Pharmacological Factors

Various studies have evaluated the use of injecting cell signaling molecules and hormones to alter and accelerate the biological mechanism of OTM. With the injection of any substance, consideration needs to be given to the potential systemic side effects that might occur if the substrate is not maintained locally. Injection of parathyroid hormone (PTH), a mediator of bone turnover and osteoclast differentiation in OTM, has been shown in animals to increase the rate of OTM up to 1.6 times,46 due to increased osteoclasts, bone resorption, and apposition on the tension side of tooth movement.47 Submucosal injections of Prostaglandin E1 (PGE1) have been found to increase OTM in humans by a rate of 1.6 to 2 times.48 Systemic PGE1 administration in rats resulted in a higher number of osteoclasts and more bone resorption.49,50 Prostaglandin E2 in rats also showed an increase in OTM.51 Macrophage colony stimulating factor, a signaling molecule in osteoclast maturation, was shown in mice to increase the recruitment of pre-osteoclasts and the rate of differentiation into mature osteoclasts. One local injection followed by force application for 6 days accelerated OTM by 14%.52 This method of accelerating OTM is still in the experimental stages.