Influence of Three Different Vertical Positions 
of MARPE Expander on Maxillofacial Complex: 
A Finite Element Analysis^*

Objective: The study was conducted to analyze the stress distribution and displacement due to three different vertical positions of the mini-implant assisted rapid palatal expansion (MARPE) appliance.

Methods: A three-dimensional finite element meshed model was created of the maxillofacial complex with the help of cone beam computed tomography (CBCT) digital imaging and communication in medicine (DICOM) data of a patient with transverse maxillary deficiency using materialise interactive medical image control system (MIMICS) software. Three different groups with varying expander heights were used to study the expansion effects on the maxillofacial structures. von Mises stress and displacement at various skeletal and dental points were evaluated using ANSYS software.

Results: In the midpalatal suture, the posterolateral portion of the hard palate and the maxillary and pterygoid bones showed the greatest amount of stress distribution and displacement pattern. Group 1 showed the maximum amount of transverse displacement compared to groups 2 and 3. Sagittally, all the teeth had a forward displacement. Vertically, groups 2 and 3 showed clockwise rotation of the occlusal plane, while all teeth showed downward displacement in group 1.

Conclusion: In conclusion, a V-shaped expansion in the maxilla with a superior and posterior vertex was noted. Group 1, that is, appliance placed in close approximation to the palate, showed greater displacement compared to groups 2 and 3.