In Vitro Resorption of Magnesium Materials and its Effect on Surface and Surrounding Environment

Abstract

Introduction: Magnesium has attracted much attention for its potential use in trauma and orthopedics fields due to its mechanical properties, biocompatibility, biodegradability and the possible ability to stimulate bone formation. It is desirable for magnesium-based alloys to have a low toxicity rate so the fractured bone heals before the implant resorbs. Materials and methods: Corrosion properties of Mg2Ag, Mg10Gd, WE43 and 99.99% pure Mg were studied under physiological conditions. The samples were placed in DMEM containing 10% fetal bovine serum (FBS) and corrosion was studied after immersion and by gas evolution tests. The corrosion rate (CR), osmolality, pH and Ca2­+ concentrations, as well as surface changes in the form of average surface roughness (Sa), developed surface area ratio (Sdr) and summit density (Sds), were determined. Results:WE43 showed the highest CR of all the materials tested-1.057 mm/year, which is almost twice as high as in the other samples. The lowest mean CR was in the Mg2Ag group. All alloys made pH more alkaline and decreased the concentration of free Ca2­+ in the solution. Osmolality decreased in all samples after day 7. Pure Mg had the most constant Sa and Sdr while WE43 had the most stable Sds of all materials over the observation period. Conclusion: The surface of alloys changed as the implants corroded: the summits became lower with time, while the pitting corrosion progressed. Mg2Ag was the most promising of all the studied materials with regard to toxicity.