What is critical for remineralization as it both acts as a vehicle to transport fluoride ions into the demineralized enamel and acts as a reservoir for calcium & phosphate ions?

• A. Saliva
• B. Blood plasma
• C. Lymph
• D. Gingival crevicular fluid

Answer: (A)

Saliva is the fluid that both delivers fluoride to the demineralized enamel and supplies the calcium and phosphate minerals needed for remineralization. Fluoride present in saliva diffuses into the subsurface lesions and becomes incorporated into the crystal lattice, forming fluorapatite or fluoridated hydroxyapatite, which is less soluble in acid and enhances remineralization. At the same time, saliva is rich in calcium and phosphate ions, providing the minerals that redeposit onto the demineralized crystal surfaces. Its buffering helps restore neutral pH after acid attacks, creating optimal conditions for mineral deposition. Other fluids don’t deliver fluoride to the enamel surface and don’t supply minerals in the same readily available form, so saliva uniquely provides both essential roles for remineralization.