Expanders are orthodontic appliances designed to widen the maxillary & mandibular arches and correct transverse discrepancies. These appliances apply controlled forces to gradually separate the palatal sutures, creating additional space for proper tooth alignment. Expanders can be fabricated in fixed or removable designs and may include jackscrews, acrylic components, or 3D metal printed bands/framework. They are frequently used in growing patients to improve arch form and bite relationships.