SURFACE MODIFICATION OF POROUS TITANIUM FOR BONE REPAIR : CONTROLLED ETCHING BY CHEMICAL AND ELECTROCHEMICAL TREATMENTS

Stress shielding and osseointegration failures are two important problems that can eventually reduce the reliability of titanium (Ti) implants; they are addressed in this work, in order to improve the whole performance of Ti in biomedical applications. To that end, we fabricated commercially pure Ti (cpTi) porous substrates via space holder technique (50% vol., with three different particle size ranges of NH4HCO3, 800 MPa, by sintering at 1250 oC, 2h in high vacuum, 10 -5 mbar). Controlled etching of cpTi porous samples and anodizing were performed from previous studies of the authors on bulk Ti: etching solution is a water based one with 2.2 vol.% of HF and a 0.5 ml/L % of an organic inhibitor; temperature was 50°C and immersion times were 0, 5, 25, 125, 625 y 3125 s. Anodizing conditions were: 2 to 10 min, 12, 18 y 40 VDC, 60 g/L H2SO4 and 150 g/L H3PO4. Micro-structural, mechanical, and micro-mechanical (P-h curves and scratch resistance) characterizations were performed. We measured the roughness of modified samples (inner roughness by confocal laser). Homogeneity, effectiveness and infiltration integrity of the coatings were also evaluated through cracking and adhesion evaluation (SEM, DRX, contact angle) and osteoblasts biological testing. ANTIBACTERIAL BEHAVIOUR OF POROUS TITANIUM FOR BONE REPAIR Clara Lebrato 1 , Mari Nieves 1 , Julián Lebrato 1 , María Dolores Garvi 1 , José Antonio Rodríguez-Ortiz 2 , Juan José Pavón 3 y Yadir Torres 2 1 UNIVERSIDAD DE SEVILLA, EPS, Calle Virgen de Africa 7, 41011, Sevilla, España. 2 UNIVERSIDAD DE SEVILLA, Avda. de los Descubrimientos s/n, 41092, Sevilla, España. 3 UNIVERSIDAD DE ANTIOQUIA, BAMR GROUP, BIOENGINEERING PROGRAM, Calle 67 Número 53 108, Medellín, Antioquia, Colombia. e-mail del autor: juan.pavon@udea.edu. co ABSTRACT Patients who require bone repair via titanium (Ti) implants still have to suffer the risk of failures. These limitations are normally reflected in facts like failures percentage between 5% and 10%, during the first five years of implantation. Accordingly, we need to solve the stress-shielding problem via development of porous Ti implants, whilst infections and interfacial loosening due to bacteria colonies and proliferation must be reduced. These are events that can be also risky for applications like joints prosthetics and ossteosynthesis. In this work, we fabricated commercially pure Ti (cpTi) porous substrates via space holder technique (50% vol., with three different particle size ranges of NH4HCO3, 800 MPa, by sintering at 1250 oC, 2h in high vacuum, 10 -5 mbar). These samples exhibit an improved biomechanical balance between stiffness and mechanical strength, as well as a proper stimulation to cells inside the pores due to controlled inner roughness. Specifically in this communication, we are reporting the preliminary antibacterial results of porous Ti samples, after evaluation of contact with a bacterial strain commonly present inside the mouth (Staphylococos aureus), normally introduced via some long term food with Escherichia coli. Bacteria growth allowed us to identify some areas with potential beneficial effects.Patients who require bone repair via titanium (Ti) implants still have to suffer the risk of failures. These limitations are normally reflected in facts like failures percentage between 5% and 10%, during the first five years of implantation. Accordingly, we need to solve the stress-shielding problem via development of porous Ti implants, whilst infections and interfacial loosening due to bacteria colonies and proliferation must be reduced. These are events that can be also risky for applications like joints prosthetics and ossteosynthesis. In this work, we fabricated commercially pure Ti (cpTi) porous substrates via space holder technique (50% vol., with three different particle size ranges of NH4HCO3, 800 MPa, by sintering at 1250 oC, 2h in high vacuum, 10 -5 mbar). These samples exhibit an improved biomechanical balance between stiffness and mechanical strength, as well as a proper stimulation to cells inside the pores due to controlled inner roughness. Specifically in this communication, we are reporting the preliminary antibacterial results of porous Ti samples, after evaluation of contact with a bacterial strain commonly present inside the mouth (Staphylococos aureus), normally introduced via some long term food with Escherichia coli. Bacteria growth allowed us to identify some areas with potential beneficial effects. DESIGN, PROCESSING AND CHARACTERIZATION OF TITANIUM WITH CONTROLLED RADIAL AND LONGITUDINAL POROSITY GRADIENT Y. Torres 1 , P. Trueba 1 , J.J. Pavón 2 , J.A. Rodríguez-Ortiz 1 1 UNIVERSIDAD DE SEVILLA, Avda. de los Descubrimientos s/n, 41092, Sevilla, España. e-mail del autor: ytorres@us.es 2 UNIVERSIDAD DE ANTIOQUIA, Calle 67 Número 53 108, Medellín, Antioquia, Colombia. e-mail del autor: juan.pavon@udea.edu. co