A CBCT Evaluation of Nasal Septal Deviation and Related Nasofacial Structures after Maxillary Skeletal Expansion

Background: The aim of this study was to evaluate three-dimensional (3D) changes in nasal septal deviation (NSD) and related nasofacial structures after maxillary skeletal expansion (MSE). Methods: This retrospective study evaluated 28 patients aged 12.0–48.4 years (mean age, 20.4 ± 7.3 years; 12 males, 16 females) diagnosed with transverse maxillary deficiency and treated with MSE. Cone-beam computed tomography (CBCT) images were taken at pre-expansion (T1), post-expansion (T2), and 6-months after MSE (T3) and were reoriented. Three-dimensional coordinates (x,y,z) were constructed using nasion (N) as the reference point (0,0,0). A paired-sample t-test and an independent sample t-test were performed to investigate and compare the 3D changes of the NSD and nasofacial structures after MSE, depending on the direction and amount of NSD and the amount of midpalatal expansion (MPE). Results: NSD was alleviated at T3–T1 in the coronal plane; nasal septal length increased significantly. The absolute nasal floor (NF) angle (2.06° at T1) decreased at T2–T1 (p > 0.05) and increased at T3–T2 (p < 0.05). The midface moved forward and downward, and pogonion (Pog) and menton (Me) moved downward and backward. There were no significant differences between the higher and lower NSD groups and greater and lesser MPE groups. Conclusions: Consequently, NSD was alleviated with variable positive nasofacial changes after MSE in both the short and long term. Therefore, MSE can be used to improve or camouflage facial deformities.