Osteoconductive potential of mesoporous titania implant surfaces loaded with magnesium : an experimental study in the rabbit

Background: Mesoporous coatings enable incorporation of functional substances and sustainedly release them at the implant site. One bioactive substance that can be incorporated in mesoporous is magnesium, which is strongly involved in bone metabolism and in osteoblast interaction. Purpose: The aim of this experimental study was to evaluate the effect of incorporation of magnesium into mesoporous coatings of oral implants on early stages of osseointegration. Material and Methods: Titanium implants were coated with thin films of mesoporous TiO2 having pore diameters of 6 nm and were loaded with magnesium. The implant surfaces were extensively characterized by means of interferometry, atomic force microscopy, scanning electron microscopy, and energy-dispersive spectroscopy and then placed in the tibiae of 10 rabbits. After 3 weeks of healing, osseointegration was evaluated by means of removal torque testing and histology and histomorphometry. Results: Histological and biomechanical analyses revealed no side effects and successful osseointegration of the implants. The biomechanical evaluation evidenced a significant effect of magnesium doping on strengthening the implant-bone interface. Conclusions: A local release of magnesium from the implant surfaces enhances implant retention at the early stage of healing (3 weeks after implantation), which is highly desirable for early loading of the implant.