How does fluoride protect our teeth?
The relationship between fluoride and tooth decay is complex and probably not yet fully understood. However, it is known that fluoride interferes with the process of tooth decay in at least four ways:
1. Children can consume fluoride through swallowed toothpaste, fluoridated water or natural food stuffs like tea. Under 7 years of age this fluoride alters the structure of the developing teeth in a beneficial way - it makes the tooth resistant to tooth decay. This was originally thought to be the most important mechanism of fluoride; however, with advances in knowledge this is now understood to be the least important mechanism.
2. Low levels of fluoride in the mouth gradually improve the strength of the tooth enamel and its ability to resist acid attack. This means that early patches of decay can be stopped by fluoride and damaged enamel will 'heal'. This explains the dramatic improvement in dental health since the introduction of fluoride into toothpaste in the mid-1970s.
3. The third way in which fluoride works is by reducing the ability of the plaque bacteria to produce acid. This is a major factor in the prevention of tooth decay.
4. In children who grow up in areas where the drinking water is fluoridated the grooves on the chewing surface of the teeth (fissures) tend to be shallower so the plaque doesn't stick in them as much. It seems that consuming enough fluoride while the teeth are developing (up to 7 years) can affect the tooth shape - which makes them easier to maintain. This is thought to be a less important effect of fluoride.