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Asociación Mexicana de Ortopedia Maxilar A.C. |
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ORTOPEDIA MAXILAR |
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DR. MED. HANS-JOACHIM MULLER |
Activador de Andresen
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Asociación Mexicana de Ortopedia Maxilar A.C. |
|
ORTOPEDIA MAXILAR |
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DR. MED. HANS-JOACHIM MULLER |
When Andresen a Norwegian Orthodontist- Introduced the ACTIVATOR
some 60 years ago it seemed to be like a revolution in in the method
of fretting malocclusions. Until then the common appliances had been
fixed to the teeth in order to apply their forces via wires soldered
to bands. All this was very stable and left the patient out of
consideration concerning compliance. Andresen however had confidence
in his functional activator.Functional means that the patient himself
had to apply the forces of muscles in order to let the activator
become active.Active in a way to change bite relationship means that
by applying muscle force bone structure can be altered.
That was new! Now of course we all know that the main factor for
moving teeth are muscles in action but still the discussion about how
bone structure is changing under the influence of functional
appliances has not come to and end yet. The degree of changes in the
bone structure is dependent on a few factors which of course we as
experienced orthodontists take into consideration whenever we start
correcting a malocclusion.
Secondly we must find out about the compliance of our patient. We
cannot expect a removable appliance to work when it most of the time
is being removed from the mouth. Then there is the type of
malocclusion which is to be treated. We must put ourselves into a
position from which we can evaluated the direction of growth of the
facial bone structure. Not only lateral x-rays can help us but as
well photographs of the patient and of his family can give us advice
of where the journey of growth may go and how it can be influenced by
our work. Now back to Andresen and his ACTIVATOR:
To correct a class ll malocclusion we need to construct it in the
proper way always having the above in mind. After having taken
impressions of the upper and lower jaws we let the patient bite
forward into a wax wall to produce the construction bite. The degree
of forward movement and opening of the lower jaw is dependent on the
degree of the class II malocclusion.
The upper and the lower casts are than set with the help of the
contraction bite into a fixture. Now the components as the labial
arches and the spurs can be bent and attached to the models and
finally the resin is been applied. After curing the activator is
being finished and polished always having in mind where to reduce
resin and whether to leave a bite plane or to erase it when necessary
because of vertical growth tendency.
When expansion of the upper jaw is needed an expansion screw can be
build in but there should be enough resin in the lower part to be
reduced while expansion goes on in the upper. Parents and their
children}n then are being instructed how to put the activator in
place and about its general use.
Normally they are instructed to wear the activator at night and at
least 2 to 3 hours during daytime in order to achieve the goal. That
means a class II malocclusion of one premolar,1 PB, can be corrected
in a little bit more than a years time if circumstances are well
arranged. The activator however is not an instrument for bite
correction of class II malocclusion only.
Patients with temporo-mandibular joint problems can be treated with
it as well, because with the help of the construction bite the
processes articularis of the lower joint is moved out of the fossa in
order to let the cartilage structure of the discus recover.
Very often the so called second phenomena of sudden pain relief is
being achieved at the moment when the activator is being insert. Even
after accidental fracture «of theprocessus articularis the
activator can be of some help because it's positioning the lower jaw
into the correct position to the upper. The deviated midline is being
corrected and the fracture can heal because the broken fragment is
uprightening itself by the tension of muscular bandage without being
compressed. The Activator leads to a stabilized function.
One of the big questions was whether such quite simple appliance can
achieve stable results and whether these results can be proved. In
order to get an answer we made a research on class II cases being
treated with an activator and compared them with those not being
treated. We were measuring the angle ANB which seemed to us a good
indicator for changes in the relationship of the lower and the upper
jaw. We could prove that relatively to the direction of growth the
angle ANB could be reduced under the influence of the activator _when
subscribed at the right period of growth and when accepted by the
patient.
These factors like construction of the appliance, state of growth,
direction of growth and necessity of cooperation determine the
success of all functional appliances which have been developed after
the origin-the Andresen activator had been accepted by the
orthodontists.
There are many variations and only a few of them can be mentioned
here. First of all the group of the ìmonoblocksî,
appliances which are made out of on piece having different wires to
guide the teeth into place. (bionator etc.). These are being followed
by the skeletal functional appliances (U-Bugel,Frankel,
Federaktivator, Hansa-Gerat).
And finally the VDP (Karwetzky) and the double spur appliance, where
an upper and a lower plate are separate and only being guided by
spurs into a saggital correct position. Treatment is achieved by
function and this makes all these appliances very modern. Andresen
must have known this or not?.
