Francisco Javier Gil

Publications of Francisco Javier Gil

• In vivo evaluation of micro-rough and bioactive titanium dental implants using histometry and pull-out tests.

  Authors: Conrado Aparicio, Alejandro Padrós, Francisco-Javier Gil

  Journal of the mechanical behavior of biomedical materials. 11/2011; 4(8):1672-82.

  We report on the in vivo histological and mechanical performance of titanium dental implants with a new surface treatment (2Step) consisting of an initial grit-blasting process to produce aWe report on the in vivo histological and mechanical performance of titanium dental implants with a new surface treatment (2Step) consisting of an initial grit-blasting process to produce a micro-rough surface, followed by a combined chemical and thermal treatment that produces a potentially bioactive surface, i.e., that can form an apatitic layer when exposed to biomimetic conditions in vitro. Our aim was to assess the short- and mid-term bone regenerative potential and mechanical retention of 2Step implants in mandible and maxilla of minipigs and compare them with micro-rough grit-blasted, micro-rough acid-etched, and smooth as-machined titanium implants. The percent of bone-to-implant contact after 2, 4, 6, and 10 weeks of implantation as well as the mechanical retention after 4, and 6 weeks of implantation were evaluated with histometric and pull-out tests, respectively, as a measure of the osseointegration of the implants. We also aimed to assess the bioactive nature of 2Step surfaces in vivo. Our results demonstrated that the 2Step treatment produced micro-rough and bioactive implants that accelerated bone tissue regeneration and increased mechanical retention in the bone bed at short periods of implantation in comparison with all other implants tested. This was mostly attributed to the ability of 2Step implants to form in vivo a layer of apatitic mineral that coated the implant and could rapidly stimulate (a) bone nucleation directly on the implant surface, and (b) bone growing from the implant surface. We also proved that roughness values of Ra≈4.5 μm favoured osseointegration of dental implants at short- and mid-term healing periods, as grit-blasted implants and 2Step implants had higher retention values than as machined and acid-etched implants. The surface quality resulting from the 2Step treatment applied on cpTi provided dental implants with a unique combination of rapid bone regeneration and high mechanical retention.

• Oxidized nickel-titanium foams for bone reconstructions: chemical and mechanical characterization.

  Authors: Maite Barrabés, Alexandra Michiardi, Conrado Aparicio, Pablo Sevilla, Josep A Planell, Francisco Javier Gil

  Journal of materials science. Materials in medicine. 12/2007; 18(11):2123-9.

  This work examines NiTi foams that have been treated using a new oxidation treatment for obtaining Ni-free surfaces that could allow the ingrowth of living tissue, thereby increasing the mechanicalThis work examines NiTi foams that have been treated using a new oxidation treatment for obtaining Ni-free surfaces that could allow the ingrowth of living tissue, thereby increasing the mechanical anchorage of implants. A significant increase in the real surface area of these materials can decrease corrosion resistance and favour the release of Ni. This chemical degradation can induce allergic reactions or toxicity in the surrounding tissues. This study determines the porosity, surface characteristics, phase transformation, mechanical properties, corrosion behaviour and Ni release into the simulated body fluid medium of foams treated by a new surface oxidation treatment that produces Ni-free surfaces. These foams have pores in an appropriate range of sizes and interconnectivity, and thus their morphology is similar to that of bone. Their mechanical properties are biomechanically compatible with bone. The titanium oxide on the surface significantly improves corrosion resistance and decreases nickel ion release, while barely affecting transformation temperatures.

• Influence of the height of the external hexagon and surface treatment on fatigue life of commercially pure titanium dental implants.

  Authors: Francisco Javier Gil, Conrado Aparicio, Jose M Manero, Alejandro Padros

  The International journal of oral & maxillofacial implants. 24(4):583-90.

  PURPOSE: This study evaluated the effect of external hexagon height and commonly applied surface treatments on the fatigue life of titanium dental implants. MATERIALS AND METHODS: ElectropolishedPURPOSE: This study evaluated the effect of external hexagon height and commonly applied surface treatments on the fatigue life of titanium dental implants. MATERIALS AND METHODS: Electropolished commercially pure titanium dental implants (seven implants per group) with three different external hexagon heights (0.6, 1.2, and 1.8 mm) and implants with the highest external hexagon height (1.8 mm) and different surface treatments (electropolishing, grit blasting with aluminium oxide, and acid etching with sulfuric acid) were tested to evaluate their mechanical fatigue life. To do so, 10-Hz triangular flexural load cycles were applied at 37 degrees C in artificial saliva, and the number of load cycles until implant fracture was determined. Tolerances of the hexagon/abutment fit and implant surface roughness were analyzed by scanning electron microscopy and light interferometry. Transmission electron microscopy and electron diffraction analyses of titanium hydrides were performed. RESULTS: First, the fatigue life of implants with the highest hexagon (8,683 +/- 978 load cycles) was more than double that of the implants with the shortest hexagons (3,654 +/- 789 load cycles) (P < .02). Second, the grit-blasted implants had the longest fatigue life of the tested materials (21,393 +/- 2,356 load cycles), which was significantly greater than that of the other surfaces (P < .001). The compressive surface residual stresses induced when blasting titanium are responsible for this superior mechanical response. Third, precipitation of titanium hydrides in grain boundaries of titanium caused by hydrogen adsorption from the acid solution deteriorates the fatigue life of acid-etched titanium dental implants. These implants had the shortest fatigue life (P < .05). CONCLUSIONS: The fatigue life of threaded root-form dental implants varies with the height of the external hexagon and/or the surface treatment of the implant. An external hexagon height of 1.8 mm and/or a blasting treatment appear to significantly increase fatigue life of dental implants.