Surface modifications for hard tissue growth
About the project
Titanium and its alloys are used in a wide range of medical applications due to their excellent biocompatibility. At the presence of oxygen, titanium spontaneously forms a 2 nm to 6 nm thick inert, oxide layers on its surface. As a result it has a high polarization resistance that hinders the release of metallic ions into the human body and thus protects it against corrosion. Titanium’s mechanical strength favors its use for dental and orthopedic implants as prosthesis and joint replacements.
Modification of the oxide layer is one of multiple approaches to increase titanium’s biocompatibility. Although the oxide layer’s thickness can be more increased more than tenfold by anodic oxidation, biocompatibility does hardly increase at all. Optimization of the surface roughness is the most common approach to improve bone healing using mechanical and chemical methods or their combination. In detail blasting with TiO2 particles, etching and multistep etching showed successful results in optimizing surface roughness.
Modification of the surface chemistry is a less explored approach. Etching of titanium in acids creates minuscule quantities of titanium hydride as a result of acidic hydrogen release. The team has shown that TiH2 induces faster bone healing and improved osseointegration compared to unmodified titanium surfaces. Cathodic polarization can induce much thicker TiH2 layers that showed over 60% higher pull-out forces in in vivo studies. Unlike titanium oxide, titanium hydride is not inert but highly reactive. This allows new approaches of surface modifications. Thus the titanium hydride could be used as an intermediate for ion implementation strategies and as an interface for attaching biomolecules to the surface to guide tissue responses at the implant surface.
The ongoing project was initiated in 2003 and has received funding from several industry partners, Innovation Norway, The Norwegian research Council and the EU.
- Marta Monjo, PhD, Department of Fundamental Biology and Health Sciences, Research Institute on Health Sciences (IUNICS), University of Balearic Islands,
Palma de Mallorca, Spain
- Marina Rupert, MSc, Department of Fundamental Biology and Health Sciences, Research Institute on Health Sciences (IUNICS), University of Balearic Islands,
Palma de Mallorca, Spain,
- Prof. Dr. med. Dr.-Ing. habil. Erich Wintermantel,Lehrstuhl für Medizintechnik, Fakultät Maschinenwesen, Technische Universität München,
Gebäude 4, Boltzmannstrasse 15 , D-85748 Garching, Germany,