OBJECTIVE: The purpose of this study is to evaluate the alterations caused by mandibular setback surgery combined or not with maxillary surgery in the upper airways. METHODS: Preoperative and immediate postoperative lateral cephalometric radiographs of 17 Class III patients were evaluated. Measurements of the diameter of air space (AS) in the sagittal plane were performed in regions corresponding to the hypopharynx and oropharynx; changes in the position of the hyoid bone were also registered. The paired t test and Pearson coefficient were used to provide possible associations between skeletal changes and those occurred in the AS. RESULTS: There was a statistically significant reduction of AS in the hypopharynx region (average of 3.10 mm, p = 0.024). The hyoid bone moved backward and downward after the surgery, and the distance between this bone and the anterior region of mandible decreased. It was not possible to correlate, quantitatively, the anteroposterior reduction of the AS after the mandibular setback. However, there was a strong correlation between the initial diameter of AS and the amount of reduction seen at the hypopharynx; this correlation was found to be moderate at the oropharynx level. CONCLUSIONS: The mandibular setback surgery can cause significant narrowing of the upper airways, especially in hypopharynx region. Therefore, it is important to evaluate this structure during treatment planning of combined orthodontic and surgical cases. Possible deleterious effects of these changes on individuals' functions were not yet discarded.
Orthognathic surgery; Mandibular setback; Airways; Oropharynx; Hypopharynx
