Features of Biological Degradation of Ceramic Hydroxyapatite Implanted into the Bone Defect, According to X-Ray Diffraction Analysis
In experiment involved 72 white rats with initial weight of 130-150 g, using X-ray diffraction analysis, we examined crystal structure of the regenerate after implantation of ceramic hydroxyapatite with a particle size less than 63 microns into the bone defect in the area of proximal tibial metaphysis. It is found that in the ceramic hydroxyapatite crystallite sizes were smaller than in the intact bone by 11.19-12.78 %, and the microtexturing coefficient, in contrast, was higher by 18.11-21.13 % at constant parameters of the unit cells of hydroxyapatite. In the group of animals in which we didn’t fill the defect, in the period from the 15th to the 30th day sizes of unit cells along the c axis and c/a ratio were higher than those in group of intact animals on the 60th and 90th day. The crystallite sizes in the group of unfilled defect within the whole study period were less than those in the group of intact rats by 2.08-9.14 %. When implanting ceramic hydroxyapatite in the defect area we detected the increase of с, a and c/a parameters, which indicates the destabilization of the unit cells of hydroxyapatite of the bone regenerate and is a consequence of its biological conversion. As a result of biodegradation, ceramic hydroxyapatite crystallites became more friable, are increased in size and would probably constitute an obstacle for the formation of uniform crystal lattice of bone mineral which is formed.