Post Processing and Biological Evaluation of the Titanium Scaffolds for Bone Tissue Engineering

Abstract

Nowadays, post-surgical or post-accidental bone loss can be substituted by custom-made scaffolds fabricated by additive manufacturing (AM) methods from metallic powders. However, the partially melted powder particles must be removed in a post-process chemical treatment. The aim of this study was to investigate the effect of the chemical polishing with various acid baths on novel scaffolds’ morphology, porosity and mechanical properties. In the first stage, Magics software (Materialise NV, Leuven, Belgium) was used to design a porous scaffolds with pore size equal to (A) 200 µm, (B) 500 µm and (C) 200 + 500 µm, and diamond cell structure. The scaffolds were fabricated from commercially pure titanium powder (CP Ti) using a SLM50 3D printing machine (Realizer GmbH, Borchen, Germany). The selective laser melting (SLM) process was optimized and the laser beam energy density in range of 91–151 J/mm3 was applied to receive 3D structures with fully dense struts. To remove not fully melted titanium particles the scaffolds were chemically polished using various HF and HF-HNO3 acid solutions. Based on scaffolds mass loss and scanning electron (SEM) observations, baths which provided most uniform surface cleaning were proposed for each porosity. The pore and strut size after chemical treatments was calculated based on the micro-computed tomography (µ-CT) and SEM images. The mechanical tests showed that the treated scaffolds had Young’s modulus close to that of compact bone. Additionally, the effect of pore size of chemically polished scaffolds on cell retention, proliferation and differentiation was studied using human mesenchymal stem cells. Small pores yielded higher cell retention within the scaffolds, which then affected their growth. This shows that in vitro cell performance can be controlled to certain extent by varying pore sizes.

Laser and Electron Beam Additive Manufacturing Methods of Fabricating Titanium Bone Implants

“…Fortunately, both SLM and EBM machines enable the production of complex three-dimensional titanium structures with controlled porosity. The minimum pore diameters obtained by EBM machines are 450 µm [30], while SLM methods can achieve a pore size of 150 µm [54] due to the small size of the beam.…”

Mechanical Behavior of Ti6Al4V Scaffolds Filled with CaSiO3 for Implant Applications

“…Three dimensional (3D) printed porous scaffolds are suitable for seeding cells, delivering drugs, and are able to carry compression/tensile loading [2,3]. Biological activities along the scaffold surface (cell growth) and structural design of the scaffolds for additive manufacturing (AM) are both very important, and extensive research has been conducted [8].…”

Packing Changes in Melting, Freezing, and Coalescence of Titanium Nanoparticles from Atomic Simulations

“…These make Ti an excellent choice in biomedical applications, such as orthopedic or dental implants. [12][13][14][15][16][17][18][19] The biocompatibility of Ti alloys has been the subject of particular focus. In the most common medical-grade alloys, alloying elements such as aluminum and vanadium have been reported to be potentially harmful and toxic to the human body.…”