For several years, dentists have recommended using fluoride toothpaste, because fluoride is said to strengthen enamel... but this is only true for laboratory enamel and not for natural tooth enamel.

Enamel is composed of 96% minerals organized into hydroxyapatite crystals. These crystals transform into fluoroapatite crystals in the presence of fluoride.

Fluoroapatite crystals are known to be more resistant than hydroxyapatite crystals, which is why fluoride is mistakenly considered an enamel strengthener.

Unfortunately, fluoroapatite crystals are smaller than hydroxyapatite crystals.

Thus, in the laboratory: adding fluoride to enamel transforms the enamel crystals into smaller crystals, causing the enamel to contract.

However, in the mouth, dental enamel cannot contract because it is attached to the dentin!

Since the tooth cannot shrink, the smaller crystals are more spaced out.

The contraction of the crystals by fluoride increases the space between them.

The spaces between the crystals are larger and therefore more fragile.