Abstract: BACKGROUND: Porous tantalum may be an ideal oral implant material to replace titanium and titanium alloys, but its optimal structure and porosity remain to be explored.
OBJECTIVE: To identify the porosity of porous tantalum with a trabecular, diamond, and cubic structure that most closely matches the elastic modulus of the jawbone using finite element analysis. Among the three groups with the most optimal elastic modulus, we further explored the structure most conducive to reducing bone stress and promoting initial cell adhesion during implantation.
METHODS: Using nTop software, we created models of the trabecular, diamond, and cubic structures with 60%, 70%, and 80% porosity, resulting in a total of nine groups. Ansys software was employed for static pressure simulation to record the deformation along the direction of applied force. The elastic modulus was calculated, and the optimal group for each structure was selected based on the closest match to the elastic modulus of the jawbone. A dental implant design with a porous scaffold in the middle and solid screw segments at the top and bottom was simulated for implantation, and the stress after implantation was simulated. The internal stress of the mandible under the stress after bone implantation of the three groups of optimal structure implants was analyzed to explore a group of porous scaffold structures that are most conducive to reducing the internal stress of the bone under similar elastic modulus. The three groups of optimal elastic modulus groups were simulated by fluid mechanics using Ansys software to explore the structure that is most conducive to early cell adhesion and osteogenesis.
RESULTS AND CONCLUSION: (1) Static pressure simulations revealed that the diamond 60%, trabecular 70%, and cubic 80% groups had the closest elastic modulus to that of the mandibular cortical bone among the different porosities of each structure. Static pressure analysis under load after tantalum implant implantation showed that the cancellous stress of the trabecular 70% group was lower than that of the diamond 60% group and cubic 80% group, and the cortical stress of the diamond 60% group was higher than that of the cubic 80% group. (2) Fluid mechanics analysis showed that the volume of the low-velocity area near the scaffold of the cubic 80% group was the largest, the volume of the low-velocity area near the scaffold of the trabecular 70% group was slightly lower than that of the cubic 80% group, and the volume of the low-velocity area near the scaffold of the diamond 60% group was the smallest. After introducing discrete phase particles to simulate cell movement, it was found that although the volume of the low-velocity area near the scaffold of the trabecular 70% group was slightly smaller than that of the cubic 80% group, the low-velocity area near the scaffold had the most particles staying, which was most conducive to early cell adhesion and osteogenesis.

Key words: finite element analysis, scaffold structure, implant, tantalum, elastic modulus, fluid mechanics, porosity