Binbin Kang

Titanium and titanium alloys are the most commonly used implant materials, but they are biologically inert. These materials lack rapid osseointegration and resistance to bacterial infections, problems that remain unsolved. The preparation of titanium dioxide coatings by microarc oxidation improves both the biocompatibility of titanium-based materials and their resistance to corrosion during long-term presence in the body. This paper discusses and summarizes the mechanisms of microarc oxidation and some classical models that need to be developed to provide a better understanding and guidance for future research. Subsequently, the effects of electrolyte type, additives, and surface modification of the microarc oxidized coating on the coating morphology were analyzed in detail. In addition, biological applications of microarc oxidation coatings are analyzed, including antimicrobial properties, osseointegration, hydrophilicity, corrosion resistance, and wear resistance.

Titanium and its alloys have been widely used in the field of oral implants over the past few decades. However, the effect of micro-arc oxidation modified titanium surface on Schwann cells has not been studied, which is of great significance for nerve regeneration around implants and improvement of osseoperception. In this study, the characterization of the titanium surface modified by micro-arc oxidation (MAO) was detected by scanning electron microscope (SEM), XPS and a contact angle measurement system. Schwann cells (SCs) were cultured on titanium surfaces of micro-arc oxidation (MAO) and pure titanium (Ti). At different time points, the morphology and adhesion of SCs on the titanium surfaces were observed by SEM. Cell proliferation activity was detected by the CCK-8 method. The expression levels of mRNA and proteins of nerve growth factor (NGF) and glial-derived neurotrophic factor (GDNF) were detected by RT-PCR, immunofluorescence and western blot. The results of this in vitro study revealed that micro-arc-oxidation-modified titanium surfaces promoted Schwann cell proliferation and secretion of neurotrophic factors compared with pure titanium. CCK-8 results showed that the number of Schwann cells on MAO surfaces was significantly higher than that of the Ti group on day 7. The mRNA expressions of Ngf and Gdnf were up-regulated in both groups from day 1 to day 7. On day 3 and day 7, the gene expression of Ngf in the MAO group was significantly higher than that of the Ti group. On day 7, the MAO group appeared significantly up-regulated in gene expression level of Gdnf. The results of western blot were consistent. Micro-arc oxidation modification provides an accurate and effective method for promoting nerve regeneration of titanium microtopography coatings, which have potential significance for promoting patients’ osseoperception ability in clinical practice.

Lacking osseointegration and peri-implantitis induced by bacterial infiltration are the pivotal issues for the long-term clinical success of implants. In order to improve the bioactivity and antibacterial properties of implant materials, volcano-shaped microporous TiO₂ coatings doped with Zinc (Zn) were fabricated via a micro-arc oxidation (MAO) method on pure titanium (Ti). The microstructure, morphology, and chemical composition of the Zn-doped coatings were systematically studied. In cell culture tests, the formed coatings promoted the adhesion and proliferation of bone mesenchymal stem cells (BMSCs), exhibiting good biocompatibility. The antibacterial experiments revealed that Zn-TiO₂ coatings possess excellent antibacterial properties against Staphylococcus aureus (S. aureus) and Porphyromonas gingivalis (P. gingivalis).