The effect of surface modification of TiMg composite on the in-vitro degradation response, cell survival, adhesion, and proliferation.

This study is aimed to evaluate the influence of mechanical surface treatment on the degradation response, cell survival, adhesion, and proliferation of a TiMg composite material. Two sets of the TiMg samples with different surface characteristics were studied: i) as-machined samples (TiMg-T) and ii) samples with a mechanically modified surface (TiMg-P). Surface roughness was determined using a confocal microscope. Degradation rates (DR) were evaluated in artificial Plasma, HBSS, and NaCl 0.9%. The cell viability was evaluated using an MTT assay. The initial cell adhesion and spreading were investigated using the direct contact assay. An xCELLigence system was employed to provide real-time cell proliferation. The focal adhesion and cell morphological changes were also examined. The DR of TiMg-P decreased by ⁓5 times compared with that of TiMg-T. Surface of the TiMg-P specimens after 72 h exposure to either HBSS or Plasma was passivated by a layer enriched with bioactive Ca/P species. The cell viability of L929 and Saos-2 after 72 h incubation for TiMg-P was 94.6% and 94.8% compared with 73.8% and 74.3% obtained for TiMg-T, respectively. The direct contact assay showed that the initial adhesion and spreading of the L929 cells incubated with TiMg-P was more pronounced compared with that of TiMg-T. The proliferation rate of Saos-2 cells incubated with TiMg-P was higher when compared with that of TiMg-T, and was almost comparable to that of the DMEM-blank between the 24 and 72 h interval. TiMg-P had a pronounced difference in the number and area of Focal Adhesions (FA) compared with that of TiMg-T. The morphology of cells incubated with TiMg-P was not altered. The results confirmed that the smooth and less strained surface of the TiMg-P samples effectively improved the in-vitro degradation response, cell survival, adhesion, and proliferation.

Bioactive Ti + Mg composites fabricated by powder metallurgy: The relation between the microstructure and mechanical properties.

Metallic implant materials are biomaterials that have experienced major development over the last fifty years, yet some demands posed to them have not been addressed. For the osseointegration process and the outcome of endosseous implantation, it is crucial to reduce the stress shielding effect and achieve sufficient biocompatibility. Powder metallurgy (PM) was utilized in this study to fabricate a new type of titanium (Ti) + magnesium (Mg) bioactive composite to enable stress-shielding reduction and obtain better biocompatibility compared with that of the traditional Ti and Ti alloys used for dental implants. Such composites are produced by well-known cost-effective and widely used PM methods, which eliminate the need for complex and costly Ti casting used in traditional implant production. The relation between the microstructure and mechanical properties of as-extruded Ti + (0-24) vol% Mg composites was investigated with respect to the Mg content. The microstructure of the composites consisted of a biodegradable Mg component in the form of filaments, elongated along the direction of extrusion, which were embedded within a permanent, bioinert Ti matrix. As the Mg content was increased, the discrete filaments became interconnected with each other and formed a continuous Mg network. Young's modulus (E) of the composites was reduced to 81 GPa, while other tensile mechanical properties were maintained at the values required for a dental implant material. The corrosion behavior of the Ti + Mg composites was studied during immersion in a Hank's balanced salt solution (HBSS) for up to 21 days. The elution of Mg pores formed at former Mg sites led to a further decrease of E to 74 GPa. The studied compositions showed that a new Ti + Mg metallic composite should be promising for load-bearing applications in endosseous dental implants in the future.