Final answer:
The primary mass of a tooth is dentin. Dentin is a bone-like tissue that surrounds the pulp cavity and is covered by enamel in the crown and cementum in the root.
Step-by-step explanation:
The primary mass of a tooth is dentin.
Within a tooth, dentin is the bone-like tissue that surrounds the pulp cavity, which contains nerves and blood vessels. It is covered by enamel in the crown of the tooth and by cementum in the root of the tooth.
Enamel is the hardest substance in the body, while cementum is a harder bone-like layer that anchors the tooth in the jaw bone.