In vitro assessment of the osteointegrative potential of a novel multiphase anodic spark deposition coating for orthopaedic and dental implants

Hydroxyapatite coatings have been proven to improve the osteointegration of metal implants through a tight binding to the bone mineral phase as well as through favorable osteoblast adhesion and proliferation onto the implant surface. However, hydroxyapatite coatings are not stable and they tend to delaminate from the metal surface when challenged by the mechanical stresses experienced by the implant. Recently, a new multiphase anodic spark deposition (ASD) method has been optimized where the formation of a thick oxide film is followed by the deposition of a calcium phosphate mineral phase and its etching by alkali. The data in this paper demonstrate that this novel type of coating, BioSpark, improves the material osteointegration potential when compared to conventional ASD while offering more mechanical stability. A faster mineralization was obtained by incubation in simulated body fluids and osteoblasts showed better adhesion, proliferation, differentiation, and collagen production. These performances were related to the surface morphology, to the film calcium/phosphate ratio and its surface oxygen content, as well as to a preferential binding of structural proteins such as fibronectin.