Production of Hydroxiapatite Phases on Titanium Alloy Surfaces

The project of PEO is performed by me jointly with Prof. M. Zinigrad, Dr. S. Lugovskoy and Dr. N. Astashina (Perm Medical Academy, Russian Federation).

HA on TiTitanium and titanium alloys are non-allergic materials which are not susceptible to oxidation in the aggressive environment of physiological liquids and cause no immune reaction by living tissues. For this reason Ti and its alloys are often used as implant materials in dental and jaw surgery. However, this application presents a serious problem because of the poor cohesion between the metal and bone tissues, which remains inert towards Ti and does not “sprout” to or through it. Attempts to improve the adhesion of titanium to the bone tissue by mechanical means (threads, tenons etc.) have had only limited success. A potentially more effective approach is to use an intermediate layer, which would have high adhesion both to the metal and to the bone tissue. Such an intermediator should be inert toward living tissues, strong and not deformable at the moment of the introduction of an implant, and have porous structure allowing better interaction with the bone tissue. One of the most promising candidates for the role of such an intermediate layer is the hydroxyapatite Ca10(PO4)6(OH)2, which is the main mineral components of the bone tissue.

A technology of production of hydroxyapatite containing ceramic layer on the surface of titanium implants is under development at our laboratory. At the first stage Plasma Electrolytic Oxidation (PEO) is used for the production of an oxide layer on titanium implants. Thus produced oxide layer is then exposed to the hydrothermal treatment, in the course of which a hydroxyapatite phase is formed in the oxide layer. Technologic regimes providing the optimal structure of the oxide layer are being tested. In vivo experiments are being performed in Perm Medical Academy (Russian Federation).