American Board of Orthodontics (ABO) Practice Exam

New attachments formed during orthodontic intrusion primarily consist of periodontal ligament (PDL) ligament cells, gingival connective tissue, and alveolar bone.

During the process of orthodontic intrusion, where teeth are moved against resistance, the biological responses involve alterations in the supporting structures surrounding the teeth. These structures include the PDL, which plays a crucial role in the tooth's mobility and stability. The PDL cells undergo remodeling as the tooth is intruded, leading to an increase in bone remodeling and new attachment formation.

Gingival connective tissue also contributes to the anchorage of the tooth during this process, as it engages in healing and adaptation to the new tooth position. The alveolar bone is essential because it provides the structural support needed for the tooth. As teeth are intruded, both the periodontal ligament and alveolar bone adapt to maintain their connection, resulting in new attachment at the site.

In contrast, options focusing solely on alveolar bone or a limited combination of structures fail to encompass the full range of tissue types involved in this process, missing the importance of the periodontal ligament and gingival connective tissue. Other combinations, like gingival tissue and enamel, do not reflect the biological realities of the new attachments formed, as enamel does not participate in