The aim of the present study was directed to investigate clinically and radiographically the influence of calcium sulphate hemihydrate fast setting powder versus granules in obliterating intra oral bony defects following surgical removal of cystic jaw lesions.Twenty cases were selected for this study from specialised dental teaching hospital at Kobri El Kobba Military Medical Compound , the selected patients age will range from 25 to 35 years old . After proper diagnosis and radiographing the patients selected were suffering from cystic lesions. The patients were 4 females and 16 males, within these patients 3 were suffering from 2 cystic lesions so each was operated using both types of bone grafts.Surgical removal of the cystic lesion and grafting of the bony cavity was done using P30 and G170 bone graft materials powder and granules respectively, 10 cases each, then radiographic follow up was done using cone beam computed tomography ILUMA computed tomography scanner at the intervals of immediately post operative , 3 month and 6 months post operative to compare it to the CBCT taken preoperative to determine the change in volume of the bony cavity after removal of the cyst.