Comparison of the skeletal and dental changes of tooth-borne vs. bone-borne expansion devices in surgically assisted rapid palatal expansion: A finite element study

Background: The aim of this study was to compare the skeletal and dental changes of a toothborne (Hyrax) and a bone-borne (Smile distractor) expansion devices using three-dimensional model of a human skull. Materials and Methods: A finite element model of human skull was generated using data from 3-D CT scans of an 11-year-old female child. Then a Hyrax expander (tooth-borne appliance) and Smile distractor (bone-borne appliance) in three different positions were adapted to the finite element model and expanded for 0.5 mm simulating the clinical situation. The 3-D pattern of displacement and stress distribution was then analyzed. Results: The results of this study showed that screw position affects the stress and displacement pattern within the nasomaxillary complex and maxillary dental arch. Conclusion: Closer teeth feel more stress and undergo more displacement than the farther ones. Moreover, skeletal effects of the Smile distractor were greater than of Hyrax in all different positions.