Functionally graded materials for load bearing implants have a long history of academic development and an already high degree of maturity. Efforts are now undertaken to improve the biocompatibility and even induce bioactivity within the implant-bone interface by optimised surface nanostructure of porous ceramic and metalic layers grown or sintered on a metallic implant, in order to arrive at cementless implants capable of fast osteointegration and high interface strength. Several new methods for surface structure and composition modification are presented for Ti-alloy based implants: a nano-structuring of the surface by re-deposition of TiO2 using an ECR-Microwave Plasma treatment combined with ion bombardment on a sintered TiO2 ceramic surface, a multiscale modification of porous Ti-coatings by means of Micro-Arc-Oxidation, MAO, and a meso-structuring of the surface by means of a laser treatment. The goal is to establish a multi-functionality in such materials by formation of a morphological and compositional gradient spanning many dimensions. The applicability of these methods to real implants is discussed for a dental implant.

The biocompatibility of TiO 2 depends on many parameters: phase composition, particle size, band gap, to name only few. The use of TiO 2 -coatings for medical applications is of particular interest with respect to the UV activity, reported in literature to be a major factor affecting not only the antimicrobial activity but also the hydroxylapatite formation in simulated body fluid [1]. Within a systematic study pigment (P25 from Degussa) as well as in-house synthesised nano-TiO 2 [2] powders were utilised to sinter coatings out of them and investigate the influence of UV radiation with and without ion bombardment on the surface morphology, the wetting behaviour, the band gap and bacteria colony growth. ECR microwave plasma treatment with Ar, O 2 and mixtures of them was performed using different bias voltages to enhance ion bombardment. The temperature was kept below 200°C. OES was used to monitor the gas phase species. The different role of UV-irradiation with and without ion bombardment on the TiO 2 -surface properties was clearly shown by the wetting angle measurement as well as optical and microscopic measurements. A new effect was found: although the TiO 2 coating was sintered at high temperature prior to plasma treatment, evaporation and re-deposition of nano-titania particles on the surface occurs, which contributes significantly to the bio-as well as the photocatalytic properties of the material.

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