Mg-Ca-Sr Biodegradable Alloys for Medical Applications: Production, Biomaterials' Properties Characterization, and In Vitro and In Vivo Biocompatibility Evaluation.

The research of biomaterials is an area of significant interest in the biomedical field, and the present study investigates how the strontium (Sr) concentration influences the microstructure, corrosion resistance, and both in vitro and in vivo behavior of alloys in the ternary Mg-Ca-Sr system. Using an induction furnace with a controlled atmosphere (argon as the shielding gas), Mg-0.5Ca-xSr alloys (x = 0.5; 1; 1.5; 2; 3 at.%) were synthesized. Microstructural analyses, performed using optical microscopy and scanning electron microscopy (SEM), revealed a uniform and refined structure. Corrosion behavior assessments, carried out using linear and cyclic potentiometry, demonstrated favorable corrosion resistance for all samples. However, for the system containing 0.5% Sr, the corrosion rate values were lower compared to the other systems, and this alloy also exhibited the lowest corrosion current density. Cytocompatibility assay indicated the cytocompatible behavior of all the studied alloys, with favorable influence on cell viability and a stimulatory effect on the osteoblastic cell proliferation. In vivo biocompatibility assessments of the alloys showed that, for alloys containing 0.5% and 1% Sr, a more rapid degradation occurred in comparison with the other alloys (1.5, 2 and 3% Sr), which still persisted at the tissue level even after 12 weeks post-implantation. In all the batches examined, the inflammatory reaction was directly proportional and persistent in relation to the presence of the material in the tissue. In regions where the material was resorbed/degraded, the local inflammatory response was reduced or absent, and the fibrous tissue was denser and better organized. The field of biomaterials is in continuous development, and this study highlighted the applicability of these five alloy systems for dental and maxillofacial applications such as implants, plates, and related devices.