contemporary orofacial science

en Evaluation of the airway, soft tissue, and hyoid bone position changes following premolar-extraction orthodontic treatment in Class I malocclusion ارتودنسی Orthodontics پژوهشي Research Background: The soft tissue profile plays a significant role in the appearance of patient and treatment satisfaction, while the airway affects breathing patterns. This study aimed to investigate the impact of premolar extraction on soft tissue profile, airway dimension, and position of the hyoid bone in Class 1 patients. Materials & Methods: This retrospective analytical study analyzed pre and post-treatment lateral cephalograms of 27 Class I patients aged 18 to 30 years, referred to Isfahan Islamic Azad University. Each patient received fixed orthodontic treatment that involved the extraction of all four first premolars. The cephalograms were captured in natural head position with the head centered between the X-ray source and the film, both before and after treatment, and traced manually. To assess soft tissue profile, E-line, UL-E line, LL-E line, U1-L1, FCA, ILA, MLA, and HNB were evaluated. For airway and hyoid bone position, S-H, H-RGN, VAL, U-MPW, TB-TPPW, and V-LPW were assessed. Data were analyzed by Paired t-test and Pearson correlation coefficients (α= 0.05). Results: The values of LL-E line (p=0.006), UL-E line (p=0.001), and the HNB angle (p=0.049) significantly decreased after treatment. Other soft tissue variables showed no significant differences(p>0.05). The airway variables did not show significant differences; however, S-H, which relates to the hyoid bone, showed a significant decrease (p=0.038). Conclusion: Treatment of Class I patients with first premolar extraction did not change the airway but resulted in the hyoid bone being positioned more superiorly. This treatment also retracted both lips and reduced facial convexity.   39 47 http://cofs.khuisf.ac.ir/browse.php?a_code=A-10-1-61&slc_lang=en&sid=1 Parnian Tadayonnezhad 1003194753284600809 1003194753284600809 No Faculty of Dentistry, Isf.c, Islamic Azad University, Isfahan, Iran Mehdi Rafiei 1003194753284600810 1003194753284600810 Yes Department of Orthodontics, Faculty of Dentistry, Isf.c, Islamic Azad University, Isfahan, Iran Azadeh Torkzadeh 1003194753284600811 1003194753284600811 No Department of Oral & Maxillofacial Radiology, Faculty of Dentistry, Isf.c, Islamic Azad University, Isfahan, Iran Ali Tabrizi 1003194753284600812 1003194753284600812 No Department of Orthodontics, Faculty of Dentistry, Isf.c, Islamic Azad University, Isfahan, Iran