Abstract:Objective To evaluate the changes in upper airway morphology, hyoid bone position, and maxillofacial skeletal indices before and after treatment with mandibular advancement (MA) in adolescents with skeletal class Ⅱ malocclusion and remaining growth potential, so as to clarify the clinical application value of clear aligner (CA) in such patients. Methods A total of 20 adolescents with skeletal class Ⅱ malocclusion and growth potential, who received non- extraction therapy with Invisalign? MA system at the Department of Stomatology, Kunshan Chinese Medicine Hospital from December 2020 to August 2024, were retrospectively enrolled. Before and after the orthodontic treatment, fixed- point measurement on lateral cephalometric radiographs and three-dimensional measurement on cone-bean CT were conducted using Dolphin software. The observed indices included skeletal angular measurements [subspinale-nasion- supramentale angle (ANB), sella-nasion-supramentale angle (SNB), maxillary central incisor-nasal plane angle (U1- SN), mandibular central incisor-mandibular plane angle (L1-MP)], upper airway anteroposterior diameters at the parameters [horizontal distance from hyoid point to C3 (H-C3), vertical distance from hyoid point to C3Me (H-C3Me)], and airway morphology indices [left-right to anteroposterior ratio (LR/AP)]. Results After treatment, the SNB significantly increased (75.53°±1.89° vs 79.93°±1.34°, t=19.03, P<0.01) and the ANB significantly decreased (6.97°± 0.27° vs 3.07°±0.39°, t=48.04, P<0.01). Both U1-SN and L1-MP significantly reduced (P<0.05). The hyoid bone shifted anteriorly and inferiorly, with significant increases in H-C3 and H-C3Me (P<0.05). Regarding the upper airway, the PP, OP, and MP posterior airway diameters all increased, with only the MP plane showing statistical significance (P<0.05). In terms of airway morphology, the nasopharyngeal LR/AP decreased (more circular shape), while the oropharyngeal LR/AP increased (more elliptical shape), with both differences statistically significant (P< 0.05). Conclusion Adolescents with skeletal class Ⅱ malocclusion and mandibular retrusion treated with MA achieved effective mandibular advancement, excellent torque control of anterior teeth, and anterior displacement of hyoid bone.