ENDOGENOUS FLUORIDATION FOR PREVENTING DENTAL CARIES.

  

Prof. d-r R.Kabaktchieva

Purpose of fluoride prevention

Purpose of fluoride prevention is to build resistant tooth structure for better oral health.

Fluoride prevention is aimed at:     - Prevention of dental caries;     - Slowing the progression of dental caries.

Forms of endogenous fluoride prevantion

Endogenous fluoride prevention is carried out by using various ways of supplying fluoride:

- Drinking water fluoridation, - Use of natural fluoride       mineral water - Tablets containing fluoride - Milk fluoridation,

- Salt fluoridattion and others.

Community water fluoridation(also referred to as fluoridation )

Fluoridation, is defined as the upward adjustment of the natural fluoride level in

a community's water supply to a level optimal for dental health.

It is a population-based method of primary prevention that uses piped water systems to deliver low doses of fluoride over frequent intervals.

Fluoridation is one of the top ten public health achievements of the twentieth century.

Fluoridation contributed to a dramatic

decline in dental caries from the 1950s to the 1980s, and continues to

effectively reduce and prevent tooth decay today when multiple sources of fluoride, such as fluoride toothpaste, are readily available.

Continued monitoring of fluoride exposure from all sources, especially from sources such as fluoride-containing dentifrices, is important to achieve the appropriate balance between maximum caries-preventive benefit and minimal risk of fluorosis.

Fluoridation has been shown to be an effective intervention and sound public policy.

The American Dental Association (ADA) officially defines water fluoridation as the adjustment of the natural fluoride concentration of fluoride-deficient water supplies to the recommended level for optimal dental health.

The optimal fluoridation level varies by geographical location according to the temperature and is a value that ranges from 0.7 ppm F to 1.2 ppm F.

Parts per million (ppm) and milligrams/liter (mg/l) are essentially equivalent, and the terms are used interchangeably.

One part per million is the same concentration as 1 mg/l.

Some documents refer to concentrations used in water fluoridation as parts per million; others use milligrams per liter.

Fluoride is the thirteenth most abundant element on Earth.

This naturally occurring substance is found in water, soil, plants, and, even in air.

Certain foods, such as tea and fish, contain significant amounts of fluoride.

The World Health Organization (WHO) identify fluoride as a nutrient important for health.

Fluoridation can be thought as a form of nutritional supplementation in which fluoride is added to the drinking water.

Fluoridation is an ideal public health intervention because it :

(1) benefits people of all ages; (2) is socially equitable and does not exclude any

group; (3) imparts continuous protection with no

compliance or conscious effort required by consumers, other than drinking optimally fluoridated water;

(4) works without requiring individuals to access care

(5) does not require the costly services of health professionals;

(8) is remarkably cost effective.

Mechanisms of Action of Fluoride

(1) systemically, by being ingested and incorporated into the enamel structure during tooth development;

(2) topically, by promoting remineralization and inhibiting demineralization of tooth surfaces after eruption;

(3) topically, by inhibiting glycolysis in microorganisms, thereby hindering the ability of bacteria to metabolize carbohydrates and produce acid.

Fluoride works in 3 ways to reduce and prevent tooth decay

The greatest effect on reducing and preventing decay is topical;

however, both systemic and topical mechanisms are important.

Systemic fluoride is ingested, or taken into the body during consumption of foods or beverages.

Systemic fluoride can be incorporated directly into the hydroxyapatite crystalline structure of the developing tooth,

the smaller fluoride ions replacing hydroxyl ions in the crystalline structure of the tooth and producing a

less-soluble apatite crystal.

Today it is accepted that the systemic effect on caries prevention is the lesser effect;

however, there is current evidence that systemic exposure to fluoride during tooth formation reduces tooth decay.

Topical fluoride concentrates in the plaque and saliva, thereby enabling it to come into frequent contact with the surfaces of the teeth.

Its effects are posteruptive and can benefit people of all ages .

The decay process involves both demineralization and remineralizaiton and can move in either direction.

Cycles of demineralization and remineralization continue throughout the lifetime of the tooth

Fluoride, especially that held in plaque, is an essential nutrient in the remineralization of teeth.

Cariogenic bacteria residing in dental plaque metabolize sugars and other carbohydrates, producing acid that begins to dissolve, or demineralize, the tooth's enamel crystal surface.

Calcium, phosphate, and carbonate are lost from the enamel and can be captured in the adjacent plaque.

The lowered pH caused by the acid also releases fluoride contained in the plaque.

Then the fluoride from the plaque and available saliva are taken up by the demineralized enamel along with calcium, phospate, and carbonate;

Тhis results in remineralization as the ions re-form into an improved enamel crystal structure that contains more fluoride and less carbonate, and is more resistant to acid

Fluoride also inhibits the process that bacteria use to metabolize carbohydrates, thus reducing bacterial acid production and reducing dissolution of tooth enamel.

Therefore, on a regular basis, water fluoridation replenishes small quantities of fluoride to the plaque and saliva, which contributes to good oral health.

Systemic fluorides also provide a topical effect because saliva contains some fluoride from ingestion, is continually available at the tooth surface, and becomes concentrated in dental plaque where it inhibits acid-producing cariogenic bacteria from demineralizing tooth enamel.

Fluoride concentration in the plaque is 50 to 100 times higher than in the whole

saliva.

In summary Fluoridation has been found to

reduce dental decay through three mechanisms:

(1) by systemic ingestion of fluoride, which is incorporated into the developing tooth structure and converts hydroxyapatite into fluorapatite, thus reducing the solubility of

tooth enamel in acid and making it more resistant to decay;

(2) by topical action of fluoride in the plaque and saliva, which enhances remineralization of tooth enamel that has been demineralized by acids produced by decay-causing bacteria,

(3) by topical interaction with bacteria in the plaque, which reduce the acid production by dental-plaque organisms.

