Silent Changes in Sleep Quality Following Mandibular Setback Surgery in Patients with Skeletal Class III Malocclusion: A Prospective Study

Abstract

Mandibular setback surgery (MSS) for skeletal class III patients can result in a relative reduction of pharyngeal airway space (PAS). Consequently, there is a possibility of the decline of sleep quality after surgery. We investigated changes in sleep quality measured by overnight polysomnography (PSG) and the three-dimensional (3D) volumes of PAS following MSS with or without Le Fort I osteotomy (LF I) in class III patients (N = 53). Overnight PSG and cone beam computed tomography were conducted at preoperative stage (T0) and postoperative 3 months (T1). Measurements of PAS volumes were performed, and the subjective symptoms of sleep were evaluated by self-questionnaires. There were significant increases in respiratory disturbance index (RDI) and total respiratory effort-related arousal (RERA) index during T0-T1. The 3D volumes of PAS showed significant decreases in the oropharyngeal airway, hypopharyngeal airway, and total airway spaces. No significant changes were observed in subjective symptoms of sleep. MSS with or without LF I for class III patients could worsen sleep quality by increasing sleep parameters such as the RDI and RERA in PSG, and reduce volumes of PAS at postoperative 3 months. Although subjective symptoms may not show significant changes, objective sleep quality in PSG might decrease after MSS.

Figure 1

Scatter plots showing positive correlations between the amounts of mandibular setback and the changes in other variables. The changes in the AHI (A), RDI (B), total RERA index (C), and N1 percentage (D) showed positive correlation with the amounts of mandibular setback. On the other hand, changes in the volume of total PAS (E), and the lowest oxygen saturation (F) showed negative correlation with the amounts of mandibular setback.

Figure 2

Scatter plot showing the correlation between the changes in mean oxygen saturation and the volume of hypopharyngeal airway space.

Figure 3

Scatter plots showing correlations between the PSQI and other variables. The amount of mandibular setback (A), changes in number of awakening (B), N1 percentage (C), and total arousal index (D) showed positive correlation with the PSQI.

Figure 4

Three-dimensional measurement of the volume of PAS and reference planes and the division of pharyngeal airway space for volumetric measurement. Cone beam computed tomography data were imported to the program for visualizing pharyngeal airway space (PAS) and measuring the volume of PAS. Reference planes were set as follow: (A), posterior nasal spine (PNS) plane (axial plane passing through the PNS); (B), uvula plane (axial plane passing through the tip of the uvula); (C), epiglottis plane (axial plane passing through the base of the epiglottis). The pharyngeal airway was divided into three spaces based on the reference planes: the nasopharyngeal airway (between the highest point of the upper airway and the PNS plane), the oropharyngeal airway (between the PNS plane and the uvula plane), and the hypopharyngeal airway (between the uvula plane and the epiglottis plane).