Haas Expander

The design of this expander allows it to apply lateral force to both the teeth and the walls of the palate. This is achieved by using an acrylic borne screw embedded in an acrylic plate. A split in the acrylic along the patient’s midline widens as the screw is turned. Heavy wires embedded in the plate are soldered to bands and run along the  lingual surfaces of the patient’s posterior teeth. Some clinicians feel that the acrylic plate aids in achieving more true lateral expansion rather than the outward tipping of the posterior teeth sometimes associated with expanders that only push against the teeth.