Caries Process and Prevention Strategies: Intervention
Fluoride in the Body and its Role in Enamel Development

Fluoride is incorporated into the inorganic part of enamel, the inorganic phase, by substitution for either hydroxyl ions or carbonate ions within the apatite lattice. In order for that to occur, in an already maturated or developed apatite crystal, there has to be some demineralization. So you have to have a demineralization and then the reverse, a reprecipitation will favor the incorporation of fluoride into the apatite crystal because fluoride is the most electro-negative of all elements and therefore bonds very firmly with calcium. The best time, the best time, for having this occur is actually right after tooth erupts. When a tooth erupts, it’s not yet fully maturated, in other words, it’s not yet fully calcified. It takes two more years for each tooth to calcify after it erupts into the oral cavity. That is the prime time for caries to occur because the tooth is very susceptible. It’s also the best time to apply fluoride, whether that be fluoride in a dentifrice or professional fluorides, and that’s true for both the primary dentition, the baby teeth, as well as the permanent dentition. So prematuration, post-eruptive, but prematuration is the best time to apply fluorides. That covers the period from two years of age up to about fifteen years of age, for different teeth in the oral cavity.