Cephalometric analysis of the upper airways of Class III patients subjected to orthosurgical treatment

Objective: The aim of this study was to evaluate the effects of orthognathic surgery for mandibular setback – with and without combined maxillary surgery – on the upper airways (UA). Methods: Immediate lateral preoperative and postoperative cephalometric radiographs of 17 Class III patients were evaluated. Measurements of airway space (AS) diameter were taken in the sagittal plane in the hypopharyngeal and oropharyngeal regions, and changes in hyoid bone position were also recorded. Paired t-test and Pearson’s coefficient were applied seeking for potential associations between skeletal and AS changes. Results: Significant AS reduction was noted in the hypopharyngeal region (mean= 3.10 mm, p= 0.024). The hyoid bone was displaced inferiorly and posteriorly, thereby reducing its distance to the anterior mandibular region. No quantitative correlation could be established between anteroposterior AS reduction and mandibular setback. However, there was a strong correlation between initial AS diameter and the amount of reduction observed in the hypopharynx, but only moderate correlation with the oropharynx. Conclusions: Mandibular setback can cause significant UA narrowing, especially in the inferior-most portion (hypopharynx). Therefore, special attention should be given to UA evaluation when formulating an orthosurgical treatment plan since the potential deleterious effects of these changes on functions of the patients should not be overlooked. Abstract