The Haas Suture-Expanding Appliance utilizes acrylic to support the screw and add stability. Haas believed that more bodily movement and less tipping occurred when palatal coverage was provided. Thus, the acrylic closely contacts the palatal mucosa and forces are generated not only against the teeth but also against the soft and hard palatal tissues. In this design, the Haas Expansion Appliance is modified by adding a force component to distal-drive the molars. Sliding lingual bars are attached to the molars via horizontal sheaths and compressed nickel titanium coil spring is packed along the bar. Note: Bands may be custom fit or pre-formed bands may be selected and sent with the prescription. Because this appliance employs four bands for retention, seating may present challenges. To overcome these challenges, we recommend the following:
• Leave separators in place until the delivery appointment.
• Apply gentle pressure when path of insertion poses a problem. This will often ensure seating over time.
• Cement the bands with a glass ionomer cement.