Bone harvesting using bone scrapers will be performed during GBR procedures with both techniques (d-PTFE and Ti-mesh). Bone harvesting using bone scrapers is for harvesting particulate autogeneous bone graft material. The investigators will use a mixture of 50:50 DBBM and autogenous bone graft material for all vertical augmentation procedures in the study. Particulate autogenous bone graft will be harvested from the retromolar region of the mandible. This area is just next to the area of GBR procedures (posterior mandible) and will be visible after flap elevation for vertical augmentation. Therefore, the investigators do not need any additional steps except harvesting autogenous bone graft. Intraoral harvesting by bone scrapers from the retromolar region is a simple and safe method for collecting cortical bone chips.