Can zirconium be a possible candidate for permanent endosseous implant??.

MARÍA ROSA KATUNAR; TAMARA VICO; ANDREA GOMEZ SANCHEZ; JOSEFINA BALLARRE; MATIAS BACA; SILVIA M. CERÉ

Taller; . 3er taller de Organos Artificiales y Biomateriales; 2013

SLABO

The use of cementless hip implants is increasing worldwide and a great effort is being done to obtain a material able to promote effective osseointegration. Metals used in cementless implants undergo some kind of surface modification before clinical insertion in order to improve their fixation to the existing tissue. Since surface plays a key role in osseointegration, the modification of the chemistry and /or topography of the implant can promote biological reactions at the interface influencing the biological events that lead to bone formation. Zirconium is presented as a promising material for intra-osseous implants for its favorable resistance to corrosion, osseointegration capability and lower metal ions migration to the biological surroundings when it is compared with stainless steel and titanium alloys. In this work Zr anodised in 1 mol/ L phosphoric acid at 30V is studied, being this surface treatment able to modify oxide thickness (and thus corrosion resistance in fluid body), topography by modifying roughness and chemistry by the incorporation of phosphate to the oxide. Zr was evaluated as permanent implant after one and two months after implantation in rat model. Male Wistar rats were employed and the implants Zr0 (without anodisation treatment) and the Zr30 (anodised 30V) were placed by press fit into femur extending into the medullar canal. The main goal of the study is to understand the biochemistry, biological and mechanical processes that lead to the generation of new bone around the metallic implants. This study demonstrates that zirconium implants show a complete and regular bone formation around the implant two months after surgery. The characteristics of bone formation were analyzed by polychrome fluorescent labeling using calcium-binding fluorochromes that are deposited at the site of active mineralization. The results show that the mineralization profile is not very homogenous around control and treated implants. It is possible to see some gaps between the implants and the new bone formation in both systems under study. When the mineral apposition rate (MAR) is quantified, a significant increased in found for the Zr30 samples suggesting that anodisation process would trigger particular events that benefit the long term fixation. When osseointegration process is analyzed one month after surgery, the results indicates that the new bone formation is a complex process presenting a not highly organized bone formation but the new bone formed may be mechanically resistant. The results indicate that in the study of the early stages of bone formation is essential to understand in detail the molecular, biochemistry and mechanical characteristics that lead to the osseointegration process around zirconium implants that have been superficially modified as a possible candidate for enodessous permanent implants.