Fluorine is an element from the halogen group, it is electronegative and commonly found in nature combines with other elements given it's high reactivity.

It is found in the calcium fluoride form, or as part of fluorpatite or cryolite. It is also found in waters at very diverse concentration levels, there are waters low in fluorine, other with optimum levels and some with excessive amounts of fluorine.

The optimum concentration level of fluorine in drinking water should be of 1mg/lt, expressed en ppm (parts per million). Waters with levels below 0.7 ppm offer poor fluorine amounts to the tooth. Water with levels between 0.7 -1.2 ppm, offer enough fluorine and water with levels over 2 -3 ppm are water that may cause an excessive accumulation of fluorine leading to intrinsic stains on the teeth, called DENTAL FLOUROSIS.

Fluorine is also found in some foods, it is abundant in tea and in decreasing order less present in: tomatoes, beans, lentils, cherries, potatoes. In animals, it can be found in mackerel, sardines, veal liver, fresh fish.

Fluorine is absorbed by the stomach and the lower intestine, transfers to the blood and deposits on teeth, bones and secondly on soft tissues, once metabolized it is eliminated through the renal tracks and in less quantity in transpiration and bowel.

FLOURINE ACTION

In order to stop the cavity process to start, the enamels resistance level must be increased, we have already mentioned that it starts to dissolve at a Ph level below 5.5.

The dental enamel is the hardest tissue on the human body, and it is formed, among others components, by hydroxyapatite, composed of calcium ions, phosphorus and hydroxyls.

An acid attack on hydroxyapatite causes it to demineralize, loosing it's crystal structure and if no other acid attack occurs then there is a certain intrinsic capacity for remineralization. But under new recurring attacks this capability is lost, therefore irreversible, and the destructive process begins.

Fluorine, replaces hydroxyls ions (OH) from hydroxyapatite and in turn this becomes fluorpatite, which is more stable and also dissolves less under acid attacks. Fluorpatite dissolves at a Ph under 4.5, one less than hydroxyapatite.

Fluorine also acts on bacterial plaque, partially inhibiting the bacterial's plaque production of acids, by causing a toxic action on them not allowing the bacteria to settle on the acquired film.

FLOURINE APPLICATION AS A CAVITY PREVENTION SYSTEM

We have already mentioned that the principal goal of fluorine is to increase the enamel's resistance and to obtain the change from hydroxyapatite to fluorpatite.

Fluorine reaches our dental pieces by two different routes:

• Systemic

• Topic

The systemic route implies the intake of a certain amount of fluorine, that through plasmatic means reaches the tooth, transforming the enamel's hydroxyapatite into fluorpatite. This happens during the teeth's formative years, in the pre-eruptive and pot-eruptive phases.

This is the reason why people should have a regular intake of fluorine, keeping in mind the different rations receives as to not exceed the limit that may lead to a fluorosis.

iIf the drinkable water taken has a fluorine concentration of less than 0.7 ppm, this indicates that the water is poor on fluorine and therefore must be accompanied by a fluorine supplement so that the dental formation can be based on fluorpatite.

When waters with levels over 0.7 ppm are drank, there is no need for a supplement since the teeth will receive enough fluorine to produce fluorpatite.

Waters with concentration levels over 1.2 ppm are not recommended and totally unacceptable those with levels exceeding 2 ppm, during the teeth's formative years since fluorosis is induced.