Abstract
ObjectiveWhether the orthodontic treatment with premolar extraction and maximum anchorage in adults will lead to a narrowed upper airway remains under debated. The study aims to investigate the airway changes after orthodontic extraction treatment in adult patients with Class II and hyperdivergent skeletal malocclusion.Materials and MethodsThis retrospective study enrolled 18 adults with Class II and hyperdivergent skeletal malocclusion (5 males and 13 females, 24.1 ± 3.8 years of age, BMI 20.33 ± 1.77 kg/m2). And 18 untreated controls were matched 1:1 with the treated patients for age, sex, BMI, and skeletal pattern. CBCT images before and after treatment were obtained. DOLPHIN 11.7 software was used to reconstruct and measure the airway size, hyoid position, and craniofacial structures. Changes in the airway and craniofacial parameters from pre to post treatment were assessed by Wilcoxon signed rank test. Mann-Whitney U test was used in comparisons of the airway parameters between the treated patients and the untreated controls. Significant level was set at 0.05.ResultsThe upper and lower incisors retracted 7.87 mm and 6.10 mm based on the measurement of U1-VRL and L1-VRL (P < 0.01), while the positions of the upper and lower molars (U6-VRL, and L6-VRL) remained stable. Volume, height, and cross-sectional area of the airway were not significantly changed after treatment, while the sagittal dimensions of SPP-SPPW, U-MPW, PAS, and V-LPW were significantly decreased (P < 0.05), and the morphology of the cross sections passing through SPP-SPPW, U-MPW, PAS, and V-LPW became anteroposteriorly compressed (P <0.001). No significant differences in the airway volume, height, and cross-sectional area were found between the treated patients and untreated controls.ConclusionsThe airway changes after orthodontic treatment with premolar extraction and maximum anchorage in adults are mainly morphological changes with anteroposterior dimension compressed in airway cross sections, rather than a decrease in size.
Highlights
Since Angle reported a narrowed upper airway in children with Class II dentofacial deformity in 1907 [1], many studies have demonstrated that certain craniofacial patterns are related with a smaller size of the upper airway, including deficient mandible, and steep mandibular plane [2,3,4]
Height, and cross-sectional area of the airway were not significantly changed after treatment, while the sagittal dimensions of SPP-SPPW, U-MPW, PAS, and V-LPW were significantly decreased (P < 0.05), and the morphology of the cross sections passing through SPP-SPPW, U-MPW, PAS, and V-LPW became anteroposteriorly compressed (P
No significant differences in the airway volume, height, and cross-sectional area were found between the treated patients and untreated controls
Summary
Since Angle reported a narrowed upper airway in children with Class II dentofacial deformity in 1907 [1], many studies have demonstrated that certain craniofacial patterns are related with a smaller size of the upper airway, including deficient mandible, and steep mandibular plane [2,3,4]. Orthodontic camouflage treatment can improve the profile in those with mild to moderate skeletal discrepancy, usually by means of teeth extraction and maximum anchorage [10,11,12]. Whether this approach will affect the size of the upper airway remains a matter of debate
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