Enamel Fluorosis Fluoridation has risks as well as benefits. Fluoride in water can cause a dental condition

known as enamel fluorosis or fluorosis.

The mild and very mild forms of fluorosis may be so minimally apparent that individuals may not even realize that their teeth are affected,

The moderate and severe forms of fluorosis result in stained and pitted teeth that are cosmetically objectionable.

Fluoridation involves finding the appropriate balance between

the benefits of caries prevention and improved oral health,

and the potential for cosmetic conditions associated with very mild and mild fluorosis.

Enamel fluorosis results from hypomineralization in enamel surfaces

of teeth that have been exposed to fluoride ingested during enamel formation.

Enamel fluorosis can present in a number of ways, from white striae to the most severe form that could be classified as a developmental defect of the enamel.

The degree of fluorosis depends on the total dose of fluoride from all sources, as well as on the timing and duration of fluoride exposure.

Enamel fluorosis occurs in children who consume fluoride when their teeth are developing;

Fluorosis cannot occur once enamel formation is complete and the teeth have erupted, regardless of intake; therefore, older children and adults are not at risk for enamel fluorosis.

Standard of 2.0 ppm F was set to protect children from moderate/severe enamel fluorosis.

Questionable, very mild, and mild stages of fluorosis often result from very young children swallowing too much fluoride-containing toothpaste or from inappropriate supplementation with prescription fluoride products such as

(1) physicians or dentists independently prescribing fluoride supplements;

(2) physicians or dentists prescribing fluoride supplements without checking the fluoride content of the child's water supply.

In either case, a child gets a "double" dose of fluoride on a daily basis.

Monitoring total fluoride intake is complicated, considering the availability of multiple sources of fluoride.

Also, fluoride from tablets/drops is ingested and absorbed at one time of day,

as opposed to fluoride in water in which the ingestion and absorption of low-dose fluoride is distributed throughout the day.

These factors have been considered in the establishment of fluoride dosage schedules, which were adjusted downward in the 1990s, particularly for children in the first 6 months of life.

The Dietary Fluoride Supplement Schedule approved by the American Dental Association, the American Academy of Pediatrics, and the American Academy of Pediatric Dentistry should be followed when fluoride supplements are prescribed

  Fluoride Ion Level in Drinking Water (ppm)a

Age <0.3 ppm F 0.3-0.6 ppm F >0.6 ppm F

Birth-6 months None None None

6 months-3 years 0.25 mg/dayb None None

3-6 years 0.50 mg/day 0.25 mg/day None

6-16 years 1.0 mg/day 0.50 mg/day None

a a-1.0 part per million (ppm) = 1 milligram/liter (mg/l)

b b-2.2 mg sodium fluoride contains 1 mg fluoride ion.

SSource: Meskin, 1995105; American Academy of Pediatrics Committee on Nutrition, 1995106; and American Academy of Pediatric Dentistry, 1995107.

Dietary Fluoride Supplement Schedule, 1994

Recommendations to reduce the risk for enamel fluorosis.

All persons should know whether the fluoride concentration in their primary source of drinking water is:

- below optimal (less than 0.7 ppm F), - optimal (0.7-1.2 ppm F), - above optimal (greater than 1.2 ppm F).

This knowledge is the basis for all individual and professional decisions regarding use of other fluoride modalities

(e.g., fluoride toothpaste, mouthrinses, or supplements).

The risk of developing very mild fluorosis versus the benefit of decreased dental caries and attendant treatment costs should be communicated to patients who express concern.

Severe fluorosis does not occur from fluoridated water alone, and most frequently occurs when there is too much naturally occurring fluoride in water.

Optimal Fluoride Levels Тhe higher the average temperature in a

community, the lower the recommended water fluoride level. For every geographic location in the United States, a specific optimal fluoride concentration is recommended for the drinking supply, with optimal levels ranging from 0.7 to 1.2 ppm F

In addition, optimal fluoride concentrations were recommended at a time before there were other regular sources of fluoride exposure, such as discretionary fluoride toothpaste, mouthrinses, or dietary supplements.

Other Fluoride Vehicles

Salt fluoridation results in small amounts of fluoride being released from plasma throughout the day.

To achieve dental-caries reductions at levels comparable to water fluoridation, the level of fluoride supplementation of refined salt should be at least 200 mg F/kg as sodium fluoride or potassium fluoride.

Salt fluoridation requires centralized salt production, as well as monitoring.

Countries using salt fluoridation include Switzerland, France, Costa Rica, Jamaica, Germany, Mexico, Colombia, Ecuador, Venezuela, and Uraguay

Milk fluoridation The addition of 5 mg of fluoride to 1 liter of

milk, has been introduced as a vehicle of school-based fluoride

delivery in some countries (Bulgaria, Chile, China, the Russian Federation, and the United Kingdom).

Additional studies are required to adequately assess milk fluoridation as a viable caries-prevention strategy.

According to the WHO report, "The distribution of fluoridated milk can be more complicated than that of fluoride supplements (tablets or drops).“

Fluoride mouthrinses School-based weekly fluoride rinse programs, use

0.2% sodium fluoride in preventing coronal caries in school children who are at risk for dental caries.

The National Preventive Dentistry Demonstration Project examined preventive efforts from 1976-1981 in ten cities in the United States and reported

fluoride mouthrinse programs had little effect in reducing caries, especially among children from fluoridated communities.

END