Extra-alveolar mini-implants in infrazygomatic crest: literature review

Abstract

Mini-implants (MI) can be considered the greatest revolution in modern orthodontics, they are temporary devices that depend on the mechanical retention of their metallic structure in the cortical bone and do not always osseointegrate, they can be installed between the roots of the teeth and also in the extra-alveolar region. MI installed in the extra-alveolar region have several advantages in relation to inter-radicular ones and have been shown to be effective in three-dimensional tooth movements: anteroposterior, transverse and vertical. The ideal location for insertion of MI in the maxilla is at the infrazygomatic ridge (IZC), over the maxillary first molar at 14/16 mm above the occlusal plane and at an angle of 55/70°. Screws should be loaded immediately after installation, the amount of initial force should be between 150 and 200 g, and gradually increased to 350 g. The MI inserted in the IZC is its size, because they are longer (> 10 mm) and with a larger diameter, they have a larger retention area, allowing several movements at the same time, optimizing the orthodontic treatment time. The patient's collaboration in these cases is only with cleaning the area where the MI is inserted, it is worth mentioning that if it is installed on the free gum, the chances of failure increase significantly. Current orthodontics saw a revolution with the use of mini-implants, due to their low cost, easy installation and possibilities for easier and faster treatments, especially in challenging and complex cases. Orthodontists are still afraid to use these devices, generally because they don't master the technique.