A three-dimensional (3d) finite element analysis for types of rapid palatal expansion techniques with or without maxillary corticotomy

Transversal maxillary deficiency is the main cause of many malocclusions. Orthopedic and orthodontic forces are routinely used to correct maxillary transversal deficiency during preadolescence. In patients who have completed their skeletal development, rapid maxillary expansion appliances alone are not sufficient and surgical osteotomy is required. Corticotomy-assisted rapid maxillary expansion reduces the undesirable effects of orthodontic appliances on the maxillofacial complex. This study was conducted to evaluate the biomechanical changes in the cortical and cancellous bone of the maxilla when the rapid maxillary expansion procedure for orthodontic treatment in patients with maxillary transversal deficiency is performed without surgical or with surgical-assisted. In this study, CBCT (Cone-beam Computed Tomography) image of a 19-year-old female patient, who has consented to use the image data in scientific studies without using a name, was used from the archive of Gazi University Faculty of Dentistry, Department of Oral and Maxillofacial Radiology. 0.5 mm tomography sections were taken from the Kodak 9300C Carestream Health Cooperation Cone-Beam CT imaging system and obtained in DICOM 3.0 format and reconstructed by transferring the 3D imaging program MIMICS. Finite element model was created using the newly created .stl format ALTAIR HYPERWORKS 2017 program. The models created in our study were divided into two groups as corticotomy-assisted and corticotomy-unassisted, and rapid maxillary expansion was simulated. Both groups were divided into three subgroups by applying 1mm, 5mm and 7mm displacement, and a total of 6 working models were obtained. In our study, using 3D finite element analysis method, Pmax (stress) and Pmin (compression) stresses in cortical and cancellous bone were analyzed and calculated with MPa (N / mm2) value. A scale containing 12 colors was used to quantitatively analyze the stress distribution in the models. When corticotomy-assisted and corticotomy-unassisted models were compared, it was determined that compression and tensile stresses were higher in rapid maxillary expansion without surgical in all three displacement amounts in cortical and cancellous bone.