Biological Orthodontics: Methods to Accelerate or Decelerate Orthodontic Tooth Movement

From the outset, orthodontists wished they could increase the velocity of tooth movement, for the benefit of their patients, and for their own sake. Expanding knowledge about cell physiology enabled researchers to explore methods for the acceleration of tooth movement. The cells in and around teeth are being used as keys to accelerated orthodontics. Some of the main cell types, whose biological responses are used as yardsticks for estimation of the degree of their involvement in the acceleration process, are osteoclasts, osteoblasts, osteocytes, and cells of the nervous, immune, and endocrine systems. This chapter reviews the ability of biochemical and physical agents to evoke cellular responses that lead to accelerated orthodontic tooth movement. The list of participating molecules includes cytokines, prostaglandins, RANKL and macrophage colony stimulating factor, parathyroid hormone, vitamin D3, relaxin, corticosteroids, osteocalcin, and vascular endothelial growth factor. The physical entities used to stimulate the target dental and paradental cells are low level lasers, direct electric currents, pulsed electromagnetic fields, vibrations, light, and surgical interventions. This review evaluates the advantages and shortcomings of each of the methods that have been proposed for reaching the goal of shortening the duration of orthodontic treatment. Additionally, this chapter discusses a few methods for slowing down the rate of tooth movement, pertaining to anchorage and relapse situations