[Orthodontic anchorage]. 
Orthodontic treatments apply forces on teeth to move them.  Since there is no fixed anatomic anchorage, every orthodontic action will cause a counter-action of equal force.  This is usually unwanted and strong bone anchorage is used to prevent this counter-action.  These anchorages provide the fixed point required for orthodontic effectiveness.  We describe some devices, their implantation site, placement, and removal.  Our experience is essentially based on the Lomas® and Orthocorrect® devices manufactured by Mondeal® (Germany) and on screwed anchorage devices manufactured by Stryker® (USA).  These screwed anchorage systems allow for previously impossible treatments, especially for orthodontics applied to adults and for preprosthetic orthodontics.  But these screws can induce apical migration of teeth; so it may be necessary to provide several anchorage sites.  Complications are rare and usually present as root perforation.