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OBTAINED RESULTS

Stage I

- Analysis of the law requirements regarding the materials used for the obtaining of the medical implantable devices.

- Analysis of the recent tendencies on the world level regarding the metallic biomaterials based on titanium for the medical implantable devices.

- Design of the alloy composition with titanium base for dental implants; an alloy from Ti-Zr system was selected, because zirconium addition improves the mechanical properties and corrosion resistance in biological fluids and increases the osseointegration capacity.

- Selection of the methods for the bioalloy surface activation based on the most recent tendencies. 2 methods: green chemical and electrochemical methods were selected. By these methods it will be obtained a significant enhancement of the alloy biocompatibility and bioactivity.

- Selection of the methods for the chemical (X-ray fluorescence spectrometry), mechanical (traction resistance and determination of the Young's modulus) and structural (optical and scanning electron microscopy) characterisation of the bioalloy.

- Selection of the methods for the characterisation of the corrosion resistance in simulated biological fluids and in extreme functional conditions: cyclic voltammetry; linear polarisation; electrochemical impedance spectroscopy - EIS; in time variation of the open circuit potentials and corresponding open circuit potential gradients; Medcalc statistical method.

- Selection of the methods for the physico-chemical characterisation of the electrochemical activated surface: scanning electron microscopy - SEM; X-ray photoelectron spectroscopy - XPS; Fourier Transform Infra Red - FTIR, X-ray diffraction- XRD; Raman microscopy.

- Elaboration of the laboratory method for the bioalloy synthesis comprises: design of the bioalloy synthesis; experimentation of the bioalloy synthesis method and samples characterisation (chemical, mechanical, structural).

- Elaboration and experimentation of the laboratory technology for the bioalloy synthesis refers to: flow of the synthesis technology for TiZr alloy, on technological phases and operations, materials consumption, establishment of the process efficiency (99 - 99.3%) and of the un-recoverable losses (0.7 - 1%).

- Characterisation of the as-cast alloy samples (chemical, mechanical, structural) evinced the obtaining of a chemical composition similar with that calculated and a homogeneous bi-phase structure.

- Design and experimentation of the methods for the bioalloy activation. 2 activation methods of the new Ti-20Zr alloy surface were applied: electrochemical by anodic oxidation and chemical in aqueous solutions with the control of all experimental parameters.

- Corrosion resistance of the as-cast bioalloy Ringer-Brown and Ringer of different pH values and Carter-Brugirard saliva un-doped and doped with 0.05M NaF of different pH values was appreciated from the values of the corrosion rates, of the main electrochemical parameters, of the impedances, of the open circuit potentials and gradients that can appear due to the pH and concentration non-uniformities on some zones of an implant.

Stage II

- Elaboration of laboratory method for the bioalloy thermo-mechanical processing; design and experimentation of the method and characterisation of the Ti-20Zr bioalloy samples in the deformation state.

- Design and experimentation of the laboratory technology for the bioalloy thermo-mechanical processing with the establishment of the processing parameters, technological flow for the plastic deformation, characterisation of the as-cast and thermo-mechanical processed Ti-20Zr alloy.

- Selection of the implant model.

- Elaboration of the method and technology for the machining and obtaining of the implant model.

- Design of the implant model.

- Design and experimentation of the laboratory technology for electrochemical activation of the bioalloy surface and the establishment of the technological flow with the specific parameters, working way, necessary equipments, material consumption.

- Determination of the bioalloy corrosion resistance after electrochemical activation, establishing the main electrochemical and corrosion parameters in Ringer solutions and artificial saliva, as well as electrochemical impedance spectra.

- The electrochemical activated surface was characterised by: optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), Raman micro-spectroscopy (RS), infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS).

- Design of the composition for the antibacterial coating resistant for long term.

- Design and experimentation of the sonochemical method for the antibacterial protection resistant for long term; the concept is based on the sonochemical process in a single step to produce nanoparticles and to impregnate them as antibacterial factors on the dental implants is new and there is not on the commercial scale.

- Experimentation of the sonochemical method for the antibacterial protection resistant for long term was realised by the deposition characterisation and verifying of the obtained coating quality by SEM and EDX techniques.

- Results dissemination

ISI articles

1. J. M. Calderon Moreno, M. Popa, S. Ivanescu, C. Vasilescu, S. I. Drob, E. I. Neacsu, M. V. Popa, A new Ti-Zr alloy with very good Young's modulus: its microstructure, mechanical properties and corrosion resistance in un-doped and doped with NaF artificial saliva, Met. Mater. Int., doi: 10.1007/s12540-013-6031-x, impact factor 1,434 (2012)

2. J. M. Calderon Moreno, E. Vasilescu, P. Drob, M. Popa, C. Vasilescu, S. I. Drob, Surface analysis and electrochemical behaviour of Ti-20Zr alloy in simulated physiological fluids, Mater. Sci. Eng. B, 178(18), 1195-1204, 2013, impact factor 1,846 (2012)

International scientific communications

1. E. Vasilescu, P. Drob, C. Vasilescu, S. I. Drob, D. Raducanu, V.D. Cojocaru, I. Cinca, Characterisation of corrosion stability of a new nanostructured alloy, Book of Abstracts of the APMAS 2012, 2nd International Advances in Applied Physics & Materials Science Congress, 26-29 April 2012, Antalya, Turkey, Paper No 179, pp. 129.

2. M. V. Popa, P. Drob, E. Vasilescu, C. Vasilescu, S. I. Drob, J. C. Mirza Rosca, Corrosion modelling of the surface films obtained on titanium alloys, Book of Abstracts of the APMAS 2012, 2nd International Advances in Applied Physics & Materials Science Congress, 26-29 April 2012, Antalya, Turkey, Paper No 182, pp. 127.

