20 research outputs found
Double acid etching treatment of dental implants for enhanced biological properties
Background: The topographical features on the surface of dental implants have been considered as a critical
parameter for enhancing the osseointegration of implants. In this work, we proposed a surface obtained by a
combination of shot blasting and double acid etching. The double acid etching was hypothesized to increase the
submicron topography and hence further stimulate the biological properties of the titanium implant.
Methods: The topographical features (surface roughness and real surface area), wettability and surface chemical
composition were analyzed.
Results: The results showed that the proposed method produced a dual roughness, mainly composed of randomly
distributed peaks and valleys with a superimposed nanoroughness, and hence with an increased specific
surface area. Despite the fact that the proposed method does not introduce significant chemical changes, this
treatment combination slightly increased the amount of titanium available on the surface, reducing potential
surface contaminants. Furthermore, the surface showed increased contact angle values demonstrating an enhanced
hydrophobicity on the surface. The biological behavior of the implants was then assessed by culturing
osteoblast-like cells on the surface, showing enhanced osteoblast adhesion, proliferation and differentiation on
the novel surface.
Conclusions: Based on these results, the described surface with dual roughness obtained by double acid etching
may be a novel route to obtain key features on the surface to enhance the osseointegration of the implant. Our
approach is a simple method to obtain a dual roughness that mimics the bone structure modified by osteoclasts
and increases surface area, which enhances osseointegration of dental implants.Peer ReviewedPostprint (author's final draft
Surface modification of HVOF thermal sprayed WC–CoCr coatings by laser treatment
In this work the affects of laser characteristics on microstructure and microhardness of high velocity oxygen fuel sprayed (HVOF) WC–CoCr coatings were investigated. The coating was deposited with a Sulzer Metco WokaJet™-400 kerosene fuel and the laser surface treatments were applied using CO2 laser with 10.6 μm wavelength. Large variations in surface properties were produced from variation in the laser processing parameters. In total, four levels of peak power (100, 200, 300 and 350 W), four levels of spot diameter (0.2, 0.4, 0.6 and 1 mm) and three levels of pulse repetition frequency (PRF) were investigated. An initial set of tests were followed by a more detailed 33 factorial design of experiments. Pulse repetition frequency and duty cycle were set in order to maintain the same overlap in the x and y directions for the raster scanned sample spot impact dimensions. Overlaps of 30% were used in the initial tests and 10% in the more detailed trials. The results have shown that care must be taken to keep the irradiance at a relatively low level compared to uncoated surfaces. High irradiance can in this case result in rough and porous surfaces. Lower levels of irradiance are shown to provide more uniform microstructures, reduced porosity and increased microhardness
Porous titanium-hydroxyapatite composite coating obtained on titanium by cold gas spray with high bond strength for biomedical applications
The lack of bioactivity of titanium (Ti) is one of the main drawbacks for its application in biomedical implants since it can considerable reduce its osseointegration capacities. One strategy to overcome this limitation is the coating of Ti with hydroxyapatite (HA), which presents similar chemical composition than bone. Nonetheless, most of the strategies currently used generate a non-stable coating and may produce the formation of amorphous phases when high temperatures are used. Herein, we proposed to generate a Ti-HA composite coating on Ti surface to improve the stability of the bioactive coating. The coating was produced by cold gas spraying, which uses relatively low temperatures, and compared to a Ti coating. The coating was thoroughly characterized in terms of morphology, roughness, porosity and phase composition. In addition, the coating was mechanically characterized using a tensile loading machine. Finally, biological response was evaluated after seeding SaOS-2 osteoblasts and measuring cell adhesion, proliferation and differentiation. The novel Ti-HA coating presented high porosity and high adhesion and bond strengths. No change in HA phases was observed after coating formation. Moreover, osteoblast-like cells adhered, proliferated and differentiated on Ti-HA coated surfaces suggesting that the novel coating might be a good candidate for biomedical applications
Characterization of IHF Binding to DNA Four-Way Junctions and Forks
The objective of the study is to characterise the mechanical properties of Ti-15Zr binary alloy dental implants and to describe their biomechanical behaviour as well as their osseointegration capacity compared with the conventional Ti-6Al-4V (TAV) alloy implants. The mechanical properties of Ti-15Zr binary alloy were characterised using Roxoli
