Question

Which of the following fluoride preparation combines with hydroxyapatite crystals to form calcium fluoride, which further diffuses to form fluorapatite crystals?

• A. Stannous fluoride
• B. Sodium fluoride
• C. Amine fluoride
• D. APF

Hint:

Sodium fluoride is effective in promoting the formation of fluorapatite, which strengthens tooth enamel and improves its resistance to decay.

Answer 1

The Correct Option is B

The question asks which fluoride preparation combines with hydroxyapatite to form calcium fluoride, and then further diffuses to form fluorapatite crystals.

Let us examine the options provided and identify the correct answer:

1. Stannous fluoride: While stannous fluoride is an effective fluoride source for dental care, its primary role is to provide fluoride ions directly that inhibit demineralization and enhance remineralization. It doesn't specifically mention forming calcium fluoride and then fluorapatite.
2. Sodium fluoride: When sodium fluoride is applied to the tooth surface, it reacts with calcium in hydroxyapatite crystals to form calcium fluoride (CaF₂). The calcium fluoride acts as a reservoir for fluoride ions, which can later convert into fluorapatite (Ca₁₀(PO₄)₆F₂) under certain conditions.
3. Amine fluoride: Amine fluoride is known for enhancing the uptake of fluoride in the enamel but is not specifically noted for the sequence of forming calcium fluoride followed by fluorapatite.
4. APF (Acidulated Phosphate Fluoride): APF also increases fluoride ion uptake but is associated more with immediate fluoride formation rather than the sequential formation involving calcium fluoride and fluorapatite as emphasized in the question.

From the explanations above, the correct answer is Sodium fluoride because it forms calcium fluoride upon reaction with hydroxyapatite, which ultimately provides conditions for the creation of fluorapatite.

Conclusion: Among the given options, Sodium fluoride is the fluoride preparation that undergoes the process mentioned in the question.