EVALUATION OF STRUCTURAL CHANGES IN THE AREA OF EXPERIMENTAL MANDIBULAR DEFECT WHEN APPLYING OSTEOPLASTIC MATERIALS BASED ON VARIOUS COMPONENT PERCENTAGE OF HYDROXYAPATITE AND POLYLACTIDE.

The main aim is to find out the mechanisms of reparative regeneration of bone tissue in artificially created transverse mandibular defects in rats when applying osteoplastic materials based on hydroxyapatite and polylactide with different component percentage. Experimental studies were carried out on 114 mature laboratory white male 180-220 g rats that were divided into groups: control group - animals whose bone defect was filled only with a blood clot; 1st experimental group - the entire defect volume was densely filled with a block with the ratio of component parts, hydroxyapatite 80% + polylactide 20%; 2nd experimental group was similar, but with the ratio of 50% + 50%. Morphological and morphometric research methods were carried out after the removed jaws had been decalcized in a 10% nitric acid solution. An x-ray study was performed using an Intra digital radiograph (Planmeca, Finland). Statistical analysis of the results was carried out according to the standard method of descriptive statistics using the software package "StatSoftStatistica 10". The use of osteoplastic material with a longer period of its biodegradation contributes to filling the defect with bone tissue, but slows down the processes of the final formation of a mature secondary bone scar, yet allows even with hypercorrection to restore the anatomical form of the lost area. Therefore, the use of this material is recommended for a defect in the alveolar ridge, mainly in extraction sockets, when one needs to avoid atrophy and to create conditions for prosthetic treatment. Osteoimplant with a faster biodegradation period allows structuring collagen fibers in the regenerate in the early stages of healing, which optimizes the formation of an organic bone matrix and promotes its faster mineralization. Therefore, such bone substitutes can be better used for insignificant defects or when the restoration of the anatomical form is not essential, mainly for defects of the body and mandibular branches.