Osteoclast and osteoblast activities during early orthodontic tooth movement and acceleration of tooth movement through the targeting of preosteoclasts with exogenous recombinant mouse M-CSF

Osteoclasts and osteoblasts play critical roles in remodelling alveolar bone during orthodontic tooth movement (OTM). The objectives of this study were (i) To characterize the spatial/temporal pattern of osteoblast and osteoclast differentiation in the periodontal ligament (PDL) during OTM, and (ii) To determine if OTM acceleration could occur with PDL administration of an osteoclastic differentiation factor, Macrophage-Colony Stimulating Factor (M-CSF). Rat/mouse OTM models were used to characterize the expression of osteoblast and osteoclast differentiation markers. Expression of markers involved in recruiting osteoclast precursors and markers found on preosteoclasts, but not monocytes, were found in the PDL during early stages of OTM. We found up-regulated expression of genes downstream of M-CSF and an increase in OTM rate after M-CSF administration. Taken together, our results showed that improved knowledge of the molecular basis of cellular activities is critical towards the development and testing of pharmacological strategies as a means to accelerate OTM.