Factors Affecting the Failure of TADs and Efforts to Improve the Biomechanical Stability of TADs

The development and commercialization of orthodontic temporary anchorage devices (TADs), which are mainly titanium miniscrew implants and miniplates, has allowed orthodontists to intrude and protract posterior teeth and to perform total arch distalization of the maxillary and mandibular teeth. This chapter focuses on miniscrew implants that are easy to use clinically. It reviews the factors that affect the stability of miniscrew implants, such as morphological characteristics, and discusses some of the methods being attempted to improve the stability of miniscrew implants and related TADs. Miniscrews with a physically rough surface may cause surface damage during insertion without any improvement in biomechanical stability as indicated by bone-implant contact and removal torque, which had values similar to those of untreated miniscrews. Hollow screw types and spike-like auxiliary skeletal anchorage devices have been developed to facilitate the use of TADs in regions much closer to the roots.