D.A. Scherbakov - Ph.D. (Med.), Doctor-Otolaryngologist, FSBI «Russian Eye and Plastic Surgery Centre» of the Russian Federation Ministry of Health, Ufa, Russia. E-mail: dmst@bk.ru

Damage of the flat bones have been found in everyday clinical practice in different specialists: ENT specialists, oph-thalmologists, oral surgeons, neurosurgeons and others. It is known that a burr hole in the flat bones normally re-placed by connective tissue scarring. The aim of our study was to develop connective tissue allografts to replace defects of the flat bones. In the first stage experimental-morphological studies was made. At the same time on the bones of the facial skull and brain skull of the laboratory animals were simulated burr defects followed by plastics with demineralized bone graft (DBG) or cartilage allografts as a stub. Clinical studies carried out on the basis of the Department of Plastic Surgery Russian Eye and Plastic Surgery center, Department of Otorhinolaryngology of Clinical Hospital № 13 and Rebublic clinical hospital of Ufa. The cartilage allografts and DBG were used to close the front wall of the frontal and maxillary sinuses. The study involved 60 pa-tients with odontogenic cysts of the maxillary sinus, 54 patients with foreign bodies of the maxillary sinus, 16 patients with cysts and osteomas of frontal sinus. All patients were aged between 12 and 68 years. Experimental studies have shown that the cartilage allograft had the characteristic type of peripheral substitution. This revealed similarities to embryonic indirect osteogenesis. On the border of newly formed bone allograft and un-substituted detected vascular buds, thanks to which the cartilage allograft formed erosional gaps. Recent filled with fibro-reticular tissue comprising osteoblasts, after which there was a formation of regenerate bone plate. Deminera-lized bone allograft was replaced, partly by lamellar bone and partly by woven bone. Due to ingrowth of vascular bud into «empty» center channel replacement graft regeneration extends from the center of the osteon to the periphery - to form lamellar bone tissue. Also detects the peripheral type of replacement DBG, where the border with biomaterial visualized connective tissue capsule, for which in the direction towards the center of the newly formed DBG followed woven bone. Clinical studies have shown that DBG as allograft cartilage in the early postoperative period are not visualized on computed tomography (CT), and therefore to clarify the provisions of the biomaterial is preferably performed magnetic resonance imaging (MRI). CT carried out after 6 months after surgery showed complete replacement of allograft bone, regardless of their origin. Cartilage allograft is advisable to apply in the case of a complex surface topography flat bones (deep canine fossa) due to higher deformation properties in comparison with the DBG. It should also be used to replace defects of the front walls of the paranasal sinuses with the cartilage allograft in early age patients because this biomaterial is replaced more slowly, and contributes to a larger volume of bone regeneration. DBG, in turn, is replaced faster and it is fixed in the defect better at the time of the operation due to «loose» the edge of the allograft, but the DBG is more susceptible to resorption and less resistant to pyogenic microflora of the paranasal sinuses.