Alejandro Padrós

Publications of Alejandro Padrós

• 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.

• The effect of shot blasting and heat treatment on the fatigue behavior of titanium for dental implant applications.

  Authors: F Javier Gil, Josep A Planell, Alejandro Padrós, Conrado Aparicio

  Dental materials : official publication of the Academy of Dental Materials. 05/2007; 23(4):486-91.

  OBJECTIVES: The effect of shot blasting treatment on the cyclic deformation and fracture behavior of a commercial pure titanium with two different microstructures; equiaxed (alpha-phase) and acicularOBJECTIVES: The effect of shot blasting treatment on the cyclic deformation and fracture behavior of a commercial pure titanium with two different microstructures; equiaxed (alpha-phase) and acicular (martensitic alpha'-phase) was investigated. METHODS: Fatigue tests were carried out in artificial saliva at 37 degrees C. Cyclic deformation tests were carried out up to fracture and fatigue crack nucleation and propagation were analysed. Residual stresses were determined by means of X-ray diffraction. RESULTS: The results show that shot blasting treatment improves fatigue life in the different microstructures studied. The equiaxed phase has improved mechanical properties compared to the acicular one. Despite the fact that control of the variables of shot blasting is not precise because of the nature of the treatment, it improves the fatigue life by the fact that the initiation site of the fatigue crack changes from the surface of the specimen to the interior of the shot blasted specimen. This is a consequence of the layer of compressive residual stresses that the treatment generates on titanium surfaces. The acicular morphology of the martensite favors crack propagation along the interface of the alpha' plates. SIGNIFICANCE: Shot blasting, which is widely used on titanium dental implants in order to favour their osseointegration, can also improve their fatigue resistance.