Investigation of the biomechanical properties of transnasal, zigomatic and pterygoid implant applications in atrophic maxilla model by finite element analysis

Aim: In the extremely atrophic maxilla, there is usually no bone available for conventional dental implant placement. Transnasal, zygomatic and pterygoid implants are preferred due to the fact that they eliminate the need for maxillary sinus augmentation and bone grafting techniques. This results in a reduction of treatment time and cost, as well as a decrease in morbidity. The objective of this study was to utilise the finite element stress analysis method to investigate the stress values of transnasal implant, zygomatic implant and pterygoid implant applications on implants and surrounding bone in patients with atrophic maxilla. Material and Method: In this study, finite element analysis (FEA) method was applied and 3 atrophic maxilla models were used. In the first model, transnasal implants were placed in sites 12 and 22 and zygomatic implants in sites 15 and 25; in the second model, zygomatic implants were placed in sites 12, 15, 22 and 25; in the third model, transnasal implants were placed in sites 12 and 22, zygomatic implants in sites 15 and 25 and pterygoid implants in sites 17 and 27. In the polymethylmethacrylate (PMMA) prosthetic restoration, a vertical force of 150 N was applied separately to the occlusal surfaces of teeth 11 and 16 through the spherical foodstuff model. Results: In the present study, the highest Von Mises stress values were measured in Model 1 in region 2 and Model 2 in region 5 in anterior loading, and in Model 1 in regions 2 and 5 in posterior loading. The lowest stress values were observed in Model 3. In the abutments, the highest Von Mises stress values were measured in Model 2 in regions 2 and 5 in anterior and posterior loading, respectively. The lowest stress values were observed in Model 3. In the metal substructure, Model 1 and Model 2 yielded analogous results in anterior and posterior loading, while the lowest stress values were observed in Model 3. When the maximum and minimum principal stresses formed in cortical bone were measured, the highest stresses were generally seen in Model 2, while the lowest stresses were seen in Model 3. When the maximum and minimum principal stresses formed in cancellous bone were measured, the highest stresses were generally seen in Model 1, while the lowest stresses were seen in Model 3. Conclusion: It was concluded that the use of transnasal implants in combination with zygomatic implants is an alternative to the quad-zygomatic concept, where 4 zygomatic implants are used in the rehabilitation of the atrophic maxilla. However, the use of pterygoid implants minimises the stress values. Keywords: Atrophic maxilla, pterygoid implant, finite element analysis, transnasal implant, zygomatic implant