Osteointegrative functionalization of titanium substrates for dental implant applications

Titanium and its alloys have been widely used for dental implants due to their non-toxicity, biocompatibility, corrosion resistance, and mechanical properties. In order to improve osseointegration, the Ti surface is generally functionalised. A typical methodology for surface modification is the coating of the Ti substrates with bioactive layers of calcium phosphate ceramics (CPCs). However, CPC coatings on metal implant usually suffer from poor adhesion. With the aim of improving the adhesion strength, the insertion of dense and compact ceramic interlayers is reported to be useful. Among various ceramics, crystalline titania (TiO2) has been extensively used as an interlayer thanks to its well-known biocompatibility and bioactivity. In this work, a new synergic deposition route for the osteointegrative functionalisation of Ti dental implants is proposed. Three types of Ti substrates (machined, sandblasted, and sandblasted/acid etched) were initially coated with a crystalline, dense and compact TiO2 interlayer via MOCVD. Then, a discontinuous and homogenously spread CPC top-layer was obtained by means of spray pyrolysis technique. Finally, a thermal treatment at high temperature was carried out in order to crystallize the final composite material. The influence of the pristine substrate morphology on the crystalline structures and morphology of the coatings is here presented. Moreover, surface wettability, ions release and in vitro acellular bioactivity have also been evaluated.