No abstract

Intrabone implants represent artificial supports for teeth and jaw system and locomotor apparatus, which are made of biocompatible materials, mostly titanium alloys. Numerous experimental and clinical investiga tions in Russia and abroad showed that bioceramic calcium-phosphate coatings on the surface of metal implants most actively stimulate their osteointegration (engraftment), thus offering an effective solution of the problem of intrabone structure rejection. Of course, the implant coatings must occur in a required structural phase state and possess a definite combina tion of properties, including high mechanical strength and developed morphological heterogeneity (in par ticular, on a nanometer scale).The implant base is most frequently made of a metal (e.g., titanium and its alloys) and then coated by spraying calcium-phosphate materials such as hydroxyapatite (HA) and tricalcium phosphate. These coatings, supported on metal implants with a proper surface microrelief, actively stimulate osteogenesis. The rate of implant engraftment is determined by its chemical and phase composition and depends on the dimensions of fine structure elements in the surface layer of coatings (in particular, on the presence of nan odimensional grains) [1]. Indeed, it is commonly accepted that the interaction between a biocompatible coating material and biological structures of the organism takes place on a nanometer scale level of col lagen fibrils. The data of atomic force microscopy for the surface of bone trabeculae show that their struc tural components (collagen fibrils) are covered by mineral (HA) plates of medium size (30-200 nm) [2]. Compatibility with biostructures of the bone bed is determined by the characteristics of developed mor phological heterogeneity, in particular, the average grain diameter. In this context, it is a topical task to establish the influence of the regime of preliminary induction heat treatment (IHT) of the titanium base on the average grain size D in plasma sprayed bio ceramic HA coatings, which in turn affects the rate of splat cooling and the character of crystallization.Well known disadvantages of coatings obtained by the traditional thermal spraying include a significant spread of the dimensions of nanograins relative to the average value, high degree of amorphization, and the related nonuniformity of the physical properties. In many cases, the underestimation of these factors leads to a significant decrease in the quality of coatings, which is manifested by insufficient reliability and working life of intrabone implants [3].One of the most important properties of thermally deposited coatings on intrabone implants is the devel oped morphological heterogeneity (i.e., combination of the surface structure elements with a large number of dimensional modes) and uniformity of the distribu tion of nanodimensional grains. It should be noted that the essential elements do not include dusty parti cles of the uppermost surface layer with weak cohe sion. The plasma spraying of HA coatings involves struct...

No abstract