Journal of AdvancedMedical and Dental Sciences Research

Objective: The goal of the present study was evaluate how first premolar extraction affected pharyngeal airway dimensions and position of hyoid bone in adults with bimaxillary proclination. Materials and method: For the present retrospective cephalometric study, pre and post orthodontic treatment records of 20 adult patients with bimaxillary proclination, treated with fixed orthodontic therapy utilising the MBT 0.022 (AO mini master)appliance were assembled.Linear airway measurements in sagittal plane (HP-PNS, BP-PNS, SPW-SPPW, U-UPPW, PgT-PPTW, UPA, LPA) , in vertical plane(TAL) and liner hyoid bone measurements (H-Pg,H-Hp,C3-H,PTM-H) in sagittal plane were measured manually on the cephalogram. To analyse changes in pre and post treatment values, a paired t-test was utilised, and Pearson's correlation coefficient was used to determine the reliability of all the parameters. Results: There was no statistically significant change between pre and after treatment outcomes in the mean values of Nasopharyngeal dimension (HP-PNS) and Total Airway Length (TAL) (p > 0.005). All other airway parameters (BP-PNS, SPW-SPPW, U-UPPW, PgT-PPTW, UPA, LPA, UPA, LPA) and hyoid parameters (H-Pg, H-Hp, C3-H, PTM-H) revealed statistically significant differences (p≤0.001). For all airway and hyoid measures, Pearson's correlation coefficient indicated statistically substantial reliability (p≤0.001). Conclusion: The retraction of anterior teeth in the extraction space reduced the oropharynx and hypopharynx dimension, but not the nasopharynx dimension or overall airway length and the hyoid bone move posteriorly and inferiorly.