In patients with severe maxillary constriction in early permanent dentition or those who have moderate maxillary constriction in late adolescence, the Haas is the suture-expanding appliance of choice. Acrylic supports the screw and adds extra stability. The acrylic closely contacts the palatal mucosa because Haas believed that more bodily movement and less tipping occurred with the presence of the palatal coverage. Forces are generated not only against the teeth, but also against the soft and hard palatal tissues. Caution: I hygiene is not carefully monitored, acrylic can cause serious inflammation. Note: Pre-formed bands may be selected and sent with the prescription or bands may be custom fit. Because this appliance uses four bands for retention, seating may present challenges.

Recommended:
• Leave separators in place until the delivery appointment.
• When the path of insertion is a problem, gentle pressure will often allow it to seat over time.
• Cement bands with a glass ionomer cement.