Fluoride and their role in dental caries prevention
FLUORIDE ANDTHEIR ROLE INDENTAL CARIES PREVENTION
Fluoride• Compound form of fluorine. – A trace element, halogen. – Very reactive gas. – Not found in free elemental form in nature.• Major source is from water – artesian wells.• Found in soils rich in fluorspar, cryolite, and other minerals.
Fluoride• Also found in plants, food, and human – calcified structures (teeth and skeleton).• Nutrient beneficial to dental health.
Dietary sources - drinking water• Waterborne fluorides are the most important source of flouride for humans.• Modern diets as a source of flouride. – Use of fluoridated water in preparation of processed foods and beverages.• For temperate climates – Optimal fluoride level: 1 ppm of fluoride.
Dietary sources - drinking water• For infants and young children – Intake of 2 – 4 glasses of water: 0.5 – 1 mg of fluoride.• For older children, adolescents and adults – Intake of 6 – 8 glasses of water: 1.5 – 2 mg of fluoride.• Ingestion of fluoride greater than optimal levels in drinking water (2 ppm) cause fluorosis.
Dietary sources - foods• Fluoride in foods by adults – Nonfluoridated communities: 1 mg/day. – Fluoridated communities: 2 – 3 mg/day.• Not known to be a significant factor in fluorosis (mottled enamel).• Small amounts: fruits, vegetables, cereals.• Rich amounts: seafoods and tea leaves.
Dietary sources - foods Table 1. Fluoride Concentration in Fresh Foods and Beverages Food Range of F in ppm Beer 0.15 – 0.86 Cereals 0.18 – 2.8 Citrus fruits 0.07 – 0.17 Coca Cola 0.07 Coffee 0.2 – 1.6 Instant (powder) 1.7 Fish without bone or skin 1.0 Fish meal 80.0 – 250.0 Milk 0.04 – 0.55 Noncitrus fruits 0.03 – 0.84 Sardines 8.0 – 40.0 Shrimp meat 0.4 Shrimp shell 18.0 – 48.0 Tea 0.1 – 2.0 Instant (solution) 0.2 Leaves 75 – 110 Vegetables and tubers 0.02 – 0.9 Wine 0.0 – 6.3
Metabolism - absorption• Major site of absorption: stomach.• Studies with animals suggest intestinal absorption also occurs.• Soluble fluoride in drinking water is completely absorbed, whereas 50 – 80% of the fluoride in foods is absorbed.
Metabolism - Distribution• Teeth and skeleton have the highest concentrations of fluoride. – Due to the affinity of fluoride to calcium. – Cementum, bone, dentin, and enamel.• Fluoride content of teeth increases rapidly during early mineralization periods and continues to increase with age, but at a slower rate.
Metabolism - Distribution• Found in both extracellular and intracellular fluids of soft tissues but at very low concentrations.• Found in saliva, 0.01 ppm. – Play a part in maintenance of fluoride concentrations in the outer layer of tooth enamel.
Metabolism - Excretion• Principal route of excretion is urine (90 – 95%).• Remaining 5 – 10% in the feces.• Outstanding characteristic of fluoride excretion is its speed. – Reabsorption of fluoride from urine is less efficient. Effective mechanisms for maintaining low concentrations of fluoride in the soft tissues and plasma.
Metabolism - Excretion Directly related to the degree of active bone growth. Fluoride excretion is lower when a child is growing rapidly and is actively depositing bone material than in adults with a mature bone structure and fully mineralized teeth.• About half of the ingested fluoride is excreted in the urine each day.
Metabolism - storage• Deposited in calcified structures.• Skeletons of older persons contain more fluoride than those of younger ones. – Amount of fluoride in bone gradually increases with age – greatest during active growth years.
Metabolism - storage• Factors that attract fluoride to bones: 1. Presence of an active growth area at the ends of long bones. 2. Small size of the bone crystals. 3. Close contact between bones and the blood supply
Metabolism - storage• Deposited in the enamel through diffusion. – Carious enamel may take up 10 times more fluoride than adjacent healthy enamel to inhibit expansion of carious lesion.• Dentin may contain even more fluoride. – Chemically similar to bone – Highest concentration found adjacent to pulp: close to blood supply.
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