, 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.
Relative safety• Low and moderate intake results to: – Skeletal fluorosis – Mottled enamel – Osteosclerosis (hardening of bone) – Exostoses (bony projections) – Calcification of ligaments• High intake may result to death.
Mottled Exostoses enamelSkeletalfluorosis osteosclerosi s
Mottled enamel (Endemic Dental Fluoride)• White or brown spotty staining of tooth enamel. – May be due to food, debris, or plaque.• Sometimes will have horizontal striations.• Enamel is deficient in: 1. Number of cells producing enamel causes pitting (hypoplasia). 2. Hypocalcification causes chalkiness.
Mottled enamel (Endemic Dental Fluoride)• Occurs only in teeth that are being formed. – When exposed to high concentrations of fluoride, opaque spots will develop on the enamel.• High intake of fluoride results to mottled enamel. – Protection of fluoride is decreased by severe fluorosis.
Fluoride and dental caries• Communal Water Fluoridation – Most effective, practical, feasible and economical public health measure for preventing caries. – Greatest resistance to caries and greatest amount of fluoride deposition are acquired by starting the intake as early as possible and using it continuously.
Fluoride and dental caries – Other factors to the decline of caries: 1. Greater dental health awareness. 2. Expansion in dental resources. 3. Application of preventive dentistry.
Fluoride and dental caries• School Water Fluoridation – Fluoridated with levels of three to seven times the optimum for communal water fluoridation resulting to reduction in caries incidence.
Fluoride and dental caries• Fluoride Tablets – Ingestion daily beginning at 5 – 9 years: permanent teeth can still be significantly protected from caries.
Fluoride and dental caries – Lozenge is much preferred than tablets or drops. Dissolves slowly, produces both topical and systemic effects. – Advantage: specific and precise dosage – Disadvantage: assurance of continuous daily ingestion and cost is greater.
Fluoride and dental caries• Prenatal Fluoride Supplement – Fluorides supplements ar