Additively manufactured mesh-type titanium structures for cranial implants: E-PBF vs. L-PBF

A patient-specific titanium-reinforced calcium phosphate (CaP-Ti) cranial implant has recently shown promising clinical results. Currently, its mesh-type titanium structure is additively manufactured using laser beam powder bed fusion (L-PBF). Nevertheless, an electron-beam(E-PBF) process could potentially be more time efficient. This study aimed to compare the geometrical accuracy and mechanical response of thin titanium structures manufactured by L-PBF (HIPed) and E-PBF (as-printed). Tensile test (phi = 1.2 mm) and implant specimens were manufactured. Measurements by mu CT revealed a deviation in cross-sectional area as compared to the designed geometry: 13-35% for E-PBF and below 2% for L-PBF. A superior mechanical strength was obtained for the L-PBF specimens, both in the tensile test and the implant compression tests. The global peak load in the implant test was 457 +/- 9 N and 846 +/- 40 N for E-PBF and L-PBF, respectively. Numerical simulations demonstrated that geometrical deviation was the main factor in implant performance and enabled quantification of this effect: 34-39% reduction in initial peak force based on geometry, and only 11-16% reduction based on the material input. In summary, the study reveals an uncertainty in accuracy when structures of sizes relevant to mesh-type cranial implants are printed by the E-PBF method. (C) 2020 The Authors. Published by Elsevier Ltd.

Automated summary

The study compared the geometrical accuracy and mechanical response of thin titanium structures manufactured by L-PBF and E-PBF, with L-PBF specimens showing superior mechanical strength in both tensile and implant compression tests. E-PBF-manufactured structures exhibited a deviation in cross-sectional area and uncertainty in accuracy when printed for mesh-type cranial implants.