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متالوژی::
هیدروکسی کربن
Regarding the CO 2- inclusion in synthetic hydroxyapa- tites, synthesis at high temperature produced type A (nonbiological) hydroxycarbon- ate apatite (HCA).
When these mixtures are in physiological environments, they evolve toward hydroxycarbonate apatite as a consequence of the chemical reactions that take place between the more stable hydroxyapatite and the more resorbable �-TCP.
Thus bioactive glasses react with body fluids from the physio- logical environment to form a layer of hydroxycarbonate apatite nanocrystals, which promotes the generation of bone matrix and accelerates the bone growth process.
This layer then attracts calcium, phosphate, and carbonate ions from the physiological solution to form an amorphous calcium phosphate layer, which crystallizes into biologically active hydroxycarbonate apatite nanocrystals.
In terms of bioactive behavior, it has been found that CaO plays an essential role (Martinez, Izquierdo-Barba, and Vallet-Reg� 2000; Vallet-Reg� et al. 2004), since Ca2+ ions leached from the glass increase the Si-OH concentration at the surface of the glass thanks to the interchange with protons from the medium, which favors the formation of the hydroxycarbonate apatite layer, and also increases the Ca2+ concentration in the solution, which leads to a supersatura- tion of the media favoring the apatite-like layer formation.
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