Fluoride that has greater cariostatic activity than sodium monofluorophosphate (MFP) is which compound?

• A. Sodium fluoride (NaF)
• B. Amorphous calcium phosphate
• C. Stannous fluoride (SnF2)
• D. Fluoride varnish

Answer: (A)

Fluoride’s cariostatic power hinges on how readily fluoride ions are released and available at the tooth surface to promote remineralization and slow demineralization. Sodium fluoride dissolves quickly in saliva, freely releasing fluoride ions that rapidly raise fluoride levels in plaque fluid and enable formation of protective fluorapatite and calcium fluoride reservoirs. Monofluorophosphate fluoride, by contrast, must be hydrolyzed to release fluoride, so its release is slower and the immediate fluoride availability is lower, yielding less cariostatic effect under the same exposure. Amorphous calcium phosphate doesn’t provide fluoride, it mainly supplies calcium and phosphate for remineralization. Fluoride varnish delivers fluoride via a coating that’s applied topically; while highly effective, the question compares inherent activity of the fluoride form, and the readily available fluoride from sodium fluoride typically shows greater cariostatic effect than MFP.