Aplication of calcium phosphate coatings produced by pulsed laser deposition to osteointegrable devices

Abstract

Among the various techniques that have been investigated to produce Hydroxyapatite (HA) coatings in order to promote fixation and osteointegration of cementless prosthesis, the plasma spray (PS) technique is the most popular method commercially in use. PS presents some disadvantages such as the poor coating-to substrate adhesion, low mechanical strength and brittleness of the coating.Pulsed laser deposition (PLD) is a novel technique suitable to produce calcium phosphate (CaP) coatings that allows to overcome the deficiencies detected for the PS. In this work we demonstrate the ability of the PLD technique to finelly control the physicochemical and mechanical properties of the CaP coatings, being able to produce CaP coatings having crystalline and/or amorphous phases in a controlled manner.The PLD system consists essentially in a vacuum chamber, evacuated up to 10-6 mbar, then filled up with water vapour up to the desired processing pressure. The laser (ArF excimer laser, wavelenght λ = 193 nm) was focused onto a calcium phosphate sintered pellet, and the substrate was placed in front of the HA target, on a temperature controlable substrate holder.CaP coatings having an apatitic structure have been applied to osteointegrable devices such as dental implants or titanium alloy screws for orthopaedics.Different analytical techniques were applied to characterize the coated samples, including Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDX); the adhesion was evaluated by the pull-test method.Among the various techniques that have been investigated to produce Hydroxyapatite (HA) coatings in order to promote fixation and osteointegration of cementless prosthesis, the plasma spray (PS) technique is the most popular method commercially in use. PS presents some disadvantages such as the poor coating-to substrate adhesion, low mechanical strength and brittleness of the coating.Pulsed laser deposition (PLD) is a novel technique suitable to produce calcium phosphate (CaP) coatings that allows to overcome the deficiencies detected for the PS. In this work we demonstrate the ability of the PLD technique to finelly control the physicochemical and mechanical properties of the CaP coatings, being able to produce CaP coatings having crystalline and/or amorphous phases in a controlled manner.The PLD system consists essentially in a vacuum chamber, evacuated up to 10-6 mbar, then filled up with water vapour up to the desired processing pressure. The laser (ArF excimer laser, wavelenght λ = 193 nm) was focuse...