American Board of Orthodontics (ABO) Practice Exam 2026 – All-in-One Resource to Master Your Orthodontics Certification!

The correct response, which indicates frontal resorption, is linked to the physiological process that occurs during orthodontic tooth movement. Frontal resorption takes place on the periodontal ligament side, specifically in the area where the force applied is directed. It involves the gradual removal of bone ahead of the moving tooth, allowing it to shift into its new position.

Understanding the mechanics of tooth movement is essential. As forces are applied through the orthodontic appliances, the periodontal ligament responds, and osteoclasts are activated to resorb bone ahead of the tooth. This process is crucial for facilitating the directional movement of the tooth along the alveolar bone.

In contrast, the other types of resorption do not describe the specific process that occurs in this context. External resorption typically refers to the loss of tooth structure from the outer surfaces, which is not specific to the periodontal ligament response. Crown resorption usually pertains to the destruction of enamel or dentin in the coronal portion of the tooth, which is also not relevant here. Root resorption describes the loss of dental root structure, which may occur for various reasons, including prolonged orthodontic force, but it does not denote the specific manner in which resorption occurs after undermining resorption.

Thus, recognizing