What attaches to the cementum?

The periodontal ligament is the correct answer because it serves as the connective tissue structure that attaches the cementum of the tooth root to the surrounding alveolar bone. This ligament plays a critical role in supporting the tooth in its socket, allowing for some degree of movement while also providing stability. The periodontal ligament is composed of collagen fibers that connect the cementum to the bone, facilitating the transmission of forces during activities like chewing.

In contrast, the other options do not attach directly to the cementum. Teeth are the ultimate structure being supported by the cementum and periodontal ligament, but they do not attach to it in the same way. The alveolus refers to the bone socket that houses the tooth but does not directly connect to the cementum—it's the periodontal ligament that links these two. Gingival tissues can surround the tooth and influence its health but do not involve a direct attachment to cementum. Understanding these relationships is vital in small animal dentistry, particularly for procedures involving tooth extrusions, periodontal disease management, and overall dental health.