Determination of osseointegration properties of magnesium doped TiN coatings in vivo

Bone implantations have been a mandatory investigative subject in cases with traumatic bone defects within the recent years. A successful implantation relies on well osseointegration and implant interface strength. Titanium implants with its alloys have been a decisive area to challenge other metallic implants for gaining an improved osseointegration. In this study, the aim is to provide a better osseointegration capabilities through the addition of the magnesium doped titanium nitride coatings onto Ti6Al4V based plates and screws. In vivo experiments were held on the femur of 16 male rabbits. A fracture was made on the femur of the animals, and then TiN and (Ti, Mg) N thin film coated plates were implanted for six weeks to observe the regeneration differences between the two implant groups. After six weeks of implantation, bone samples were dissected and evaluated with Micro CT-Scan analysis, X-ray imaging, histological analysis, scanning electron microscopy (SEM), and von Kossa staining, in order to examine the de novo bone formation around fracture site and bone responses to the implant's surfaces. Micro CT-images and histological analysis results indicated that both TiN and (Ti, Mg) N coated plates enhanced callus formation around the fracture line. Thus, (Ti, Mg) N implants led not only to bone formation but also complete regeneration of the bone. Moreover, SEM and von Kossa stain evaluations showed that Mg coated surfaces influenced intensive osteoblast formation and mineralization of bones. EDS analysis revealed the elemental characterization of the plates and it was observed that hydroxyapatite was formed only on (Ti, Mg) N coated plates. This ensures that the addition of Mg significantly increased the osseointegration rates with accelerated healing process. In conclusion, higher remodeling process was obtained from the addition of magnesium into the coatings, which clarifies that (Ti, Mg) N thin film coated implants can be used in further clinical applications as a hard tissue implant for bone.