This document discusses the twin block appliance, which uses occlusal inclined planes to induce mandibular displacement and correct malocclusions. It describes how twin blocks modify the occlusal plane to guide favorable occlusal forces, and can be used with intermaxillary traction or orthopedic traction in more severe cases. The document provides details on appliance design, clinical management, and outcomes such as rapid correction of arch relationships and facial changes. It also outlines guidelines for case selection and treatment with twin blocks.