Pre-extraction preparation
STERILE
Before extraction, periapical radiographs were taken to assess the level of the alveolar bone. Informed consent was taken from all participants. 20 ml of venous blood was collected from each patient using two sterile vacutainer red-cap tubes (10 ml each). The venous blood was spun in the centrifugation machine (PRF DUO® Centrifuge, France) at 1300 rpm for 8 min (relative centrifugal force: 208 g) in accordance to Fujioka-Kobayashi et al. protocol. [