Effect of tissue fixatives on the corrosion of biomedical magnesium alloys

Guanqi Liu; Ziyu Yan; Yuzhu Guo; Chuanbin Guo; Chengwen Tan; Jianhua Zhu; Jianmin Han

doi:10.1016/j.heliyon.2024.e30286

Effect of tissue fixatives on the corrosion of biomedical magnesium alloys

Heliyon. 2024 Apr 25;10(9):e30286. doi: 10.1016/j.heliyon.2024.e30286. eCollection 2024 May 15.

Authors

Guanqi Liu^{1

2}, Ziyu Yan^{1

3}, Yuzhu Guo^{1

2}, Chuanbin Guo³, Chengwen Tan², Jianhua Zhu³, Jianmin Han¹

Affiliations

¹ Central laboratory, Peking University School and Hospital of Stomatology, National Center for Stomatology, National Clinical Research Center for Oral Diseases, National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing Key Laboratory of Digital Stomatology, NHC Key Laboratory of Digital Stomatology, NMPA Key Laboratory for Dental Materials, Beijing, 100081, China.
² School of Materials Science and Engineering, Beijing Institute of Technology, Beijing, 100081, China.
³ Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, National Center for Stomatology, National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing Key Laboratory of Digital Stomatology, NHC Key Laboratory of Digital Stomatology, NMPA Key Laboratory for Dental Materials, Beijing, 100081, China.

Abstract

In this work, the corrosion behavior of pure Mg, Mg3Ag, Mg6Ag, and MgZnYNd alloys in different fixatives (ethyl alcohol (EA), 85 % ethyl alcohol (85 % EA), 10 % neutral buffered formalin (10 % NBF), 4 % glutaric dialdehyde (4 % GD), and 4 % paraformaldehyde (4 % PFA)) was investigated to provide a valuable reference for the selection of fixatives during the histological evaluation of Mg implants. Through the hydrogen evolution test, pH test, and corrosion morphology and product characterization, it was found that corrosion proceeded slowest in the EA and 85 % EA groups, slightly faster in 4 % GD, faster in 10 % NBF, and fastest in 4 % PFA. After corrosion, the EA group surface remained unchanged, while the 85%EA group surface developed minor cracks and warping. The 4%GD fixative formed a dense needle-like protective layer on the Mg substrate. The 10%NBF group initially grew a uniform layer, but later developed irregular pits due to accelerated corrosion. In contrast, the 4%PFA solution caused more severe corrosion attributed to chloride ions. The main corrosion products in the EA and 85%EA groups were MgO and Mg(OH)₂, while the other fixatives containing diverse ions also yielded phosphates like Mg₃(PO₄)₂ and MgHPO₄. In 4 % PFA, AgCl formed on the surface of Mg6Ag alloy after corrosion. Therefore, to minimize Mg alloy corrosion without compromising staining quality, EA or 85 % EA is recommended, while 4 % PFA is not recommended due to its significant impact.

Keywords: Corrosion behavior; Magnesium alloys; Microstructure; Tissue fixative.