Comparative Evaluation and Correlation of Three Dimensional Skeletal and Dentoalveolar Effects of Sawangi Flexiforce Expander as Against Niti Expander in Class Ii Cases With Maxillary Constriction - a Fem Study

BACKGROUND Maxillary constriction, a common malocclusion characterized by reduced transverse maxillary width, is often associated with Class II skeletal patterns and posterior crossbite. It disrupts craniofacial balance and may contribute to functional issues like dental crowding and airway obstruction. While rapid maxillary expansion is widely used, slow maxillary expanders (SMEs) offer a more conservative, stable alternative. The Sawangi Flexiforce Expander (SFE), a novel stainless-steel SME, is designed to provide controlled skeletal and dentoalveolar expansion. This study evaluates the three-dimensional skeletal and dentoalveolar effects of SFE compared to the conventional NiTi expander using Finite Element Analysis (FEA). OBJECTIVE To compare and correlate the three-dimensional skeletal and dentoalveolar effects produced by the SFE and NiTi expander in Class II cases with maxillary constriction using the Finite Element Method. METHODS A high-resolution CT scan of a 13-year-old girl with Class II malocclusion was used to generate a 3D geometric skull model. The NiTi and SFE appliances were digitally modelled and positioned on the maxillary arch. Material properties and boundary conditions were assigned based on the literature. The model was meshed into 2,53,378 elements and analyzed using ANSYS software. Von Mises stress (MPa) and displacement (mm) were measured at various dental, dentoalveolar, and skeletal landmarks for both expanders. A statistical comparison was made using the students' unpaired t-test and Pearson’s correlation coefficient. RESULTS SFE showed significantly higher displacement than the NiTi expander across all planes—transverse (X), sagittal (Y), and vertical (Z)—with the greatest movement at the first permanent molar. Von Mises stress levels increased with activation, reaching effective expansion thresholds only at 3mm activation for SFE. Although SFE produced relatively higher stress values, differences were not statistically significant. Both appliances showed a strong, statistically significant positive correlation between stress and displacement, with SFE demonstrating greater skeletal effects and NiTi primarily inducing dentoalveolar changes. CONCLUSION The SFE appliance exhibited superior three-dimensional skeletal and dentoalveolar displacement compared to the NiTi expander. The positive correlation between stress and displacement confirms its biomechanical efficacy, making SFE a promising alternative for managing Class II malocclusions with maxillary constriction.