American Board of Orthodontics (ABO) Practice Exam 2025 - Free Orthodontics Practice Questions and Study Guide

The vertical chin cup is known for its effectiveness in altering the shape of the mandible in hyperdivergent patients. This device applies a downward and backward force on the mandible, which can help in reducing the vertical growth of the mandible and improving the positioning of the chin. In hyperdivergent patients, where there is an increased vertical growth tendency and a prominent chin, the vertical chin cup serves to reposition the mandible and modify the facial profile, leading to a more balanced aesthetic.

The other devices listed do not specifically target the alteration of mandibular shape in the same way. For instance, headgear typically focuses on correcting the position of the maxilla and influences the maxillary relationship rather than directly impacting the mandible's shape. A palatal expander primarily widens the upper arch and addresses crossbites but does not affect the mandibular form. Functional appliances are also used to modify jaw positioning and can impact growth but are not as directly effective in shaping the mandible specifically for hyperdivergent profiles as the vertical chin cup.