Split-plate appliances apply force primarily through a point of contact on the crown rather than along the entire root surface. This force system creates a moment that causes the tooth to tip rather than move bodily. Since the force is not distributed evenly across the root, the center of resistance remains fixed, resulting in tipping movement instead of translation or bodily movement. These appliances cannot generate the complex force-moment systems needed for controlled bodily movement or rotation. Therefore, split-plate appliances produce only tipping movement of teeth.

Reference: Proffit, Contemporary Orthodontics, 6th Edition.