An anterior occlusal interference can lead to an underdeveloped premaxilla -- and retroclined maxillary anteriors that are locked lingually in cross bite to the lower anteriors. Left untreated, this pseudo Class III can become a permanent skeletal defect over time. The Han Appliance is an excellent tool for correcting said defect. It ties the posterior aspect of the maxilla and the entire mandibular arch together, creating sufficient anchorage for the use of sagittally-placed expansion screws in developing the premaxillary segment labially. Turning the screws, develops the premaxilla and tips the anteriors labially. Once the anterior segment is developed sufficiently to create a positive overjet, the appliance can typically be replaced with a simple Hawley Retainer. Note: A carefully taken construction bite is essential for the proper fit and function of this appliance. The construction bite must be taken in the most retruded arc of mandibular closure possible, making sure that the patient does not posture forward. This is important because these patients will want to posture their lower jaw forward to avoid the incisal interference that is created in an end-to-end bite.

CONSTRUCTION BITE:
A carefully taken construction bite to the desired vertical and A/P (anterior/posterior) relationship is required for the proper fit and function of this appliance.  For the HAN appliance, the construction bite is registered in the most retruded arc of mandibular closure possible.  This negates the patient posturing their lower jaw forward out of habit (during construction bite registration) to avoid incisal interference in the end-to-end bite.  Adequate vertical opening is also required when taking the construction bite. This provides the necessary clearance for anterior crossbite correction.