Cone-Beam Computed Tomography-Based Evaluation of Immediate Maxillary Transverse Changes Following Invisalign Palatal Expander in Mixed-Dentition Patients: A Three-Case Series

Maxillary constriction in the mixed dentition is commonly associated with a narrow arch form, space deficiency, and impaired eruption guidance. Although the use of the Invisalign Palatal Expander has increased in growing patients, case-based evidence regarding its immediate skeletal, dentoalveolar, and dental effects remains limited. This case series aimed to evaluate immediate maxillary transverse changes after Invisalign Palatal Expander treatment in three patients with mixed dentition using cone-beam computed tomography. In all cases, Invisalign Palatal Expander treatment was performed using sequential removable expanders, with each active stage programmed to achieve 0.25 mm of expansion, followed by an 8-stage overcorrection phase. Post-treatment cone-beam computed tomography scans were obtained 1 month after completion of the expansion phase. Transverse changes were assessed at the skeletal, dentoalveolar, and dental levels. All three cases demonstrated transverse increases across the evaluated levels. Case 1 showed transverse increases across all three levels, with comparatively greater skeletal-level changes than the other two cases. Case 2 showed overall transverse increases, although the skeletal-level changes were relatively smaller than the dentoalveolar and dental-level changes within the same case. Case 3 demonstrated skeletal-level changes; however, larger absolute increases were observed at the dentoalveolar and dental levels than at the skeletal level. These findings suggest that the Invisalign Palatal Expander may contribute to immediate transverse changes with skeletal involvement in mixed-dentition patients. However, because the Invisalign Palatal Expander is removable, inadequate wear compliance may limit the full clinical expression of programmed expansion. Therefore, monitoring of appliance wear and occlusal changes is essential during treatment.