Clinicians continue lo need anchorage thai displays a high resistance to displacement. According to Newton's Third Law, there is a reaction (or every action, control of which is difficult to achieve intraorally. Earlier, orthodontists used extraoral traction to reinforce intraoral anchorage. Nevertheless, patients seldom used headgears 24 hours a day - 7 days a week, hence this source of anchorage was often compromised.
The ideal intraoral anchorage would not displace, and would require a source devoid of periodontal membrane, which tends to respond to tension and pressure allowing movement through bone. Recently, prosthetic osseointegrated implants have been used as intraoral orthodontic anchorage, but their bulky size, cost and invasiveness have limited their orthodontic application.
We have used ordinary bone screws first to provide intraoral anchorage, but the screw heads failed to protect the gingiva from the impingement by the ligatures or attached elastomers. These became a source of constant gingival irritation and inflammation, which limited the usefulness of this type of implants... (from authors)