Damien Storey - Theory 1

Andresen, with the use of his appliance, aimed at correcting malocclusion by changing the functional pattern of the chewing apparatus.
Explain his hypothesis (claims) that a Class II Div. I can be gradually changed to a Class I relationship by an appliance that makes the patient bite with the lower jaw in a normal relationship to the upper jaw.

The original Andresen activator was a tooth-borne, loosely fitting passive appliance consisting of a block of
plastic covering the palate and the teeth of both arches, designed to advance the mandible several millimeters
for Class II correction and open the bite 3 to 4 mm. The original design had facets incorporated into the body of the appliance to direct erupting posterior teeth mesially or distally, so, despite the simple design, dental relationships in all 3 planes of space could be changed.5
In designing an inert appliance that fitted loosely in the mouth and, because of its mobility, transferred
muscular stimuli to the teeth, jaws, and supporting structures, Andresen had taken a decisive step in
orthodontic treatment. Although he had effectively redesigned Robin’s monobloc to correct Class II Division
1 malocclusions, he declared that he had no knowledge of Robin’s work at the time.
Andresen’s novel device was not initially well received. First, removable appliances were not much accepted at that time. Second, the profession was under the influence of Martin Schwarz, whose active plate was then a common form of removable—not functional— appliance. Finally, Andresen advocated extractions, although not necessarily in connection with activator treatment. And, in contrast to Angle’s concept of ideal occlusion that was then prevalent, Andresen advocated a more realistic “individual and functional gnathological optimum.” Thus he was subjected to the same type of ridicule that Tweed endured years later.2
In 1925, Andresen, then director of the orthodontic department at the University of Oslo, began developing
for the government a simple method of treating Norwegian children. He modified his retainer into an
orthodontic appliance, using a wax bite to register the mandible in an advanced position.