Suchergebnisse

[Abstract] The failure of titanium implants is associated with two main problems that include the bone resorption and fracture of the surrounding bone tissue (stiffness incompatibility) and implant loosening (poor osseointegration). The development of porous titanium implants with low Young modulus solve the stress shielding phenomenon, while the modification of the implant surface must be implemented to promote a fast bond between the implant and bone. In this work, femtosecond laser micromachining was applied to modify the topography of the surface of Ti porous samples obtained by a space-holder technique to obtain hierarchical structures (micro and nano roughness patterns) to enhance osseointegration. Scanning electron microscopy, confocal laser microscopy, and image analysis were used for characterization of the surface morphology, roughness, and porosity before and after performing the laser treatment. Based on these results, the effect of the treatment on the mechanical behavior of the samples was estimated. In addition, a preliminary in-vitro test was performed to verify the adhesion of osteoblasts (filopodia presence) on modified titanium surface. Results revealed that laser texturing generated clusters of micro-holes and micro-columns both on the flat surface of the samples and inside the macro-pores, and periodic nanometric structures across the entire surface. The porous substrate offers suitable biomechanics (stiffness and yield strength) and bio-functional behavior (bone ingrowth and osseointegration), which improves the clinic success of titanium implants ; Junta de Andalucía; US-1259771 ; The regional government from Andalusia through FEDER-Junta de Andalucía Research Project US-1259771, (Modeling and implementation of the freeze casting technique: gradients of porosity with a tribomechanical equilibrium and electro-stimulated cellular behavior) funded this research.

The modern military industry demands the most innovative and high-quality metals and alloys, as well as processing technologies. Iron and its alloys are a common material used for different types of weapons and military equipment. Lasers have been widely used in the metal surface processing, but the changes that occur on laser treated metal surfaces have not yet been sufficiently investigated. A study of morphological and chemical changes on the metal surface induced by Nd:YAG laser treatment in ambient air is presented. A pulsed Nd:YAG laser (1064 nm, Gaussian spatial profile, FWHM 8 ns, energy up to 525 mJ, beam diameter of 1-10 mm and fluence up to 3.5 J/cm 2 ) was used. Micro-morphological analyses of sample surfaces before and after laser treatment process were performed by optical and SEM microscopies. EDX method was used for chemical analyses and Spectra colorimeter for investigation of induced color changes. The laser irradiation effects were studied as a function of two laser parameters, number of laser pulses and laser fluencies, around and over the damage threshold. The results show that there are significant differences depending on these laser parameters.