Dental Assistant Practice Exam

What substance makes up the bulk of the tooth?

1. Dentin

2. Enamel

3. Dental pulp

4. Cemento-Enamel Junction

The correct answer is: Dentin

Dentin is indeed the substance that makes up the bulk of the tooth. It forms the main structure beneath the enamel and surrounds the dental pulp. Dentin is a hard tissue that is primarily composed of hydroxyapatite, a mineral form of calcium phosphate, along with collagen and other organic materials. This composition gives dentin its strength and resilience, allowing it to support the tooth and withstand the forces of chewing. The enamel, while essential for protecting the tooth, is the outermost layer and much thinner compared to dentin. It does not contribute to the bulk of the tooth but rather serves to protect the underlying dentin and pulp from decay and physical damage. The dental pulp is the innermost part of the tooth containing nerves and blood vessels, but it is also not substantial in terms of volume compared to the surrounding dentin. The cemento-enamel junction is the area where the enamel and cementum meet, marking an important anatomical boundary but not contributing significantly to the bulk of the tooth itself. Overall, dentin plays a crucial role in the structure of the tooth, making up the majority of its mass.