In cavity formation, which tissue is demineralized?

• A. Dentin
• B. Enamel
• C. Cementum
• D. Pulp

Answer: (B)

Cavities start when acid produced by plaque dissolves the mineral content of tooth tissues. Enamel is the tissue that undergoes demineralization first because it is the outer, highly mineralized layer made mainly of hydroxyapatite and lacks an organic remodeling matrix. When acid attacks, minerals diffuse out of enamel, creating subsurface lesions that can progress if the demineralization continues. Dentin, cementum, and pulp aren’t the initial targets: dentin can demineralize as the lesion breaches enamel, cementum is less susceptible in early caries, and pulp is soft tissue inside the tooth that isn’t mineralized. So the tissue most directly demineralized in the early stage of cavity formation is enamel.