[A comparative study of bone regeneration potency of alfa and beta-tricalcium phosphate bone substitute materials].

Review of the literature and our own investigations describe structure, synthesis and participation in biomineralisation of bone of synthetic bone scaffold tricalcium phosphate with original surface.

[Octacalcium phosphate--precursor of biomineralization, novel bone scaffold].

Review of the literature and our own investigations describes structure, synthesis, hydrolysis, participation in biomineralisation of bone and teeth of octacalcium phosphate, a new synthetic bone scaffold.

In vitro study of matrix surface properties of porous granulated calcium phosphate ceramic materials made in Russia.

We performed in vitro screening of monophasic (hydroxyapatite, beta-tricalcium phosphate, carbonate-substituted hydroxyapatite with 0.59 and 5.9 wt% substitution with CO(3)(2-)) and biphasic (hydroxyapatite-tricalcium phosphate with various percentage of the components 80/20, 60/40, 20/80, silicon-substituted hydroxyapatite with 0.79 wt% SiO(2)) porous granulated ceramics composed of calcium phosphate powders synthesized by methods of heterophasic interaction of reagents and precipitation from aqueous solutions using MTT test and cultured human fibroblasts. Acute toxicity of materials (24-h incubation with cell culture) and matrix properties (3, 5, 7, 14, 18, 21, 28 days in culture) were evaluated. We selected a batch of materials obtained by precipitation from aqueous solutions, which were non-toxic and were characterized by good matrix properties (for cells). Biphasic ceramics with hydroxyapatite-tricalcium phosphate ratio of 80/20 exhibited best characteristics, and ceramics on the basis of silicon-substituted hydroxyapatite showed moderate characteristics.

Study of in vivo biocompatibility and dynamics of replacement of rat shin defect with porous granulated bioceramic materials.

Biocompatibility of porous granulated bioceramic materials (hydroxyapatite, beta-tricalcium phosphate, hydroxyapatite-b-tricalcium phosphate complex (80:20 wt%), carbonate-containing hydroxyapatite, and silicon-containing hydroxyapatite) was shown in a subcutaneous test on BDF1 mice. Dynamic (up to 8 months) observation showed gradual replacement of the granular substance with de novo forming bone tissue with hemopoiesis foci on a model of fenestral defect in the shin bone in Wistar rats. By the rate of resorption, the materials rank as follows: silicon-containing hydroxyapatite

[Development and laboratory analysis of new remineralizing means].

In laboratory research there were studied different combinations of remineralizing agents allowing production of substances close by chemical composition to hydroxyapatite of hard dental tissues. The most acceptable for practical use in case of demineralizing foci of hard dental tissues treatment can be only 2 calcium orthophosphates that may be synthesized under physiological conditions from solutions of calcium nitrate and twice-substituted ammonium phosphate, in particular, dicalcium phosphate dihydrate (structure of brushite, CaHP0(4) x 2H(2)O) and the so called precipitated hydroxyapatite (Ca(10-x) (HPO(4))(x)(PO(4))(6-x)(OH)(2-x)). The data are the bases for development of remineralizing agents and their further experimental and clinical studies.

Carbonate release from carbonated hydroxyapatite in the wide temperature rage.

Synthetic carbonated apatite ceramics are considered as promising alternative to auto- and allograft materials for bone substitute. The aim of this study was to investigate the thermal stability of an AB-type carbonated apatite in the wide temperature range. The data on the thermal stability have to allow the conditions of the sintering of the ceramics to be controlled. Initial carbonated apatite powders were prepared by interaction between calcium oxide and ammonium hydrogen phosphate with addition of ammonium carbonate. Decomposition process was monitored by infra red spectroscopy, weight loss and X-ray diffraction of solid, and by infra red analysis of condensed gas phase resulted from the thermal decomposition of the sample in equilibrium conditions. Features of carbon monoxide and carbon dioxide release were revealed. The synthesized AB-type carbonated apatite is started to decompose at about 400 degrees Celsius releasing mainly carbon dioxide, but retained some carbonate groups and apatite structure at the temperature 1100 degrees Celsius useful to prepare porous carbonate-apatite ceramics intended for bone tissue engineering scaffolds.

FTIR study of carbonate loss from carbonated apatites in the wide temperature range.

The mineral constituent of bone tissue is a carbonate-substituted apatite (CHA). The thermal stability of the CHA has been revealed to depend on the substitution type and degree, although relatively little is known about this behavior. The aim of this study was to investigate the carbonate loss from synthetic CHAs in equilibrium conditions in a wide temperature range. An approach based on FTIR spectroscopy of condensed gas phase was applied to evaluate the CO and CO2 release with increasing temperature. Four different CHAs were studied, which were prepared by either precipitation from solution or the solid-state interaction. The samples differ from each other by the substitution degree. In one of the samples calcium was partially substituted by magnesium. Decomposition was shown to start at surprisingly low temperature, about 400 degrees C, and the CO content increases monotonously with the increase of temperature. The CO2 content goes through a maximum due to its decomposition into carbon monoxide and oxygen, the temperature of this maximum being strongly dependent on the chemical synthesis route. Therefore, control of the sintering atmosphere with respect to the CO2/CO ratio is needed when preparing the carbonated apatite bioceramics.