Does pterygomaxillary disjunction in surgically assisted rapid maxillary expansion influence upper airway volume? A prospective study using Dolphin Imaging 3D.

Surgically assisted rapid maxillary expansion has been used for the treatment of transverse maxillary deficiency. This prospective study aimed to evaluate the effect of this surgery (with or without pterygomaxillary disjunction) on the upper airway volume. The patients were randomly divided into two groups: without pterygomaxillary disjunction (-PD) and with pterygomaxillary disjunction (+PD). Eleven patients per group were estimated to obtain a representative sample (90% of power and 95% of confidence level). Volumetric images of cone beam computed tomography scans were obtained preoperatively, immediately after Hyrax screw stabilization and 6 months after Hyrax screw stabilization. Volumetric measurements of the nasal cavity, maxillary sinuses, nasopharynx, and oropharynx, and of the minimum oropharynx cross-sectional area were obtained using Dolphin 3D Imaging Software. The final sample consisted of 25 adult individuals (+PD group, n=12; -PD group, n=13). In the +PD group, we observed a statistically significant increase immediately after Hyrax screw stabilization for the nasopharynx volume (P=0.003), oropharynx volume (P=0.007) and oropharynx cross-sectional area (P=0.001). Pterygomaxillary disjunction resulted in a significant (P <0.05) increase in volumetric measurements of the nasopharynx and minimum oropharynx cross-sectional area 6 months after the expander device stabilization.