Multifunctional Coatings of Titanium Implants Toward Promoting Osseointegration and Preventing Infection: Recent Developments

Titanium and its alloys are dominant material for orthopedic/dental implants due to their stable chemical properties and good biocompatibility. However, aseptic loosening and peri-implant infection remain problems that may lead to implant removal eventually. The ideal orthopedic implant should possess both osteogenic and antibacterial properties and do proper assistance to in situ inflammatory cells for anti-microbe and tissue repair. Recent advances in surface modification have provided various strategies to procure the harmonious relationship between implant and its microenvironment. In this review, we provide an overview of the latest strategies to endow titanium implants with bio-function and anti-infection properties. We state the methods they use to preparing these efficient surfaces and offer further insight into the interaction between these devices and the local biological environment. Finally, we discuss the unmet needs and current challenges in the development of ideal materials for bone implantation.

Osteogenic properties of bioactive sodium titanate/titanium oxide composite coating prepared by anodic oxidation in NaOH electrolyte

Our sodium titanate/titanium oxide coating has excellent osteogenic performance and has potential to be used as a bone repair material.

Osteogenic activity and antibacterial ability on titanium surfaces modified with magnesium-doped titanium dioxide coating

Aim: To improve the bioactivity and antibacterial activity of titanium (Ti) implants. Materials & methods: Magnesium (Mg)-doped titanium dioxide microporous coatings (Mg-TiO₂) were prepared on the surface of Ti implants by plasma electrolytic oxidation. Results: Ti surfaces were covered with porous Mg-TiO₂, and Mg was evenly distributed throughout the coating. Mg-TiO₂ could not only promote osteoblast adhesion, proliferation and differentiation but also inhibit the colonization and growth of Staphylococcus. In addition, Mg-TiO₂ may promote osteogenesis through the ERK/c-Fos signaling pathway as well as the early osseointegration of Ti implants. Conclusion: Mg-TiO₂ has both osteogenic and antibacterial effects and thus presents important theoretical significance and clinical potential.

Enhanced Osseointegration of Hierarchically Structured Ti Implant with Electrically Bioactive SnO2-TiO2 Bilayered Surface

The poor osseointegration of Ti implant significantly compromise its application in load-bearing bone repair and replacement. Electrically bioactive coating inspirited from heterojunction on Ti implant can benefit osseointegration but cannot avoid the stress shielding effect between bone and implant. To resolve this conflict, hierarchically structured Ti implant with electrically bioactive SnO₂-TiO₂ bilayered surface has been developed to enhance osseointegration. Benefiting from the electric cue offered by the built-in electrical field of SnO₂-TiO₂ heterojunction and the topographic cue provided by the hierarchical surface structure to bone regeneration, the osteoblastic function of basic multicellular units around the implant is significantly improved. Because the individual TiO₂ or SnO₂ coating with uniform surface exhibits no electrical bioactivity, the effects of electric and topographic cues to osseointegration have been decoupled via the analysis of in vivo performance for the placed Ti implant with different surfaces. The developed Ti implant shows significantly improved osseointegration with excellent bone-implant contact, improved mineralization of extracellular matrix, and increased push-out force. These results suggest that the synergistic strategy of combing electrical bioactivity with hierarchical surface structure provides a new platform for developing advanced endosseous implants.