Magnesium-based alloys with adapted interfaces for bone implants and tissue engineering

Research status and prospects of biodegradable magnesium-based metal guided bone regeneration membranes

Biodegradable magnesium-based metal guided bone regeneration (GBR) membranes possess excellent mechanical properties, biodegradability, and osteopromotive capabilities, making them ideal implants for the treatment of maxillofacial bone defects. This review summarizes the current status and future research trends related to magnesium-based GBR membranes. First, the research history and application fields of magnesium-based metals are introduced, and the advantages of the use of magnesium-based materials for GBR membranes, including their mechanical properties, biocompatibility, osteopromotive performance, and underlying mechanisms are discussed. Finally, this review addresses the current limitations of magnesium-based GBR membranes and their applications and prospects in the field of dentistry. In conclusion, considerable advancements have been in fundamental and translational research on magnesium-based GBR membranes, which lays a crucial foundation for the treatment of maxillofacial bone defects.

Surface engineering of pure magnesium in medical implant applications

This review comprehensively surveys the latest advancements in surface modification of pure magnesium (Mg) in recent years, with a focus on various cost-effective procedures, comparative analyses, and assessments of outcomes, addressing the merits and drawbacks of pure Mg and its alloys. Diverse economically feasible methods for surface modification, such as hydrothermal processes and ultrasonic micro-arc oxidation (UMAO), are discussed, emphasizing their exceptional performance in enhancing surface properties. The attention is directed towards the biocompatibility and corrosion resistance of pure Mg, underscoring the remarkable efficacy of techniques such as Ca-deficientca-deficient hydroxyapatite (CDHA)/MgF2 bi-layer coating and UMAO coating in electrochemical processes. These methods open up novel avenues for the application of pure Mg in medical implants. Emphasis is placed on the significance of adhering to the principles of reinforcing the foundation and addressing the source. The advocacy is for a judicious approach to corrosion protection on high-purity Mg surfaces, aiming to optimize the overall mechanical performance. Lastly, a call is made for future in-depth investigations into areas such as composite coatings and the biodegradation mechanisms of pure Mg surfaces, aiming to propel the field towards more sustainable and innovative developments.

Challenges and Pitfalls of Research Designs Involving Magnesium-Based Biomaterials: An Overview

Magnesium-based biomaterials hold remarkable promise for various clinical applications, offering advantages such as reduced stress-shielding and enhanced bone strengthening and vascular remodeling compared to traditional materials. However, ensuring the quality of preclinical research is crucial for the development of these implants. To achieve implant success, an understanding of the cellular responses post-implantation, proper model selection, and good study design are crucial. There are several challenges to reaching a safe and effective translation of laboratory findings into clinical practice. The utilization of Mg-based biomedical devices eliminates the need for biomaterial removal surgery post-healing and mitigates adverse effects associated with permanent biomaterial implantation. However, the high corrosion rate of Mg-based implants poses challenges such as unexpected degradation, structural failure, hydrogen evolution, alkalization, and cytotoxicity. The biocompatibility and degradability of materials based on magnesium have been studied by many researchers in vitro; however, evaluations addressing the impact of the material in vivo still need to be improved. Several animal models, including rats, rabbits, dogs, and pigs, have been explored to assess the potential of magnesium-based materials. Moreover, strategies such as alloying and coating have been identified to enhance the degradation rate of magnesium-based materials in vivo to transform these challenges into opportunities. This review aims to explore the utilization of Mg implants across various biomedical applications within cellular (in vitro) and animal (in vivo) models.

Mechanical and Computational Fluid Dynamic Models for Magnesium-Based Implants

Today, mechanical properties and fluid flow dynamic analysis are considered to be two of the most important steps in implant design for bone tissue engineering. The mechanical behavior is characterized by Young's modulus, which must have a value close to that of the human bone, while from the fluid dynamics point of view, the implant permeability and wall shear stress are two parameters directly linked to cell growth, adhesion, and proliferation. In this study, we proposed two simple geometries with a three-dimensional pore network dedicated to a manufacturing route based on a titanium wire waving procedure used as an intermediary step for Mg-based implant fabrication. Implant deformation under different static loads, von Mises stresses, and safety factors were investigated using finite element analysis. The implant permeability was computed based on Darcy's law following computational fluid dynamic simulations and, based on the pressure drop, was numerically estimated. It was concluded that both models exhibited a permeability close to the human trabecular bone and reduced wall shear stresses within the biological range. As a general finding, the proposed geometries could be useful in orthopedics for bone defect treatment based on numerical analyses because they mimic the trabecular bone properties.

Bone Regeneration Induced by Patient-Adapted Mg Alloy-Based Scaffolds for Bone Defects: Present and Future Perspectives

Treatment of bone defects resulting after tumor surgeries, accidents, or non-unions is an actual problem linked to morbidity and the necessity of a second surgery and often requires a critical healthcare cost. Although the surgical technique has changed in a modern way, the treatment outcome is still influenced by patient age, localization of the bone defect, associated comorbidities, the surgeon approach, and systemic disorders. Three-dimensional magnesium-based scaffolds are considered an important step because they can have precise bone defect geometry, high porosity grade, anatomical pore shape, and mechanical properties close to the human bone. In addition, magnesium has been proven in in vitro and in vivo studies to influence bone regeneration and new blood vessel formation positively. In this review paper, we describe the magnesium alloy's effect on bone regenerative processes, starting with a short description of magnesium's role in the bone healing process, host immune response modulation, and finishing with the primary biological mechanism of magnesium ions in angiogenesis and osteogenesis by presenting a detailed analysis based on a literature review. A strategy that must be followed when a patient-adapted scaffold dedicated to bone tissue engineering is proposed and the main fabrication technologies are combined, in some cases with artificial intelligence for Mg alloy scaffolds, are presented with examples. We emphasized the microstructure, mechanical properties, corrosion behavior, and biocompatibility of each study and made a basis for the researchers who want to start to apply the regenerative potential of magnesium-based scaffolds in clinical practice. Challenges, future directions, and special potential clinical applications such as osteosarcoma and persistent infection treatment are present at the end of our review paper.