National Board Dental Hygiene Examination (NBDHE) Dental Hygienist Practice Test

What provides the hardest layer of protection for a tooth?

1. Dentin

2. Pulp

3. Enamel

4. Cementum

The correct answer is: Enamel

Enamel is the hardest layer of protection for a tooth, composed primarily of hydroxyapatite, a crystalline calcium phosphate. This dense mineral structure gives enamel its remarkable strength and durability, essential for withstanding the forces of chewing and resisting wear over time. Additionally, enamel acts as a barrier against cavities and potential infections by protecting the underlying dentin and pulp from bacterial invasion and external trauma. The other layers, such as dentin, which is less hard than enamel and provides some structural support, do not offer the same level of protection. Pulp, the innermost part of the tooth, contains nerves and blood vessels, making it critical for tooth vitality but not for physical protection. Cementum, while it covers the root of the tooth and helps anchor it within the gums, is also softer than enamel and does not serve the primary protective role that enamel does. Thus, enamel is uniquely suited for its purpose as the hardest protective layer of the tooth.