Kinetics of cell proliferation and migration associated with orthodontically-induced osteogenesis

Cell kinetics of rat molar periodontal ligament (PDL) during orthodontically-induced osteogenesis revealed: 1) primary growth fraction of 59%, 2) proliferating cells from throughout the PDL migrate toward the bone surface, 3) preosteoblasts, capable of forming osteoblasts without synthesizing DNA, are present in the PDL, 4) osteoblasts are derived from local PDL cells, and 5) cell death is a characteristic feature of the osteogenic response.