Fluorides in Dentistry
Definition
Fluorides are compounds containing the fluoride ion (F⁻) that help in the prevention of dental caries by increasing enamel resistance and inhibiting demineralization.
Mechanism of Action
Enhances remineralization
Fluoride converts hydroxyapatite → fluorapatite, which is more acid-resistant.
Inhibits demineralization
Reduces enamel solubility during acid attack.
Antibacterial effect
Inhibits bacterial enzymes (e.g., enolase) → ↓ acid production by Streptococcus mutans.
Post-eruptive effect (most important)
Works topically on erupted teeth.
Sources of Fluoride
1. Systemic Fluorides
Act before tooth eruption.
Fluoridated water
Optimal level: 0.7–1.2 ppm
Dietary supplements
Tablets, drops
Fluoridated milk and salt
Advantages
Pre-eruptive enamel strengthening
Community-wide benefit
Disadvantages
Risk of dental fluorosis
Difficult dosage control
2. Topical Fluorides
Act after tooth eruption (most effective).
A. Professionally Applied
Type
Concentration
Sodium fluoride (NaF)
2%
Acidulated phosphate fluoride (APF)
1.23%
Stannous fluoride (SnF₂)
8%
Fluoride varnish
5% NaF (22,600 ppm)
Indications
High caries risk
Children
Xerostomia
Orthodontic patients
B. Self-Applied
Toothpastes (1000–1500 ppm; 5000 ppm for high risk)
Mouth rinses (0.05% daily / 0.2% weekly NaF)
Fluoridated gels
Methods of Application
Tray technique
Paint-on method
Varnish application
Mouth rinsing
