Microstructural, Electrochemical, and Mechanical Assessment of Additive Manufactured Titanium Grade 23 for Dental Implants Application.

Background/aim: Due to its excellent mechanical properties and biocompatibility, the titanium grade 23 alloy is the material of choice for dental implants. Additive manufacturing enables patient-specific manufacturing and the reduction of stress shielding by using lattice structures instead of solid material. For the simulation and design of such structures, a comprehensive knowledge of the mechanical properties under quasi-static and cyclic loading, the microstructure, and the electrochemical properties is required. In addition, suitable heat treatments must be selected and validated. These properties were determined uniformly and will provide a complete database and benchmark for future applications.

Materials and methods: The mechanical behavior of the laser powder bed fusion (PBF-LB/M) manufactured alloy Ti6Al4V in the as-built and heat-treated state was characterized in tensile and constant amplitude tests, as well as hardness and microstructure analysis. To characterize the electrochemical properties, electrochemical impedance spectroscopy and potentiodynamic polarization measurements were performed.

Results: For use in medical implants, both conditions fulfilled the mechanical required specification in DIN EN ISO 5832-3, but heat treatment also reduced the high residual stresses caused by the manufacturing process. In the high cycle fatigue range, no significant difference was found between the two material states. The fatigue strength was increased compared to the literature. In electrochemical corrosion investigations, no remarkable differences between the two material states were detected by electrochemical impedance spectroscopy or potentiodynamic polarization measurements, but the high corrosion resistance of PBF-LB/M Ti6Al4V was demonstrated.

Conclusion: The study provides a wide electrochemical and mechanical database for the design of the PBF-LB/M manufactured alloy Titanium grade 21 as an implant material.