Cephalometric evaluation of pharyngeal airway space after orthodontic extraction treatment in adult patients with Class II malocclusion: an integration with subjective sleep quality assessment

Objectives: This study (1) compared the changes in regional pharyngeal airway space (PAS) after orthodontic treatment among 3 groups of adult patients with Class II malocclusion and (2) identified correlations between questionnaire results and PAS dimensions after orthodontic treatment. Materials and methods In this retrospective cohort study, 79 consecutive patients were divided into normodivergent nonextraction, normodivergent extraction, and hyperdivergent extraction groups. Serial lateral cephalograms were used to evaluate the patients’ PASs and hyoid bone positions. The Pittsburgh Sleep Quality Index and STOP-Bang questionnaire were used for sleep quality evaluation and obstructive sleep apnea (OSA) risk assessment, respectively, after treatment. Results The greatest airway reduction was observed in hyperdivergent extraction group. However, the changes in PAS and hyoid positions did not differ significantly among 3 groups. The PAS behind the soft palate and tongue was determined to be susceptible to reduction. According to questionnaire results, all 3 groups had high sleep quality and low risk of OSA, with no significant intergroup differences. Moreover, pretreatment-to-posttreatment changes in PAS were not correlated with sleep quality or risk of OSA. Conclusions Orthodontic extraction and incisor retraction do not affect the dimensions of pharyngeal airway. Vertical control of Class II skeletal malocclusion, especially in cases involving retrusive chins, can be applied to prevent the worsening of facial profile and to mitigate a tendency of reduction of airway dimensions. Clinical relevance Orthodontic treatment with premolar extractions does not exhibit a reduction in airway dimensions or diminish the patients’ sleep quality or increase their risk of OSA.