most of the airway and hyoid bone variables before and after orthodontic treatment in our Spanish pediatric population, especially in the nasopharynx.