Three-dimensional finite element analysis of traumatic forces on zygoma with zygomatic implants

The aim of this study is to evaluate the stress distribution of traumatic forces to zygoma with zygomatic implants (ZI) placed by different surgical techniques and apical placement by using three-dimensional (3D) finite element analysis. 3D images were generated from computed tomography (CT) images in MIMICS 12.1 software. Rough models were imported to GEOMAGİC 3D software to reconstruct smooth surface 3D computer aided design (CAD) models, construction and insertion of ZI models were performed by SOLIDWORKS software. Totally 9 models were used including the non-ZI control model. Intrasinus, extrasinus, extramaxillary and dual extramaxillary techniques were modeled with each having sub-groups according to ZI apex perforating the lateral outer cortex of zygoma anchoring 1 mm distal and non-perforating variations. FEA software ANSYS was used to generate mesh for the bone and implant models, following material parameter assignment by BoneMat© program, boundary conditions were created. Models were fixed in all degrees of freedom and 3247 N static force was applied horizontally at an angle of 45° to the sagittal plane on zygoma at an area of 40 mm2 in 1 second. Yield criteria for bone was defined 153 MPa and the colored visual scales were used to demonstrate von Mises stress values on bone and implants. While maximum von Mises stress values on bone around ZI apex on all perforated zygoma models were higher (9380 ± 3812 MPa), stress on zygomatic sutures were lower. The distribution of Von Mises stress values were higher on zygomaticofrontal, zygomaticotemporal, zygomaticomaxillary sutures and lateral wall of maxillary sinus on extramaxillary models and lower on intrasinus models with extrasinus models demonstrating highest alveolar process stress. The results of this study showed that bicortical anchorage from zygoma provides homogeneous distribution of the stress on zygomatic sutures while the loss of bicortical anchorage from alveolar bone with ZI body advancing lateral to maxilla increases the stress on sutures, creating higher risk of fracture.