Cellular response to orthodontic force.

Orthodontic force systems, by way of stress/strain, are transduced to a biologic signal that affects a multifaceted bone remodeling response. Tooth movement involves not only a periodontal ligament response (alveolus translocation), but also bursts of resorption associated with truncated remodeling events in the path of the advancing tooth. Osteoclasts are recruited primarily from the macrophage/monocyte series, whereas osteoblasts are produced by local periodontal ligament cell proliferation and differentiation. Based on nuclear size, periodontal cells are a multicompartmental population. The relatively large nuclei (D fraction) are the immediate precursors of osteoblasts, and the cells with small nuclei (A fraction are apparently the undifferentiated, germinal compartment.