3. M. V. Popa, C. Vasilescu, E. Vasilescu, P. Drob, M. F. Popa, S. I. Drob, Study of an advanced biomaterial behaviour in biofluids, Book of Abstracts APMAS 2012, 2nd International Advances in Applied Physics & Materials Science Congress, 26-29 April 2012, Antalya, Turkey, Paper No 177, pp. 125.

4. M.V. Popa, E. Vasilescu, P. Drob, D. Raducanu, C. Vasilescu, V. D. Cojocaru, S. I. Drob, Corrosion resistance and structural and mechanical properties of a titanium base alloy by thermo-mechanical processing, Book of Abstracts of the 3rd Regional Symposium on Electrochemistry: South - East Europe, 13-17 May 2012, Bucharest, Romania, Paper CPA-P-08, pp. 91.

Stage III

- Reproducibility demonstration of the Ti-20Zr bioalloy synthesis and thermo-mechanical processing technologies.

- Obtained results concerning the chemical composition, physico-mechanical and structural characteristics of the alloy confirm the corresponding melting procedure and process parameters.

- The laboratory synthesis technology for Ti-20Zr alloy is based on a new procedure at national level and is of big actuality at European and International level - the melting in levitation in furnace with cold crucible.

- The laboratory thermo-mechanical processing technology is new at national and International level, being elaborated for a titanium alloy with original composition that directly influences the plastic deformation process and its parameters.

- Experimentation and demonstration of execution technology for dental implant showed that the new alloy workability to longitudinal lathe is comparable with that of reference alloy Ti-6Al-4V and in the case of the cut lathe is better.

- Test lot of dental implant: zero series of cylindrical implant was realised.

- Design and experimentation of the laboratory technology for antibacterial, long-term resistant protection. The technology was successfully realised at laboratory level, demonstrating that due to the special properties of the sonochemical method, the antibacterial nanoparticles can be permanently adsorbed on the substrate, assuring a long-term antibacterial protection. The proposed technological flux is approach for the first time.

- Reproducibility demonstration of the process parameters for the laboratory technology of the electrochemical activation and antibacterial protection.

- The application of the electrochemical coating based on TiO2 oxide that thickens the native passive film of Ti-20Zr alloy leads to the increase of the anticorrosive resistance in comparison with that of bare alloy; all corrosion parameters for the coated alloy enhanced their values in time, as result of the thickening of the initial protective layer with new depositions from the physiological solutions.

- The antibacterial coating improved the protective capacity of the native passive film on the Ti-20Zr alloy surface; in time, the antibacterial coating presented little more favourable values of the corrosion parameters, namely it slightly thickened in time.

- The characterisation of the antibacterial coating was realised by world level techniques, SEM, EDX, XPS; it was proved that this coating is stable and can assure long-term antibacterial resistance by the progressively release of bacteriostatic nanoparticles.

- Tests concerning the corrosion resistance of the antibacterial coating. This coating improved the protective capacity of the native passive film on the Ti-20Zr alloy surface. Antibacterial coating thickened in time.

- Tests concerning the cell adhesion and proliferation on the antibacterial coated bioalloy surface. The in vitro experimental studies on short term indicated that the antibacterial treated Ti-20Zr alloy is biocompatible presenting very good cell responses.

- Tests concerning the bacteriostatic activity of the bioalloy with antibacterial coating. The new coating prevents the colonisation, spreading and development of the micro organisms, eliminates the bacterial biofilms and completely inhibits the development of bacteria (surplus objective).

- Evaluation and selection of the scientific, innovative results. Identification and establishment of the intellectual rights. A patent proposal was deposited to OSIM.

- Implementation programme of the project results regarding the new implants with long-term antibacterial protection by technological transfer that comprises: preparation and realisation of the new product certification, elaboration of strategy for market enter, development of the existing facilities for the realisation of a complete production chain with possibilities to begin the production in 2017 (surplus objective).

- Elaboration of the technico-economical study regarding the implementation of the project results. The technico-economical study comprises the analysis of the industrial application of the technologies referring to the long-term antibacterial protected dental implant manufacturing, to the SME, partner in project, SC TEHNOMED SA. From analysis it resulted the favourable implementation conditions and economical efficiency of the industrial application of the project results to this economical unit.

- Elaboration of the technical specifications for: synthesis technology of the Ti-20Zr bioalloy; technology of thermo-mechanical processing; thermo-mechanical processed Ti-20Zr bioalloy; dental implant.

- Results dissemination

ISI articles

1. J.M. Calderon Moreno, P. Osiceanu, C. Vasilescu, M. Anastasescu, S.I. Drob, M. Popa, Obtaining, structural and corrosion characterization of anodized nanolayers on Ti-20Zr alloy surface, Surf. Coat. Technol., 235, 792-802, 2013, factor impact 1,941 (2012)

International scientific communications

1. J.M. Calderon Moreno, M.F. Popa, C. Vasilescu, S.I. Drob, M. Popa, ZnO antibacterial coating on new Ti-Zr biomedical alloy with the Young's modulus of bone, 3rd International Advances in Applied Physics & Materials Science Congress, 24-28 April 2013, Antalya, Turkey

2. J.M. Calderon Moreno, M. Popa, C. Vasilescu, S.I. Drob, E.I. Neacsu, E. Vasilescu, Microstructure, mechanical properties and corrosion resistance of a new bioalloy in artificial saliva, 11th Conference on Colloid and Surface Chemistry, 9-11 May 2013, Iasi, Romania