Effect of thermomechanical treatment on the mechanical and microstructural evolution of a β-type Ti-40.7Zr-24.8Nb alloy

Recent Advances and Prospects in β-type Titanium Alloys for Dental Implants Applications

Titanium and its alloys, especially Ti-6Al-4V, are widely studied in implantology for their favorable characteristics. However, challenges remain, such as the high modulus of elasticity and concerns about cytotoxicity. To resolve these issues, research focuses on β-type titanium alloys that incorporate elements such as Mo, Nb, Sn, and Ta to improve corrosion resistance and obtain a lower modulus of elasticity compatible with bone. This review comprehensively examines current β titanium alloys, evaluating their mechanical properties, in particular the modulus of elasticity, and corrosion resistance. To this end, a systematic literature search was carried out, where 81 articles were found to evaluate these outcomes. In addition, this review also covers the formation of the alloy, processing methods such as arc melting, and its physical, mechanical, electrochemical, tribological, and biological characteristics. Because β-Ti alloys have a modulus of elasticity closer to that of human bone compared to other metal alloys, they help reduce stress shielding. This is important because the alloy allows for a more even distribution of forces by having a modulus of elasticity more similar to that of bone. In addition, these alloys show good corrosion resistance due to the formation of a noble titanium oxide layer, facilitated by the incorporation of β stabilizers. These alloys also show significant improvements in mechanical strength and hardness. Finally, they also have lower cytotoxicity and bacterial adhesion, depending on the β stabilizer used. However, there are persistent challenges that require detailed research in critical areas, such as optimizing the composition of the alloy to achieve optimal properties in different clinical applications. In addition, it is crucial to study the long-term effects of implants on the human body and to advance the development of cutting-edge manufacturing techniques to guarantee the quality and biocompatibility of implants.

An injectable magnesium-loaded hydrogel releases hydrogen to promote osteoporotic bone repair via ROS scavenging and immunomodulation

Background: The repair of osteoporotic bone defects remains challenging due to excessive reactive oxygen species (ROS), persistent inflammation, and an imbalance between osteogenesis and osteoclastogenesis. Methods: Here, an injectable H2-releasing hydrogel (magnesium@polyethylene glycol-poly(lactic-co-glycolic acid), Mg@PEG-PLGA) was developed to remodel the challenging bone environment and accelerate the repair of osteoporotic bone defects. Results: This Mg@PEG-PLGA gel shows excellent injectability, shape adaptability, and phase-transition ability, can fill irregular bone defect areas via minimally invasive injection, and can transform into a porous scaffold in situ to provide mechanical support. With the appropriate release of H2 and magnesium ions, the 2Mg@PEG-PLGA gel (loaded with 2 mg of Mg) displayed significant immunomodulatory effects through reducing intracellular ROS, guiding macrophage polarization toward the M2 phenotype, and inhibiting the IκB/NF-κB signaling pathway. Moreover, in vitro experiments showed that the 2Mg@PEG-PLGA gel inhibited osteoclastogenesis while promoting osteogenesis. Most notably, in animal experiments, the 2Mg@PEG-PLGA gel significantly promoted the repair of osteoporotic bone defects in vivo by scavenging ROS and inhibiting inflammation and osteoclastogenesis. Conclusions: Overall, our study provides critical insight into the design and development of H2-releasing magnesium-based hydrogels as potential implants for repairing osteoporotic bone defects.

Mechanobiologically optimized Ti-35Nb-2Ta-3Zr improves load transduction and enhances bone remodeling in tilted dental implant therapy

The tilted implant with immediate function is increasingly used in clinical dental therapy for edentulous and partially edentulous patients with excessive bone resorption and the anatomic limitations in the alveolar ridge. However, peri-implant cervical bone loss can be caused by the stress shielding effect. Herein, inspired by the concept of “materiobiology”, the mechanical characteristics of materials were considered along with bone biology for tilted implant design. In this study, a novel Ti–35Nb–2Ta–3Zr alloy (TNTZ) implant with low elastic modulus, high strength and favorable biocompatibility was developed. Then the human alveolar bone environment was mimicked in goat and finite element (FE) models to investigate the mechanical property and the related peri-implant bone remodeling of TNTZ compared to commonly used Ti–6Al–4V (TC4) in tilted implantation under loading condition. Next, a layer-by-layer quantitative correlation of the FE and X-ray Microscopy (XRM) analysis suggested that the TNTZ implant present better mechanobiological characteristics including improved load transduction and increased bone area in the tilted implantation model compared to TC4 implant, especially in the upper 1/3 region of peri-implant bone that is “lower stress”. Finally, combining the static and dynamic parameters of bone, it was further verified that TNTZ enhanced bone remodeling in “lower stress” upper 1/3 region. This study demonstrates that TNTZ is a mechanobiological optimized tilted implant material that enhances load transduction and bone remodeling.

