Isfahan University of Technology Journal of Computational Methods in Engineering 2228-7698 45 1 2026 05 22 Investigating the Effect of Bidirectional Functionally Graded Structure on the Mechanical Behavior of Bone and Fatigue Life of Dental Implants Investigating the Effect of Bidirectional Functionally Graded Structure on the Mechanical Behavior of Bone and Fatigue Life of Dental Implants 53 72 3767 10.47176/jcme.45.1.1067 FA Ali Rezamand Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran. Mehdi Salmani Tehrani Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran. Journal Article 2025 11 01 <span>Nowadays, due to high quality and efficiency of dental implants, implantation is considered as the best method for replacing the missing teeth. However, some challenges such as the stress-shielding phenomenon can affect the successfulness of this approach. In this research, the effect of a bidirectional functionally graded titanium-hydroxyapatite structure on the mechanical properties and fatigue life of a dental implant screw, by providing a suitable function for changing the mechanical properties from titanium to hydroxyapatite in the implant screw, was investigated using the finite element simulation. The aim of this study is to compare the performance of the bidirectional functionally graded implant screw with unidirectional functionally graded and titanium implant screws, to reduce the stress-shielding phenomenon and evaluate its fatigue life. Some simplifying assumptions such as isotropic linear elastic behavior for the jawbone were employed. The implant screw and the abutment were modeled as an integrated unit. A rigid ceramic crown with simplified geometry was modeled tied to the abutment. For modeling the jawbone geometry, the section of the lower jaw in the molar teeth area was adopted. The influence of adjacent teeth was ignored, and a single tooth was modeled within the jawbone. The results indicate that the bidirectional functionally graded structure for the screw may reduce the stress-shielding effect. Moreover, compared to the unidirectional functionally graded case, the displacements experienced by the jawbone decrease and hence, prevent damaging the adjacent teeth and jawbone. It is worth mentioning that the proposed bidirectional functionally graded screw satisfy the infinite fatigue life condition, as it should be.</span> <span>Nowadays, due to high quality and efficiency of dental implants, implantation is considered as the best method for replacing the missing teeth. However, some challenges such as the stress-shielding phenomenon can affect the successfulness of this approach. In this research, the effect of a bidirectional functionally graded titanium-hydroxyapatite structure on the mechanical properties and fatigue life of a dental implant screw, by providing a suitable function for changing the mechanical properties from titanium to hydroxyapatite in the implant screw, was investigated using the finite element simulation. The aim of this study is to compare the performance of the bidirectional functionally graded implant screw with unidirectional functionally graded and titanium implant screws, to reduce the stress-shielding phenomenon and evaluate its fatigue life. Some simplifying assumptions such as isotropic linear elastic behavior for the jawbone were employed. The implant screw and the abutment were modeled as an integrated unit. A rigid ceramic crown with simplified geometry was modeled tied to the abutment. For modeling the jawbone geometry, the section of the lower jaw in the molar teeth area was adopted. The influence of adjacent teeth was ignored, and a single tooth was modeled within the jawbone. The results indicate that the bidirectional functionally graded structure for the screw may reduce the stress-shielding effect. Moreover, compared to the unidirectional functionally graded case, the displacements experienced by the jawbone decrease and hence, prevent damaging the adjacent teeth and jawbone. It is worth mentioning that the proposed bidirectional functionally graded screw satisfy the infinite fatigue life condition, as it should be.</span> https://jcme.iut.ac.ir/article_3767_d74cb35426f3d808325876f45b69dbf1.pdf