The present study shows that the processes of reparative osteogenesis start in the parietal area of the osseous defect and are directed to the apex. Synchronism of these processes is significant which occurs simultaneously being linked with the degree of demineralization of the implant induced into the osseous defect. It has been stated that indigenous bone grafting material «bioOst» with interfacial demineralization in filling of infected bone defects possesses both osteoinductive and osteoconductive properties. K E y w o r d s -apical periodontal cyst, osteoplastic materials, cystectomy.