Optimizing Design of Porous Titanium Alloy Constructs for Mandibular Reconstruction

Objectives: Titanium alloy constructs are used in mandibular reconstruction and include various devices including plates, trays and implants. Titanium 6-aluminium 4-vanadium (Ti6Al4V) alloy is used for mandibular devices due to its mechanical strength, biocompatibility, and ability to osseointegrate. Porous constructs have the potential to permit the ingrowth of blood vessels and bone, while minimizing stress shielding. The objective of this study was to optimize the design of porous Ti6Al4V constructs for mandibular devices.
Methods: We used Simulia Abaqus to perform computer-aided design (CAD) and finite element analysis (FEA). A series of CAD models were prepared as either rectangular prisms or dumbbell-shaped constructs with cubic pores for the entire rectangular prism and between the solid dumbbell grips. Each construct was built with a uniform strut thickness that varied between 150 and 650 μm. Solid construct models were used as controls. FEA was then used to perform three-point bending, tensile, and compressive loading simulations, providing estimates of the flexural, tensile, and compressive mechanical properties of the models.
Results: Elastic modulus values derived from the mechanical simulations showed second-order polynomial increases with increasing strut thickness. Simulations also showed second-order polynomial increases of strength with increase in strut thickness. Cubic porous lattice structures with strut thicknesses ranging between 220 and 260 μm had elastic modulus values matching those of mandibular cortical bone. The corresponding pore sizes of 740-780 μm fall within the range reported by others to be optimal for bone ingrowth.
Conclusions: These FEA simulations are the first step to optimize the design of porous lattice Ti6Al4V constructs for intraosseous mandibular devices. Use of patient-specific, functionally-graded, intraosseous, porous devices is anticipated to facilitate vascularization and bone ingrowth. In addition, matching the elastic modulus to that of mandibular bone is expected to minimize stress shielding.