3-Dimensional Evaluation of Upper Airway Following Orthognathic Surgery Operations

Methods: The upper airways of 14 consecutive patients (7 males, 7 females), who underwent mandibular advancement by bilateral sagittal split ramus osteotomy (BSRO), were measured on cone beam computed tomography (CBCT) scans obtained before and at least 1 year after surgery. Dolphin 11.7 software (Patterson Dental Supply Inc., Chatsworth, CA) was used for cephalometric analysis and for segmentation and measurement of the upper airway. The Kolmogorov-Smirnov test was used to check the normality of distribution. Paired t-test was used to determine the differences in airway measurements pre- and postoperatively. Spearman’s rank correlation was used to test the associations between airway changes, mandibular advancement and changes in craniocervical inclination. Method error was assessed. The study was reviewed and approved by the ethics committee of Riga Stradins University.

Results: Surgical advancement was 5.6 ± 2.1 mm. The oropharyngeal minimal cross sectional area (CSAmin) changed from 172.4 ± 85.9mm² preoperatively to 199.1 ± 73.1mm² postoperatively; however, the change did not reach statistical significance (95% CI: -70.72 to 17.2). In 5 patients the decrease of CSAmin from preoperative values one year after surgery was recorded. The only significant correlation was found for CSAmin and alteration in craniocervical inclination (r=-0.78, p<0.001).

Conclusions: With 95% confidence, there are no significant changes in the upper airway dimensions 1 year after isolated mandibular advancement. In some patients (36%) even the decrease of dimensions of the upper airways could be recorded. The decrease of smallest cross sectional area is associated with the significant increase of craniocervical inclination.