American Board of Orthodontics (ABO) Practice Exam 2026 - Free Orthodontics Practice Questions and Study Guide

Clear aligners can be less effective for anterior extrusion due to the nature of their design and how they apply force to the teeth. Extrusion involves moving a tooth vertically out of the bone, which requires a significant amount of force directed specifically at that tooth. Aligners primarily use a system of pressure points that are exerted on the crown of the teeth, and they don't provide the same kind of controlled, vertical force that might be applied with other orthodontic appliances, such as braces or temporary anchorage devices. This makes achieving the desired amount of anterior extrusion challenging with clear aligners.

In contrast, anterior intrusion, which is the movement of the anterior teeth vertically into the bone, is something aligners can accomplish more effectively by applying consistent pressure. Similarly, the bilateral inclination of posterior teeth can be managed with the design of aligners, which can be customized to allow for tipping movements. Finally, leveling of occlusion can be achieved through clear aligners as they can help in a variety of tooth movements necessary for occlusal adjustment. Thus, while clear aligners have several advantages, anterior extrusion remains a limitation in their efficacy.