Abstract
The aim of this study was to evaluate three-dimensional (3D) effects of Twin-block functional appliance (TB) on the pharyngeal airway by using cone beam computed tomography (CBCT). A total of 30 patients (14 females, 16 males; mean age 12.50 ± 1.23 and 12.83 ± 1.17 years, respectively) with skeletal Class II malocclusion were included in this study and were treated with TB. On the pretreatment (T1) and posttreatment (T2) CBCT scans, volumetric changes in the pharyngeal airway; SNA, SNB, and ANB angles; and bilateral effective mandibular (Co-Gn) and midfacial length (Co-A) were also evaluated. The statistical differences were accessed by Wilcoxon signed-rank tests, and Mann-Whitney U tests were used to analyze the scores of male and female subjects. In this study, an increase was observed in SNB and Co-Gn (p < 0.01) while a decrease in ANB and SNA (p < 0.01 and p < 0.05, respectively) was found. However, increase in midfacial length was not statistically significant (p > 0.05). In the evaluation of volumetric pharyngeal airway changes, statistically significant increases (p < 0.01) in the upper and lower division and total airway volume were determined. Gender differences were insignificant for all measurements (p > 0.05). Volumetric changes in the pharyngeal airway after functional therapy can be successfully evaluated by CBCT images. The anterior repositioning of the mandible by TB increases the mandibular length and pharyngeal airway volume in patients with retrognathic mandible.
Highlights
The upper airway has been the subject of interest in orthodontic literature since its obstruction may affect the development of dentofacial structures by altering the breathing pattern of growing patients [1]
Reliability was evaluated by using intraclass correlation coefficients (ICCs) and Bland-Altman plots (Table 1)
Functional therapy is the preferred treatment choice in growing patients if the skeletal Class II malocclusion depends on retrognathic mandible
Summary
The upper airway has been the subject of interest in orthodontic literature since its obstruction may affect the development of dentofacial structures by altering the breathing pattern of growing patients [1]. Trenouth and Timms [7] showed that oropharyngeal volume is correlated positively with the mandibular length, third cervical vertebra and hyoid bone distance, and the cranial base angle. These studies revealed that Class II patients had significantly reduced airway volume according to patients with Class I and Class III malocclusion [8,9,10,11]. Respiratory function problems such as upper respiratory resistance syndrome, snoring, and obstructive sleep apnea (OSA) can be observed more frequently in Class II patients due to retrognathic mandible [12, 13]
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