Physics, Chemistry, and Mechanics of Formation of Bioactive Surfaces on Implants. Review

The analysis of the literature on bioactive surfaces of volume implants and plasma coatings on their surface is performed. The influence of the porous sizes on the process of growing new bone in an implant surface is described. The traditional porous structure of a plasma titanic coating, which is formed owing to a decrease in extent of deformation of spraying particles on a substrate, is not optimum for growing of a new bone tissue. Modern dense hydroxyapatite (HA)-titanium coatings do not have the necessary porous structure, and transfer of cyclic loading through an external layer is not reliable. At the same time, comparative studies of 17 surfaces of implants indicate obvious advantages of plasma HA coatings during implantation, which are not dependent on the degree of their crystallinity. Three-dimensional capillary-porous (TCP) titanium coatings in the form of ridges and cavities with additional HA plasma and microplasma coatings are prospective for medical application owing to division of dense and porous volumes of a coating, increase in the area of the border with a new bone tissue, higher shear, and the possibility of spraying of the HA coating with equilibrium structure at a temperature of the surface of titanium of 550°C. The analysis of HA coating content phase is made depending on the modes of plasma spraying.