The metallic biomaterials used in the substitution of hard tissues are subjected to the action of the physiological environment and mechanical efforts like fatigue, wear or friction that alter the operation success of implants and affect drastically the electrochemical properties of the surface. That is the case of Ti and its alloys, in which in vivo conditions alter the stability of the passive layer and provoke the release of both metallic ions and particles.

The search for new treatments that increase the wear resistance, improve the bioactivity in order to facilitate the formation of bone tissue around it and decrease the titanium release is increasingly important. Among them, thermal oxidation treatments aimed to obtain “in situ” ceramic coatings can offer thick, highly crystalline oxide films with very good protective performances. The authors have proved that oxidation treatments of Ti6Al4V alloy at 700 °C for 1 h provoke the formation of an oxide layer, mainly composed of rutile whose ion release is reduced to the half. In vitro experiments with primary osteoblasts cell culture revealed that the surface modification does not alter even improve the excellent biocompatible behaviour. In fact, cell adhesion is favoured on the thermally treated surfaces. However, in vivo evidences have not been previously studied by the authors. At the same way, sandblasting of Ti6Al4V alloys in order to increase the roughness and subsequent thermal treatment improves the osteoblast response. The enhancement of the osseointegration process can be achieved modifying the quality of the surface of the implant in terms of chemical, physical and topographical properties, all of them influencing the functional activity of cells around the implant surface.

On the other hand, in those cases where there is a delay in the physiological mechanisms of bone repair, either by aging or due to problems of osteoporosis, the solution must be taken by means of external substances that stimulate the bone metabolism. Patients diagnosed with systemic diseases such as osteoporosis and diabetes are considered to be medically compromised for implant therapy. Research has been focused on the local application of substances on the implant surface, or directly in the implantation site, able to accelerate the osseointegration process. Hormones, growth factors and osseoconductive proteins are being used to stimulate the bone growth. Studies carried out by Becker et al. revealed that local application of diverse growth factors (IGF-I and PDGF) induce the statistical increase in bone repair and the increase of bone density, around Ti implants, compared with the control group. Numerous studies highlight the importance of the growth hormone (GH) in the repair of bone fractures as young as old animals. The administration is able to increase up to 400 % the mechanical properties with respect to the control group, stimulate the osteoblast activity and enhance the bone neoformationa around implants.

The aim of this study is to study the influence of the thermal treatment of Ti6Al4V dental implants and topical administration of growth hormone on the osseointegration process of osteoporotic rabbits during the first month of implantation.