The split plate appliance was introduced by Martin Schwarz as a removable orthodontic device designed to correct transverse discrepancies such as crossbites by allowing separate movement of the two halves of the appliance. This design enables selective expansion of the maxillary arch by activating each half independently, which aids in precise correction of unilateral or bilateral dental arch constrictions. The appliance is particularly beneficial in early mixed dentition for transverse arch development. Its unique split design differentiates it from other fixed or removable appliances introduced by contemporaries.

Reference: Graber’s Orthodontics, 6th Edition.