Current status of skeletal anchorage dental applications in orthodontics, part I.

Orthodontic tooth movement involves application of forces and moments on the dentition. Every force applied on a tooth or group of teeth will generate reactive forces on adjacent structures. Some reactive forces will produce secondary effects that must be controlled. Historically, these reactive forces were dissipated by different strategies. One strategy uses a group of teeth as anchorage in order to move a smaller group of teeth or a single tooth, which can be done within the same dental arch or between upper and lower dental arches. A second strategy would dissipate these unwanted reactive forces against structures external to the dental arches. These include the use of appliances that anchor teeth against the palatal mucosa (Nance button), against the lip pressure (lip-bumper), and against craniofacial structures (headgear).