What is the calcified substance that protects the dentin and covers the entire anatomic crown of the tooth?

The calcified substance that protects the dentin and covers the entire anatomic crown of the tooth is enamel. Enamel is the hardest and most outer layer of a tooth, composed mainly of hydroxyapatite, a crystalline structure of calcium phosphate. Its primary function is to provide a protective barrier for the underlying dentin and pulp, shielding them from physical and thermal trauma, as well as from acid attacks due to dietary acids and bacteria.

In contrast, the other options refer to different components of the tooth structure. Dentin is the connective tissue located underneath the enamel, providing support and containing microscopic tubules that can transmit sensations. Cementum covers the roots of the teeth and helps anchor them to the jawbone, serving a different role than enamel. Pulp is the innermost part of the tooth containing nerves and blood vessels, primarily responsible for nourishing the tooth and providing sensory functions. Each of these components plays a crucial role in oral health, but enamel is specifically responsible for covering and protecting the crown of the tooth from external harm.