Laser-deposited beta type Ti-42Nb alloy with anisotropic mechanical properties for pioneering biomedical implants with a very low elastic modulus
Present commercial titanium alloy implants have an elastic modulus higher than 100 GPa, whereas that of the cortical bone is much smaller (17–28 GPa). This elastic modulus mismatch produces a stress shielding effect and the resorption of the bone surrounding the implant. In the present work, a fiber texture is developed in ß type Ti-42Nb (wt%) alloy ingots generated by laser-directed energy deposition (LDED) in order to achieve anisotropic mechanical properties. In addition, we demonstrate that laser-deposited ß type Ti-42Nb alloy ingots with an intense fiber texture exhibit a very low elastic modulus in the building direction (Ez 700 MPa) and tensile (UTSz > 700 MPa) strengths. Laser-deposited Ti-42Nb alloy enhances the osteoinductive effect, promoting the adhesion, proliferation, and spreading of human osteoblast-like cells. Hence, we propose that laser-deposited ß type Ti-42Nb alloy is a potentially promising candidate for the manufacturing of pioneering biomedical implants with a very low elastic modulus that can suppress stress shielding.Peer ReviewedPostprint (published version
Three-dimensional fluid simulation of a plasma display panel cell
In order to understand the discharge characteristics in an alternating current plasma display panel (ac PDP) and optimize it further, a three-dimensional fluid code (FL3P) has been developed. Using this simulator, various three-dimensional features of discharges are investigated in the sustain mode of PDP. First, the striations of wall charge are observed at both the anode and cathode side. Second, the local efficiency is obtained as a function of position. It is mainly divided into the anode region and the cathode region and highest near the anode center. Finally, the effects of various three-dimensional parameters are studied. As one of the examples showing the effect of electrode shaping, the discharge characteristics of a T-shaped electrode cell are compared with those of a conventional cell. The phosphor on barrier ribs contributes to over 44% of the total luminance, but barrier ribs themselves do not play an important role in the overall discharge efficiency. Address electrode width is not always proportional to the size of the discharge because of the wall loss of the particles to barrier ribs.open435
Lectura d'imatges
Crédito común en el que se pretende profundizar en el análisis e interpretación de la imagen, para ello se articula el crédito en dos bloques, en el primero se estudia la imagen en dos bellas artes tradicionales 'Pintura y Escultura', haciendo especial hincapié en el uso del vocabulario técnico básico, así como en el comentario de imágenes y textos. En la segunda parte se analiza la imagen en los nuevos medios de comunicación basados en la imagen técnica: fotografía, cine, etc. Analizando especialmente el significado de la imagen, así como su estructura y sus técnicas visuales y compositivas.Generalitat de Catalunya. Direcció General d'Ordenació i Innovació EducativaCataluñaES
Double acid etching treatment of dental implants for enhanced biological properties
Background: The topographical features on the surface of dental implants have been considered as a critical
parameter for enhancing the osseointegration of implants. In this work, we proposed a surface obtained by a
combination of shot blasting and double acid etching. The double acid etching was hypothesized to increase the
submicron topography and hence further stimulate the biological properties of the titanium implant.
Methods: The topographical features (surface roughness and real surface area), wettability and surface chemical
composition were analyzed.
Results: The results showed that the proposed method produced a dual roughness, mainly composed of randomly
distributed peaks and valleys with a superimposed nanoroughness, and hence with an increased specific
surface area. Despite the fact that the proposed method does not introduce significant chemical changes, this
treatment combination slightly increased the amount of titanium available on the surface, reducing potential
surface contaminants. Furthermore, the surface showed increased contact angle values demonstrating an enhanced
hydrophobicity on the surface. The biological behavior of the implants was then assessed by culturing
osteoblast-like cells on the surface, showing enhanced osteoblast adhesion, proliferation and differentiation on
the novel surface.
Conclusions: Based on these results, the described surface with dual roughness obtained by double acid etching
may be a novel route to obtain key features on the surface to enhance the osseointegration of the implant. Our
approach is a simple method to obtain a dual roughness that mimics the bone structure modified by osteoclasts
and increases surface area, which enhances osseointegration of dental implants.Peer Reviewe