Fluoride

Fluoride (F^–) is the inorganic anion of Fluorine. In dentistry it is used to aid the prevention of dental caries.

The anti-cariogenic effects of fluoride first became understood in the 1940s.

Fluoride products can be applied via topical or systemic route.

Mechanism of Action

The formula for fluoride mineralization of teeth involves the exchange of ions between the fluoride in the saliva and the hydroxyapatite crystals that make up the tooth enamel. This process is known as remineralization and occurs in the following way:

Ca₁₀(PO₄)₆(OH)₂ + 2F → Ca₁₀(PO₄)₆F₂ + 2OH

In this formula, Ca10(PO4)6(OH)2 represents the hydroxyapatite crystals in the enamel, and 2F represents the fluoride ions in the saliva. The reaction results in the formation of fluorapatite Ca₁₀(PO₄)₆F₂, which is a more stable and more resistant form of enamel than hydroxyapatite. The addition of 2OH represents the replacement of a hydroxyl ion with a fluoride ion, which results in the strengthening and remineralization of the enamel.

It’s important to note that this process occurs continuously in the mouth, with the enamel constantly undergoing a cycle of demineralization and remineralization. The use of fluoride can help to increase the rate of remineralization and reduce the rate of demineralization, leading to stronger and healthier teeth.

Topical routes
-Toothpaste
-Rinses
-Gels
-Varnishes

Systemic routes
-Water fluoridation(community fluoridation)
-Sodium Fluoride tablets
-Mineral Waters
-Salt fluoridation

Fluorosis
An irreversible defect originating during the formative phase of enamel.
After 8 years old, fluorosis cannot manifest as enamel mineralisation is complete.

Prevention: Limiting F^– supply during enamel mineralisation
Treatment is focused on improving aesthetics.

Dean’s Index
– only the two most affected teeth are included

0	Normal	No enamel changes
1	Questionable	Isolated white spots
2	Very mild	White opaque spots covering less than 25% of the tooth surface
3	Mild	White opaque spots covering up to 50% of the tooth surface
4	Moderate	Brownish spots covering more than 50% of the tooth surface
5	Severe	Brownish spots, hypoplastic changes, erosions, abrasions