Three-dimensional structure of laser-modified Ti6Al4V and bone interface revealed with STEM tomography
2011 (English)In: Frontiers in Electron Microscopy in Materials Science, 2011Conference paper (Refereed)
The Ti6Al4V titanium alloy is one of the most routinely used materials in implant technologies. It is a suitable biomaterial due to its intrinsic mechanical properties, the excellent biocompatibility of its native surface titanium-dioxide layer, and its ability to osseointegrate. The early interaction between an implant’s surface and bone is a leading factor for implant success, where multiple surface properties contribute to improved bone anchorage. An important parameter is surface topography, both on the micron and nanoscale. Laser-modification has been performed in the thread valleys of Ti6Al4V screws to alter their surface chemistry and topography to form a nanostructured surface titanium-dioxide. Since the valley regions are associated with increased bone formation kinetics and influential to implant bonding, the modified screws may exhibit enhanced bone attachment. In order to understand the underlying mechanisms and structure of the interface to nanostructured implant surfaces, characterization techniques with sufficient resolution are needed. Z-contrast electron tomography offers the possibility to explore the interfacial structure with high-resolution in three-dimensions. Furthermore, by operating in STEM mode, artifacts arising from diffraction contrast in the crystalline implant are avoided, while a high-degree of compositional contrast is maintained in the bone matrix. The aim of the present paper was to evaluate Z-contrast electron tomography as a tool to analyze the bone interface to a nanostructured implant surface. Implants were placed in the rabbit tibia and removed with surrounding bone after 8 weeks. Focused ion beam (FIB) was used to prepare specimens for transmission electron microscopy (TEM). Elemental analysis with energy dispersive x-ray spectroscopy (EDXS) over the implant-bone interface confirms the intermixing of bone apatite and titanium dioxide. This was further substantiated with three-dimensional reconstructions created from Z-contrast electron tomograms. Collagen fibers of the surrounding bone appear to have been laid down parallel to the implant surface. Accordingly, visualization of the laser-modified interface with nanoscale three-dimensional resolution, as offered by Z-contrast electron tomography, gives new insights into bone bonding mechanisms between roughened titanium-dioxide surfaces and bone.
Place, publisher, year, edition, pages
Medical Materials Engineering and Technology
Research subject Engineering Science with specialization in Materials Science
IdentifiersURN: urn:nbn:se:uu:diva-164326OAI: oai:DiVA.org:uu-164326DiVA: diva2:467332
Frontiers of Electron Microscopy in Materials Science