This is a application specific thing, where the use of Mg is intended for short time period- higher degradation rate is applicable. Similarly for long term application slow degradation is desirable.

First of all, the degradation rate of Mg-made implant should not be too high in order to permit the body to recover, namely: the implant should not disappear too early.

Secondly, too fast degradation of Mg is accompanied by enhanced Hydrogen release into the body, which is harmful.

So Mg degradation rate in biodegradable implants should be optimized.

read Bowen 2013

Zinc Exhibits Ideal Physiological Corrosion Behavior for Bioabsorbable Stents

Dear Ahmad,

Scientists tried to analyze the degradation of magnesium which can be a biggest step forward over wince last decade leading to models predicting the in vivo degradation rate. However, the mechanisms are still not very clear and it is far from complete understanding and more effort will need to determine these. It’s not so easy. Despite the many desirable properties of magnesium for medical implant and device applications, the rapid degradation of magnesium in vivo remains a critical challenge.

As we know, magnesium alloys are a promising class of degradable implant materials, a thorough understanding of their degradation under physiological conditions is a challenge in the field of biomaterial science. As we also understand the rapid degradation of magnesium-based materials reduces the mechanical properties of implants prematurely and severely increases alkalinity of the local environment. Magnesium alloys can enhance bone growth as compared with current implant materials, i.e., titanium alloys or stainless steels. Magnesium serves this aim best; it plays the essential role in body metabolism and should be completely excreted within a few days after degradation.

Factors affecting MG degradation

Many interacting factors affect magnesium degradation, such as bulk composition of magnesium alloys, microstructure and composition at the surface of the magnesium alloy, and the composition of surrounding fluids. Understanding the interactions between these factors is as important as recognizing the role of each individual factor on magnesium degradation.

Alternatives to controlling MG degradation or implant other biomaterials (corrosion point of view)

Another way, one method of controlling magnesium degradation is effective to add certain alloying elements into the magnesium and Yttrium (Y) is often added to magnesium alloys to increase material strength ductility, and degradation (or corrosion) resistance. However, Y can exhibit both degradation inhibiting and degradation promoting activities in magnesium alloys, depending on other factors I mentioned above. Yttrium oxide (Y2O3) accumulates in the degradation layer when Y migrates to the metal surface and is oxidized further. When a stable degradation layer is present, yttrium oxide in the degradation layer can slow down magnesium degradation by inhibiting cathodic reactions. Zn-based alloys may also be promising candidates for biodegradable implants. The advantages of Zn-based alloys are its low melting point and low reactivity in molten state.

Ashish

Hi

It is well known that Mg element is an excellent sacrificial, i.e., degradable, anode for cathodic protection of metals/alloys in corrosive environments. In contrast, if Mg element became part of a composite of biomaterials, i.e., implants, therefore, a control of the Mg degradation is essential.

Magnesium (Mg) is a biodegradable metal that can be used in various applications, including in the production of biodegradable implants and other medical devices, as well as in the construction and automotive industries. The biodegradability of magnesium is due to its ability to corrode and disintegrate in the presence of water and oxygen, leading to the formation of a protective layer of oxide on its surface.

While the biodegradability of magnesium can be advantageous in certain applications, in other cases, it may be desirable to reduce the degradation rate of magnesium in order to extend its lifespan and improve its performance. This is especially important in applications where magnesium is used as a structural material, such as in the construction or automotive industries, where the integrity and stability of the material are critical.

In general, the degradation rate of magnesium can be influenced by various factors, including the type and concentration of the electrolyte, the presence of other elements or compounds, the pH and temperature of the environment, and the surface finish of the magnesium. It is therefore possible to optimize the degradation rate of magnesium in order to achieve the desired performance and lifespan of the material in a particular application.