Pharyngeal airway changes in Class III patients treated with double jaw orthognathic surgery--maxillary advancement and mandibular setback

Abstract

Purpose: The pharyngeal airway may change after skeletal movement in patients who have undergone orthognathic surgery. The aim of this study was to evaluate the skeletal and pharyngeal airway changes in subjects with a Class III facial pattern who underwent double-jaw surgery (maxillary advancement and mandibular setback).

Materials and methods: The present retrospective study assessed preoperative (T0), 2- to 4-month postoperative (T1), and 6- to 12-month postoperative (T2) radiographs of subjects with a Class III facial pattern treated at São Lucas Hospital (Porto Alegre, Brazil) using imaging software (Dolphin Imaging 3D 11.5). Five measurements of the pharyngeal airway space (nasopharynx; upper, middle, and lower oropharynges; hypopharynx) were evaluated and correlated with the skeletal movement of the jaws (lines perpendicular to the Frankfurt horizontal plane passing through the nasion point to points A and B). The Student t test for paired samples was used to assess the presence of significant differences between the intervals, and the Spearman correlation coefficient was used to assess the significant correlation existing between the skeletal movement and the pharyngeal airway changes. The results were considered at a maximum level of significance of 5% (P < .05).

Results: In the sample of 58 subjects (38 female and 20 male, 18 to 48 years old), measurements of the nasopharynx, upper oropharynx, and middle oropharynx increased, whereas measurements of the lower oropharynx and hypopharynx decreased during these periods (T0 to T1, T0 to T2). Decreases from T1 to T2 in the measurements of the nasopharynx and upper oropharynx were also identified. A correlation between the jaw movements and the change in airway measurement was found between the line perpendicular to the Frankfurt horizontal plane passing through the nasion point to point A and the nasopharynx and between the line perpendicular to the Frankfurt horizontal plane passing through the nasion point to point B and the lower oropharynx for T0 to T1 and T0 to T2.

Conclusions: A correlation between skeletal movements and changes in the measurements of pharyngeal airway was found between maxillary advancement and the nasopharynx, with proportions of 102.8% and 85.5% in the short and medium terms, respectively, and between mandibular setback and the low oropharynx, with proportions of 44.8% and 43.5% in the short and medium terms. A correlation for pharyngeal airway measurements was found between those located anatomically near each other, showing the importance of the pharyngeal muscles in this relation.