The importance of fluoride in cavity prevention is well-supported by extensive scientific literature and is recognized by the World Health Organization and the Italian Ministry of Health.

Fluoride helps prevent cavities by slowing down enamel breakdown and accelerating the remineralization process.

More specifically, its preventive function works through the following mechanisms:

• Formation of fluorapatite: This is a modified form of hydroxyapatite, which naturally makes up tooth enamel. In fluorapatite, fluoride replaces hydrogen ions, creating a material that is more resistant to demineralization and attacks from acids and bacterial plaque. Fluorapatite forms during tooth development (amelogenesis), highlighting the importance of fluoride in children's diet and oral hygiene.
• Enamel remineralization: On already erupted teeth, fluoride binds to the outer layer of the enamel along with calcium and phosphate ions, forming fluorapatite, which helps restore areas eroded by plaque acids.
• Antibacterial action: Fluoride can prevent the adhesion of *Streptococcus mutans*, the primary bacteria responsible for cavities, to tooth surfaces.

Aside from food sources, one of the main sources of fluoride is drinking water. However, fluoride levels vary significantly depending on the water source. In Italy, most drinking water contains insufficient fluoride to provide effective cavity protection. The website "Acqueitaliane" provides information on fluoride concentrations (expressed in mg/L) in commonly available bottled mineral waters in Italy.

This highlights the importance of supplementing fluoride intake through both topical and systemic means:

• **Topical application**: This involves direct fluoride application to tooth surfaces in high concentrations. Examples include fluoride toothpaste and mouthwashes, as well as professional fluoride gel treatments applied periodically by a dentist.
• **Systemic intake**: Fluoride can also be administered orally in the form of drops or tablets.

The current scientific approach is to first assess the patient's risk of developing cavities (cariogenic risk). This involves evaluating oral hygiene habits, the ability to use toothpaste correctly, and the fluoride concentration in the local drinking water.

In high-risk children aged 6 months to 6 years, systemic fluoride supplementation through tablets or drops may be recommended. Alternatively, a dentist can apply fluoride varnish directly to high-risk tooth surfaces.

For individuals who are not at high risk of cavities, using fluoride toothpaste with a concentration of 1000 ppm twice a day is usually sufficient.

Fluoride supplementation during pregnancy, intended to reduce cavity risk in newborns, is not recommended due to a lack of clear scientific evidence supporting its effectiveness.