•

The mechanical properties and deformation mechanisms of Ti–35Nb–2Ta–3Zr alloys were studied.

•

The cell biocompatibility, a layer-by-layer correlation of the finite element and X-ray Microscopy analysis were evaluated.

•

Ti–35Nb–2Ta–3Zr implant improves load transduction and enhances bone remodeling in tilted implantation models.

•

Mechanobiologically optimized Ti–35Nb–2Ta–3Zr alloy meets the clinical application requirements of tilted implant therapy.

Effect of Thermomechanical Treatments on Microstructure, Phase Composition, Vickers Microhardness, and Young’s Modulus of Ti-xNb-5Mo Alloys for Biomedical Applications

The development of new β-Ti alloys has been extensively studied in the medical field in recent times due to their more suitable mechanical properties, such as a relatively low Young’s modulus. This paper analyzes the influence of heat treatments (homogenization and annealing) and hot rolling on the microstructure, phase composition, and some mechanical properties of ternary alloys of the Ti-xNb-5Mo system, with an amount of Nb varying between 0 and 30 wt%. The samples are produced by argon arc melting. After melting, the samples are homogenized at 1000 °C for 24 h and are hot rolled and annealed at 1000 °C for 6 h with slow cooling. Structural and microstructural analyses are made using X-ray diffraction and optical and scanning electron microscopy. Mechanical properties are evaluated by Vickers microhardness and Young’s modulus. The amount of β phase increases after heat treatment and reduces after hot rolling. The microhardness and Young’s modulus of all heat-treated samples decrease when compared with the hot rolled ones. Some samples exhibit atypical Young’s modulus and microhardness values, such as 515 HV for the as-cast Ti-10Nb-5Mo sample, indicating the possible presence of ω phase in the microstructure. The Ti-30Nb-5Mo sample suffers less variation in its phase composition with thermomechanical treatments due to the β-stabilizing effect of the alloying elements. The studied mechanical properties indicate that the annealed Ti-30Nb-5Mo sample has potential for biomedical applications, exhibiting a Young’s modulus value of 69 GPa and a microhardness of 236 HV.

Effects of Cold Rolling Deformation and Solution Treatment on Microstructural, Mechanical, and Corrosion Properties of a Biocompatible Ti-Nb-Ta-Zr Alloy

One of the most important requirements for a metallic biomaterial is the mechanical biocompatibility, which means excellent mechanical properties—high strength and fatigue strength, but low elastic modulus, to be mechanically harmonized with hard tissues. In order to improve the mechanical and biocompatible performance of the Ti-25.5Nb-4.5Ta-8.0Zr wt% alloy, the influence of cold plastic deformation and solution treatment on its properties were investigated. The Ti-25.5Nb-4.5Ta-8.0Zr wt% alloy was fabricated by melting in a cold crucible furnace (in levitation) and then subjected to several treatment schemes, which include cold rolling and different solution treatments. Microstructural and mechanical characteristics of specimens in as-cast and thermo-mechanically processed condition were determined by SEM microscopy and tensile testing, for different structural states: initial as-cast/as-received, cold rolled and solution treated at different temperatures (800, 900, and 1000 °C) and durations (5, 10, 15, and 20 min), with water quenching. It was concluded that both cold rolling and solution treatment have important positive effects on structural and mechanical properties of the biomaterial, increasing mechanical strength and decreasing the elastic modulus. Samples in different structural states were also corrosion tested and the results provided important information on determining the optimal processing scheme to obtain a high-performance biomaterial. The final processing route chosen consists of a cold rolling deformation with a total deformation degree of 60%, followed by a solution heat treatment at 900 °C with maintenance duration of 5 min and water quenching. By applying this thermo-mechanical processing scheme, the Ti-25.5Nb-4.5Ta-8.0Zr wt% alloy showed an elastic modulus of 56 GPa (5% higher than in the as-cast state), an ultimate tensile strength of 1004 MPa (41.8% higher than in the as-cast state), a yield strength of 718 MPa (40.6% higher than in the as-cast state), and increased corrosion resistance (the corrosion rate decreased by 50% compared to the as-cast state).

