Mechanical Behavior and Bioadaptability of Nonmonotonic Functional Gradient Material ( FGM ) Implants at Different Tilting Angles

In this study, finite element simulations of implants with different tilting angles (15°, 30°, 45° to the axial plane) were performed to analyze the mechanical behavior and bioadaptability of four functional gradient materials (FGM) implants with complex gradients, and compared with conventional implants and monotonic FGM implants proposed in the literature. The results showed that as the tilting angle increases, the implant generates more stresses and strains in the bone, especially at the implant tilt corner contact. Notably, compared with conventional implants, nonmonotonic FGM implants (A-L-H-L, R-L-H-L), and monotonic FGM implants (R-H-L) have lower material stiffness at the base and at the tilt corners of the implant, which effectively reduces the stresses and strains in this area and reduces the risk of bone destruction. In addition, the strain intensities generated by FGM A-L-H-L and R-L-H-L implants at different tilting angles are within the range that promotes bone remodeling (1500-3000 με), which is conducive to postoperative bone recovery and long-term growth. In conclusion, the proposed nonmonotonic FGM A-L-H-L and R-L-H-L implants provide more effective stress reduction compared with high-density titanium implants and better bioadaptability compared with monotonic FGM implants. For clinical research, this study aims to obtain a gradient distribution of tilted FGM implants with better mechanical properties and biological adaptability at different tilting angles to provide a research basis for clinical and subsequent implant development.