The VDP Jumping Bite Appliance according to Prof. Dr. Franz Günter Sander (also known as Sander II appliance) is an appliance for the orthodontic treatment of skeletal class II cases.
The VDP consists of two separate removable active plates for the maxilla and mandible. It consists of two corresponding elements – the maxillary expansion screw with integrated memory spring and the mandibular memory expansion screw with place holder and mounting plate for the inclined plane. The spring deflection is 0.8 mm each, at a spring force of 500 g. A maximum expansion of 5 mm can be achieved.
The forward movement of the mandible is created by the interaction of the protrusion bars and the inclined plane. When the mouth is closed, the maxillary bars slide over the inclined plane incorporated in the mandibular plate. Through this force transmission the lower jaw is moved forward.