Coinciding significance of the crystallographic orientation and nanostructuring on the biocompatibility of TZNT-Ag1 .5 alloy deformed by the cold rolling process

In this study, the simultaneous significance of the crystallographic texture and nanostructuring on the cytocompatibility of as-cast (Ti₅₅ Zr₂₅ Nb₁₀ Ta₁₀ )_98.5 -Ag_1.5 alloy (at. %, TZNT-Ag_1.5 ), subjected to cold rolling up to 90% reduction, along with the changes of Young's modulus and hardness under cold rolling were investigated. For this purpose, the as-cast and cold-rolled TZNT-Ag_1.5 alloy test specimens were analyzed by XRD, TEM, HRTEM, SEM, contact angle, nanoindentation, and OM techniques. Moreover, to evaluate the effect of severe cold deformation on the biocompatibility, MG-63 osteoblastic cell was cultured on the surface of 90% cold-rolled and as-cast test specimens of TZNT-Ag_1.5 alloy. The results showed that severe cold deformation was led to fast grain refinement of β grains of the as-cast TZNT-Ag_1.5 alloy in the range of 50-100 nm. In addition to the nanostructuring, upon severe cold deformation, the <gamma>-fiber (<111>// normal direction) texture was formed and after 90% reduction, the (111)<1 1 ¯ 0 > γ_-fiber component was strengthened. The micro-hardness and reduced Young's modulus are 235 ± 5.29, 246 ± 1.73, 271 ± 4.0, and 283 ± 6.25 (HV); and 73.725 ± 1.70, 83.98 ± 5.10, 81.26 ± 6.55, and 88.66 ± 7.16 (GPa) for TZNT-Ag_1.5 (as-cast), TZNT-Ag_1.5 (20%CR), TZNT-Ag_1.5 (50%CR), and TZNT-Ag_1.5 (90%CR) test specimens, respectively. Further, with increasing the cold deformation degree, the dislocation density of TZNT-Ag_1.5 alloy increased as this parameter is 2.79 × 10¹⁵ (m^-2 ) for the 90%CR test specimen. On the other hand, the values of the contact angle for the 90%CR test specimen (46.2 ± 3.5°) exhibit a higher hydrophilic and wettable surface as compared to the other studied test specimens. After 5 days of incubation, osteoblastic cells on the surface of the 90% cold-rolled TZNT-Ag_1.5 test specimens revealed significant differences in cell proliferation and differentiation as compared to the as-cast alloy test specimens and/or CP-Ti. Finally, because the maximum orientation intensities were generally <3, it was deduced that grain refinement rather than the crystallographic texture plays a significant role in improving the surface biocompatibility of the new TZNT-Ag_1.5 alloy.

A review on alloy design, biological response, and strengthening of β-titanium alloys as biomaterials

From the past few years, developments of β-Ti alloys have been the subject of active research in the medical domain. The current paper highlights significant findings in the area of β-Ti alloy design, biological responses, strengthening mechanisms, and developing low-cost implants with a high degree of biocompatibility. It is evident that an astonishing demand for developing the low modulus-high strength implants can be fulfilled by synchronizing β stabilizer content and incorporating tailored thermo-mechanical techniques. Furthermore, the biological response of the implants is as important as the physical properties that regulate healing response; hence, the optimum selection of alloying elements plays a curial role for clinical success. The paper also presents the evolution of patents in this field from the year 2010 to 2020 showing the relevant innovations that may benefit a wide range of researchers.

Improving the Mechanical Properties of a β-type Ti-Nb-Zr-Fe-O Alloy

The influence of complex thermo-mechanical processing (TMP) on the mechanical properties of a Ti-Nb-Zr-Fe-O bio-alloy was investigated in this study. The proposed TMP program involves a schema featuring a series of severe plastic deformation (SPD) and solution treatment (STs). The purpose of this study was to find the proper parameter combination for the applied TMP and thus enhance the mechanical strength and diminish the Young’s modulus. The proposed chemical composition of the studied β-type Ti-alloy was conceived from already-appreciated Ti-Nb-Ta-Zr alloys with high β-stability by replacing the expensive Ta with more accessible Fe and O. These chemical additions are expected to better enhance β-stability and thus avoid the generation of ω, α’, and α” during complex TMP, as well as allow for the processing of a single bcc β-phase with significant grain diminution, increased mechanical strength, and a low elasticity value/Young’s modulus. The proposed TMP program considers two research directions of TMP experiments. For comparisons using structural and mechanical perspectives, the two categories of the experimental samples were analyzed using SEM microscopy and a series of tensile tests. The comparison also included some already published results for similar alloys. The analysis revealed the advantages and disadvantages for all compared categories, with the conclusions highlighting that the studied alloys are suitable for expanding the database of possible β-Ti bio-alloys that could be used depending on the specific requirements of different biomedical implant applications.