Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 12 4 2015 10 12 Three Dimensional Finite Element Analysis of Stress Distribution and Displacement of the Maxilla Following Surgically Assisted Rapid Maxillary Expansion with Tooth- and Bone-Borne Devices 298 305 EN Mohsen Dalband Assistant Professor, Dental Research Center, Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Hamadan University of Medical Sciences, Hamadan, Iran Jamal Kashani PhD in Mechanical Engineer, Medical Implant Technology Group, Faculty of Biosciences and Medical Engineering, Universiti Teknologi, Malaysia, Malaysia Hadi Hashemzehi Assistant Professor, Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Zahedan University of Medical Sciences, Zahedan, Iran 2015 10 12 2015 10 12 Objectives: The aim of this study was to investigate the displacement and stress distri- bution during surgically assisted rapid maxillary expansion under different surgical conditions with tooth- and bone-borne devices. Materials and Methods: Three-dimensional (3D) finite element model of a maxilla was constructed and an expansion force of 100 N was applied to the left and right molars and premolars with tooth-borne devices and the left and right of mid-palatal sutures at the first molar level with bone-borne devices. Five CAD models were simulated as fol- lows and surgical procedures were used:  G1: control group (without surgery); G2: Le Fort I osteotomy; G3: Le Fort I osteotomy and para-median osteotomy; G4: Le Fort I osteotomy and pterygomaxillary separation; and G5: Le Fort I osteotomy, para-median osteotomy, and pterygomaxillary separation. Results: Maxillary displacement showed a gradual increase from group 1 to group 5 in all three planes of space, indicating that Le Fort I osteotomy combined with para-me- dian osteotomy and pterygomaxillary separation produced the greatest displacement of the maxilla with both bone- and tooth-borne devices. Surgical relief and bone-borne devices resulted in significantly reduced stress on anchored teeth. Conclusion: Combination of Le Fort I and para-median osteotomy with pterygomaxil-lary separation seems to be an effective procedure for increasing maxillary expansion, and excessive stress side effects are lowered around the anchored teeth with the use of bone-borne devices. https://fid.tums.ac.ir/index.php/fid/article/view/302 https://fid.tums.ac.ir/index.php/fid/article/download/302/284