Advancing of titanium medical implants by surface engineering: recent progress and challenges

ABSTRACT

Introduction:

Titanium (Ti) and their alloys are used as main implant materials in orthopedics and dentistry for decades having superior mechanical properties, chemical stability and biocompatibility. Their rejections due lack of biointegration and bacterial infection are concerning with considerable healthcare costs and impacts on patients. To address these limitations, conventional Ti implants need improvements where the use of surface nanoengineering approaches and the development of a new generation of implants are recognized as promising strategies.

Areas covered:

This review presents an overview of recent progress on the application of surface engineering methods to advance Ti implants enable to address their key limitations. Several promising surface engineering strategies are presented and critically discussed to generate advanced surface properties and nano-topographies (tubular, porous, pillars) able not only to improve their biointegration, antibacterial performances, but also to provide multiple functions such as drug delivery, therapy, sensing, communication and health monitoring underpinning the development of new generation and smart medical implants.

Expert opinion:

Recent advances in cell biology, materials science, nanotechnology and additive manufacturing has progressively influencing improvements of conventional Ti implants toward the development of the next generation of implants with improved performances and multifunctionality. Current research and development are in early stage, but progressing with promising results and examples of moving into in-vivo studies an translation into real applications.

KEYWORDS:

• Titanium implants
• surface engineering
• osseointegration
• antibacterial surfaces
• titania nanotubes

Article highlights

- The clinical failure of Ti implants due bacterial infections and lack of biointegration are concerning to patients and healthcare services with the needs to be addressed.

- The key performance requirements for Ti implants and their related surface parameters such as surface topography, chemical functionality, wettability and charge are discussed to understand challenges to achieve these performances and advance conventional implants and develop new generation of smart implants are discussed.

-Several structural surface engineering technologies to generate nanostructures on Ti surface with different shapes and dimensions (nanotubes, nanopilars etc) are presented showing their successful demonstrations for addressing key limitations of Ti implants with improved osteointegration, antibacterial and other properties.

-An electrochemical anodization of Ti with generated arrays of nanotubular (TNTs) structures is shown to have a considerable potential for development of advanced and new generation of implants with multiple functions including drug delivery, combination therapy, sensing and antibacterial protection.

- More in-vivo and long-term performance studies are required to evaluate the viability of these surface engineering development and advancement of Ti implants progressed in recent years at lab scale.

- Additive manufacturing (AM) or 3D printing of Ti implants combined with surface nanoengineering and other chemical functionalization approaches is offering exciting new prospects for the development of the next generation of smart implants which can be patient-tailored, fabricated ‘on demand’ and have multiple functions such drug delivery, therapy, sensing, wire-less communication and health monitoring.

This box summarizes key points contained in the article.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

The author acknowledges the support from Australian Research Council (IH 150000003).