A novel digital 3D study protocol using STL and CBCT superimpositions to assess maxillary transverse correction with hyrax expanders in cleft lip and palate patients-A pilot study

Background: Cleft lip and palate (CLP) frequently present with transverse maxillary deficiency due to disrupted midpalatal fusion, surgical scarring, and muscular imbalance. Accurate differentiation between skeletal and dental contributions to expansion is essential for treatment planning in these patients. Aim and Objectives: This pilot study evaluated a three-dimensional (3D) digital workflow combining cone-beam computed tomography (CBCT) and stereolithography (STL)-based superimpositions for assessing maxillary expansion in unilateral CLP (UCLP) cases. Materials and Methods: Nonsyndromic UCLP patients with transverse deficiency were treated using a banded Hyrax rapid maxillary expansion appliance. CBCT datasets were oriented to a midsagittal reference plane and registered through voxel-based cranial base superimposition in Dolphin 3D Imaging. Pre- and postexpansion dental casts were digitized and aligned in 3Shape OrthoAnalyzer using three-point surface-based registration on palatal rugae, with color-coded displacement maps for visualization. STL models were further integrated with CBCT datasets to provide a combined assessment of skeletal and dental effects. Results: Results demonstrated significant increases in intermolar and nasal widths, alongside controlled dental expansion. The proposed workflow achieved sub-millimetric accuracy, high reproducibility, and effective visualization of complex cleft anatomies. Conclusion: This study protocol offers a practical, scalable solution for cleft care, enhancing diagnostic precision and supporting individualized treatment planning.