Fabrication of compositionally and structurally graded Ti-TiO2 structures using laser engineered net shaping (LENS)

Current implant designs often require multiple components with distinct material properties. Prior research has shown that combining porous and dense regions in a single structure improves mechanical performance. However, achieving functional gradation in both composition and structure remains a challenge. No prior work had resolved how to integrate ceramic coatings onto porous titanium using additive manufacturing. This gap motivated the investigation into laser-based fabrication techniques. It was already known that TiO2 enhances surface properties like wettability and hardness. But the effect of graded Ti-TiO2 structures on biocompatibility had not been fully explored. The need for unitized implant structures with tailored properties is well established. This paper's contribution addresses the fabrication and evaluation of such graded structures.

The study aimed to fabricate Ti-TiO2 structures with graded composition and structure using laser engineered net shaping. The specific problem addressed was the integration of ceramic coatings onto porous titanium for biomedical applications. The motivation was to create unitized structures that combine mechanical support with surface functionality. This approach could reduce the need for multiple implant components. The goal was to evaluate how compositionally graded structures affect surface properties. The study also sought to assess biocompatibility and potential for reducing wear in implants. By combining porous and dense regions in one structure, the design could better mimic natural bone. The findings could inform the development of more efficient implant systems.

Laser engineered net shaping (LENS) was used to fabricate Ti-TiO2 structures with graded composition. The process involved depositing layers of Ti powder mixed with varying concentrations of TiO2. The structures were designed to have a porous Ti base and a dense TiO2 surface. Surface wettability and hardness were measured using standard techniques. Biocompatibility was assessed using cell culture experiments. The study compared graded structures with non-graded controls. Friction coefficient measurements were conducted against polyethylene liners. The experimental setup included controlled deposition parameters to achieve desired gradation.

The fabricated structures showed a significant increase in surface wettability and hardness when TiO2 was added. The graded structures exhibited non-toxic and biocompatible properties. The top surfaces with higher TiO2 concentration had improved lubrication potential. Friction coefficient measurements indicated a potential reduction in wear rate against polyethylene. The porous Ti base provided structural support while the dense TiO2 surface offered functional benefits. The study found that the graded structures could eliminate the need for multiple implant components. The combination of open porosity and low friction surface was achieved in a single unit. These results suggest that LENS can produce functional graded structures suitable for implants.

The authors proposed that LENS can successfully fabricate Ti-TiO2 structures with functional gradation. The study demonstrated that adding TiO2 to porous Ti enhances surface properties. The graded structures were found to be non-toxic and biocompatible. The increased wettability and hardness suggest potential benefits for implant applications. The ability to form chemisorbed lubricating films was highlighted as a key finding. The study suggests that these structures could reduce the need for multiple implant parts. The findings support the use of graded structures in load-bearing implants like hip prostheses. The authors emphasized the importance of combining structural and functional properties in a single unit.