Effects of different hyrax maxillary expansion protocols compared with novel magnetic expansion on the pharyngeal airway and maxillary sinus spaces: A retrospective CBCT-based observational study

Abstract

Purpose

To evaluate three-dimensional changes in the maxillary sinus (MS) and pharyngeal airway space (PAS) following rapid (RME), slow (SME), and magnetic maxillary expansion (MME) using cone-beam computed tomography (CBCT).

Methods

This retrospective observational study included 60 patients (35 males, 25 females; mean age 12.83 ± 0.92 years) with transverse maxillary deficiency, allocated equally to RME, SME, and MME groups (n = 20 each). Expansion was carried out according to protocol-specific activation schedules, with appliances retained for three months post-expansion. CBCT scans were obtained at baseline (T1), post-expansion (T2), and after retention (T3). Measurements of MS volume, area, minimum constriction area, and PAS subdivisions (nasopharynx, oropharynx, hypopharynx) were analyzed using Dolphin Imaging software. An adjusted p-value of <0.05 was considered statistically significant.

Results

All three expansion protocols demonstrated numerical increases in maxillary sinus and pharyngeal airway dimensions during the active expansion phase (T1–T2); however, after adjustment for multiple comparisons, statistically significant changes were limited. Significant within-group increases in maxillary sinus volume were observed only in the slow maxillary expansion group, while no pharyngeal airway parameter showed a statistically significant change after correction. No significant dimensional changes were detected during the retention period (T2-T3). Inter-group comparisons revealed no statistically significant differences among the three expansion protocols.

Conclusion

Magnetic maxillary expansion demonstrates anatomical effects comparable to conventional expansion protocols; importantly, no distinct or superior pharyngeal airway benefit was identified, highlighting the limits of airway-related effects of maxillary expansion rather than evidence of enhanced functional respiratory impact.