Expansion screws for Class III double plates (RDP)

Letting the muscles play, in the mouth
The RDP device according to Prof. Dr. Franz Günter Sander (also known as Sander III appliance) is an appliance for the orthodontic treatment of skeletal class III cases (mandibular protrusion). It is suitable for use in children in the early transitional dentition.

Two removable plates effect a retraction of the mandible by means of corresponding inter-maxillary elements. The corresponding elements are two bars in the maxilla and two activated expansion screws in the mandible. Adjustable and gradual retraction of the mandible is achieved by successive activation of the two expansion screws.

Through the bars in the maxillary plate the bite force is transmitted to the upper jaw, where it results in a force impulse directed to the anterior. This promotes the growth of the maxilla. At the same time the force affects an intrusive force in the molars, therefore preventing an open bite. Depending on the indication (e.g. narrow jaw, lateral cross bite), an additional Memory expansion screw can be integrated in the maxilla or mandible plate.