BACKGROUND: This study aimed to investigate changes in the upper airway of adult patients after lingual orthodontic treatment with premolar extractions and analyze the correlation between airway changes and dentomaxillary indices. METHODS: For this retrospective study, 40 adult patients were included: 20 treated with lingual appliances and 20 adults treated with labial appliances. All patients underwent extraction of four first premolars and had pretreatment and posttreatment cone-beam computed tomography scans. CBCT data were subjected to three-dimensional reconstruction to measure volumes and minimal cross-sectional areas of the oropharyngeal, palatopharyngeal, glossopharyngeal, and laryngopharyngeal airway segments, as well as changes in incisor retraction, maxillary/mandibular arch width, mandibular position, and hyoid bone position. RESULTS: In the lingual group, glossopharyngeal airway volume decreased by 1127.19 mm³, while the minimal cross-sectional areas of the glossopharyngeal, oropharyngeal, and overall upper airway decreased by 31.28 mm², 28.14 mm², and 26.25 mm², respectively (all P < 0.05). These changes differed significantly from those in the labial group, which showed no significant alterations in any airway segment. Glossopharyngeal airway changes were not significantly correlated with incisor retraction or arch width but were significantly associated with mandibular position. CONCLUSIONS: For adult patients undergoing extraction of four first premolars, lingual orthodontic treatment results in significant reductions in glossopharyngeal airway volume and cross-sectional area. These reductions are not significantly associated with incisor retraction or arch width changes but may be associated with mandibular descent.
Zhang et al. (Mon,) studied this question.
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