Clinicians continue to need anchorage that displays
a high resistance to displacement. According to
Newton's Third Law, there is a reaction for 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.
The design of the screw heads also made
it difficult to connect coil springs and other elastomers
to these ordinary bone screws. The development of
small diameter titanium microimplants with specially
designed heads that accept ligatures, coil springs
and elastomers have helped to solve the main objections
to previous implants and screws.
A typical surgical microscrew (left) and the newly
designed Absoanchor£— microimplant with
nickel titanium coil springs attached (right)
