3D printing of titanium-coated gradient composite lattices for lightweight mandibular prosthesis

Compared with conventional prosthesis with homogenous structures, functionally graded lattice prosthesis with optimized stress distribution have both mechanical and biological advantages, thus better adapt to the gradient nature of host bones. In this study, we focus on design and fabricating mandibular prosthesis based on polymer stereolithography apparatus (SLA) 3D printing with metallic coating, to explore the graded lattice prosthesis application. Firstly, mandibular stress distribution under the centric occlusal condition was obtained by finite element method (FEM). Titanium (Ti)-coated polymer lattices with gradient porosities were then made by SLA and physical vapor deposition (PVD). Compression test was performed to characterize the fabricated lattices, and Gibson-Ashby crushing strength formula was fitted to obtain gradient porosity distribution of the lattices corresponding to mandibular stress distribution. Our results show that the Ti-coated lattices were able to withstand compressive strains exceeding 20% with 2-3 times increase in compressive strength, while the porosities of the lattices corresponding to the maximum and minimum stress regions of human mandible (68.3% and 86.3%, respectively) shows similar to 20% gradient difference, suggesting the practical application of functionally graded lattices in potential prosthesis design as well as other biomedical applications.